JP4779710B2

JP4779710B2 - Joining method and inverter using the same

Info

Publication number: JP4779710B2
Application number: JP2006058165A
Authority: JP
Inventors: 郁朗中川; 学小澤
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2006-03-03
Filing date: 2006-03-03
Publication date: 2011-09-28
Anticipated expiration: 2026-03-03
Also published as: JP2007229801A

Description

本発明は、被接合材を接合する接合部材、その製造方法、及び接合方法であって、特に、電子部品などの接合に好適な接合部材、その製造方法、及び接合方法に関する。 The present invention relates to a joining member for joining materials to be joined, a method for producing the joining member, and a joining method, and more particularly to a joining member suitable for joining electronic components and the like, a method for producing the joining member, and a joining method.

従来から、機械装置を構成する部品を接合する際には、Ｓｎ−Ｐｂ系はんだが幅広く用いられてきたが、環境負荷物質の低減の世界的動向の中で、このＳｎ−Ｐｂ系はんだに代わるものとして、鉛（Ｐｂ）フリーの接合部材の研究、開発が活発に行われてきている。例えば、研究段階として、Ａｕ−Ｓｎ系はんだ、Ｂｉ−Ａｇ系はんだなどの高温用の鉛フリーはんだを用いた例が挙げられるが、これらのはんだは、金属間化合物を多量に含むため脆く、特にＡｕは、貴金属であるため非常に高価である。そして、このようなはんだを、半導体デバイスとベース材と（被接合材同士）の間に使用した場合には、半導体デバイスの発熱による熱応力を緩和することができず、デバイスの破壊、はんだ接続部の亀裂の発生などを引き起してしまい、信頼性の高い接合を行うことができなかった。 Conventionally, Sn-Pb solder has been widely used to join parts constituting a mechanical device. However, in the global trend of reducing environmental load substances, it replaces this Sn-Pb solder. For example, research and development of lead (Pb) -free joining members have been actively conducted. For example, as a research stage, examples using high-temperature lead-free solders such as Au-Sn solder and Bi-Ag solder can be cited, but these solders are brittle because they contain a large amount of intermetallic compounds. Since Au is a noble metal, it is very expensive. And when such solder is used between the semiconductor device and the base material (to-be-joined materials), the thermal stress due to heat generation of the semiconductor device cannot be relieved, and the device is destroyed, the solder connection This causes the occurrence of cracks in the part, and it has been impossible to perform highly reliable joining.

そこで、このような部品（被接合材）同士の接合の信頼性を高めるために、例えば粒径０．０５〜１ｍｍの、銅、アルミニウム又は樹脂からなるボール状のコア材（核材）を包囲するように、厚さ３〜５０μｍの銀及びスズの合金からなるはんだ層（被覆材）を形成したはんだ被覆ボールが提案されている。 Therefore, in order to increase the reliability of joining of such parts (materials to be joined), for example, a ball-shaped core material (core material) made of copper, aluminum or resin having a particle size of 0.05 to 1 mm is surrounded. Thus, a solder-coated ball is proposed in which a solder layer (coating material) made of an alloy of silver and tin having a thickness of 3 to 50 μm is formed.

特開２００４−１２８２６２号公報JP 2004-128262 A

特許文献１に記載の如き、はんだ被覆ボールは、２つの被接合材のうち一方の被接合材の接合面にはんだ被覆ボールを配列し、他方の被接合材の接合面を、配列したはんだ被覆ボールに当接させ、この状態で、はんだ被覆ボールのはんだ層の融点近傍まで加熱することにより、２つの被接合材を接合するものであるが、この場合、半導体デバイスなどの電子部品（被接合材）の耐熱温度を考慮して、被覆されるはんだ層の材料は、銀及びスズの合金の如く、低融点（約２２０℃程度）の材料を選定しなければならなかった。この結果、このはんだ被覆ボールのはんだ層が溶融して形成された接合部は、はんだ層に低融点の材料を用いたため高温強度を期待することはできなかった。そして、このような接合部には、電子部品の繰返し使用に伴う熱サイクルによって熱応力が作用し、該熱応力により接合部に亀裂が発生する損傷するおそれがあった。 As described in Patent Document 1, a solder-coated ball is a solder coating in which solder-coated balls are arranged on the joining surface of one of the two materials to be joined, and the joining surface of the other material to be joined is arranged. In this state, the two materials to be joined are joined by heating to the vicinity of the melting point of the solder layer of the solder-coated ball. In consideration of the heat resistant temperature of the material, a material having a low melting point (about 220 ° C.) such as an alloy of silver and tin has to be selected as the material of the solder layer to be coated. As a result, the joint portion formed by melting the solder layer of the solder-coated ball could not be expected to have high temperature strength because a low melting point material was used for the solder layer. In such a joint portion, thermal stress is applied by a thermal cycle accompanying repeated use of the electronic component, and there is a possibility that the joint portion may be cracked due to the thermal stress.

本発明は、このような問題に鑑みてなされたものであって、その目的とするところは、接合部材が、被接合材の耐熱温度よりもかなり高い融点を有する材料から構成されていたとしても、この構成材料の融点よりも低く前記耐熱温度を越えない温度条件下で被接合材を接合することが可能となり、さらには、このように接合された接合部の熱サイクルによる耐久性を確保することができる接合部材を提案することにある。 The present invention has been made in view of such problems, and the object thereof is that even if the joining member is made of a material having a melting point considerably higher than the heat resistant temperature of the material to be joined. In addition, it becomes possible to join the materials to be joined under a temperature condition that is lower than the melting point of the constituent material and does not exceed the heat-resistant temperature, and further, the durability of the joined portion thus joined is ensured by the thermal cycle. It is in proposing the joining member which can do.

このような目的を達成すべく、発明者らは、鋭意検討を重ねた結果、接合部材をナノオーダまで微細化することにより、接合部材の表面の活性は高まり、接合部材同士は結合し易くなると考えた。 In order to achieve such an object, the inventors have intensively studied and as a result, by miniaturizing the joining member to nano-order, the activity of the surface of the joining member is increased, and the joining members are easily bonded to each other. It was.

そして、発明者らは、このような考えに基づいて、微細化した接合部材を、核材と該核材の表面を被覆する被覆材とにより構成し、該核材の粒径及び被覆材の厚みが所定の範囲を満たした場合には、接合部材の群が結合した結合体（接合部）は、せん断強度などの機械的強度が向上し、熱サイクルによる耐久性を確保することができるとの新たな知見を得た。 And based on such an idea, the inventors configured a refined joining member by a core material and a covering material that covers the surface of the core material, the particle size of the core material and the covering material When the thickness satisfies a predetermined range, the joined body (joined part) in which the group of joining members is joined has improved mechanical strength such as shear strength and can secure durability by thermal cycling. I got new knowledge.

本発明は、この新たな知見に基づくものであり、本発明に係る接合部材は、被接合材同士の接合を行うための接合部材であり、該部材は、粒状の核材と、該核材の表面に被覆した被覆材とを少なくとも備えたものであって、前記接合部材の核材の粒径は、５〜１００ｎｍであり、前記接合部材の被覆材の厚みは、５〜１００ｎｍであることを特徴としている。 The present invention is based on this new knowledge, and the joining member according to the present invention is a joining member for joining materials to be joined. The member comprises a granular core material and the core material. The core material of the bonding member has a particle size of 5 to 100 nm, and the thickness of the bonding material of the bonding member is 5 to 100 nm. It is characterized by.

本発明の如き接合部材は、このような範囲の核材の粒径と被覆材の厚みにすることにより、接合部材の表面の活性を高めることができ、接合部材は結合し易くなる。その結果として、このような接合部材を介して被接合材同士の接合を行う場合には、接合部材の被覆材の融点よりも低い温度条件、具体的には被覆材の融点の絶対温度３０％程度の温度条件で、接合部材がその周りの接合部材及び被接合材に結合し、被接合材同士の接合を行うことができる。また、このような接合を行うことにより、被接合材間において接合部材の群が結合した接合部（結合体）は、核材と被覆材の融点近傍まで、耐熱性を確保することができる。 In the joining member according to the present invention, the activity of the surface of the joining member can be increased by setting the particle diameter of the core material and the thickness of the covering material in such a range, and the joining member is easily joined. As a result, when joining materials to be joined through such a joining member, the temperature condition is lower than the melting point of the covering material of the joining member, specifically, the absolute temperature of the melting point of the covering material is 30%. Under such temperature conditions, the joining member is bonded to the surrounding joining member and the material to be joined, and the materials to be joined can be joined to each other. Further, by performing such joining, the joined portion (joined body) in which the group of joining members are joined between the materials to be joined can ensure heat resistance up to the vicinity of the melting point of the core material and the covering material.

さらに、接合部材は、核材表面に上記の厚さの被膜を形成したものであるので、接合部材を複数用いて接合を行ったとしても、接合により得られた接合部内の核材が偏り集まることはなく、均一に分散される。その結果、均一分散した粒状の核材は、粒形状に起因して接合部の残留応力を緩和させると共に接合部の亀裂の進展を抑制するように作用し、熱サイクルによる接合部の強度の低下を抑制することができる。 Furthermore, since the joining member is formed by forming a coating with the above-mentioned thickness on the surface of the core material, even if the joining is performed using a plurality of joining members, the core material in the joining portion obtained by joining is unevenly gathered. It is not dispersed evenly. As a result, the uniformly dispersed granular core material acts to relieve the residual stress in the joint due to the grain shape and to suppress the progress of cracks in the joint, thereby reducing the strength of the joint due to thermal cycling. Can be suppressed.

そして、核材の粒径が５ｎｍよりも小さい場合には、粒径が小さすぎるため、核材の粒形状に起因した接合部の残留応力の緩和、接合部の亀裂進展の抑制の効果を得ることができない。また、核材の粒径が１００ｎｍよりも大きい場合には、接合部材の表面は活性を充分に高めることができないため、接合部材の結合性は低下する。さらに、被覆材の厚みが５ｎｍよりも小さい場合には、核材に対して被覆材の割合が少ないため、接合部材の結合性は低下する。また、被覆材の厚みが、１００ｎｍよりも大きい場合には、上述と同様に、接合部材の表面は活性を高めることができないため、被接合材の結合性は低下する。 And when the particle size of the core material is smaller than 5 nm, the particle size is too small, so that the effect of relaxing the residual stress at the joint due to the particle shape of the core material and suppressing the crack propagation at the joint is obtained. I can't. In addition, when the particle size of the core material is larger than 100 nm, the surface of the joining member cannot sufficiently increase the activity, so that the bonding property of the joining member is lowered. Furthermore, when the thickness of the covering material is smaller than 5 nm, the bonding material has a low bondability because the ratio of the covering material to the core material is small. Further, when the thickness of the covering material is larger than 100 nm, the surface of the joining member cannot increase the activity similarly to the above, and the bonding property of the joined material is lowered.

さらに、接合後の接合部に介在する核材の形状が保持することができるのであれば、核材の融点と被覆材の融点との関係は特に限定されるものではないが、より好ましくは、本発明に係る接合部材は、接合部材の核材の融点が、前記被覆材の融点よりも高いことが好ましい。このような融点となるように核材と被覆材とを選定した場合には、接合時に、被覆材の融点近傍まで接合部材を加熱したとしても核材の形状を保持することができ、接合により得られた接合部は上述の如き核材の作用を発揮することができる。さらに、このような核材の作用を効果的にもたらすためには、核材は、被覆材よりも、引張り強度及び硬さが高いものが好ましい。 Furthermore, the relationship between the melting point of the core material and the melting point of the coating material is not particularly limited as long as the shape of the core material interposed in the bonded portion after bonding can be maintained, but more preferably, In the joining member according to the present invention, the melting point of the core material of the joining member is preferably higher than the melting point of the covering material. When the core material and the covering material are selected so as to have such a melting point, the shape of the core material can be maintained even when the joining member is heated to the vicinity of the melting point of the covering material at the time of joining. The obtained joint can exhibit the function of the core material as described above. Furthermore, in order to effectively bring about such an action of the core material, the core material preferably has a higher tensile strength and hardness than the covering material.

また、本発明に係る接合部材の被覆材の融点は、２５０℃以上であることが好ましい。このように、被覆材の融点を、半導体デバイスなどの一般的な電子部品の耐熱温度よりも高い温度にすることにより、電子部品の信頼性を高めることができる。 Moreover, it is preferable that melting | fusing point of the coating | covering material of the joining member which concerns on this invention is 250 degreeC or more. Thus, the reliability of an electronic component can be improved by setting the melting point of the covering material to a temperature higher than the heat resistance temperature of a general electronic component such as a semiconductor device.

さらに、被覆材の融点は１５００℃以下であることがより好ましい。このように、被覆材の融点が１５００℃の被覆材を含む接合部材を用いたとしても、被覆材の融点以下の温度条件であって、かつ、一般的な電子部品の耐熱温度を超えない温度条件で、被接合材の接合を行うことができる。 Furthermore, the melting point of the covering material is more preferably 1500 ° C. or lower. As described above, even when a joining member including a coating material having a melting point of 1500 ° C. is used, the temperature is a temperature condition not higher than the melting point of the coating material and does not exceed the heat resistance temperature of a general electronic component. Under the condition, the materials to be joined can be joined.

さらに、このような核材の材料としては、金属、セラミックス、樹脂、又はこれらを組み合わせた混合物等が挙げられる。例えば、金属の場合には、Ａｌ，Ｂｉ，Ｃｒ，Ｃｕ，Ａｕ，Ｆｅ，Ｍｇ，Ｎｉ，Ｐｄ，Ｐｔ，Ａｇ，Ｔｉ，Ｚｎ等の元素のうちの一種からなる材料、これらのうち２種以上を組み合わせた材料、または、これらの合金材料などが挙げられる。また、セラミックスの場合には、アルミナ（酸化アルミニウム），シリカ，酸化チタン，窒化アルミニウム，窒化チタン，窒化ケイ素，炭化ケイ素，炭化チタン等のうち一種からなる材料又はこれらのうちの２種以上の組み合わせた材料が好ましい。さらに、樹脂の場合には、ポリイミド，ポリアミドイミド、又はこれらの混合物が好ましい。 Furthermore, examples of the material for such a core material include metals, ceramics, resins, and mixtures thereof. For example, in the case of a metal, a material composed of one of elements such as Al, Bi, Cr, Cu, Au, Fe, Mg, Ni, Pd, Pt, Ag, Ti, and Zn, and two or more of these materials Or a combination of these materials. In the case of ceramics, a material composed of one of alumina (aluminum oxide), silica, titanium oxide, aluminum nitride, titanium nitride, silicon nitride, silicon carbide, titanium carbide, or a combination of two or more of these materials. The material is preferred. Further, in the case of a resin, polyimide, polyamideimide, or a mixture thereof is preferable.

さらに、このような被覆材の材料としては、前記核材とはことなる材料であって、Ａｌ，Ｂｉ，Ｃｒ，Ｃｕ，Ａｕ，Ｆｅ，Ｍｇ，Ｎｉ，Ｐｄ，Ｐｔ，Ｓｉ，Ａｇ，Ｔｉ，Ｚｎ等の元素のうちの一種からなる材料、又はこれらのうちの２種以上を組み合わせた材料、または、エポキシ，ウレタン，アクリル，又はポリイミドなどのいずれかの樹脂であることが好ましい。特に、低温環境下で使用する場合には、エポキシ，ウレタン，アクリルが好ましく、高温環境下で使用する場合には、ポリイミドが好ましい。 Further, as a material of such a covering material, it is a material different from the above-mentioned core material, and Al, Bi, Cr, Cu, Au, Fe, Mg, Ni, Pd, Pt, Si, Ag, Ti, A material composed of one of elements such as Zn, a material combining two or more of these, or any resin such as epoxy, urethane, acrylic, or polyimide is preferable. In particular, epoxy, urethane, and acrylic are preferable when used in a low temperature environment, and polyimide is preferable when used in a high temperature environment.

そして、核材と被覆材との最適な材料の組み合わせとしては、まず、接合後に得られる接合部の使用環境（たとえば温度）に応じて選定しなければならない。また、熱サイクルにより、接合部の核材の界面からクラックが発生することを抑制すべく、核材と被覆材との熱膨張係数の差が小さい材料を選定することが好ましい。さらに、核材と被覆材の元素が相互に拡散して、核材と被覆材との界面強度を向上させることができるような材料を選定することが好ましい。 And as an optimal material combination of a core material and a coating | covering material, you must select first according to the use environment (for example, temperature) of the junction part obtained after joining. Moreover, it is preferable to select a material having a small difference in thermal expansion coefficient between the core material and the coating material in order to suppress the occurrence of cracks from the interface of the core material at the joint due to the thermal cycle. Furthermore, it is preferable to select a material that can improve the interfacial strength between the core material and the covering material by diffusing the elements of the core material and the covering material.

以上の点を考慮すると、核材と被覆材との材料のより好ましい組み合わせは、核材が、酸化アルミニウムからなり、被覆材が、ニッケルからなる組み合わせである。このような材料を選択することにより、酸化アルミニウムとニッケルが、核材と被覆材との界面において相互拡散し、界面の強度を向上させることができる。さらに、接合後の接合部は、アルミニウムとニッケルの熱膨張率が近いため、これら材料の熱膨張差の影響を受け難い。そして、接合により得られた接合部は、従来使用されているＰｂ‐Ｓｎ系はんだからなる接合部よりも機械的強度が高く、熱サイクルによる耐久性に優れている。 Considering the above points, a more preferable combination of the material of the core material and the covering material is a combination in which the core material is made of aluminum oxide and the covering material is made of nickel. By selecting such a material, aluminum oxide and nickel can be interdiffused at the interface between the core material and the covering material, and the strength of the interface can be improved. Furthermore, since the joint portions after joining are close in thermal expansion coefficient between aluminum and nickel, they are hardly affected by the difference in thermal expansion between these materials. And the joining part obtained by joining has higher mechanical strength than the joining part which consists of Pb-Sn type solder conventionally used, and is excellent in durability by a thermal cycle.

さらに本発明は、前記接合部材を製造するに好適な製造方法をも以下に開示する。本発明に係る接合部材の製造方法は、被接合材同士の接合を行うための接合部材の製造方法であって、前記製造方法は、粒径５〜１００ｎｍの粒状の核材の表面に、厚さ５〜１００ｎｍの被覆材を被覆することを特徴としている。 Furthermore, this invention also discloses the manufacturing method suitable for manufacturing the said joining member below. The method for manufacturing a joining member according to the present invention is a method for producing a joining member for joining materials to be joined, and the manufacturing method is performed on the surface of a granular core material having a particle size of 5 to 100 nm. It is characterized by coating a 5-100 nm coating material.

このような核材に被覆材を被覆する方法としては、例えば、核材となる粉末を被覆材の材料により鍍金する方法が挙げられる。また、別の被覆する方法としては、界面活性作用を利用して被覆材の元素を含む化合物を核材の周りに凝集させ、凝集した化合物を加熱することにより加水分解し、無水物となった化合物を被覆材として核材に形成させる方法などが挙げられる。そして、被覆材が上記の如き厚さの範囲を満たすことができるのであれば、その被覆方法は特に限定されるものではないが、より簡易的に被覆材の厚みを調整して、核材の表面に被覆材を被覆するためには、このような被覆方法を化学気相成長法（ＣＶＤ）または物理気相成長法（ＰＶＤ）により行うことがより好ましい。 As a method of coating the core material with such a coating material, for example, a method of plating a powder serving as the core material with a material of the coating material can be mentioned. As another coating method, the compound containing the element of the coating material is aggregated around the core material by utilizing the surface active action, and the aggregated compound is hydrolyzed by heating to become an anhydride. Examples thereof include a method of forming a compound on a core material as a coating material. If the covering material can satisfy the thickness range as described above, the coating method is not particularly limited, but the thickness of the covering material can be adjusted more simply by adjusting the thickness of the covering material. In order to coat the surface with a coating material, it is more preferable to perform such a coating method by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

また、接合部材の製造方法において、核材の融点が、前記被覆材の融点よりも高いことが好ましい。このような核材と被覆材とを選定することにより、たとえ、被覆材となる材料を溶融して核材に鍍金を行った場合、又は、スパッタリングなどのＰＶＤにより被覆した場合であっても、核材は溶融することなく、その形状を保持することができる。このような条件を満たす接合部材の製造方法として、核材に酸化アルミニウムを用い、前記被覆材にニッケルを用いることがより好ましい。また、接合部の使用環境を考慮すると、前記被覆材の融点は、２５０℃以上であることがより好ましい。 Moreover, in the manufacturing method of a joining member, it is preferable that melting | fusing point of a core material is higher than melting | fusing point of the said coating | covering material. By selecting such a core material and a covering material, even if the core material is plated by melting the material to be the covering material, or even when coated by PVD such as sputtering, The core material can maintain its shape without melting. As a method for manufacturing a joining member that satisfies such conditions, it is more preferable to use aluminum oxide as the core material and nickel as the covering material. Moreover, when the use environment of a junction part is considered, it is more preferable that melting | fusing point of the said covering material is 250 degreeC or more.

さらに、本発明は上述した如き接合部材を用いて、被接合材の接合面同士を接合するに好適な接合方法についても開示する。前記接合部材を介して、被接合材の接合面同士を接合する接合方法であって、少なくとも一方の前記接合面に複数の前記接合部材を配置する工程と、前記接合面同士が対向するように前記被接合材を配置する工程と、前記対向した接合面により前記接合部材を加圧すると共に前記接合部材を加熱しながら前記接合面同士を接合する工程と、を含むことを特徴としている。 Furthermore, the present invention also discloses a joining method suitable for joining the joining surfaces of the materials to be joined using the joining member as described above. A bonding method for bonding bonded surfaces of materials to be bonded to each other via the bonding member, the step of arranging a plurality of the bonding members on at least one of the bonding surfaces, and the bonding surfaces facing each other. A step of arranging the material to be joined, and a step of pressurizing the joining member by the opposed joining surfaces and joining the joining surfaces while heating the joining member.

このような加圧は、接合部材が接合するためのエネルギーを接合部材に与え、この加圧によるエネルギーと、ナノオーダにまで微細化された接合部材の表面エネルギーとにより、接合時における加熱温度を低く設定することができる。 Such pressurization gives the joining member energy for joining, and the heating temperature at the time of joining is lowered by the energy by this pressurization and the surface energy of the joining member refined to nano-order. Can be set.

そして、接合面に複数の前記接合部材を配置する方法としては、たとえば、複数の接合部材をスプレーなどにより接合面に噴霧する方法、複数の接合部材を溶媒中に分散させた液体を接合面に噴霧後、接合面を加熱して溶媒を除去する方法、接合部材を溶媒中に分散させたペーストを接合面に塗布後、接合面を加熱して溶媒を除去する方法、などが挙げられる。 And as a method of arrange | positioning the said some joining member on a joining surface, the method of spraying a some joining member on a joining surface by spray etc., for example, the liquid which disperse | distributed the some joining member in the solvent is used for a joining surface Examples include a method of removing the solvent by heating the bonding surface after spraying, and a method of removing the solvent by heating the bonding surface after applying the paste in which the bonding member is dispersed in the solvent to the bonding surface.

さらに、接合面同士を接合する工程において、接合部材への加圧力は大きい方が、加熱温度を低くすることができるので好ましいが、接合部材への加圧力は、被接合材の材料強度等を考慮して調整されるとよい。また、このような接合部材は、被覆材の融点よりも低い温度条件、具体的には被覆材の融点の絶対温度の３０％程度の温度条件で、被接合材同士を接合することができるので、被接合材に過大な熱負荷与えないためにも、接合部材の加熱は、前記被覆材の融点よりも低い温度条件で加熱されることがより好ましい。 Further, in the step of joining the joining surfaces, it is preferable that the pressure applied to the joining member is large because the heating temperature can be lowered. However, the pressure applied to the joining member is not limited to the material strength of the material to be joined. It is good to adjust in consideration. Moreover, since such a joining member can join the materials to be joined under a temperature condition lower than the melting point of the covering material, specifically about 30% of the absolute temperature of the melting point of the covering material. In order not to give an excessive heat load to the material to be joined, it is more preferable that the joining member is heated under a temperature condition lower than the melting point of the covering material.

そして、これらの接合方法は、耐熱温度が２００〜３００℃程度と低く、熱サイクルによる耐久性を持続することが必要とされるインバータなどの電子機器に使用されることが好ましい。具体的には、接合方法により接合面同士を接合した被接合材を備えたインバータであって、一方の被接合材は、前記インバータを構成する半導体デバイスであり、他方の被接合材は、前記インバータを構成するベース材であることが好ましい。 These joining methods are preferably used for electronic devices such as inverters that have a heat resistant temperature as low as about 200 to 300 ° C. and need to maintain durability by thermal cycling. Specifically, it is an inverter provided with a material to be joined that are joined together by a joining method, wherein one material to be joined is a semiconductor device constituting the inverter, and the other material to be joined is It is preferable that it is a base material which comprises an inverter.

本発明によれば、接合部材が、被接合材の耐熱温度よりも高い融点を有する材料から構成されていたとしても、この構成材料の融点よりも低く前記耐熱温度を越えない温度条件下で被接合材を接合することが可能となり、さらには、このように接合された接合部の熱サイクルによる耐久性を確保することができる。 According to the present invention, even if the joining member is made of a material having a melting point higher than the heat resistant temperature of the material to be joined, the joining member is covered under a temperature condition that is lower than the melting point of the constituent material and does not exceed the heat resistant temperature. It becomes possible to bond the bonding material, and further, it is possible to ensure the durability of the bonded portion bonded in this way by thermal cycling.

以下、図面に基づき本発明に係る被接合材の接合方法を好適に行うことができる接合部材の一実施形態について説明する。図１は、本実施形態に係る接合部材の全体構成図であり、図２は、この接合部材を用いた被接合材の接合方法を説明するための図である。 DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a joining member that can suitably perform a joining method for materials to be joined according to the invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a joining member according to the present embodiment, and FIG. 2 is a diagram for explaining a joining method of materials to be joined using the joining member.

図２に示すように、本実施形態に係る接合部材１は、被接合材２１，２２同士の接合を行うための接合部材であり、図１に示すように、粒状の核材１１と、該核材を被覆する被覆材１２とを少なくとも備えている。そして、この接合部材１の核材１１の粒径は、５〜１００ｎｍの範囲にあり、接合部材１の被覆材１２の厚みは、５〜１００ｎｍの範囲にある。さらに、この核材の融点は、前記被覆材の融点よりも高くなるように、核材と被覆材の材料が選定されており、さらに、被覆材の融点が、２５０℃〜１５００℃の範囲となるように、被覆材の材料が選定されている。 As shown in FIG. 2, the joining member 1 according to the present embodiment is a joining member for joining the materials to be joined 21 and 22, and as shown in FIG. And a covering material 12 for covering the core material. And the particle size of the core material 11 of this joining member 1 exists in the range of 5-100 nm, and the thickness of the coating | covering material 12 of the joining member 1 exists in the range of 5-100 nm. Furthermore, the material of the core material and the covering material is selected so that the melting point of the core material is higher than the melting point of the covering material, and the melting point of the covering material is in the range of 250 ° C to 1500 ° C. Thus, the material of the covering material is selected.

そして、このような接合部材１は、複数の部材１，１，・・・として、図２（ａ）に示すように、被接合材２１，２２のいずれか一方の接合面２１ａ，２２ａに配置され、被接合材２１，２２の接合面２１ａ，２２ａ同士が対向するように被接合材２１，２２を配置し、さらに対向した接合面２１ａ，２２ａにより接合部材１，１，・・・を加圧すると共に接合部材１，１，・・・を加熱しながら接合面２１ａ，２２ａ同士を接合する。このようにして接合された被接合材２１，２２の間には、図２（ｂ）に示すように、接合部材１の被覆材１２同士が焼結により結合して接合部１０を形成するので、この接合部１０には、核材１１が均一に分散されることになる。 And such a joining member 1 is arrange | positioned on any one joining surface 21a, 22a of the to-be-joined materials 21 and 22 as shown to Fig.2 (a) as several member 1,1, .... Then, the materials 21 and 22 are disposed so that the bonding surfaces 21a and 22a of the materials 21 and 22 are opposed to each other, and the bonding members 1, 1,. The joining surfaces 21a and 22a are joined together while pressing and heating the joining members 1, 1,. As shown in FIG. 2 (b), the covering materials 12 of the bonding member 1 are bonded together by sintering to form the bonded portion 10 between the bonded materials 21 and 22 bonded in this way. The core material 11 is uniformly dispersed in the joint 10.

このような、ナノオーダ範囲の核材１１の粒径と被覆材１２の厚みとなるように接合部材１を介して被接合材２１，２２の接合面２１ａ，２２ａを接合する場合には、接合部材１の表面の活性が高いため、被覆材１２の融点よりも低い温度で、被接合材同士を接合することができる。そして、接合後の接合部１０は、この核材１１と被覆材１２の融点近傍まで、耐熱性を確保することができる。さらに、接合部１０の粒状の核材１１が、接合部１０の残留応力を緩和し、接合部１０の亀裂の進展を抑制し、接合部１０の機械的強度を向上させることができる。 In the case where the joining surfaces 21a and 22a of the materials 21 and 22 to be joined are joined via the joining member 1 so as to have the particle size of the core material 11 in the nano-order range and the thickness of the covering material 12, Since the surface activity of 1 is high, the materials to be joined can be joined at a temperature lower than the melting point of the covering material 12. And the joined part 10 after joining can ensure heat resistance to the melting | fusing point vicinity of this core material 11 and the coating | covering material 12. FIG. Furthermore, the granular core material 11 of the joint 10 can relieve the residual stress of the joint 10, suppress the progress of cracks in the joint 10, and improve the mechanical strength of the joint 10.

なお、図１に示すように、本実施形態に係る接合部材１の核材１１は球形であり、接合部材１の被覆材１２の厚さは略一定であるが、この核材１１は粒状であればその形状は特に限定されず、被覆材１２の厚さも、このような厚さの範囲内にあるのであれば、その厚さも一定である必要はない。 As shown in FIG. 1, the core material 11 of the joining member 1 according to the present embodiment is spherical, and the thickness of the covering material 12 of the joining member 1 is substantially constant, but the core material 11 is granular. If it exists, the shape will not be specifically limited, If the thickness of the coating | covering material 12 exists in the range of such thickness, the thickness does not need to be constant.

本実施形態による実施例を以下に説明する。
［実施例１］
＜被接合材＞
被接合材として、図３に示すような直径ｄ５ｍｍ、高さｈ２ｍｍの小径円柱片２１（無酸素銅）、及び直径Ｄ１０ｍｍ、高さＨ５ｍｍの大径円柱片２２（無酸素銅）を製作した。 Examples according to the present embodiment will be described below.
[Example 1]
<Material to be joined>
As the materials to be joined, a small-diameter cylindrical piece 21 (oxygen-free copper) having a diameter d5 mm and a height h2 mm as shown in FIG. 3 and a large-diameter cylindrical piece 22 (oxygen-free copper) having a diameter D10 mm and a height H5 mm were manufactured.

＜接合部材＞
この２つの円柱片の端面を接合面として接合を行うための接合部材として、図１に示すような粒状の核材１１と、該核材１１を被覆する被覆材１２とを備えた接合部材１を製作した。具体的には、以下の表１の（○）に示す如き核材１１の粒径と被覆材１２の厚みの組み合わせとなるように、接合部材１の核材１１にアルミナ（酸化アルミニウム）を用い、接合部材１の被覆材１２にニッケルを用い、核材の粒径を５〜１００ｎｍの範囲とし（具体的には粒径が５ｎｍ，６０ｎｍ，１００ｎｍのいずれかの粒径とし）、この核材の表面に、ニッケル金属ターゲットを用いたアンバランスドマグネトロンスパッタリング装置（神戸製鋼所製）を用いて、物理気相成長法（ＰＶＤ）によりスパッタリングを行い、核材の表面に、被覆材の厚みが５〜１００ｎｍの範囲となるように（具体的には、被覆材の厚みが５ｎｍ，３０ｎｍ，６０ｎｍ，１００ｎｍのいずれかの被覆材の厚みとなるように）、被覆材を形成した。 <Joint member>
As a joining member for joining the end faces of the two cylindrical pieces as joining surfaces, a joining member 1 including a granular core material 11 as shown in FIG. 1 and a covering material 12 covering the core material 11. Was made. Specifically, alumina (aluminum oxide) is used for the core material 11 of the joining member 1 so as to be a combination of the particle size of the core material 11 and the thickness of the covering material 12 as shown in (◯) of Table 1 below. In addition, nickel is used for the covering material 12 of the joining member 1 and the particle size of the core material is set in the range of 5 to 100 nm (specifically, the particle size is any one of 5 nm, 60 nm, and 100 nm). Sputtering is performed by physical vapor deposition (PVD) using an unbalanced magnetron sputtering apparatus (manufactured by Kobe Steel) using a nickel metal target, and the thickness of the coating material is The covering material was formed so as to be in the range of 5 to 100 nm (specifically, the thickness of the covering material was 5 nm, 30 nm, 60 nm, or 100 nm).

＜接合方法＞
これら接合部材のうち１つを選択し、エタノール溶媒中に複数の接合部材を分散してペースト状にして、前述した小径円柱片２１の端面（接合面）に塗布し、大気中１００℃×３０分で溶媒を除去した。さらに、真空条件下で、接合部材が塗布された小径円柱片２１の端面と大径円柱片２２の端面とを対向させて、接合部材を圧力５ＭＰａで加圧すると共に、接合部材の温度が３００℃になるように加熱した。そして、接合部材からなる接合部１０の厚さが５０μｍとなるように、小径円柱片２１と大径円柱片２２とを接合し、図３に示すような、試験片を製作した。 <Join method>
One of these joining members is selected, and a plurality of joining members are dispersed in an ethanol solvent to form a paste, which is applied to the end surface (joining surface) of the small-diameter cylindrical piece 21 described above, and is 100 ° C. × 30 in the atmosphere. The solvent was removed in minutes. Further, under vacuum conditions, the end surface of the small-diameter columnar piece 21 coated with the bonding member and the end surface of the large-diameter columnar piece 22 are opposed to each other and pressurize the bonding member at a pressure of 5 MPa, and the temperature of the bonding member is 300 ° C. It was heated to become. And the small diameter cylindrical piece 21 and the large diameter cylindrical piece 22 were joined so that the thickness of the junction part 10 which consists of a joining member might be 50 micrometers, and the test piece as shown in FIG. 3 was manufactured.

＜性能評価試験１（せん断強度測定試験）＞
図３に示す試験片の大径円柱片側を保持し、接合した小径円柱片２１の側面に荷重を負荷させて、試験片の接合部１０にせん断力を与え、接合部１０のせん断強度の測定を行った。この結果を表１に示す。 <Performance evaluation test 1 (shear strength measurement test)>
The test piece shown in FIG. 3 is held on the side of the large-diameter cylindrical piece, a load is applied to the side surface of the joined small-diameter cylindrical piece 21, a shearing force is applied to the joint 10 of the test piece, and the shear strength of the joint 10 is measured. Went. The results are shown in Table 1.

＜性能評価試験２（冷熱サイクル耐久試験）＞
さらに、上記と同様の試験片を製作し、この試験片を４０℃〜２５０℃に加熱しさらに２５０℃〜４０℃に冷却する工程を１サイクルとし、このサイクルを１０００サイクル繰り返した。そして、この試験後の接合部の組織観察及び上記と同様のせん断強度測定試験を行った。この結果を以下の表２に示す。 <Performance evaluation test 2 (cooling cycle endurance test)>
Further, a test piece similar to the above was manufactured, and the process of heating the test piece to 40 ° C. to 250 ° C. and further cooling to 250 ° C. to 40 ° C. was defined as one cycle, and this cycle was repeated 1000 cycles. And the structure | tissue observation of the junction part after this test and the shear strength measurement test similar to the above were done. The results are shown in Table 2 below.

［比較例１］
実施例１と同じようにして試験片の製作を行った。実施例１と異なる点は、表１の（●）に示す如き核材の粒径と被覆材の厚みの組み合わせとなるようにして、接合部材を製作した。具体的には、前述した実施例の接合部材のうち、核材の粒径又は被覆材の厚みのいずれか一方又は双方を３ｎｍ（５ｎｍよりも小さく）した接合部材、核材の粒径又は被覆材の厚みのいずれか一方又は双方を１５０ｎｍ（１００ｎｍよりも大きく）した接合部材、または、核材の粒径又は被覆材の厚みのいずれか一方を３ｎｍとし、他方を１５０ｎｍにした接合部材を製作した。そして、これらの接合部材を用いて実施例１と同様の接合方法により試験片を製作し、せん断強度測定試験を行った。この結果を表１に示す。 [Comparative Example 1]
A test piece was produced in the same manner as in Example 1. The difference from Example 1 was that the joining member was manufactured so as to have a combination of the particle size of the core material and the thickness of the coating material as shown in (●) of Table 1. Specifically, among the joining members of the above-described embodiments, a joining member in which one or both of the particle size of the core material and the thickness of the coating material are 3 nm (smaller than 5 nm), the particle size of the core material, or the coating Produces a bonded member with either or both of the material thicknesses set to 150 nm (greater than 100 nm), or a bonded member with either the particle size of the core material or the thickness of the coating material set to 3 nm and the other set to 150 nm. did. And using these joining members, the test piece was manufactured by the joining method similar to Example 1, and the shear strength measurement test was done. The results are shown in Table 1.

［比較例２］
実施例１と同じ被接合材を用いて、試験片を製作した。実施例１と異なる点は、接合部材の代わりにＳｎ−Ｐｂ系の高温はんだを用いて試験片を接合した点である。そして、実施例と同じように、せん断強度測定試験及び冷熱サイクル耐久試験をおこなった。この結果を表１及び表２に示す。 [Comparative Example 2]
A test piece was manufactured using the same material to be joined as in Example 1. The difference from Example 1 is that the test piece was joined using Sn-Pb high temperature solder instead of the joining member. And the shear strength measurement test and the thermal cycle durability test were done like the Example. The results are shown in Tables 1 and 2.

［結果］
表１に示すように、比較例１，２に比べて、実施例１の試験片のせん断強度は高かった。また、比較例１の試験片のせん断強度は、比較例２に比べて、低かった。表２に示すように、比較例２に比べて、実施例１の冷熱サイクル耐久試験後のせん断強度の低下はほとんどなかった。さらに、比較例２の冷熱サイクル耐久試験後の試験片の接合部には、大きな亀裂が発生していたが、実施例１の試験片の接合部には、損傷はみられなかった。 [result]
As shown in Table 1, the shear strength of the test piece of Example 1 was higher than that of Comparative Examples 1 and 2. Further, the shear strength of the test piece of Comparative Example 1 was lower than that of Comparative Example 2. As shown in Table 2, compared to Comparative Example 2, there was almost no decrease in shear strength after the cold cycle endurance test of Example 1. Furthermore, although a large crack occurred in the joint portion of the test piece after the thermal cycle durability test of Comparative Example 2, no damage was observed in the joint portion of the test piece of Example 1.

［考察］
このような結果から、実施例の試験片１は、被覆材の融点よりも低い３００℃の温度条件（被覆材の融点の絶対温度３０％程度の温度条件）下で接合したにもかかわらず、たとえ、接合温度に近い温度である２５０℃の熱サイクルを接合部に加えたとしても、安定した接合状態が維持可能であることがわかった。これは、実施例１の接合部材の如く、核材の粒径を、５〜１００ｎｍとし、被覆材の厚みを、５〜１００ｎｍと、ナノオーダの大きさの粒子としたことにより、接合部材が結合し易くなったことによると考えられる。さらに、この接合部に介在した核材により、接合部の残留応力の緩和、接合部の亀裂進展の抑制が可能となり、熱サイクルにより機械的強度の低下が低減され、耐久性が向上したと考えられる。 [Discussion]
From such a result, although the test piece 1 of the example was joined under a temperature condition of 300 ° C. lower than the melting point of the coating material (temperature condition of about 30% of the absolute temperature of the melting point of the coating material), Even if a thermal cycle of 250 ° C., which is a temperature close to the bonding temperature, is applied to the bonded portion, it has been found that a stable bonded state can be maintained. This is because, as in the joining member of Example 1, the core member has a particle size of 5 to 100 nm, and the coating material has a thickness of 5 to 100 nm, which is a nano-order particle. This is thought to be because it became easier to do. Furthermore, the core material intervening in the joint makes it possible to relieve the residual stress in the joint and suppress the crack growth in the joint, and the decrease in mechanical strength due to thermal cycling is considered to have improved durability. It is done.

そして、比較例１の試験片のうち核材の粒径が５ｎｍよりも小さいものは、核材の粒形状に起因した接合部の残留応力の緩和、接合部の亀裂進展の抑制の効果を得ることができず、核材の大きさが１００ｎｍよりも大きいものは、接合部材の表面が活性を高めることができないため、接合部材同士が結合し難く、実施例１よりもせん断強度（機械的強度）が小さくなったものと考えられる。 And the thing whose particle size of a core material is smaller than 5 nm among the test pieces of the comparative example 1 obtains the effect of relaxation of the residual stress of a junction resulting from the grain shape of a nucleus, and the suppression of the crack progress of a junction. In the case where the size of the core material is larger than 100 nm, the surface of the joining member cannot increase the activity, so that the joining members are not easily bonded to each other, and the shear strength (mechanical strength) is higher than that of Example 1. ) Is considered to be smaller.

さらに、比較例１の試験片のうち被覆材の厚みが５ｎｍよりも小さいものは、接合部材同士を結合する被覆材の割合が少ないため充分なせん断強度を得ることができず、被覆材の厚みが１００ｎｍよりも大きいものは、接合部材の表面は活性を充分に高めることができないため、接合部材同士が結合し難く、実施例１よりもせん断強度が小さくなったものと考えられる。 Furthermore, among the test pieces of Comparative Example 1, the coating material having a thickness of less than 5 nm cannot obtain sufficient shear strength because the ratio of the coating material that bonds the joining members to each other is small. When the thickness is larger than 100 nm, the surface of the bonding member cannot sufficiently increase the activity, and thus the bonding members are difficult to bond with each other, and it is considered that the shear strength is smaller than that of Example 1.

なお、実施例１においては、核材の材料にアルミナ、被覆材の材料に、ニッケルを用いたが、この接合部のせん断強度の向上には、核材の粒径及び被覆材の厚みが大きく起因しているため、例えば、核材に金属合金、セラミックス、樹脂を用いても良く、被覆材としては、所望のせん断強度を含む接合強度が確保できるのであれば、他の金属，またはその合金，樹脂であっても同様の効果を期待することができると考えられる。 In Example 1, alumina was used as the core material and nickel was used as the coating material. However, in order to improve the shear strength of the joint, the particle size of the core material and the thickness of the coating material were increased. Therefore, for example, a metal alloy, ceramics, or resin may be used as the core material, and as the coating material, other metals or alloys thereof may be used as long as a bonding strength including a desired shear strength can be secured. It is considered that the same effect can be expected even with a resin.

本発明の如き接合部材は、低温条件下で接合することができ、接合により形成された接合部は、高温環境下においても耐久性を確保することができるので、例えば、インバータを構成する半導体デバイスとそのベース材との接合を行う際に利用されることが好ましい。 The joining member according to the present invention can be joined under a low temperature condition, and the joined portion formed by joining can ensure durability even in a high temperature environment. For example, a semiconductor device constituting an inverter It is preferable to be used when joining with the base material.

本実施形態に係る接合部材の全体構成図。The whole block diagram of the joining member concerning this embodiment. （ａ）は、図１に示す接合部材を被接合材に配置した模式図であり、（ｂ）は、（ａ）の状態で、接合面により前記接合部材を加圧すると共に前記接合部材を加熱しながら接合面同士を接合して得られた接合部の模式図。(A) is the schematic diagram which has arrange | positioned the joining member shown in FIG. 1 to a to-be-joined material, (b) is a state of (a), pressurizes the said joining member with a joining surface, and heats the said joining member. The schematic diagram of the junction part obtained by joining joining surfaces, joining. 実施例１及び比較例１，２の試験片を示した模式図。The schematic diagram which showed the test piece of Example 1 and Comparative Examples 1 and 2. FIG.

符号の説明Explanation of symbols

１：接合部材，１０：接合部，１１：核材，１２：被覆材，２１，２２：被接合材，２１ａ，２２ａ：接合面 DESCRIPTION OF SYMBOLS 1: Joining member, 10: Joining part, 11: Core material, 12: Coating | covering material, 21 and 22: To-be-joined material, 21a, 22a: Joining surface

Claims

被接合材同士の接合を行うための接合部材を介して、被接合材の接合面同士を接合する接合方法であって、
前記接合部材として、粒状の核材と、該核材の表面に被覆した被覆材とを少なくとも備え、前記核材の融点は、前記被覆材の融点よりも高く、前記接合部材の核材の粒径は、５〜１００ｎｍであり、前記接合部材の被覆材の厚みは、５〜１００ｎｍである接合部材を用い、
少なくとも一方の前記接合面に複数の前記接合部材を配置する工程と、前記接合面同士が対向するように前記被接合材を配置する工程と、前記対向した接合面により前記接合部材を加圧すると共に、前記被覆材の融点よりも低い温度条件で前記接合部材を加熱しながら前記接合面同士を接合する工程と、を含むことを特徴とする接合方法。 A joining method for joining the joining surfaces of the materials to be joined together via a joining member for joining the materials to be joined,
The joining member includes at least a granular core material and a coating material coated on the surface of the core material, the melting point of the core material being higher than the melting point of the coating material, and the core material grains of the joining member The diameter is 5 to 100 nm, and the thickness of the covering material of the joining member is 5 to 100 nm .
A step of arranging a plurality of the joining members on at least one of the joining surfaces, a step of arranging the material to be joined so that the joining surfaces face each other, and pressurizing the joining member by the facing joining surfaces And joining the joining surfaces while heating the joining member under a temperature condition lower than the melting point of the covering material .

前記被覆材の融点が、２５０℃以上である被覆材を用いることを特徴とする請求項１に記載の接合方法。 The joining method according to claim 1 , wherein a covering material having a melting point of 250 ° C. or higher is used .

前記核材に、酸化アルミニウムを用い、前記被覆材に、ニッケルを用いることを特徴とする請求項１または２に記載の接合方法。 The core material, using the aluminum oxide, the coating material bonding method according to claim 1 or 2, characterized in that nickel is used.

請求項１〜３のいずれかに記載の接合方法により接合面同士を接合した被接合材を備えたインバータであって、前記一方の被接合材は、前記インバータを構成する半導体デバイスであり、前記他方の被接合材は、前記インバータを構成するベース材であることを特徴とするインバータ。 It is an inverter provided with the to-be-joined material which joined the joining surfaces by the joining method in any one of Claims 1-3, Comprising : Said one to-be-joined material is a semiconductor device which comprises the said inverter, The other material to be joined is a base material constituting the inverter.