JP2018047497A - Bi-BASED SOLDER ALLOY AND METHOD FOR PRODUCING THE SAME, AND ELECTRONIC COMPONENT AND ELECTRONIC COMPONENT-MOUNTED SUBSTRATE COMPRISING THE SOLDER ALLOY - Google Patents

Bi-BASED SOLDER ALLOY AND METHOD FOR PRODUCING THE SAME, AND ELECTRONIC COMPONENT AND ELECTRONIC COMPONENT-MOUNTED SUBSTRATE COMPRISING THE SOLDER ALLOY Download PDF

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JP2018047497A
JP2018047497A JP2016186196A JP2016186196A JP2018047497A JP 2018047497 A JP2018047497 A JP 2018047497A JP 2016186196 A JP2016186196 A JP 2016186196A JP 2016186196 A JP2016186196 A JP 2016186196A JP 2018047497 A JP2018047497 A JP 2018047497A
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solder alloy
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永田　浩章
Hiroaki Nagata
浩章 永田
雅人 高森
Masahito Takamori
雅人 高森
希 谷上
Nozomi Tanigami
希 谷上
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Sumitomo Metal Mining Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a Bi-based solder alloy that is substantially free of Pb, Zn, Al, Sb, has excellent wettability and joining reliability, and is also suitable for mounting a semiconductor element on a joining object member having one of Ni layer, Ni/Au layer, and Ni/Pd/Au layer on its surface.SOLUTION: A Bi-based solder alloy contains Ag and Sn, with the Bi content of 70 mass% or more. The Ag content is 7.5 mass% or more and 18 mass% or less, the Sn content is 7.5 mass% or more and 12 mass% or less, and the Sn content is 1/1 or less relative to the Ag content, and the Bi-based solder alloy contains a particle containing an intermetallic compound of Ag and Sn, with the balance being Bi, excluding inevitable elements in production.SELECTED DRAWING: None

Description

本発明は、Ｂｉ基はんだ合金及びその製造方法、並びに、そのはんだ合金を用いた電子部品及び電子部品実装基板に関し、さらに詳しくは、Ｐｂ、Ｚｎ、Ａｌ、Ｓｂを実質的に含まず、機械加工性、機械的強度および接合信頼性に優れ、特に、表面にＮｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかを有する接合対象部材への半導体素子の実装に適した、Ｂｉ基はんだ合金及びその製造方法、並びに、そのはんだ合金を用いた電子部品及び電子部品実装基板に関する。   The present invention relates to a Bi-based solder alloy, a manufacturing method thereof, an electronic component using the solder alloy, and an electronic component mounting substrate, and more particularly, substantially free of Pb, Zn, Al, and Sb, and machined. Bi base suitable for mounting of semiconductor elements on a member to be joined having a Ni layer, Ni / Au layer, or Ni / Pd / Au layer on the surface. The present invention relates to a solder alloy, a manufacturing method thereof, an electronic component using the solder alloy, and an electronic component mounting substrate.

電子部品実装基板を製造する際、まず、半導体チップなどの半導体素子をリードフレームなどの接合対象部材へ、第１のはんだ合金を介して接合（ダイボンディング）して電子部品を製造し、次に、プリント基板等の基板上に供給した、第１のはんだ合金とは別のはんだ合金であって第１のはんだ合金に比べて固相線温度が低い第２のはんだ合金を溶融（リフロー）して、電子部品をプリント基板等の基板へ実装することや、半導体素子を接合対象部材である基板へ、第１のはんだ合金を介して実装後、当該基板の他の部位に、第２のはんだ合金をリフローして、他の半導体素子や電子部品を実装することが一般に行われている。このように、電子部品実装基板を製造する際に使用するはんだは、その使用限界温度によって高温用（約２６０℃〜４００℃）と中低温用（約１４０℃〜２３０℃）に大別される。   When manufacturing an electronic component mounting substrate, first, a semiconductor element such as a semiconductor chip is bonded (die bonding) to a member to be bonded such as a lead frame via a first solder alloy, and then an electronic component is manufactured. The second solder alloy supplied on a substrate such as a printed circuit board is different from the first solder alloy and has a solidus temperature lower than that of the first solder alloy, and is melted (reflowed). Then, after mounting the electronic component on a substrate such as a printed circuit board, or mounting the semiconductor element on the substrate that is a member to be bonded via the first solder alloy, the second solder is applied to other portions of the substrate. It is common practice to reflow the alloy and mount other semiconductor elements and electronic components. As described above, the solder used when manufacturing the electronic component mounting board is roughly classified into a high temperature (about 260 ° C. to 400 ° C.) and a medium / low temperature (about 140 ° C. to 230 ° C.) depending on the use limit temperature. .

従来、電子部品の基板への実装には、中低温用はんだ合金として、Ｓｎ−３７質量％Ｐｂの共晶はんだ合金（融点１８３℃）が広く用いられ、実装時、２２０〜２３０℃でリフローが行われていた。一方、電子部品内部におけるリードフレームなどの接合対象部材への半導体チップなどの半導体素子の実装には、電子部品の基板への実装時のリフロー温度（２２０〜２３０℃）で再溶融して接続不良が発生するのを防ぐため、電子部品の基板への実装時のリフロー温度に比べて高い温度の固相線温度を有する高温用はんだ合金として、Ｐｂ−５質量％Ｓｎ（固相線温度３０５℃）、Ｐｂ−３質量％Ｓｎ（固相線温度３１５℃）などが用いられてきた。   Conventionally, a Sn-37 mass% Pb eutectic solder alloy (melting point 183 ° C.) is widely used as a low-temperature solder alloy for mounting electronic components on a substrate, and reflow is performed at 220 to 230 ° C. during mounting. It was done. On the other hand, when mounting a semiconductor element such as a semiconductor chip on a member to be joined such as a lead frame inside an electronic component, it is melted again at the reflow temperature (220 to 230 ° C.) when mounting the electronic component on the substrate, resulting in poor connection. In order to prevent generation of Pb-5 mass% Sn (solidus temperature 305 ° C.) as a high temperature solder alloy having a solidus temperature higher than the reflow temperature when mounting electronic components on a substrate. ), Pb-3 mass% Sn (solidus temperature 315 ° C.) and the like have been used.

しかし、鉛（Ｐｂ）入りはんだ合金を用いた製品は、廃棄処分後、製品からＰｂが流出して土壌に浸透し、農作物等に蓄積して人間に健康被害を及ぼす危険性が指摘され、さらに、酸性雨による廃棄処分された製品からのＰｂの流出の加速が指摘されていることから、近年、Ｐｂを含まない無鉛はんだ合金の開発が盛んに行われている。   However, products that use lead (Pb) -containing solder alloys have been pointed out that after disposal, Pb flows out of the product, penetrates into the soil, accumulates in crops, etc., and can cause health damage to humans. In recent years, lead-free solder alloys that do not contain Pb have been actively developed because it has been pointed out that the outflow of Pb from discarded products due to acid rain has been pointed out.

中低温用のＰｂ入りはんだ合金の代替品としては、Ｓｎ−Ａｇ−Ｃｕ等のＰｂを含まない無鉛はんだ合金が実用化されている。
しかしながら、Ｓｎ−Ａｇ−Ｃｕ等の無鉛はんだ合金の融点は、従来のＰｂ−Ｓｎ共晶はんだ合金より高く約２２０℃前後となるため、実装時のリフロー温度は２５０℃付近となる。このため、電子部品内部での接合に用いる無鉛はんだ合金には、リフロー温度２５０℃で１０秒間保持するサイクルを５回程度繰り返した後でも、電子部品内部の接合信頼性等に問題が生じない高温用の無鉛はんだ合金が必要とされている。 As an alternative to Pb-containing solder alloys for medium and low temperatures, lead-free solder alloys that do not contain Pb, such as Sn—Ag—Cu, have been put into practical use.
However, since the melting point of a lead-free solder alloy such as Sn—Ag—Cu is about 220 ° C. which is higher than that of a conventional Pb—Sn eutectic solder alloy, the reflow temperature during mounting is around 250 ° C. For this reason, the lead-free solder alloy used for joining inside the electronic component has a high temperature that does not cause a problem in the joining reliability and the like inside the electronic component even after the cycle of holding at a reflow temperature of 250 ° C. for 10 seconds is repeated about 5 times. There is a need for lead-free solder alloys.

すなわち、電子部品内部での接合に用いる高温用の無鉛はんだ合金には、熱放散性、応力緩和性、耐熱疲労特性、電気伝導性等の特性以外に、電子部品の基板への実装時のリフロー温度（２５０℃）での再溶融による接続不良を防ぐため、接合後２５５℃以上の固相線温度を有することが必要である。   In other words, high-temperature lead-free solder alloys used for joining inside electronic components include reflow when mounting electronic components on a substrate, in addition to properties such as heat dissipation, stress relaxation, thermal fatigue resistance, and electrical conductivity. In order to prevent poor connection due to remelting at a temperature (250 ° C.), it is necessary to have a solidus temperature of 255 ° C. or higher after joining.

また、電子部品内部での接合に用いる高温用の無鉛はんだ合金の液相線温度が４００℃以上の場合、ダイボンディング時の作業温度を４００℃以上に上げる必要があるが、このような高温処理を行うと、半導体素子の特性が変化したり、接合対象部材の表面酸化が促進したりする等の悪影響が生じる場合がある。したがって、液相線温度は、４００℃以下である必要があり、実際の生産工程を考慮すると、３５０℃以下であることが求められている。   In addition, when the liquidus temperature of a high-temperature lead-free solder alloy used for joining inside an electronic component is 400 ° C. or higher, it is necessary to increase the working temperature during die bonding to 400 ° C. or higher. In some cases, adverse effects such as changes in the characteristics of the semiconductor elements and acceleration of surface oxidation of the members to be joined may occur. Therefore, the liquidus temperature needs to be 400 ° C. or lower, and it is required to be 350 ° C. or lower in consideration of an actual production process.

２５５℃〜３５０℃の融点を持つ無鉛はんだ合金として、Ａｕ−Ｓｎはんだ合金や、Ｂｉ−Ａｇはんだ合金等が提案されている。Ａｕ−Ｓｎはんだ合金は、Ｓｎを２０質量％含有する組成で融点が２８０℃であり、実装時の再溶融の問題がなく実用化されているが、高価であるため、高付加価値品への適用に留まり、汎用品には用いられていないのが実情である。   As a lead-free solder alloy having a melting point of 255 ° C. to 350 ° C., an Au—Sn solder alloy, a Bi—Ag solder alloy, and the like have been proposed. The Au—Sn solder alloy has a composition containing 20% by mass of Sn and has a melting point of 280 ° C., and has been put to practical use without the problem of remelting at the time of mounting. The actual situation is that it is not applied to general-purpose products.

特許文献１には、ＢｉにＡｌを０.０３質量％以上０.７０質量％以下含有し、Ｚｎを０.２質量％以上１４.０質量％以下含有し、２６５℃以上の融点を有する、はんだ合金が提案されている。   Patent Document 1 contains Bi in an amount of 0.03 mass% to 0.70 mass%, Zn is contained in an amount of 0.2 mass% to 14.0 mass%, and has a melting point of 265 ° C. or higher. Solder alloys have been proposed.

また、特許文献２には、Ｂｉが９０質量％以上、Ｓｎが１〜５質量％、Ｓｂおよび／またはＡｇから選択された少なくとも１種の元素がそれぞれ０．５〜５質量％含有することにより、接合強度を高くした、はんだ合金が提案されている。   Patent Document 2 includes Bi of 90% by mass or more, Sn of 1 to 5% by mass, and at least one element selected from Sb and / or Ag each containing 0.5 to 5% by mass. A solder alloy having a high bonding strength has been proposed.

ＷＯ２０１１／１５８６６８号公報WO2011 / 158668 ＷＯ２０１２／００２１７３号公報WO2012 / 002173 Publication

はんだ合金が塗布されるリードフレームなどの、半導体素子との接合対象部材のアイランド部は、従来、素材そのままであるベアＣｕであったり、予め表面にＡｇめっきが施されていたりする場合が多かったが、近年、材料が小型化し、かつ、車載関係などのデバイスで高耐食性が求められるようになり、Ａｇめっきの代わりに耐食性に優れるＮｉめっきが施されることが多くなっている。Ｎｉは、基本的に、はんだ濡れ性に劣る場合が多いので、その表面に非常に薄いＡｕめっきやＰｄめっきを施す場合がある。
ところが、Ｎｉめっきが施された接合対象部材への半導体素子との接合用はんだ合金としてＢｉ基はんだ合金を用いた場合、Ｎｉと主成分のＢｉとが反応し、接合界面に脆弱なＢｉ３Ｎｉ合金層を形成する場合がある。このような脆弱なＢｉ３Ｎｉ合金層が形成されると接合信頼性が悪化する場合があり、特に、接合対象部材の表面がＮｉ層の場合、顕著に悪化する。特許文献１や特許文献２に記載のはんだ合金を用いた場合においても、接合面の状態により十分な接合信頼性を得られない場合が発生する。 Conventionally, the island part of a member to be joined to a semiconductor element such as a lead frame to which a solder alloy is applied has often been bare Cu, which is a raw material, or has been previously plated with Ag. However, in recent years, materials have become smaller and high corrosion resistance has been required for devices such as in-vehicle devices, and Ni plating having excellent corrosion resistance is often applied instead of Ag plating. Ni is basically inferior in solder wettability in many cases. Therefore, a very thin Au plating or Pd plating may be applied to the surface of Ni.
However, when a Bi-based solder alloy is used as a solder alloy for joining a semiconductor element to a member to be joined that has been subjected to Ni plating, Ni reacts with Bi as a main component, and Bi 3 Ni which is brittle at the joint interface An alloy layer may be formed. When such a fragile Bi 3 Ni alloy layer is formed, the bonding reliability may be deteriorated. In particular, when the surface of the member to be bonded is a Ni layer, the bonding reliability is significantly deteriorated. Even when the solder alloys described in Patent Document 1 and Patent Document 2 are used, there are cases where sufficient bonding reliability cannot be obtained due to the state of the bonding surface.

本発明の目的は、かかる従来技術の問題点に鑑み、Ｐｂ、Ｚｎ、Ａｌ、Ｓｂを実質的に含まず、接合性が改善され接合信頼性に優れ、特に、表面にＮｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかを有する接合対象部材に半導体素子を実装するのにも適した高温用Ｂｉ基はんだ合金及びその製造方法、並びに、そのはんだ合金を用いた電子部品及び電子部品実装基板を提供することにある。   In view of the problems of the prior art, the object of the present invention is substantially free of Pb, Zn, Al, and Sb, has improved bondability and excellent bonding reliability, and in particular, has a Ni layer, Ni / Au on the surface. Bi-base solder alloy suitable for mounting a semiconductor element on a member to be joined having any one of a layer and a Ni / Pd / Au layer, a manufacturing method thereof, and an electronic component and an electronic using the solder alloy It is to provide a component mounting board.

本発明者らは、上記課題を解決するため、鋭意研究を重ねた結果、従来のＢｉ−Ａｇはんだ合金において、さらに、所定量のＳｎを混合し合金化することにより、はんだ合金内に形成されるＡｇとＳｎとの金属間化合物を含む粒子がＢｉとＮｉの反応を抑制する効果があることを見出し、はんだ合金が塗布されるリードフレームのアイランド部に、Ｎｉめっき、Ｎｉ／Ａｕめっき、Ｎｉ／Ｐｄ／Ａｕめっきのいずれかが施されている場合でも、Ｂｉ基はんだ合金の接合後の接合強度が低下することもなく接合信頼性に優れた電子部品を製造しうることを見出し、本発明を完成させるに至った。また、本発明者らは、上記Ｂｉ−Ａｇ−Ｓｎはんだ合金に、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕから選ばれる１種以上の金属を所定量含有させることにより、濡れ性をさらに改善させ、より接合信頼性に優れた電子部品を製造し得ることを見出し、本発明を完成させるに至った。   In order to solve the above-mentioned problems, the present inventors have conducted extensive research. As a result, in a conventional Bi-Ag solder alloy, a predetermined amount of Sn is further mixed and alloyed to form a solder alloy. It is found that particles containing an intermetallic compound of Ag and Sn have an effect of suppressing the reaction between Bi and Ni, and Ni plating, Ni / Au plating, Ni is applied to the island portion of the lead frame to which the solder alloy is applied. The present invention has found that even when any one of Pd / Pd / Au plating is applied, an electronic component having excellent bonding reliability can be produced without reducing the bonding strength after bonding of the Bi-based solder alloy. It came to complete. Further, the present inventors further improve the wettability by adding a predetermined amount of one or more metals selected from Cu, Ni, Pd, and Au to the Bi-Ag-Sn solder alloy, The present inventors have found that an electronic component having higher bonding reliability can be manufactured, and have completed the present invention.

すなわち、本発明によるＢｉ基はんだ合金は、ＡｇとＳｎを含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７.５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、前記Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなることを特徴としている。   That is, the Bi-based solder alloy according to the present invention is a Bi-based solder alloy containing Ag and Sn, substantially free of Pb, Zn, Al, and Sb and having a Bi content of 70% by mass or more. The Ag content is 7.5 mass% or more and 18 mass% or less, the Sn content is 7.5 mass% or more and 12 mass% or less, and the Sn content is 1/1 relative to the Ag content. The Bi-based solder alloy includes particles containing an intermetallic compound of Ag and Sn, and the balance is made of Bi except for elements that are inevitably included in production.

また、本発明によるＢｉ基はんだ合金は、ＡｇとＳｎを含有し、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、前記Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を含有し、かつ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を総量で０．００１質量％以上３．０質量％以下の範囲で含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなることを特徴としている。   The Bi-based solder alloy according to the present invention contains Ag and Sn, and further contains one or more of Cu, Ni, Pd, and Au, and substantially contains Pb, Zn, Al, and Sb. A Bi-based solder alloy having a Bi content of 70% by mass or more, wherein the Ag content is 7.5% by mass or more and 18% by mass or less, and the Sn content is 7.5% by mass or more and 12% by mass. In addition, the Sn content is 1/1 or less than the Ag content, and the Bi-based solder alloy contains particles containing an intermetallic compound of Ag and Sn, and Cu. One or more of Ni, Pd, and Au are contained in a total amount in the range of 0.001% by mass to 3.0% by mass, and the balance is made of Bi except for elements that are inevitably included in production. It is characterized by.

また、本発明のＢｉ基はんだ合金においては、前記Ｂｉ基はんだ合金内に形成される前記ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、粒径８０μｍ未満の粒子が９７体積％以上存在することが好ましい。   In the Bi-based solder alloy of the present invention, the particle size is less than 80 μm with respect to a total volume of 100% by volume of the entire particle including the intermetallic compound of Ag and Sn formed in the Bi-based solder alloy. It is preferable that 97% by volume or more of the particles are present.

また、本発明のＢｉ基はんだ合金においては、表面にＮｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかが形成された接合対象部材との接合に用いることが好ましい。   In addition, the Bi-based solder alloy of the present invention is preferably used for joining with a member to be joined having a Ni layer, a Ni / Au layer, or a Ni / Pd / Au layer formed on the surface.

また、本発明によるＢｉ基はんだ合金の製造方法は、ＡｇとＳｎを含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上のはんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、残部が製造上、不可避的に含まれる元素を除きＢｉからなる、前記Ｂｉ基はんだ合金の溶湯を鋳型に流し込んだ後、２５５℃まで３℃／ｓｅｃ以上の冷却速度で冷却し固化させることで、ＡｇとＳｎとの金属間化合物を含む粒径８０μｍ未満の粒子を、該ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、９７体積％以上前記Ｂｉ基はんだ合金内に形成させることを特徴としている。   The method for producing a Bi-based solder alloy according to the present invention is a solder alloy containing Ag and Sn, substantially free of Pb, Zn, Al, and Sb and having a Bi content of 70% by mass or more. The Ag content is 7.5% by mass or more and 18% by mass or less, the Sn content is 7.5% by mass or more and 12% by mass or less, and the Sn content is 1 / M with respect to the Ag content. 1 or less, and the balance is made of Bi except for elements inevitably included in the production. After pouring a molten metal of the Bi-based solder alloy into the mold, the molten metal is cooled to 255 ° C. at a cooling rate of 3 ° C./sec or more. By solidifying, particles having a particle size of less than 80 μm containing an intermetallic compound of Ag and Sn are 97% by volume or more with respect to 100% by volume of the total volume of the particles containing the intermetallic compound of Ag and Sn. It is formed in the Bi-based solder alloy It is.

また、本発明によるＢｉ基はんだ合金の製造方法は、ＡｇとＳｎを含有し、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を総量で０．００１質量％以上３．０質量％以下の範囲で含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなる、前記Ｂｉ基はんだ合金の溶湯を鋳型に流し込んだ後、２５５℃まで３℃／ｓｅｃ以上の冷却速度で冷却し固化させることで、ＡｇとＳｎとの金属間化合物を含む粒径８０μｍ未満の粒子を、該ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、９７体積％以上前記Ｂｉ基はんだ合金内に形成させることを特徴としている。   The method for producing a Bi-based solder alloy according to the present invention contains Ag and Sn, and further contains at least one of Cu, Ni, Pd, and Au, and substantially contains Pb, Zn, Al, and Sb. A Bi-based solder alloy having a Bi content of 70% by mass or more, an Ag content of 7.5% by mass or more and 18% by mass or less, and a Sn content of 7.5% by mass or more. 12 mass% or less, Sn content is 1/1 or less with respect to Ag content, and one or more of Cu, Ni, Pd, and Au is 0.001 mass% or more in total After pouring a molten metal of the Bi-based solder alloy, which is contained in the range of 3.0% by mass or less and the balance is made of Bi except for elements inevitably contained in production, up to 255 ° C. up to 3 ° C./sec. By cooling and solidifying at the above cooling rate, intermetallication of Ag and Sn In the Bi-based solder alloy, particles having a particle size of less than 80 μm including the product are formed in the Bi-based solder alloy by 97% by volume or more with respect to 100% by volume of the total volume of the particles including the intermetallic compound of Ag and Sn It is said.

また、本発明による電子部品は、接合対象部材と、上記本発明のいずれかのＢｉ基はんだ合金と、前記Ｂｉ基はんだ合金を介して前記接合対象部材に実装された半導体素子を有してなることを特徴としている。   An electronic component according to the present invention includes a member to be bonded, a Bi-based solder alloy according to any one of the present invention, and a semiconductor element mounted on the member to be bonded via the Bi-based solder alloy. It is characterized by that.

また、本発明による電子部品実装基板は、上記本発明のいずれかのＢｉ基はんだ合金を用いて製造されたことを特徴としている。   An electronic component mounting board according to the present invention is manufactured using any of the Bi-based solder alloys of the present invention.

本発明のＢｉ基はんだ合金は、Ｐｂ、Ｚｎ、Ａｌ、Ｓｂを実質的に含有せず、Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む微細な粒子を含有するので、はんだ接合時の接合性が改善し接合不良の発生を抑えることができ、さらに接合信頼性を高くすることができるため、電子部品内部での接合対象部材への半導体素子の実装のためのダイボンディング等に好適に用いることができる。特に、Ｂｉ基はんだ合金が塗布されるリードフレームのアイランド部に、Ｎｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかが形成されている場合においても、Ｂｉ基はんだ合金の接合後の接合強度が低下することもなく良好な接合性を有する電子部品を形成することができる。これは、上記ＡｇとＳｎとの金属間化合物を含む微細な粒子が、Ｎｉの拡散を抑制し脆弱なＢｉ−Ｎｉ合金を形成しにくくすることによると考えられる。また、添加元素として上記Ａｇ、Ｓｎのほか、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕのいずれか一種以上の元素を含有させることにより、Ｂｉ基はんだ合金の濡れ性を向上させることができる。
また、本発明のＢｉ基はんだ合金の製造方法のように、Ｂｉ基はんだ合金の溶湯を鋳型に流し込んだ後、２５５℃まで３℃／ｓｅｃ以上の冷却速度で冷却し固化させれば、上記ＡｇとＳｎとの金属間化合物を含む粒子を、より容易に粒径８０μｍ未満の粒子に形成することができる。
さらに、本発明のＢｉ基はんだ合金を用いた電子部品や電子部品実装基板により、半導体チップなどの半導体素子の特性の変化や部材酸化が発生せず、機械的強度が高い電子部品実装基板を提供することができる。 The Bi-based solder alloy of the present invention does not substantially contain Pb, Zn, Al, Sb, and contains fine particles containing an intermetallic compound of Ag and Sn in the Bi-based solder alloy. This improves the bondability at the time, suppresses the occurrence of defective bonding, and further increases the bonding reliability, so that it can be used for die bonding for mounting semiconductor elements on members to be bonded inside electronic components. It can be used suitably. In particular, even when any of the Ni layer, Ni / Au layer, and Ni / Pd / Au layer is formed on the island portion of the lead frame to which the Bi-based solder alloy is applied, after the Bi-based solder alloy is joined Thus, it is possible to form an electronic component having good bondability without reducing the bonding strength. This is considered to be because the fine particles containing the intermetallic compound of Ag and Sn suppress Ni diffusion and make it difficult to form a brittle Bi—Ni alloy. In addition to the above Ag and Sn as additive elements, the wettability of the Bi-based solder alloy can be improved by adding at least one element of Cu, Ni, Pd, and Au.
Further, as in the method for producing a Bi-based solder alloy according to the present invention, the molten Ag of the Bi-based solder alloy is poured into a mold and then cooled to 255 ° C. at a cooling rate of 3 ° C./sec or more and solidified. Particles containing an intermetallic compound of Sn and Sn can be more easily formed into particles having a particle size of less than 80 μm.
Furthermore, the electronic component mounting board using the Bi-based solder alloy of the present invention provides an electronic component mounting board with high mechanical strength without causing a change in characteristics or member oxidation of a semiconductor element such as a semiconductor chip. can do.

本発明のＢｉ基はんだ合金を用いた半導体パッケージの一例を示す断面図である。It is sectional drawing which shows an example of the semiconductor package using the Bi group solder alloy of this invention.

以下、Ｂｉに所定量のＡｇとＳｎを含有させ、はんだ合金内にＡｇとＳｎとの金属間化合物を含む微細な粒子を形成させた、本発明のＢｉ基はんだ合金に関する技術について説明する。
本発明のＢｉ基はんだ合金は、ＡｇとＳｎを含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７.５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を形成し、残部が製造上、不可避的に含まれる元素を除きＢｉからなる。
また、本発明の他の実施形態のＢｉ基はんだ合金は、ＡｇとＳｎを含有し、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を含有し、実質的にＰｂ、Ｚｎ、Ａｌ、Ｓｂを含有せず、Ｂｉの含有率が７０質量％以上含有するＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を含有し、かつ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を総量で０．００１質量％以上３．０質量％以下の範囲で含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなる。
上述のように本発明のＢｉ基はんだ合金は、ＡｇとＳｎとの金属間化合物を含む粒子とそれ以外のＢｉを主成分とするＢｉ基はんだ合金の母相とから構成されることを特徴としている。 Hereinafter, a technique related to the Bi-based solder alloy of the present invention, in which Bi contains a predetermined amount of Ag and Sn, and fine particles including an intermetallic compound of Ag and Sn are formed in the solder alloy will be described.
The Bi-based solder alloy of the present invention is a Bi-based solder alloy containing Ag and Sn, substantially free of Pb, Zn, Al, and Sb and having a Bi content of 70% by mass or more. Is 7.5 mass% or more and 18 mass% or less, Sn content is 7.5 mass% or more and 12 mass% or less, and Sn content is 1/1 or less with respect to Ag content. In addition, particles containing an intermetallic compound of Ag and Sn are formed in a Bi-based solder alloy, and the balance is made of Bi except for elements that are inevitably included in production.
Further, the Bi-based solder alloy according to another embodiment of the present invention contains Ag and Sn, and further contains at least one of Cu, Ni, Pd, and Au, and substantially contains Pb, Zn, and Al. , A Bi-based solder alloy containing 70 mass% or more of Bi without containing Sb, Ag content is 7.5 mass% or more and 18 mass% or less, and Sn content is 7.5 mass%. Contains particles that are not less than 12% by mass and not more than 12% by mass and that the Sn content is 1/1 or less than the Ag content and that the Bi-based solder alloy contains an intermetallic compound of Ag and Sn. And one or more of Cu, Ni, Pd, and Au in a total amount of 0.001% by mass to 3.0% by mass, with the remainder being unavoidably included in production. Except for Bi.
As described above, the Bi-based solder alloy of the present invention is characterized by being composed of particles containing an intermetallic compound of Ag and Sn and a parent phase of a Bi-based solder alloy containing Bi as a main component. Yes.

本発明のＢｉ基はんだ合金の母相は、高温はんだ合金として適度な融点を有している。このため、半導体素子を接合対象部材へ実装して電子部品を製造した以降の電子部品を基板に実装する際や、半導体素子を接合対象部材である基板へ実装後、当該基板の他の部位に、他の半導体素子や電子部品を実装する際などのリフローにおいて再溶融することなく、電子部品内部でのＢｉ基はんだ接合部の状態を、初期接合時の状態のまま保つことができ、接合信頼性等に優れる。
以下、本発明のＢｉ基はんだ合金に用いられる各元素、形成される金属間化合物、Ｂｉ基はんだ合金の製造方法、得られたＢｉ基はんだ合金を用いた電子部品及び電子部品実装基板について詳細に説明する。 The parent phase of the Bi-based solder alloy of the present invention has an appropriate melting point as a high-temperature solder alloy. For this reason, when mounting an electronic component on a substrate after mounting a semiconductor element on a member to be bonded and manufacturing the electronic component, or after mounting the semiconductor element on a substrate that is a member to be bonded, Without remelting during reflow when mounting other semiconductor elements or electronic components, the Bi-based solder joint state inside the electronic component can be kept as it was at the initial bonding, and the bonding reliability Excellent in properties.
Hereinafter, each element used in the Bi-based solder alloy of the present invention, the intermetallic compound to be formed, the manufacturing method of the Bi-based solder alloy, the electronic component using the obtained Bi-based solder alloy, and the electronic component mounting substrate will be described in detail. explain.

１．Ｂｉ
本発明のＢｉ基はんだ合金は、周期表のＶａ族元素に属し、結晶構造が対称性の低い三方晶（菱面体晶）で非常に脆弱な金属のＢｉを主成分とする。なお、ここでいう主成分とは、はんだ合金中に質量比で最も多く含まれている成分であることを意味する。
Ｂｉの融点は２７１℃であるため、Ｂｉを主成分とすることで、高温鉛フリーはんだ合金に要求される、２００℃程度の温度で再溶融せず、３５０℃以下の温度で、はんだ付けが可能なはんだ合金とすることが比較的容易にできる。 1. Bi
The Bi-based solder alloy of the present invention is mainly composed of Bi, which belongs to the group Va element of the periodic table, and has a trigonal crystal (rhombohedral crystal) with very low crystal structure and is very fragile. In addition, the main component here means that it is a component that is contained most in the solder alloy by mass ratio.
Since the melting point of Bi is 271 ° C., the main component of Bi is that it does not remelt at a temperature of about 200 ° C., which is required for a high-temperature lead-free solder alloy, and can be soldered at a temperature of 350 ° C. or less. A possible solder alloy can be made relatively easily.

本発明のＢｉ基はんだ合金においてＢｉの含有量は、Ａｇ、Ｓｎなどの添加元素の含有量に応じて決まる値であるが、Ｂｉ基はんだ合金の全量に対して、７０質量％以上でなければならない。Ｂｉの含有量が７０質量％を下回ると、本発明のＢｉ基はんだ合金母相の液相線の上昇が大きくなる場合があり、はんだ付け時に十分に溶融せず溶け残りを生じるなどして、ボンディング不良や接合信頼性へ悪影響を生じる場合があるので好ましくない。   In the Bi-based solder alloy of the present invention, the Bi content is a value determined according to the content of additive elements such as Ag and Sn, but is not 70% by mass or more with respect to the total amount of the Bi-based solder alloy. Don't be. If the content of Bi is less than 70% by mass, the increase in the liquidus of the Bi-based solder alloy matrix of the present invention may increase, and it may not melt sufficiently during soldering, resulting in an undissolved residue, This is not preferable because it may adversely affect bonding failure and bonding reliability.

２．Ａｇ
ＢｉにＡｇを含有するはんだ合金は、鉛を含まず、電子部品の基板実装時のリフロー温度の上限２５０℃に比べて高い固相線温度を有する高温はんだ合金として従来から知られている。例えば、Ｂｉ−２．５質量％Ａｇはんだ合金は、共晶型合金であり、固相線温度が２６２℃で、純Ｂｉの融点２７１℃に比べて約９℃低いが、２５０℃を上回っている。 2. Ag
A solder alloy containing Ag in Bi is conventionally known as a high-temperature solder alloy that does not contain lead and has a solidus temperature higher than the upper limit of 250 ° C. when the electronic component is mounted on a substrate. For example, Bi-2.5 mass% Ag solder alloy is a eutectic type alloy, the solidus temperature is 262 ° C., which is about 9 ° C. lower than the melting point 271 ° C. of pure Bi, but more than 250 ° C. Yes.

また、ＢｉにＡｇを含有させることにより、Ｂｉの脆性を改善し、応力緩和性を向上させることができる。しかしながら、リードフレームなどの接合対象部材との濡れ性が十分であるとは言い難く、特に、接合対象部材がＮｉ層を有する場合、接合対象部材への濡れ広がりが非常に悪かった。また、接合対象部材がＮｉ層を有する場合、ＮｉがＢｉと反応し、脆弱なＢｉ−Ｎｉ合金を形成してしまう。このため、従来のＢｉ−Ａｇはんだでは、接合時の不良発生やその後の信頼性試験で不具合が発生しやすかった。   Moreover, by including Ag in Bi, the brittleness of Bi can be improved and the stress relaxation property can be improved. However, it is difficult to say that the wettability with a member to be joined such as a lead frame is sufficient. In particular, when the member to be joined has a Ni layer, wetting and spreading to the member to be joined was very bad. Moreover, when the member to be joined has a Ni layer, Ni reacts with Bi to form a fragile Bi—Ni alloy. For this reason, in the conventional Bi-Ag solder, it was easy to generate | occur | produce the malfunction at the time of joining generation | occurrence | production at the time of joining, and subsequent reliability test.

そこで、本発明者らは、Ｂｉ−Ａｇはんだ合金の利点を損なうことなく、上述の問題点を改善させるため、更なる添加元素とその配合量を鋭意研究した。その結果、Ａｇに対して所定の割合でＳｎを含有させると、Ｂｉ基はんだ合金母相の応力緩和性を向上させつつ、濡れ性を向上させ、接合性が良く接合不良が発生せず、接合信頼性を向上させることができることを見出した。   Therefore, the present inventors diligently studied further additive elements and their blending amounts in order to improve the above-mentioned problems without impairing the advantages of the Bi-Ag solder alloy. As a result, when Sn is contained at a predetermined ratio with respect to Ag, the stress relaxation property of the Bi-based solder alloy matrix is improved, the wettability is improved, the bonding property is good, and the bonding failure does not occur. It has been found that reliability can be improved.

本発明のＢｉ基はんだ合金は、ＡｇとＳｎを所定量含有させることにより、ＡｇやＳｎがＢｉの脆弱性を改善させるほか、Ａｇ−Ｓｎ金属間化合物を形成し、その粒子がＢｉ基はんだ合金中に分散することで、Ｂｉ基はんだ合金を効果的に分散強化しＢｉの脆弱性をより効果的に改善すると共に、ＢｉとＮｉの反応も阻害し、脆弱なＢｉ−Ｎｉ合金の形成を抑制することができると考えられる。Ａｇ−Ｓｎ金属間化合物については、後ほど詳細に説明する。
Ａｇの含有量は、７．５質量％以上１８質量％以下とする。Ａｇの含有量が７．５質量％を上回ると、Ａｇ−Ｓｎ金属間化合物が十分に発生しＢｉの脆弱な機械的特性を改善する他、濡れ性が十分改善されるため、十分な接合信頼性を得ることができ、はんだ合金の機械加工性が向上することにより、装置による連続供給性も可能となり、製品の製造を容易に行うことが可能となる。Ａｇ含有量が７．５質量％未満であると、後述するＳｎの含有量のＡｇの含有量に対する比率が１／１を上回り、接合後に単独で存在する余剰Ｓｎの量が多くなりすぎ、ＢｉとＳｎの脆弱なＢｉ−Ｓｎ合金を形成して、クラックが発生するなど接合信頼性が悪化する場合がある。
また、Ａｇの含有量が１８質量％を上回ると、液相線が３９０℃以上となり、半導体チップなどの半導体素子を実装するための接合対象部材との接合時に、Ｂｉ基はんだ合金が十分溶解せず、溶け残りが発生するなどして接合不良が発生してしまうため好ましくない。本発明において、更に好ましいＡｇの含有量は、７．５質量％以上１５質量％以下である。 The Bi-based solder alloy of the present invention contains Ag and Sn in a predetermined amount to improve the brittleness of Ag and Sn, and forms an Ag-Sn intermetallic compound, and the particles thereof are a Bi-based solder alloy. Dispersion in the steel effectively disperses and strengthens the Bi-based solder alloy and improves the fragility of Bi more effectively, and also inhibits the reaction between Bi and Ni, thereby suppressing the formation of a fragile Bi-Ni alloy. I think it can be done. The Ag—Sn intermetallic compound will be described in detail later.
The content of Ag is 7.5% by mass or more and 18% by mass or less. When the Ag content exceeds 7.5% by mass, an Ag—Sn intermetallic compound is sufficiently generated to improve the brittle mechanical properties of Bi, and the wettability is sufficiently improved. Therefore, by improving the machinability of the solder alloy, it is possible to continuously supply by the apparatus, and the product can be easily manufactured. When the Ag content is less than 7.5% by mass, the ratio of the Sn content to be described later to the Ag content exceeds 1/1, and the amount of surplus Sn present alone after joining becomes too large. In some cases, a Bi-Sn alloy that is brittle with Sn is formed and cracks are generated, resulting in a deterioration in bonding reliability.
Further, when the Ag content exceeds 18% by mass, the liquidus becomes 390 ° C. or higher, and the Bi-based solder alloy is sufficiently dissolved at the time of joining with a joining target member for mounting a semiconductor element such as a semiconductor chip. However, it is not preferable because unsuccessful melting occurs and bonding failure occurs. In the present invention, the more preferable Ag content is 7.5% by mass or more and 15% by mass or less.

３．Ｓｎ
本発明のＢｉ基はんだ合金において、Ｓｎは、Ａｇと組み合わせることでＡｇ−Ｓｎ金属間化合物を形成する元素である。また、接合対象部材の金属と反応することにより接合対象部材との接合性を向上させる効果もある。
また、従来のＢｉ−Ａｇはんだ合金は、接合対象部材にＮｉが存在すると脆弱なＢｉ−Ｎｉ合金であるＢｉ３Ｎｉ合金を形成することにより、接合信頼性を大きく低下させていた。これに対し、本発明のＢｉ基はんだ合金のように、Ｂｉ−Ａｇ−Ｓｎ合金とすると、Ｂｉ−Ｎｉ合金の生成を抑えることができる。これは、本発明のＢｉ基はんだ合金内に形成される上述のＡｇ−Ｓｎ金属間化合物が、Ｂｉ基はんだ合金内に微細に分散し、ＢｉとＮｉの反応を阻害する他、ＳｎがＮｉと反応して形成するＮｉ−Ｓｎ層が、ＮｉのＢｉ基はんだ合金内への拡散を抑えることができるためと考えられる。このことにより、本発明のＢｉ基はんだ合金を用いた接合対象部材と半導体素子との接合部で構成される電子部品は、長期接続信頼性も大幅に向上し、従来使用されているＰｂ−Ｓｎはんだと同等の信頼性を得ることができる。
Ｓｎの含有量は、接合対象部材と反応し濡れ性や接合性を向上させるためとＡｇ−Ｓｎ金属間化合物を形成するために必要な量とするのが好ましい。Ｓｎを必要量以上に含有させると、余剰のＳｎがＢｉと反応して、実装時のリフロー温度２５０度よりも低い、融点が１４０℃のＢｉ−Ｓｎ合金を形成してしまうので好ましくない。そのため、Ｓｎの含有量については、余剰のＳｎを生じさせないように、Ａｇの含有量との比率を適切に保つ必要がある。Ａｇ−Ｓｎ金属間化合物には、ζ相(Ａｇ０．８Ｓｎ０．２相)とε相(Ａｇ３Ｓｎ相)が存在し、いずれもＢｉとＮｉの反応を阻害する効果が確認された。
また、ＳｎはＡｇと反応してＡｇ−Ｓｎ金属間化合物を形成する他にも、接合対象部材の金属とも容易に反応して、Ｓｎの化合物を形成し、濡れ性や接合性を向上させる。そのため、Ｂｉ基はんだ合金中にＡｇ−Ｓｎ金属間化合物を形成するために必要なＳｎ量と、接合対象部材と反応するために必要なＳｎ量を適切に制御する必要がある。ＡｇとＳｎの配合量を様々に異ならせて試験を行った結果、Ｓｎの含有量は、Ａｇの含有量に対して１／１以下とする必要があることが分かった。Ａｇの含有量に対するＳｎの含有量が１／１を上回ると、接合後に単独で存在する余剰Ｓｎの量が多くなりすぎ、ＢｉとＳｎの脆弱なＢｉ−Ｓｎ合金を形成して、クラックが発生するなど接合信頼性が悪化する場合がある。より好ましいＳｎ含有量の配合比は、Ａｇ含有量に対して１／２以下である。
また、Ｓｎの含有量は、７．５質量％以上１２質量％以下である。Ｓｎの含有量が７．５質量％を上回ると、Ａｇ−Ｓｎ金属間化合物が十分に発生しＢｉの脆弱な機械的特性を改善する他、濡れ性が十分改善され、十分な接合信頼性を得ることができる。また、はんだ合金の機械加工性が向上し、装置による連続供給性が可能となり、製品の製造を容易に行うことが可能となる。Ｓｎの含有量が１２質量％を上回ると、形成されるＡｇ−Ｓｎの量が多くなりすぎて、逆に加工性や応力緩和性が低下したり、余剰のＳｎがＢｉと反応することで、Ｂｉ−Ｓｎ合金の１４０℃での低融点層が形成され、その低融点層の溶け出しからクラックが出現し、接合信頼性の低下を引き起こしたりする場合がある。 3. Sn
In the Bi-based solder alloy of the present invention, Sn is an element that forms an Ag—Sn intermetallic compound in combination with Ag. Moreover, there exists an effect which improves the bondability with a joining object member by reacting with the metal of a joining object member.
Further, the conventional Bi—Ag solder alloy has greatly reduced the bonding reliability by forming a Bi 3 Ni alloy which is a fragile Bi—Ni alloy when Ni is present in the members to be bonded. On the other hand, when a Bi—Ag—Sn alloy is used like the Bi-based solder alloy of the present invention, the formation of a Bi—Ni alloy can be suppressed. This is because the above-mentioned Ag—Sn intermetallic compound formed in the Bi-based solder alloy of the present invention is finely dispersed in the Bi-based solder alloy and inhibits the reaction between Bi and Ni, and Sn is also This is probably because the Ni—Sn layer formed by reaction can suppress the diffusion of Ni into the Bi-based solder alloy. As a result, the electronic component composed of the joint portion between the member to be joined using the Bi-based solder alloy of the present invention and the semiconductor element has greatly improved long-term connection reliability, and Pb-Sn that has been conventionally used Reliability equivalent to that of solder can be obtained.
The content of Sn is preferably set to an amount necessary for improving the wettability and bondability by reacting with the member to be bonded and for forming the Ag—Sn intermetallic compound. If Sn is contained in an amount more than necessary, excess Sn reacts with Bi to form a Bi—Sn alloy having a melting point of 140 ° C. that is lower than the reflow temperature of 250 degrees during mounting, which is not preferable. Therefore, regarding the Sn content, it is necessary to appropriately maintain the ratio with the Ag content so as not to generate excessive Sn. The Ag-Sn intermetallic compound has a ζ phase (Ag 0.8 Sn 0.2 phase) and an ε phase (Ag 3 Sn phase), both of which have been confirmed to inhibit the reaction between Bi and Ni. .
In addition to reacting with Ag to form an Ag—Sn intermetallic compound, Sn also reacts easily with the metal of the member to be joined to form a Sn compound to improve wettability and bondability. Therefore, it is necessary to appropriately control the Sn amount necessary for forming the Ag—Sn intermetallic compound in the Bi-based solder alloy and the Sn amount necessary for reacting with the joining target member. As a result of performing the test with various amounts of Ag and Sn being varied, it was found that the Sn content needs to be 1/1 or less with respect to the Ag content. If the Sn content with respect to the Ag content exceeds 1/1, the amount of surplus Sn that exists alone after bonding becomes too large, forming a Bi-Sn fragile Bi-Sn alloy and causing cracks. In some cases, bonding reliability may deteriorate. A more preferable mixing ratio of the Sn content is 1/2 or less with respect to the Ag content.
Moreover, content of Sn is 7.5 mass% or more and 12 mass% or less. When the Sn content exceeds 7.5% by mass, an Ag-Sn intermetallic compound is sufficiently generated to improve the brittle mechanical properties of Bi, and the wettability is sufficiently improved, so that sufficient bonding reliability is achieved. Can be obtained. Further, the machinability of the solder alloy is improved, the continuous supply by the apparatus is possible, and the product can be easily manufactured. When the content of Sn exceeds 12% by mass, the amount of Ag—Sn formed is too large, and conversely, workability and stress relaxation properties are reduced, or excess Sn reacts with Bi. A low melting point layer at 140 ° C. of the Bi—Sn alloy is formed, and cracks may appear due to the melting of the low melting point layer, which may cause a decrease in bonding reliability.

４．Ａｇ−Ｓｎ金属間化合物
本発明の配合比でＢｉ基はんだ合金を作製することにより、Ｂｉ基はんだ合金内に本発明に必須のＡｇとＳｎの金属間化合物を含む粒子を形成することができる。ＡｇとＳｎから形成される金属間化合物は、ζ相のＡｇ０．８Ｓｎ０．２相とε相のＡｇ３Ｓｎ相である。これらの金属間化合物を含む粒子は微細にするのが好ましい。また、Ａｇ−Ｓｎ金属間化合物の融点は高く、はんだ接合時においても、Ａｇ−Ｓｎ金属間化合物を含む粒子が溶融しない場合もあると考えられるため、各種原料を溶解してはんだ母合金を作製する時に、微細な粒子にすることが好ましい。
また、電子部品の小型化に伴い、接合部の薄層化も求められている。このため、Ａｇ−Ｓｎ金属間化合物を含む粒子は、粒径が８０μｍ未満であることが好ましい。また、粒径８０μｍ未満の粒子が、粒子総体積１００体積％に対して、９７体積％以上であることが好ましく、９８体積％以上であることがより好ましく、９９体積％以上であることが特に好ましい。粒径８０μｍ以上の粒子が３体積％を上回ると、その大粒径の粒子の部分から破壊が起こり全体として脆弱性が改善されず、接合信頼性不足や取扱い不良を生じる場合があるので好ましくない。これは、金属間化合物を含む粒子が大粒径化することにより、金属間化合物による分散強化が発揮されない箇所が局所的に発生し、その数が増えることによりＢｉの脆弱性が十分改善されない場合があるためと考えられる。
なお、本発明において、Ａｇ−Ｓｎ金属間化合物を含む粒子の粒径は、各試片を２００倍の光学顕微鏡で観察し、視野中の全金属間化合物を含む粒子の数を計数すると共に、各粒子の断面径を測定し、その測定値を１．１２倍して求めている。そして、本発明では、このようにして算出した粒径をもとに、すべての金属間化合物粒子を真球とした場合の体積を計算し、すべての粒子中の粒径８０μｍ未満の粒子の割合を体積％で算出している。本算出方法については、後ほど詳細に説明する。 4). Ag-Sn intermetallic compound By producing a Bi-based solder alloy with the compounding ratio of the present invention, particles containing an intermetallic compound of Ag and Sn essential to the present invention can be formed in the Bi-based solder alloy. The intermetallic compound formed from Ag and Sn is an Ag 0.8 Sn 0.2 phase of ζ phase and an Ag 3 Sn phase of ε phase. The particles containing these intermetallic compounds are preferably made fine. Also, the melting point of Ag-Sn intermetallic compound is high, and it is considered that the particles containing Ag-Sn intermetallic compound may not melt even during solder joining. It is preferable to make the particles fine.
In addition, as electronic components are miniaturized, it is also required to reduce the thickness of the joint. For this reason, it is preferable that the particle | grains containing an Ag-Sn intermetallic compound have a particle size of less than 80 micrometers. Further, the particles having a particle size of less than 80 μm are preferably 97% by volume or more, more preferably 98% by volume or more, and particularly preferably 99% by volume or more with respect to 100% by volume of the total particle volume. preferable. If the particle size is more than 3% by volume, the particle portion of the large particle size breaks, and the overall vulnerability is not improved, which may result in insufficient bonding reliability and poor handling. . This is because when the particle containing the intermetallic compound is enlarged, a portion where the dispersion strengthening due to the intermetallic compound is not exhibited locally occurs, and the vulnerability of Bi is not sufficiently improved by increasing the number of particles. It is thought that there is.
In the present invention, the particle diameter of the particles containing the Ag-Sn intermetallic compound was observed with each optical specimen 200 times with an optical microscope, and the number of particles containing all the intermetallic compounds in the field of view was counted. The cross-sectional diameter of each particle is measured, and the measured value is obtained by multiplying it by 1.12. In the present invention, based on the particle size calculated in this way, the volume when all intermetallic compound particles are assumed to be true spheres is calculated, and the proportion of particles having a particle size of less than 80 μm in all the particles. Is calculated by volume%. This calculation method will be described in detail later.

なお、本発明のＢｉ基はんだ合金中に形成されるＡｇ−Ｓｎ金属間化合物を含む粒子とは、ＡｇとＳｎから形成される金属間化合物を主に指すが、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕが混在した金属間化合物も包含するものとする。   In addition, although the particle | grains containing the Ag-Sn intermetallic compound formed in the Bi group solder alloy of this invention mainly point out the intermetallic compound formed from Ag and Sn, Cu, Ni, Pd, and Au are included. Including mixed intermetallic compounds.

５．Ｃｕ、Ｎｉ、Ｐｄ、Ａｕ
本発明の他の態様のＢｉ基はんだ合金は、添加元素として上記のほか、さらに、はんだ合金の濡れ性を改善し、接合後の接合強度を高めるために、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕのいずれか一種以上を含有する。Ｃｕ、Ｎｉ、Ｐｄ、Ａｕは、Ｂｉ、Ａｇ、Ｓｎに比べて優先的に接合界面に移動し、Ｎｉなどの接合界面の金属元素と初期反応層を形成することにより、はんだ合金の濡れ性を改善し、接合後の接合強度を高めることができるものと考えられる。
Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの含有量の総量は、０．００１質量％以上３．０質量％以下である。Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの含有量の総量が３．０質量％を上回ると、接合界面に形成される金属間化合物が粗大な初晶として生成され、部分的に金属間化合物が形成されて成長することにより、接合界面の反応が不均一となり、溶融時の濡れ性が低下することがあるので好ましくない。また、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの含有量の総量が０．００１質量％を下回ると、接合界面で金属間化合物が十分に形成されず濡れ性の向上効果が得られない場合がある。本発明の他の態様のＢｉ基はんだ合金におけるＣｕ、Ｎｉ、Ｐｄ、Ａｕの含有量の総量は、０．０３質量％以上０．８質量％以下であるのがさらに好ましい。 5. Cu, Ni, Pd, Au
In addition to the above as an additive element, the Bi-based solder alloy according to another aspect of the present invention further includes any one of Cu, Ni, Pd, and Au in order to improve the wettability of the solder alloy and increase the bonding strength after bonding. Or one or more. Cu, Ni, Pd, and Au move preferentially to the bonding interface compared to Bi, Ag, and Sn, and form an initial reaction layer with a metal element at the bonding interface such as Ni, thereby improving the wettability of the solder alloy. It is considered that the bonding strength after bonding can be improved.
The total content of Cu, Ni, Pd, and Au is 0.001 mass% or more and 3.0 mass% or less. When the total content of Cu, Ni, Pd, and Au exceeds 3.0% by mass, intermetallic compounds formed at the bonding interface are generated as coarse primary crystals, and intermetallic compounds are partially formed. By growing, the reaction at the bonding interface becomes non-uniform and the wettability at the time of melting may be lowered, which is not preferable. On the other hand, if the total content of Cu, Ni, Pd, and Au is less than 0.001% by mass, the intermetallic compound is not sufficiently formed at the bonding interface, and the effect of improving the wettability may not be obtained. The total content of Cu, Ni, Pd, and Au in the Bi-based solder alloy according to another aspect of the present invention is more preferably 0.03% by mass or more and 0.8% by mass or less.

６．Ｂｉ基はんだ合金の製造
本発明のＢｉ基はんだ合金の製造方法は、特に限定されず、上記した各成分を用いて、従来から用いられている公知の方法により製造することができる。
また、はんだ製品の形状は特に限定されず、ワイヤーや、リボン状、ボール状などの他、適切なロジン等を含むフラックスと混合させて、はんだペーストとして用いることもできる。
製造方法の一例を下記に示す。
原料としては、溶融後のＢｉ基はんだ合金内の組成ばらつきを低減させるために、ショット形状または細かく加工されたもので、直径が５ｍｍ以下、より好ましくは３ｍｍ以下の微細な形状のものを用いることが好ましい。 6). Production of Bi-based solder alloy The production method of the Bi-based solder alloy of the present invention is not particularly limited, and can be produced by a known method that has been conventionally used, using each of the components described above.
The shape of the solder product is not particularly limited, and may be used as a solder paste by mixing with a flux containing an appropriate rosin or the like in addition to a wire, a ribbon shape, a ball shape, or the like.
An example of the manufacturing method is shown below.
The raw material should be shot or finely processed to reduce compositional variation in the Bi-based solder alloy after melting, and should have a fine shape with a diameter of 5 mm or less, more preferably 3 mm or less. Is preferred.

このような形状の原料を溶解炉に入れ、原料の酸化を抑制するために溶解エリアを窒素や不活性ガスの雰囲気とし、その後、５００〜６００℃、好ましくは５００〜５５０℃で加熱溶融させる。金属が溶融しはじめたときに攪拌を開始し、局所的な組成のばらつきが起きないように十分に攪拌を続ける。攪拌時間は、装置や原料の量などによっても異なるが、１〜５分間とすることが好ましい。   In order to suppress the oxidation of the raw material, the raw material having such a shape is put in an atmosphere of nitrogen or an inert gas, and then heated and melted at 500 to 600 ° C., preferably 500 to 550 ° C. Stirring is started when the metal begins to melt, and stirring is continued sufficiently so that local variations in composition do not occur. The stirring time varies depending on the apparatus and the amount of raw materials, but is preferably 1 to 5 minutes.

その後、例えば、内径が３０ｍｍ以下で肉厚が１０ｍｍ程度の円筒状の黒鉛製鋳型に、５００℃以上の温度で溶解した、Ｂｉ基はんだ合金の溶湯を流し込み鋳造する。鋳造する際、この鋳型の外側に熱伝導性の良い材料、例えば、Ｃｕからなる冷やし金を密着させるか、望ましくは中空構造として冷却水を通水した冷やし金を密着させることにより、この鋳型に溶湯を流し込んだ後、２５５℃程度まで３℃／ｓｅｃ以上、より好ましくは２０℃／ｓｅｃ以上の冷却速度で速やかに冷却し固化させる。このような方法により、ほとんどの析出粒子の粒径を８０μｍ未満とする、Ｂｉ基はんだ合金の鋳塊を、安定して作製することができる。
また、連続鋳造法を用いて製造する場合には、連続鋳造してできる鋳塊の断面積を小さくすることで冷却効率を向上させることが好ましい。例えば、内径が３０ｍｍ以下のダイスを用いることが好ましい。また、ダイスを水冷ジャケットで覆うことにより、５０℃／ｓｅｃ以上の冷却速度で冷却することがさらに好ましい。 Thereafter, for example, a molten Bi-based solder alloy melted at a temperature of 500 ° C. or higher is cast into a cylindrical graphite mold having an inner diameter of 30 mm or less and a thickness of about 10 mm. When casting, a material having good heat conductivity, for example, a chill metal made of Cu, is adhered to the outside of the mold, or preferably a chill metal with cooling water flowing in a hollow structure is adhered to the mold. After pouring the molten metal, it is rapidly cooled and solidified at a cooling rate of 3 ° C./sec or higher, more preferably 20 ° C./sec or higher, to about 255 ° C. By such a method, it is possible to stably produce an ingot of a Bi-based solder alloy in which the particle size of most of the precipitated particles is less than 80 μm.
Moreover, when manufacturing using a continuous casting method, it is preferable to improve cooling efficiency by reducing the cross-sectional area of the ingot formed by continuous casting. For example, it is preferable to use a die having an inner diameter of 30 mm or less. Further, it is more preferable to cool the die at a cooling rate of 50 ° C./sec or more by covering the die with a water cooling jacket.

こうして得られる本発明のＢｉ基はんだ合金を用いて、リードフレームなどの接合対象部材に半導体素子を実装して得られた電子部品を、別のはんだ合金を介して基板に実装する際や、本発明のＢｉ基はんだ合金を用いて、半導体素子を接合対象部材である基板へ実装後、当該基板の他の部位に、他の半導体素子や電子部品を実装する際の、それぞれのリフロー温度で再溶融することがないため、はんだ接合部がはんだ接合した際の初期の接合状態から劣化することのない信頼性の高い電子部品を得ることができる。   Using the Bi-based solder alloy of the present invention thus obtained, when mounting an electronic component obtained by mounting a semiconductor element on a member to be joined such as a lead frame on a substrate via another solder alloy, Using the Bi-based solder alloy of the invention, after mounting a semiconductor element on a substrate that is a member to be joined, re-flow at each reflow temperature when mounting another semiconductor element or electronic component on another part of the substrate. Since it does not melt, it is possible to obtain a highly reliable electronic component that does not deteriorate from the initial joined state when the solder joint is soldered.

７．電子部品及び電子部品実装基板
図１に、本発明のＢｉ基はんだ合金を用いた電子部品の一例である半導体パッケージの断面模式図を示す。このような半導体パッケージの場合、リードフレームのアイランド部４の中央部表面に本発明のＢｉ基はんだ合金３を供給し、Ｂｉ基はんだ合金３を溶融させた後に、その上に半導体チップ１を載せ、その後、冷却し固化させることにより、はんだ付け（ダイボンディング）を行う。次に、半導体チップ１上の電極２とリードフレームのリード部５をボンディングワイヤ６で接続し、その後、リードフレームのリード部５の外部接続端子部を除き、それ以外の部分をモールド樹脂７で覆い半導体パッケージを得ることができる。 7). The electronic component and the electronic component mounting board Figure 1 shows a schematic cross section of a semiconductor package, which is an example of an electronic component using a Bi based solder alloy of the present invention. In the case of such a semiconductor package, the Bi-based solder alloy 3 of the present invention is supplied to the center surface of the island portion 4 of the lead frame, and the Bi-based solder alloy 3 is melted, and then the semiconductor chip 1 is mounted thereon. Then, by cooling and solidifying, soldering (die bonding) is performed. Next, the electrode 2 on the semiconductor chip 1 and the lead portion 5 of the lead frame are connected by the bonding wire 6, and then the other portions except for the external connection terminal portion of the lead portion 5 of the lead frame are molded resin 7. A covered semiconductor package can be obtained.

本発明のはんだ合金３が塗布されるリードフレームのアイランド部４には、ボンディングワイヤ６などで接合するリードフレームのリード部５の接合面とともにＡｇめっきが施されることがあるが、費用を低減させるために、リードフレームのアイランド部４のみＡｇめっき処理が施されない場合もある。その場合、リードフレームのアイランド部４は、リードフレームの素材であるＣｕのみで形成される。また、車載関連では、ボンディングワイヤ６などで接合するリードフレームのリード部５の接合面を保護し接合信頼性を向上させるため、Ａｇめっきの代わりに、Ｎｉ層、Ｎｉ／Ａｕ層、またはＮｉ／Ｐｄ／Ａｕ層を形成するためのめっき処理が施される場合があり、近年用いられている微細なリードフレームの場合は、作業性向上などの面から、リードフレームのアイランド部４にも同様のめっき処理が施される場合がある。   The island portion 4 of the lead frame to which the solder alloy 3 of the present invention is applied may be subjected to Ag plating together with the joint surface of the lead portion 5 of the lead frame to be joined by the bonding wire 6 or the like. Therefore, only the island part 4 of the lead frame may not be subjected to the Ag plating process. In that case, the island portion 4 of the lead frame is formed only of Cu which is a material of the lead frame. In addition, for in-vehicle use, in order to protect the joint surface of the lead portion 5 of the lead frame joined by the bonding wire 6 and improve the joining reliability, instead of Ag plating, a Ni layer, a Ni / Au layer, or Ni / A plating process for forming a Pd / Au layer may be performed. In the case of a fine lead frame used in recent years, the same is applied to the island portion 4 of the lead frame from the viewpoint of improving workability. A plating process may be performed.

ところで、ＣｕやＮｉは、他の元素との反応速度が、Ａｇと比べて遅いため、濡れ広がりが悪化する。Ｐｂ系はんだ合金は他元素との反応性が高いため、接合面がＣｕやＮｉである場合でも、一定量濡れ広がることにより接合が維持され、特にＮｉめっきを有する接合対象部材では、Ｎｉ層による防食効果によりＰｂ系はんだ合金と接合対象部材との接合界面での反応層の成長が抑制され、長期信頼性を高くすることができた。しかし、Ｐｂフリーのはんだ合金は、Ｐｂ系はんだ合金に比べて濡れ性が劣る場合が多く、接合面がＣｕやＮｉである場合、十分に濡れ広がることができず、十分な接合性が得られない場合が多かった。特にＢｉ基はんだ合金の場合は、ＢｉがＮｉと反応し、脆弱なＢｉ−Ｎｉ合金を形成してしまう場合があるため、Ｎｉ層を有する接合対象部材との接合には用いることが困難であった。
しかるに、本発明のＢｉ基はんだ合金のように、ＡｇとＳｎを適切な配合比で含有させれば、Ａｇ−Ｓｎ金属間化合物をＢｉ基はんだ合金内に分散させ、ＮｉとＢｉとの反応を阻害させ、かつ、Ｓｎの反応により濡れ性も向上させることができる。また、本発明の他の実施形態のＢｉ基はんだ合金は、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕを含有することにより、濡れ性をさらに向上させることができる。このため、本発明のＢｉ基はんだ合金によれば、従来のＢｉ基はんだ合金が十分な接合性を得ることのできなかった、Ｎｉ層、Ｎｉ／Ａｕ層、またはＮｉ／Ｐｄ／Ａｕ層を有する接合対象部材に対しても、しっかり接合することができ、十分な接合信頼性を有することができる。
すなわち、本発明の電子部品の製造方法によれば、Ｂｉ基はんだ合金の濡れ性を改善させ、さらに従来困難であった、銅材表面にＮｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかがめっき形成されているリードフレームなどの接合対象部材への半導体素子などの実装を、Ｂｉ基はんだ合金を用いても接合信頼性低下の問題を生じること無く行うことができる。
例えば、接合対象部材に半導体チップ等の半導体素子をはんだ付けした電子部品は、基板へ実装される際、２５０℃までのリフロー温度で再加熱されることが多いが、本発明のＢｉ基はんだ合金の固相線温度は、２５５℃以上なので、電子部品内のはんだ接合部が再溶融することはない。また、融点を３２０℃以下とすることで初期接合温度を比較的低くすることができ、半導体チップ特性の変化や部材酸化が発生しないため、はんだ接合部を含む実装基板の特性を劣化させること無く、機械的強度を維持することができる。 By the way, Cu and Ni have a slower reaction rate with other elements than Ag, so that wetting spread deteriorates. Since the Pb-based solder alloy has high reactivity with other elements, even when the bonding surface is Cu or Ni, the bonding is maintained by spreading by a certain amount, especially in a member to be bonded having Ni plating, depending on the Ni layer. Due to the anticorrosion effect, the growth of the reaction layer at the bonding interface between the Pb-based solder alloy and the member to be bonded was suppressed, and long-term reliability could be increased. However, Pb-free solder alloys often have inferior wettability compared to Pb-based solder alloys, and when the joint surface is Cu or Ni, the wettability cannot be sufficiently spread and sufficient bondability is obtained. There were often no cases. In particular, in the case of a Bi-based solder alloy, Bi may react with Ni to form a fragile Bi—Ni alloy, so that it is difficult to use it for joining with a member to be joined having a Ni layer. It was.
However, as in the Bi-based solder alloy of the present invention, if Ag and Sn are contained at an appropriate blending ratio, the Ag-Sn intermetallic compound is dispersed in the Bi-based solder alloy, and the reaction between Ni and Bi is caused. It is possible to inhibit the wettability by Sn reaction. Further, the Bi-based solder alloy according to another embodiment of the present invention can further improve wettability by containing Cu, Ni, Pd, and Au. Therefore, according to the Bi-based solder alloy of the present invention, the conventional Bi-based solder alloy has a Ni layer, a Ni / Au layer, or a Ni / Pd / Au layer, which has not been able to obtain sufficient jointability. It can join firmly also to a member to be joined, and can have sufficient joining reliability.
That is, according to the method for manufacturing an electronic component of the present invention, the wettability of a Bi-based solder alloy is improved, and a Ni layer, a Ni / Au layer, a Ni / Pd / Au layer on the surface of a copper material, which has been difficult in the past. Even if a Bi-based solder alloy is used, mounting of a semiconductor element or the like on a member to be bonded such as a lead frame on which any of the above is plated can be performed without causing a problem of deterioration in bonding reliability.
For example, an electronic component in which a semiconductor element such as a semiconductor chip is soldered to a member to be joined is often reheated at a reflow temperature up to 250 ° C. when mounted on a substrate. Since the solidus temperature is 255 ° C. or higher, the solder joint in the electronic component does not remelt. In addition, by setting the melting point to 320 ° C. or lower, the initial bonding temperature can be made relatively low and no change in semiconductor chip characteristics or member oxidation occurs, so that the characteristics of the mounting substrate including the solder joints are not deteriorated. , Mechanical strength can be maintained.

すなわち、本発明の電子部品実装基板は、上記本発明のＢｉ基はんだ合金を用いて、リフロー作業ピーク温度を２５０℃として電子部品を実装したものである。なお、電子部品実装用の基板としては、従来公知の基板を用いることができ、セラミック基板が一般的であるが、樹脂製のプリント基板やＳｉ基板を用いることもできる。   That is, the electronic component mounting board of the present invention is obtained by mounting an electronic component using the Bi-based solder alloy of the present invention at a reflow work peak temperature of 250 ° C. In addition, as a board | substrate for electronic component mounting, a conventionally well-known board | substrate can be used and although a ceramic substrate is common, a resin-made printed board and Si board | substrate can also be used.

本発明を実施例により、さらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。   EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

１．測定方法、評価方法
実施例と比較例のＢｉ基はんだ合金に対しては、以下の測定方法、評価方法を用いた。
（１）Ａｇ−Ｓｎ金属間化合物の観察方法と粒子径や体積比率の算出方法
０．７５ｍｍφのワイヤー状のＢｉ基はんだ合金を樹脂に埋め込み、断面研磨を行う。Ｂｉ基はんだ合金の断面が露出した評価用試料を常温の硝酸水溶液（硝酸濃度２０％）に５秒間浸漬してエッチングする。
エッチング後の評価用試料は、Ｂｉ基はんだ合金の母相は腐食して黒く見える一方、Ａｇ−Ｓｎ金属間化合物を含む析出粒子は白く光って見えるため、光学顕微鏡観察によって析出粒子の大きさや分布状態を容易に判別することができる。そこで、各評価用試料を２００倍の光学顕微鏡で観察し、視野中の析出粒子の断面径を測定する。断面径は、計測した粒子の最も長い径とそれに直交する径で最も短い径の平均値から求める。また、断面径は粒子の任意断面となり、実際の粒子の粒径に比べて小さく計測されるため、得られた測定値を１．１２倍したものをその粒子の粒径とみなした。上記方法に従って、観察されたすべての粒子の粒径を算出し、その算出した粒径を用いて、各粒子が真球であると仮定した場合の体積をそれぞれ算出する。算出した各粒子の体積から、粒径が８０μｍ未満の粒子の割合を体積％で算出する。 1. Measurement method and evaluation method The following measurement methods and evaluation methods were used for the Bi-based solder alloys of the examples and comparative examples.
(1) Observation method of Ag—Sn intermetallic compound and calculation method of particle diameter and volume ratio Wire-shaped Bi-based solder alloy having a diameter of 0.75 mmφ is embedded in a resin, and cross-sectional polishing is performed. The evaluation sample with the exposed cross section of the Bi-based solder alloy is immersed in a nitric acid aqueous solution (nitric acid concentration 20%) for 5 seconds and etched.
In the sample for evaluation after etching, the matrix phase of the Bi-based solder alloy looks corroded and black, while the precipitated particles containing the Ag-Sn intermetallic compound appear white. Therefore, the size and distribution of the precipitated particles by optical microscope observation The state can be easily determined. Therefore, each evaluation sample is observed with a 200 × optical microscope, and the cross-sectional diameter of the precipitated particles in the field of view is measured. The cross-sectional diameter is obtained from an average value of the longest diameter of the measured particles and the shortest diameter perpendicular to the longest diameter. Moreover, since the cross-sectional diameter is an arbitrary cross-section of the particle and is measured to be smaller than the actual particle size, a value obtained by multiplying the obtained measured value by 1.12 was regarded as the particle size of the particle. In accordance with the above method, the particle diameters of all the observed particles are calculated, and the volume when each particle is assumed to be a true sphere is calculated using the calculated particle diameter. From the calculated volume of each particle, the ratio of particles having a particle size of less than 80 μm is calculated in volume%.

（２）濡れ性の評価方法
ダイボンダーにＮｉめっき層を有するＣｕ製リードフレームを供給し、処理エリアを窒素雰囲気で満たした後、３７０℃まで加熱し、その後上記（１）のＡｇ−Ｓｎ金属間化合物の観察方法において断面観察したのと同じ０．７５ｍｍφのＢｉ基はんだ合金を、Ｎｉめっき層上に供給する。Ｂｉ基はんだ合金が十分に溶融した後、はんだ接合面にＡｕを蒸着させた１ｍｍ角のシリコンダミーチップを、Ｂｉ基はんだ合金上に載せ、Ｎｉめっき付きＣｕ製リードフレームに接合させる。その後、窒素雰囲気中のまま熱のかからないエリアに試料を移して冷却し、評価用の試料を得る。なお、Ｂｉ基はんだ合金の供給量は、シリコンダミーチップ接合後の厚みが５０μｍになるように調整している。
はんだ濡れ性評価は、評価用試料を上部から観察し、シリコンダミーチップのいずれの辺からも、Ｂｉ基はんだ合金のはみ出しがないことが確認された場合を「不良」、はみ出しが確認された場合を「良」、シリコンダミーチップの各辺からほぼ均一にはみ出しが確認された場合を「優」と評価する。 (2) Evaluation method of wettability After supplying a Cu lead frame having a Ni plating layer to a die bonder and filling the treatment area with a nitrogen atmosphere, it is heated to 370 ° C., and then between the Ag-Sn metals in (1) above The same 0.75 mmφ Bi-based solder alloy as the cross-section observed in the compound observation method is supplied onto the Ni plating layer. After the Bi-base solder alloy is sufficiently melted, a 1 mm square silicon dummy chip having Au deposited on the solder joint surface is placed on the Bi-base solder alloy and joined to a Cu lead frame with Ni plating. Thereafter, the sample is transferred to an area that is not heated in a nitrogen atmosphere and cooled to obtain a sample for evaluation. The supply amount of the Bi-based solder alloy is adjusted so that the thickness after bonding the silicon dummy chip is 50 μm.
For solder wettability evaluation, the sample for evaluation is observed from the top, and it is confirmed that there is no protrusion of the Bi-based solder alloy from any side of the silicon dummy chip. Is evaluated as “excellent” when the protrusion is confirmed to be almost uniform from each side of the silicon dummy chip.

（３）接合信頼性の評価方法
上記（２）の濡れ性評価用試料の作製方法と同様に、シリコンダミーチップを、Ｎｉめっき付きＣｕ製リードフレームに、Ｂｉ基はんだ合金を用いて接合させる。その後、エポキシ樹脂でモールドしたものを、接合信頼性評価用の試料として、それぞれ同条件で２個ずつ作製する。接合信頼性試験は、各試料を、まず２５０℃で１０秒間保持するリフロー処理を行い、その後−５０℃／１５０℃の温度サイクル試験を３００サイクル、５００サイクル実施する。その後、各試料を樹脂埋めした後、断面研磨をして、はんだ接合部の断面観察を行う。
接合信頼性評価は、Ｂｉ基はんだ合金や、はんだ接合部界面などに割れの発生が確認されなかった場合を「良」、接合不良や割れの発生が確認された場合を「不良」と評価する。 (3) Evaluation Method of Bonding Reliability Similar to the method for preparing the wettability evaluation sample in (2) above, a silicon dummy chip is bonded to a Cu lead frame with Ni plating using a Bi-based solder alloy. Thereafter, two molds molded with an epoxy resin are prepared under the same conditions as samples for evaluation of bonding reliability. In the bonding reliability test, each sample is first subjected to a reflow process of holding at 250 ° C. for 10 seconds, and then a temperature cycle test of −50 ° C./150° C. is performed for 300 cycles and 500 cycles. Then, after filling each sample with resin, cross-section polishing is performed, and cross-section observation of the solder joint is performed.
In the joint reliability evaluation, a case where cracks are not confirmed at the Bi-base solder alloy or the solder joint interface is evaluated as “good”, and a case where joint failure or cracks are confirmed as “bad”. .

２．Ｂｉ基はんだ合金の製造
まず、原料として、Ｂｉ、Ａｇ、Ｓｎ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕ（各元素の純度：９９．９９質量％以上）を準備した。原料は基本的に３ｍｍφ以下のショット形状原料を用いたが、原料が大きな薄片やバルク状の場合は、切断や粉砕等を行い、３ｍｍ以下の大きさに細かくして、溶解時の偏析要因を極力減らし溶解後のはんだ合金内に組成ばらつきが生じず均一になるようにした。
次に、高周波溶解炉用グラファイト坩堝に、目的とするＢｉ基はんだ合金の組成に対応する原料を所定量秤量して入れた。
次に、原料の入った坩堝を高周波溶解炉に入れ、酸化を抑制するために窒素を原料１ｋｇ当たり０．７Ｌ／分以上の流量で流し、高周波溶解エリアを窒素雰囲気とした。高周波溶解エリアが十分窒素雰囲気となった状態で、高周波溶解炉の内部を５００℃まで５℃／ｓｅｃの昇温速度で加熱し、原料を加熱溶融させた。原料が溶融しはじめたときに、局所的な組成のばらつきが起きないように、攪拌棒を用いて３分間撹拌を行った。原料金属が十分溶融し、溶け残りがないことを確認した後、高周波電源を切り、速やかに坩堝を取り出し、坩堝内の溶湯を、はんだ母合金の鋳型に流し込んだ。
鋳型には、内径が３０ｍｍで肉厚が１０ｍｍ程度の円筒状の黒鉛製鋳型を使用し、鋳型の外側には、冷却水を通水することのできる中空構造のＣｕからなる冷やし金を密着させる構造とした。この鋳型に溶湯を流し込んだ後、冷却水を通水した冷やし金を密着させ２５５℃程度まで５℃／ｓｅｃの冷却速度で速やかに冷却し固化させた。
得られたＢｉ基はんだ母合金を押し出し加工にて直径０．７５ｍｍのワイヤー形状のＢｉ基はんだ合金とした。 2. Production of Bi-based solder alloy First, Bi, Ag, Sn, Cu, Ni, Pd, and Au (purity of each element: 99.99% by mass or more) were prepared as raw materials. The raw material was basically shot-shaped raw material of 3mmφ or less. However, if the raw material is large flakes or bulk, cut and pulverize it to make it smaller than 3mm, and cause segregation during melting. As much as possible, it was made uniform with no variation in composition in the solder alloy after melting.
Next, a predetermined amount of raw material corresponding to the composition of the target Bi-based solder alloy was weighed into a graphite crucible for a high-frequency melting furnace.
Next, the crucible containing the raw material was put into a high-frequency melting furnace, and nitrogen was flowed at a flow rate of 0.7 L / min or more per 1 kg of the raw material in order to suppress oxidation, so that the high-frequency melting area was a nitrogen atmosphere. With the high frequency melting area in a sufficiently nitrogen atmosphere, the inside of the high frequency melting furnace was heated to 500 ° C. at a rate of 5 ° C./sec to heat and melt the raw material. When the raw material started to melt, stirring was performed for 3 minutes using a stirring bar so that local variations in composition did not occur. After confirming that the raw metal was sufficiently melted and did not melt, the high frequency power supply was turned off, the crucible was quickly taken out, and the molten metal in the crucible was poured into the solder mother alloy mold.
As the mold, a cylindrical graphite mold having an inner diameter of 30 mm and a thickness of about 10 mm is used, and a cooling metal made of Cu having a hollow structure capable of passing cooling water is adhered to the outside of the mold. The structure. After pouring the molten metal into the mold, a chilled metal with cooling water was brought into close contact therewith, and rapidly cooled to about 255 ° C. at a cooling rate of 5 ° C./sec and solidified.
The obtained Bi-based solder mother alloy was extruded to form a wire-based Bi-based solder alloy having a diameter of 0.75 mm.

得られたワイヤー形状のＢｉ基はんだ合金を用いて、各Ｂｉ基はんだ合金の組成確認、及び、上記８０μｍ未満のＡｇ−Ｓｎ金属間化合物を含む粒子の割合測定や濡れ性評価、接合信頼性評価を行った。
これらの結果を、表１に示す。なお、接合信頼性評価結果は、「良」と判定されたサイクルのうち、最も多いサイクル数を表１に示した。また、最も少ない３００サイクルで「不良」と判定された試料の場合は「不良」と表記した。 Using the obtained wire-shaped Bi-based solder alloy, composition confirmation of each Bi-based solder alloy, measurement of the proportion of particles containing the Ag-Sn intermetallic compound of less than 80 μm, wettability evaluation, and joint reliability evaluation Went.
These results are shown in Table 1. Table 1 shows the most reliable cycle number among the cycles judged as “good” as the result of the joint reliability evaluation. In addition, in the case of a sample determined to be “defective” in the least 300 cycles, it was described as “defective”.

Figure 2018047497
Figure 2018047497

３．評価
本発明範囲内の試料１〜４は、表１に示したとおり断面観察により、Ｂｉ基はんだ合金中の添加物や金属間化合物の粒子の９９．５体積％以上が、粒径８０μｍ未満になっていることが確認された。また、濡れ性が「良」レベルまで改善し、接合信頼性試験において、３００サイクルまでシリコンダミーチップおよび接合部に割れなどの欠陥が確認されず、接合性および脆弱性が改善されていることが確認できた。
さらに、試料５〜１２では、濡れ広がりを良くするＣｕ、Ｎｉ、Ｐｄ、Ａｕを含有させているので、Ｃｕ、Ｎｉ、Ｐｄ、ＡｕとＮｉ面が界面反応し、濡れ広がりが更に向上し、濡れ性の評価結果は、「優」となった。また、濡れ性が向上し界面接合がより強固になったため、温度サイクル試験５００サイクルまで、シリコンダミーチップおよび接合部に割れなどの欠陥が発生しなかった。ただし、これらの元素を含有させると、８０μｍ未満の金属間化合物粒子の体積比率は、試料５が９９．４％、試料６、７、９〜１１が９８％台、試料８が９９．０％、試料１２が９７．３％と若干低めになることが確認された。これは、はんだ合金内に存在するＣｕなどの添加元素が、金属間化合物粒子生成の核となって成長を促進しまうことによると考えられる。
また、本発明範囲内の試料１〜１２を用いてモールドした試料を基板に実装し、２５０℃、１０秒間の熱処理を５回行った。該処理後の実装基板を断面カットし、シリコンダミーチップおよび接合部の異常の有無を調べた結果、いずれも異常は見られず、目立ったボイドも確認できず、再溶融の痕跡は確認できなかった。よって、本発明に係るはんだ合金で接合された部位は、その後、リフロー温度２５０℃に１０秒間保持される処理を５回程度施されても、溶融することなく保たれることを確認した。 3. Evaluation Samples 1 to 4 within the scope of the present invention had a particle size of less than 80 μm with 99.5% by volume or more of the additive and intermetallic particles in the Bi-based solder alloy, as shown in Table 1. It was confirmed that In addition, the wettability is improved to a “good” level, and in the bonding reliability test, defects such as cracks are not confirmed in the silicon dummy chip and the bonded portion up to 300 cycles, and the bondability and fragility are improved. It could be confirmed.
Furthermore, since Samples 5 to 12 contain Cu, Ni, Pd, and Au that improve wetting and spreading, Cu, Ni, Pd, Au, and the Ni surface undergo an interfacial reaction to further improve wetting and spreading. The evaluation result of sex was “excellent”. Further, since the wettability was improved and the interfacial bonding became stronger, defects such as cracks did not occur in the silicon dummy chip and the joint until the temperature cycle test 500 cycles. However, when these elements are contained, the volume ratio of intermetallic compound particles of less than 80 μm is 99.4% for sample 5, 98% for samples 6, 7, and 9 to 11, and 99.0% for sample 8. It was confirmed that Sample 12 was slightly lower at 97.3%. This is thought to be due to the fact that additive elements such as Cu present in the solder alloy serve as a nucleus for the formation of intermetallic compound particles and promote growth.
Moreover, the sample molded using the samples 1-12 within the scope of the present invention was mounted on a substrate, and heat treatment was performed 5 times at 250 ° C. for 10 seconds. As a result of cutting the mounting substrate after the processing and examining the presence or absence of abnormalities in the silicon dummy chip and the joint, no abnormality was found, no conspicuous voids could be confirmed, and no trace of remelting could be confirmed. It was. Therefore, it was confirmed that the parts joined by the solder alloy according to the present invention were maintained without melting even after being subjected to a treatment for 10 seconds at a reflow temperature of 250 ° C. for about 5 times.

これに対して、本発明の範囲外である試料１３〜１８は、濡れ広がりにくいＮｉ面のリードフレームに対しては接合信頼性試験において３００サイクルまで持たず、接合信頼性に劣ることが確認された。
試料１３は、Ｓｎを含有しないためＮｉ面との反応が十分に進まず濡れ不足になり、かつＡｇ−Ｓｎ金属間化合物を形成しないため、脆弱なＢｉ−Ｎｉ合金の形成を抑制できず接合信頼性に劣ったと考えられる。また、試料１４は、Ｓｎの含有量が多すぎるため、形成されるＡｇ−Ｓｎ化合物が多くなりすぎてしまい、濡れ性は良好であるものの、応力緩和性に劣りサイクル試験でクラックを生じ、接合信頼性に劣ったと考えられる。また、試料１５は、Ａｇの含有量に対するＳｎの含有量の比率が高すぎるため、Ｓｎが過剰に存在してしまったため、濡れ性は良好であるものの、低融点相のＢｉ−Ｓｎ合金を形成してしまい、接合信頼性に劣ったと考えられる。また、試料１６は、Ａｇの含有量が多すぎるため、液相線が高くなりすぎてしまい、はんだ接合時に溶け残りが発生し、濡れ広がりが改善せず、濡れ広がりが不十分なため接合信頼性にも劣ったと考えられる。
また、試料１７および１８は、ＣｕやＮｉなどの添加元素の含有量が本発明の上限値を外れているため、接合界面に粗大な化合物が発生して濡れ広がりの邪魔をして濡れ性を悪化させ、しかも、微細な金属間化合物粒子の割合も低くなってしまったため、接合界面やはんだ合金内に形成された粗大な化合物を起点として温度サイクル試験時に一部割れが生じ接合信頼性に劣ったと考えられる。 On the other hand, samples 13 to 18 outside the scope of the present invention did not have up to 300 cycles in the bonding reliability test for Ni-faced lead frames that are difficult to spread and were confirmed to be inferior in bonding reliability. It was.
Since sample 13 does not contain Sn, the reaction with the Ni surface does not proceed sufficiently, resulting in insufficient wetting, and the formation of Ag-Sn intermetallic compound does not occur. It is thought that it was inferior. Sample 14 has too much Sn content, so too much Ag-Sn compound is formed and the wettability is good, but the stress relaxation property is inferior and cracks are generated in the cycle test. It is thought that it was inferior in reliability. Moreover, since the ratio of the Sn content to the Ag content was too high for the sample 15, Sn was present excessively, so that the wettability was good, but a Bi-Sn alloy having a low melting point phase was formed. Therefore, it is considered that the bonding reliability is inferior. In addition, since the sample 16 has too much Ag content, the liquidus line becomes too high, undissolved material is generated at the time of soldering, wetting spread is not improved, and wetting spread is insufficient. It is thought that it was also inferior.
In Samples 17 and 18, since the content of additive elements such as Cu and Ni deviates from the upper limit of the present invention, a coarse compound is generated at the bonding interface, and the wettability is disturbed. In addition, since the ratio of fine intermetallic compound particles has also decreased, some cracks have occurred in the temperature cycle test starting from coarse compounds formed in the bonding interface and solder alloy, resulting in poor bonding reliability. It is thought.

なお、上記各試料における測定及び評価は、便宜上、Ｎｉ基はんだ合金と接合する接合対象部材であるＣｕ製リードフレームとして、表面にＮｉめっき層のみを有するものを用いて行ったが、Ｎｉめっき層上に保護用の薄いＡｕめっき層やＰｄ／Ａｕめっき層を有するＣｕ製リードフレームを用いた場合も、はんだ接合時にＡｕめっき層やＰｄめっき層をＮｉやＢｉが拡散して同様の結果を示すことが確認できた。また、Ｎｉめっきが無くＣｕ表面が露出しているＣｕ製リードフレームを用いた場合は、Ｎｉめっき面より良好な接合性を示すことが確認できた。   In addition, the measurement and evaluation in each of the above samples were performed using, as a matter of convenience, a Cu lead frame that is a bonding target member to be bonded to the Ni-based solder alloy, and having a Ni plating layer on the surface. Even when a Cu lead frame having a thin protective Au plating layer or Pd / Au plating layer on top is used, Ni or Bi diffuses in the Au plating layer or Pd plating layer at the time of soldering, and the same result is shown. I was able to confirm. In addition, it was confirmed that when a Cu lead frame having no Ni plating and having an exposed Cu surface was used, it showed better bondability than the Ni plated surface.

以上により、本発明に係るＢｉ基はんだ合金で接合された、Ｂｉ基はんだ合金接合部には、半導体チップなどの半導体素子を接合対象部材に実装した電子部品を基板に実装するためのリフローの際や、半導体素子を接合対象部材である基板へ実装後、当該基板の他の部位に、他の半導体素子や電子部品を実装するためのリフローの際においても剥離及びボイド等は発生せず、特に、Ｎｉ層を有する濡れ性や接合信頼性の悪化する接合対象部材においても、Ｂｉ基はんだ合金接合部の特性に問題が生じないため、従来よりも信頼性の高い電子部品を供給することができるといえる。   As described above, the Bi-based solder alloy joint portion joined by the Bi-based solder alloy according to the present invention is subjected to reflow for mounting an electronic component in which a semiconductor element such as a semiconductor chip is mounted on a member to be joined to the substrate. In addition, after mounting a semiconductor element on a substrate that is a member to be joined, peeling and voids do not occur in other parts of the substrate even during reflow for mounting other semiconductor elements and electronic components. In addition, even in a member to be joined that has a Ni layer and deteriorates in wettability and joint reliability, there is no problem in the characteristics of the Bi-based solder alloy joint, so that it is possible to supply more reliable electronic components than in the past. It can be said.

本発明のＢｉ基はんだ合金は、Ｐｂ−５質量％Ｓｎ等の高温はんだ合金の代替として、Ｎｉ層、Ｎｉ／Ａｕ層や、Ｎｉ／Ｐｄ／Ａｕ層などの、Ｎｉを含むめっきが接合対象部材の表面に施されたフレーム基板用のプリフォームはんだ合金や本発明のＢｉ基はんだ合金を含むはんだペーストとして好適に用いることができ、パワーデバイスやパワーモジュール等の半導体パッケージの半導体チップの接合等に特に好適に用いることができる。   The Bi-based solder alloy of the present invention is a member to be joined by plating containing Ni, such as a Ni layer, a Ni / Au layer, or a Ni / Pd / Au layer, as an alternative to a high-temperature solder alloy such as Pb-5 mass% Sn. It can be suitably used as a solder paste containing a preform solder alloy for a frame substrate applied to the surface of the substrate or a Bi-based solder alloy of the present invention, and for joining semiconductor chips of semiconductor packages such as power devices and power modules. It can be particularly preferably used.

１ 半導体チップ
２ 電極
３ はんだ
４ リードフレームのアイランド部
５ リードフレームのリード部
６ ボンディングワイヤ
７ モールド樹脂 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Electrode 3 Solder 4 Island part of lead frame 5 Lead part of lead frame 6 Bonding wire 7 Mold resin

Claims (8)

ＡｇとＳｎを含有し、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、前記Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなることを特徴とするＢｉ基はんだ合金。   A Bi-based solder alloy containing Ag and Sn and having a Bi content of 70% by mass or more, wherein the Ag content is 7.5% by mass or more and 18% by mass or less, and the Sn content is 7.5% by mass. % And 12% by mass or less, and Sn content is 1/1 or less with respect to the Ag content, and the Bi-based solder alloy contains particles containing an intermetallic compound of Ag and Sn. A Bi-based solder alloy characterized in that the balance is made of Bi except for elements inevitably contained in production. ＡｇとＳｎを含有し、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を含有し、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、前記Ｂｉ基はんだ合金内にＡｇとＳｎとの金属間化合物を含む粒子を含有し、かつ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を総量で０．００１質量％以上３．０質量％以下の範囲で含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなることを特徴とするＢｉ基はんだ合金。   A Bi-based solder alloy containing Ag and Sn, further containing at least one of Cu, Ni, Pd, and Au, and having a Bi content of 70% by mass or more, wherein the Ag content is 7 0.5 mass% or more and 18 mass% or less, Sn content is 7.5 mass% or more and 12 mass% or less, and Sn content is 1/1 or less with respect to Ag content, and The Bi-based solder alloy contains particles containing an intermetallic compound of Ag and Sn, and one or more of Cu, Ni, Pd, and Au are added in a total amount of 0.001% by mass to 3.0% by mass. A Bi-based solder alloy, which is contained in the following range, and the balance is made of Bi except for elements inevitably included in production. 前記Ｂｉ基はんだ合金内に形成される前記ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、粒径８０μｍ未満の粒子が９７体積％以上存在することを特徴とする請求項１または２に記載のＢｉ基はんだ合金。   The present invention is characterized in that 97% by volume or more of particles having a particle diameter of less than 80 μm are present with respect to 100% by volume of the total volume of particles including the intermetallic compound of Ag and Sn formed in the Bi-based solder alloy. The Bi-based solder alloy according to claim 1 or 2. 表面にＮｉ層、Ｎｉ／Ａｕ層、Ｎｉ／Ｐｄ／Ａｕ層のいずれかが形成された接合対象部材との接合に用いることを特徴とする請求項１〜３のいずれかに記載のＢｉ基はんだ合金。   The Bi-based solder according to any one of claims 1 to 3, wherein the Bi-based solder is used for joining to a joining target member on which any one of a Ni layer, a Ni / Au layer, and a Ni / Pd / Au layer is formed. alloy. ＡｇとＳｎを含有し、Ｂｉの含有率が７０質量％以上のＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、残部が製造上、不可避的に含まれる元素を除きＢｉからなる、前記Ｂｉ基はんだ合金の溶湯を鋳型に流し込んだ後、２５５℃まで３℃／ｓｅｃ以上の冷却速度で冷却し固化させることで、ＡｇとＳｎとの金属間化合物を含む粒径８０μｍ未満の粒子を、該ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、９７体積％以上前記Ｂｉ基はんだ合金内に形成させることを特徴とするＢｉ基はんだ合金の製造方法。   A Bi-based solder alloy containing Ag and Sn and having a Bi content of 70% by mass or more, wherein the Ag content is 7.5% by mass or more and 18% by mass or less, and the Sn content is 7.5% by mass. % To 12% by mass and Sn content is 1/1 or less with respect to Ag content, and the balance is made of Bi except for elements inevitably contained in production. After pouring the molten metal into a mold, it is cooled and solidified to a temperature of 255 ° C. at a cooling rate of 3 ° C./sec or more, so that particles having a particle diameter of less than 80 μm containing an intermetallic compound of Ag and Sn are obtained. 97% by volume or more in the Bi-based solder alloy with respect to the total volume of 100% by volume of the entire particle including the intermetallic compound. ＡｇとＳｎを含有し、さらに、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を含有し、Ｂｉの含有率が７０質量％以上含有するＢｉ基はんだ合金であって、Ａｇの含有量が７．５質量％以上１８質量％以下、Ｓｎの含有量が７．５質量％以上１２質量％以下、かつ、Ｓｎの含有量がＡｇの含有量に対して１／１以下であり、かつ、Ｃｕ、Ｎｉ、Ｐｄ、Ａｕの中から１種以上を総量で０．００１質量％以上３．０質量％以下の範囲で含有し、残部が製造上、不可避的に含まれる元素を除きＢｉからなる、前記Ｂｉ基はんだ合金の溶湯を鋳型に流し込んだ後、２５５℃まで３℃／ｓｅｃ以上の冷却速度で冷却し固化させることで、ＡｇとＳｎとの金属間化合物を含む粒径８０μｍ未満の粒子を、該ＡｇとＳｎとの金属間化合物を含む粒子全体の総体積１００体積％に対して、９７体積％以上前記Ｂｉ基はんだ合金内に形成させることを特徴とするＢｉ基はんだ合金の製造方法。   A Bi-based solder alloy containing Ag and Sn, further containing at least one of Cu, Ni, Pd, and Au, and having a Bi content of 70% by mass or more, wherein the Ag content is 7.5 mass% or more and 18 mass% or less, Sn content is 7.5 mass% or more and 12 mass% or less, and Sn content is 1/1 or less with respect to Ag content, and One or more of Cu, Ni, Pd, and Au are contained in a total amount in the range of 0.001% by mass to 3.0% by mass, and the balance is made of Bi except for elements that are inevitably included in production. After pouring the molten Bi-based solder alloy into the mold, the particles are cooled to a temperature of 255 ° C. at a cooling rate of 3 ° C./sec or more and solidified, and particles containing an intermetallic compound of Ag and Sn are less than 80 μm. Of the whole particle containing the intermetallic compound of Ag and Sn Against 100 vol%, the production method of the Bi based solder alloy, characterized in that to form the 97 vol% or more the Bi based solder the alloy. 接合対象部材と、請求項１〜４のいずれかに記載のＢｉ基はんだ合金と、前記Ｂｉ基はんだ合金を介して前記接合対象部材に実装された半導体素子を有してなることを特徴とする電子部品。   A joining target member, the Bi-based solder alloy according to claim 1, and a semiconductor element mounted on the joining target member through the Bi-based solder alloy. Electronic components. 請求項１〜４のいずれかに記載のＢｉ基はんだ合金を用いて製造されたことを特徴とする電子部品実装基板。   An electronic component mounting board manufactured using the Bi-based solder alloy according to claim 1.
JP2016186196A 2016-09-23 2016-09-23 Bi-BASED SOLDER ALLOY AND METHOD FOR PRODUCING THE SAME, AND ELECTRONIC COMPONENT AND ELECTRONIC COMPONENT-MOUNTED SUBSTRATE COMPRISING THE SOLDER ALLOY Pending JP2018047497A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020136979A1 (en) * 2018-12-28 2020-07-02 Ｊｘ金属株式会社 Solder joint

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020136979A1 (en) * 2018-12-28 2020-07-02 Ｊｘ金属株式会社 Solder joint
CN111630646A (en) * 2018-12-28 2020-09-04 Ｊｘ金属株式会社 Solder joint
JPWO2020136979A1 (en) * 2018-12-28 2021-09-09 Ｊｘ金属株式会社 Solder joint

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