JP6111952B2 - Lead-free solder alloy, bonding material and bonded body - Google Patents
Lead-free solder alloy, bonding material and bonded body Download PDFInfo
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- JP6111952B2 JP6111952B2 JP2013199016A JP2013199016A JP6111952B2 JP 6111952 B2 JP6111952 B2 JP 6111952B2 JP 2013199016 A JP2013199016 A JP 2013199016A JP 2013199016 A JP2013199016 A JP 2013199016A JP 6111952 B2 JP6111952 B2 JP 6111952B2
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
- B23K35/264—Bi as the principal constituent
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Description
本発明は、無鉛はんだ合金、接合材及び接合体に関するものであり、特にＳｎ−Ｂｉ系の無鉛はんだ合金、当該無鉛はんだ合金を用いた接合材及び当該接合材により接合された接合体に関するものである。 The present invention relates to a lead-free solder alloy, a bonding material, and a bonded body, and more particularly to a Sn-Bi-based lead-free solder alloy, a bonding material using the lead-free solder alloy, and a bonded body bonded by the bonding material. is there.
有鉛はんだであるＳｎ−Ｐｂ系はんだ合金は、融点が適度であり（Ｓｎ−３７質量％Ｐｂで融点１８３℃）、濡れ性に優れ、価格も安い。しかし、毒性のあるＰｂが使われており、またクリープ特性が悪いため、耐疲労特性に劣るという問題点がある。 The Sn—Pb solder alloy, which is a leaded solder, has an appropriate melting point (Sn-37 mass% Pb, melting point 183 ° C.), excellent wettability, and low price. However, since toxic Pb is used and the creep characteristics are poor, there is a problem that the fatigue resistance is inferior.
一方、無鉛はんだとしては、代表的なものにＳｎ−Ａｇ−Ｃｕ系はんだ合金がある。Ｓｎ−Ｐｂ系はんだ合金より耐疲労特性に優れるが、高価なＡｇを含むため価格が高いという欠点がある。また、融点もＳｎ−Ｐｂ系はんだ合金より高く（Ｓｎ−３Ａｇ−０．５Ｃｕで融点２２０℃）、応力緩和しにくいため、熱膨張率が大きく違う材料の接合（例えばＣｕ導体とメタライズされたＳｉなど）においては、はんだ付け後の冷却過程で熱応力が大きくなりやすく、部品が破損するという問題点がある。 On the other hand, as a typical lead-free solder, there is a Sn-Ag-Cu solder alloy. Although it is more excellent in fatigue resistance than Sn—Pb solder alloys, it has the disadvantage that it is expensive because it contains expensive Ag. In addition, since the melting point is higher than that of Sn-Pb solder alloy (Sn-3Ag-0.5Cu, melting point 220 ° C.), it is difficult to relieve stress. Etc.), there is a problem that the thermal stress tends to increase in the cooling process after soldering, and the parts are damaged.
従来の有鉛はんだより低融点の無鉛はんだとしては、Ｓｎ−Ｉｎ系（Ｓｎ−５１質量％Ｉｎで融点１２０℃）及びＳｎ−Ｂｉ系（Ｓｎ−５７質量％Ｂｉで融点１３９℃）のはんだ合金がある。Ｓｎ−Ｉｎ系はんだ合金は、耐疲労特性に優れるが、高価なＩｎを多く含むため、価格が非常に高い。ゆえに、現在、有鉛はんだよりも融点の低い無鉛はんだで、コストを抑えることができるものはＳｎ−Ｂｉ系はんだ合金しかない。 Lead-free solder having a melting point lower than that of conventional leaded solder includes Sn—In (Sn-51 mass% In melting point: 120 ° C.) and Sn—Bi (Sn-57 mass% Bi melting point: 139 ° C.) solder alloys. There is. Sn—In solder alloys are excellent in fatigue resistance, but are expensive because they contain a lot of expensive In. Therefore, at present, the only lead-free solder having a melting point lower than that of leaded solder and capable of reducing the cost is Sn-Bi solder alloy.
接合温度の低温化は、はんだ接合時の熱応力を下げることができることから、実装基板の反りを抑え、高密度化、薄型化を可能とする。また、熱に弱い部品の接合では必須の要件である。 Lowering the bonding temperature can reduce the thermal stress at the time of solder bonding, so that the warping of the mounting substrate can be suppressed, and the density and thickness can be reduced. It is also an essential requirement for joining heat-sensitive components.
Ｓｎ−Ｂｉ系はんだ合金としては、例えば、非特許文献１に、Ｓｎ−Ｂｉ共晶はんだにＡｇ、Ｃｕ、Ｚｎ、Ｓｂを０．５質量％加えた時の破断伸びを調査した結果が記載されている。しかし、前述したようにＡｇの添加はコスト上昇の要因となるため望ましくない。また、Ｓｂの添加は現時点で法規制されていないが、Ｐｂより毒性が強いことが、動物実験の結果で分かっており、添加は極力避けるべきである。 As the Sn-Bi based solder alloy, for example, Non-Patent Document 1 describes the results of investigating the elongation at break when Ag, Cu, Zn, Sb is added by 0.5 mass% to Sn-Bi eutectic solder. ing. However, as described above, addition of Ag is not desirable because it causes an increase in cost. Although addition of Sb is not currently regulated by law, it is known from animal experiments that it is more toxic than Pb and should be avoided as much as possible.
また、特許文献１には、Ｓｎ−Ｂｉ系はんだ合金として、Ｓｎ−Ｂｉ−Ｎｉ及びＳｎ−Ｂｉ−Ｃｕ−Ｎｉを基本組成とし、さらにＧｅ、Ｇａ、Ｐから選択される１種以上の元素を添加したはんだ合金について開示されている。当該はんだ合金は、はんだ接合部界面にＮｉＡｓ型結晶構造に代表される六方最密充填構造（稠密六方格子）を有する金属間化合物を形成させることを特徴としている。 In Patent Document 1, Sn-Bi-based solder alloy includes Sn-Bi-Ni and Sn-Bi-Cu-Ni as a basic composition, and one or more elements selected from Ge, Ga, and P. An added solder alloy is disclosed. The solder alloy is characterized in that an intermetallic compound having a hexagonal close-packed structure (dense hexagonal lattice) typified by a NiAs type crystal structure is formed at the interface of the solder joint.
銅及び銅合金とはんだの界面には一般的にＣｕ６Ｓｎ５金属間化合物層が形成される。Ｃｕ６Ｓｎ５は、高温では六方晶であるが、低温では斜方晶に変態し、クラックの原因となる。これを防ぐため、適量のＮｉを添加し、界面化合物を（Ｃｕ,Ｎｉ）６Ｓｎ５とすれば、六方晶が室温でも安定となるため、クラックが生じがたいことが特許文献２に述べられている。 A Cu 6 Sn 5 intermetallic compound layer is generally formed at the interface between copper and copper alloy and solder. Cu 6 Sn 5 is a hexagonal crystal at a high temperature, but transforms to an orthorhombic crystal at a low temperature, causing cracks. To prevent this, Patent Document 2 states that if an appropriate amount of Ni is added and the interfacial compound is (Cu, Ni) 6 Sn 5 , the hexagonal crystal is stable even at room temperature, and cracks are unlikely to occur. ing.
しかし、Ｐを添加した場合はＮｉとＰが結びつきやすいため、界面に作用するＮｉが消失し、界面化合物を（Ｃｕ,Ｎｉ）６Ｓｎ５とすることができないことが問題である。ゆえに、Ｎｉを添加する場合、酸化抑制のための元素としてＰではなくＧｅやＧａを添加するのが一般的であるが、ＧｅやＧａはＩｎと同様に希少金属の１種であるため、価格が高いという問題がある。 However, when P is added, since Ni and P are easily combined, Ni acting on the interface disappears and the interface compound cannot be (Cu, Ni) 6 Sn 5 . Therefore, when Ni is added, it is common to add Ge or Ga instead of P as an element for suppressing oxidation. However, Ge and Ga are one of rare metals like In, so the price is low. There is a problem that is high.
本発明の目的は、耐疲労特性の向上と反りの抑制とが両立されたＳｎ−Ｂｉ系の無鉛はんだ合金、当該無鉛はんだ合金を用いた接合材及び当該接合材により接合された接合体を提供することにある。 An object of the present invention is to provide a Sn-Bi lead-free solder alloy in which both improvement in fatigue resistance and suppression of warpage are achieved, a bonding material using the lead-free solder alloy, and a bonded body bonded by the bonding material. There is to do.
上記目的を達成するため、本発明によれば、以下の無鉛はんだ合金、接合材及び接合体が提供される。 In order to achieve the above object, according to the present invention, the following lead-free solder alloy, bonding material and bonded body are provided.
［１］Ｂｉ：２０〜６０質量％、Ｎｉ：０．００５〜０．４質量％、Ｐ：０．００１〜０．１質量％、Ｓｎ：残部、及び不可避不純物からなり、かつＰ／Ｎｉ質量比が１／４以下であることを特徴とする無鉛はんだ合金。
［２］更に３質量％以下のＣｕが添加されたことを特徴とする前記［１］に記載の無鉛はんだ合金。
［３］更に０．００１〜０．５質量％のＴｉが添加されたことを特徴とする前記［１］又は前記［２］に記載の無鉛はんだ合金。
［４］銅又は銅合金とのはんだ接合部界面に（Ｃｕ,Ｎｉ）6Ｓｎ5金属間化合物層を形成することを特徴とする前記［１］〜［３］のいずれか１つに記載の無鉛はんだ合金。
［５］はんだ合金中にＮｉ−Ｓｎ−Ｐ系金属間化合物が晶出していることを特徴とする前記［１］〜［４］のいずれか１つに記載の無鉛はんだ合金。
［６］前記［１］〜［５］のいずれか１つに記載の無鉛はんだ合金を用いた接合材。
［７］金属線の外周に前記無鉛はんだ合金が被覆されている前記［６］に記載の接合材。
［８］前記［６］又は前記［７］に記載の接合材を用いて接合物と被接合物とが接合されている接合体。
[1] Bi: 20~60 wt%, Ni: 0.005-0.4 wt%, P: 0.001 to 0.1 mass%, Sn: remainder, and made inevitable impurities, and P / Ni mass A lead-free solder alloy having a ratio of 1/4 or less.
[2] The lead-free solder alloy according to [1], further containing 3% by mass or less of Cu.
[3] The lead-free solder alloy according to [1] or [2], further including 0.001 to 0.5% by mass of Ti.
[4] The (Cu, Ni) 6 Sn 5 intermetallic compound layer is formed at a solder joint interface with copper or a copper alloy, as described in any one of the above [1] to [3] Lead-free solder alloy.
[5] The lead-free solder alloy according to any one of [1] to [4], wherein a Ni—Sn—P intermetallic compound is crystallized in the solder alloy.
[6] A bonding material using the lead-free solder alloy according to any one of [1] to [5].
[7] The bonding material according to [6], wherein an outer periphery of a metal wire is coated with the lead-free solder alloy.
[8] A joined body in which a joined article and an article to be joined are joined using the joining material according to [6] or [7].
本発明によれば、耐疲労特性の向上と反りの抑制とが両立されたＳｎ−Ｂｉ系の無鉛はんだ合金、当該無鉛はんだ合金を用いた接合材及び当該接合材により接合された接合体が提供される。 According to the present invention, there are provided a Sn-Bi lead-free solder alloy having both improved fatigue resistance and suppression of warpage, a bonding material using the lead-free solder alloy, and a bonded body bonded by the bonding material. Is done.
以下、本発明の無鉛はんだ合金の実施形態について具体的に説明する。 Hereinafter, embodiments of the lead-free solder alloy of the present invention will be specifically described.
〔無鉛はんだ合金〕
本発明の実施形態に係る無鉛はんだ合金は、Ｂｉ：２０〜６０質量％、Ｎｉ：０．００５〜０．４質量％、Ｐ：０．００１〜０．１質量％、Ｓｎ：残部、及び不可避不純物からなり、かつＰ／Ｎｉ質量比が１／４以下である。なお、不可避不純物とは、はんだ合金の原料中に存在するものや、製造工程において不可避的に混入するものをいう。
[Lead-free solder alloy]
The lead-free solder alloy according to the embodiment of the present invention includes Bi: 20 to 60% by mass, Ni: 0.005 to 0.4% by mass, P: 0.001 to 0.1% by mass, Sn: balance, and inevitable It consists of impurities, and P / Ni mass ratio is 1/4 or less. Inevitable impurities refer to those present in the raw material of the solder alloy and those inevitably mixed in the manufacturing process.
（Ｂｉ）
本実施の形態に係る無鉛はんだ合金は、２０〜６０質量％のＢｉを含有する。Ｂｉ含量の下限値は、２５質量％であることが好ましく、３０質量％であることがより好ましく、３５質量％であることがさらに好ましい。Ｂｉ含量の上限値は、５７質量％であることが好ましく、５５質量％であることがより好ましく、５０質量％であることがさらに好ましい。
(Bi)
The lead-free solder alloy according to the present embodiment contains 20 to 60% by mass of Bi. The lower limit of the Bi content is preferably 25% by mass, more preferably 30% by mass, and further preferably 35% by mass. The upper limit of Bi content is preferably 57% by mass, more preferably 55% by mass, and further preferably 50% by mass.
本実施の形態に係る無鉛はんだ合金に添加されるＢｉの量が多くなるほど無鉛はんだ合金の融点が下がる。例えば、Ｓｎ−５７質量％Ｂｉの共晶組成を有する無鉛はんだ合金では、融点が１３９℃であり、有鉛はんだの融点１８３℃と比較して大幅に融点を下げることができる。 As the amount of Bi added to the lead-free solder alloy according to the present embodiment increases, the melting point of the lead-free solder alloy decreases. For example, in a lead-free solder alloy having a eutectic composition of Sn-57 mass% Bi, the melting point is 139 ° C., and the melting point can be lowered significantly compared to the melting point of leaded solder of 183 ° C.
一方、共晶組成よりＢｉ濃度の低い範囲（0mass%＜Bi＜57mass%）の領域では、液相線と固相線の温度差が大きくなり、はんだ接続時の熱応力発生が液相線と固相線の間のどの温度で起こるのか不明であった。本発明者らが鋭意研究した結果、実施例及び参考例に示すように、はんだ接続時の熱応力が、従来の有鉛はんだ（Ｓｎ−３７質量％Ｐｂ）と同等となる組成はＳｎ−２０質量％Ｂｉであることを見出した。すなわち、２０質量％〜５７質量％Ｂｉの領域では、従来の有鉛はんだより、熱応力を小さくできる。 On the other hand, in the region where the Bi concentration is lower than the eutectic composition (0 mass% <Bi <57 mass%), the temperature difference between the liquidus and solidus becomes large, and the generation of thermal stress during soldering is It was unknown at what temperature during the solidus. As a result of intensive studies by the present inventors, as shown in Examples and Reference Examples, the composition in which the thermal stress at the time of solder connection is equivalent to that of conventional leaded solder (Sn-37 mass% Pb) is Sn-20. It was found that the mass was Bi. That is, in the region of 20% by mass to 57% by mass Bi, the thermal stress can be made smaller than that of the conventional leaded solder.
一方、Ｂｉは硬くて脆い金属であるため、融点を下げる目的に対し必要以上の量、すなわち、６０質量％を超える量の添加は機械的特性の劣化を招き、好ましくない。 On the other hand, since Bi is a hard and brittle metal, the addition of an amount more than necessary for the purpose of lowering the melting point, that is, an amount exceeding 60% by mass, causes deterioration of mechanical properties, which is not preferable.
（Ｎｉ及びＰ）
本実施の形態に係る無鉛はんだ合金は、０．００５〜０．４質量％のＮｉを含有する。その含量は、０．０１〜０．３質量％であることが好ましく、０．０５〜０．２質量％であることがより好ましい。発明の効果を奏するために０．００５質量％の添加が必要であり、過度の添加は液相線温度の上昇を招くので、０．４質量％以下の添加とする。
(Ni and P)
The lead-free solder alloy according to the present embodiment contains 0.005 to 0.4 mass% Ni. The content is preferably 0.01 to 0.3% by mass, and more preferably 0.05 to 0.2% by mass. Addition of 0.005% by mass is necessary to achieve the effects of the invention, and excessive addition causes an increase in liquidus temperature, so 0.4% by mass or less is added.
また、本実施の形態に係る無鉛はんだ合金は、０．００１〜０．１質量％のＰを含有する。その含量は、０．００５〜０．０５質量％であることが好ましく、０．０１〜０．０３質量％であることがより好ましい。発明の効果を奏するために０．００１質量％の添加が必要であり、後述するようにＰ／Ｎｉ質量比は１／４以下であるので、０．１質量％以下の添加とする。 The lead-free solder alloy according to the present embodiment contains 0.001 to 0.1% by mass of P. The content is preferably 0.005 to 0.05% by mass, and more preferably 0.01 to 0.03% by mass. Addition of 0.001% by mass is necessary to achieve the effects of the invention, and the P / Ni mass ratio is ¼ or less, as will be described later.
ＮｉはＰと共に添加することにより、はんだ合金中に微細なＮｉ−Ｓｎ−Ｐ系金属間化合物が晶出する。ＮｉとＰは、はんだ合金中のＳｎとともにＮｉ−Ｓｎ−Ｐ系金属間化合物の形で晶出し、その組成は分析の結果、Ｎｉ２ＳｎＰであることが分かった。図１は、本発明の実施の形態に係る無鉛はんだ合金中に晶出するＮｉ２ＳｎＰ金属間化合物を示す図であり、Ｓｎ−Ｂｉ共晶組成付近のはんだ合金にＮｉとＰを添加し、凝固させた組織を撮影したものである。 When Ni is added together with P, a fine Ni—Sn—P intermetallic compound is crystallized in the solder alloy. Ni and P crystallize in the form of a Ni—Sn—P intermetallic compound together with Sn in the solder alloy, and the analysis revealed that the composition was Ni 2 SnP. FIG. 1 is a diagram showing a Ni 2 SnP intermetallic compound that crystallizes in a lead-free solder alloy according to an embodiment of the present invention. Ni and P are added to a solder alloy near the Sn—Bi eutectic composition. A photograph of the coagulated tissue.
これにより、Ｓｎ−Ｂｉはんだ合金の耐熱性を向上させることができる。すなわち、はんだ高温保持時のＳｎリッチ相とＢｉ相の粗大化を抑制し、機械的特性及び疲労特性の劣化を抑制する効果を発揮する。 Thereby, the heat resistance of Sn-Bi solder alloy can be improved. That is, the effect of suppressing the coarsening of the Sn rich phase and the Bi phase at the time of holding the solder at a high temperature and suppressing the deterioration of the mechanical characteristics and fatigue characteristics is exhibited.
ここで、Ｐの添加量が多いと、添加したＮｉが上述したＮｉ２ＳｎＰの形成にすべて消費され、銅導体との界面等のはんだ接合部界面に作用するＮｉが消失してしまう。Ｎｉ２ＳｎＰの形成にＮｉをすべて消費させないためには、添加するＰとＮｉのＰ／Ｎｉ原子数比を１／２未満とすれば良い。これはＰ／Ｎｉ質量比で表すと１／４以下ということになる。Ｐ／Ｎｉ質量比を１／４以下とすることで、はんだ合金と銅導体とのはんだ接合部界面に（Ｃｕ，Ｎｉ）６Ｓｎ５の金属間化合物を形成することができる。より好ましくは、界面に多くのＮｉを作用させるために、Ｐ／Ｎｉ質量比を１／５以下とすることが好ましく、１／７以下とすることがより好ましく、１／１０以下とすることがさらに好ましい。また、Ｐの添加による効果を得るために１／４００以上とする。 Here, the addition amount of P is large, the added Ni is consumed in the formation of Ni 2 SnP described above, Ni acting on solder joint interface of the interface such as the copper conductor is lost. In order not to consume all Ni for formation of Ni 2 SnP, the P / Ni atomic ratio of P and Ni to be added should be less than ½. This is 1/4 or less in terms of P / Ni mass ratio. By setting the P / Ni mass ratio to 1/4 or less, an intermetallic compound of (Cu, Ni) 6 Sn 5 can be formed at the solder joint interface between the solder alloy and the copper conductor. More preferably, in order to cause a large amount of Ni to act on the interface, the P / Ni mass ratio is preferably 1/5 or less, more preferably 1/7 or less, and more preferably 1/10 or less. Further preferred. Moreover, in order to acquire the effect by addition of P, it shall be 1/400 or more.
より具体的には、ＮｉとＰとを併用したときにＮｉはＰと優先的に結びつくが、Ｐが多いと添加したＮｉがＮｉ２ＳｎＰ化合物の晶出のためにすべて消費されてしまう。これに対して、Ｐ／Ｎｉ質量比を１／４以下にすることで、Ｐと結びつかずに残るＮｉが銅及び銅合金とのはんだ接合部界面で（Ｃｕ，Ｎｉ）６Ｓｎ５の金属間化合物の形成に作用する。そのため、ＮｉとＰとを併用してもクラックの発生を防止できるとともに、はんだ合金中におけるＮｉ２ＳｎＰ晶出によって熱疲労特性の向上効果が奏されることになる。 More specifically, Ni is preferentially combined with P when Ni and P are used in combination, but if the amount of P is large, the added Ni is consumed for crystallization of the Ni 2 SnP compound. On the other hand, when the P / Ni mass ratio is ¼ or less, Ni that remains without being connected to P is between (Cu, Ni) 6 Sn 5 metal at the solder joint interface with copper and copper alloy. It affects the formation of compounds. Therefore, even if Ni and P are used in combination, the generation of cracks can be prevented, and the effect of improving thermal fatigue characteristics can be achieved by Ni 2 SnP crystallization in the solder alloy.
（Ｃｕ）
本発明の実施形態に係る無鉛はんだ合金は、更に３質量％以下のＣｕが添加されていることが好ましい。
(Cu)
The lead-free solder alloy according to the embodiment of the present invention preferably further contains 3% by mass or less of Cu.
Ｃｕははんだ合金に添加されることにより、ＳｎとＣｕ６Ｓｎ５金属間化合物を形成し、これがはんだ合金中に微細に分散することで、機械的強度や疲労特性を向上させることができる。一方、添加しすぎると、凝固過程において金属間化合物が粗大化するため、３質量％以下の添加が好ましい。 When Cu is added to the solder alloy, it forms Sn and Cu 6 Sn 5 intermetallic compound, which is finely dispersed in the solder alloy, so that the mechanical strength and fatigue characteristics can be improved. On the other hand, if too much is added, the intermetallic compound becomes coarse during the solidification process, so addition of 3% by mass or less is preferable.
（Ｔｉ）
また、本発明の実施形態に係る無鉛はんだ合金は、更に０．００１〜０．５質量％のＴｉが添加されていることが好ましい。
(Ti)
Moreover, it is preferable that 0.001 to 0.5 mass% Ti is further added to the lead-free solder alloy which concerns on embodiment of this invention.
Ｔｉははんだ合金に添加されることにより、はんだ凝固組織のＢｉ相を微細化することができ、機械的強度や疲労特性を向上させることができる。加えて、Ｔｉは活性な金属であるため、Ｔｉを添加することにより、ガラスやセラミック等にも溶着することができる。 By adding Ti to the solder alloy, the Bi phase of the solder solidified structure can be refined, and the mechanical strength and fatigue characteristics can be improved. In addition, since Ti is an active metal, it can be welded to glass, ceramics, and the like by adding Ti.
（Ｓｎ）
本発明の実施形態に係る無鉛はんだ合金は、上記成分の残部としてＳｎを含有する。
(Sn)
The lead-free solder alloy which concerns on embodiment of this invention contains Sn as a remainder of the said component.
（その他の添加金属）
本実施の形態に係る無鉛はんだ合金は、上記成分の他、効果を損なわない範囲で、その他の金属、例えば、Ｉｎ、Ａｇ、Ｇｅ、Ｇａを添加してもよいが、コストの観点からはこれらの高価な金属は添加しない方が望ましい。
(Other additive metals)
In addition to the above components, the lead-free solder alloy according to the present embodiment may add other metals such as In, Ag, Ge, and Ga as long as the effects are not impaired. It is desirable not to add expensive metals.
（用途）
本実施の形態に係る無鉛はんだ合金は、耐疲労特性の向上と反りの抑制とが両立されたＳｎ−Ｂｉ系の無鉛はんだ合金を提供できるため、接合物と被接合物とを接合させて得られる接合体の接合部分に用いる接合材として好適に使用できる。接合体を接合する際の接合材としては、無鉛はんだ合金のみを単体で用いる場合に限らず、金属線（例えば銅又は銅合金からなる導体）の外周に無鉛はんだ合金が被覆されているものを用いても良い。
(Use)
The lead-free solder alloy according to the present embodiment can provide a Sn-Bi-based lead-free solder alloy that achieves both improved fatigue resistance and suppression of warpage, and is obtained by joining a joined object and an object to be joined. It can use suitably as a joining material used for the joined part of the joined object. As a joining material for joining the joined body, not only a lead-free solder alloy is used alone, but a metal wire (for example, a conductor made of copper or a copper alloy) is coated with a lead-free solder alloy. It may be used.
（実施の形態の効果）
本実施の形態によれば、以下の効果を奏する。
（１）Ｂｉ：２０〜６０質量％含有するＳｎ−Ｂｉ系の無鉛はんだ合金において、Ｐ／Ｎｉ質量比が１／４以下となるようにＮｉ：０．００５〜０．４質量％及びＰ：０．００１〜０．１質量％を添加したことにより、耐疲労特性の向上と反りの抑制とが両立されたＳｎ−Ｂｉ系の無鉛はんだ合金を提供できる。すなわち、本実施形態によれば、はんだ接続時の熱応力を従来のＳｎ−Ｐｂ系はんだと同等以下に抑え、疲労寿命を向上させることができる。また、本実施形態によれば、融点が従来のＳｎ−Ｐｂ系有鉛はんだ以下の無鉛はんだ合金を得ることができるため、実装基板の反りを抑え、かつ、市場環境においても長期にわたりはんだ接合部の信頼性を維持できる。
（２）高価なＡｇ、Ｉｎ等を含まない構成にすることができるので、無鉛はんだを低コストで製造することができる。
（３）毒性のあるＰｂ、Ｓｂ等を含まない構成にすることができるので、環境、生体に対する影響を低減することができる。
(Effect of embodiment)
According to the present embodiment, the following effects can be obtained.
(1) Bi: In Sn-Bi-based lead-free solder alloy containing 20 to 60% by mass, Ni: 0.005 to 0.4% by mass and P: so that the P / Ni mass ratio is 1/4 or less. By adding 0.001 to 0.1% by mass, it is possible to provide a Sn-Bi lead-free solder alloy in which both improvement in fatigue resistance and suppression of warpage are achieved. That is, according to the present embodiment, the thermal stress at the time of solder connection can be suppressed to the same level or lower as that of the conventional Sn-Pb solder, and the fatigue life can be improved. In addition, according to the present embodiment, since a lead-free solder alloy having a melting point equal to or lower than that of the conventional Sn-Pb leaded solder can be obtained, the warping of the mounting substrate is suppressed, and the solder joint portion is long-term even in the market environment. Can be maintained.
(2) Since it can be configured not to include expensive Ag, In, etc., lead-free solder can be manufactured at low cost.
(3) Since it can be configured not to contain toxic Pb, Sb, etc., the influence on the environment and the living body can be reduced.
以下に、本発明の無鉛はんだ合金を、実施例を用いて説明する。なお、本発明は、以下の実施例によって、いかなる制限を受けるものではない。 Below, the lead-free solder alloy of the present invention will be described using examples. Note that the present invention is not limited in any way by the following examples.
（実施例１〜５、比較例１〜２、参考例１〜８、従来例のはんだ合金の製造）
表１に示す添加量の各成分を融かして混合し、実施例１〜５、比較例１〜２及び参考例１〜８の無鉛はんだ合金、並びに、従来例の有鉛はんだ合金（Ｓｎ−３７質量％Ｐｂ）を製造した。
(Examples 1-5, Comparative Examples 1-2, Reference Examples 1-8, Production of Conventional Solder Alloys)
The components of the addition amount shown in Table 1 are melted and mixed, and lead-free solder alloys of Examples 1 to 5, Comparative Examples 1 and 2 and Reference Examples 1 to 8, and leaded solder alloys of conventional examples (Sn -37 wt% Pb) was produced.
以下に示す各種評価試験及び分析を行なった。その結果を表１に示す。 The following various evaluation tests and analyzes were performed. The results are shown in Table 1.
（１）反り量の測定
各種組成のはんだ合金を用いたときの、はんだ接続部に発生する熱応力の大きさを比較するために、実装基板の模擬としてのインバー基板の反り量を以下の方法で測定し、相対的に比較した。
まず、試料を以下の方法で作製した。
溶解めっき法により、断面形状のサイズが０．３ｍｍ×５．０ｍｍ、長さが５０ｍｍの平角Ｃｕ線に、製造したはんだ合金ではんだめっきを施したはんだめっき平角Ｃｕ線をそれぞれ作製した。次に、断面形状のサイズが０．２ｍｍ×１０ｍｍ、長さが５０ｍｍのインバー基板（Ｆｅ−３６質量％Ｎｉ）にフラックスを塗布し、作製したはんだめっき平角Ｃｕ線をインバー基板の片面に配置の上、セットし、ホットプレートを用いてはんだ接続することで試料を得た。
その後、室温に冷却し、インバー基板の反り量をノギスにより測定した。
(1) Measurement of warpage amount In order to compare the amount of thermal stress generated in the solder joint when using solder alloys of various compositions, the warpage amount of the invar substrate as a simulation of the mounting substrate is as follows. And measured relative to each other.
First, a sample was prepared by the following method.
Solder-plated rectangular Cu wires obtained by applying solder plating to the rectangular Cu wires having a cross-sectional size of 0.3 mm × 5.0 mm and a length of 50 mm by the produced solder alloy were produced by the solution plating method. Next, a flux is applied to an invar substrate (Fe-36 mass% Ni) having a cross-sectional size of 0.2 mm × 10 mm and a length of 50 mm, and the produced solder-plated rectangular Cu wire is arranged on one side of the invar substrate. A sample was obtained by setting and soldering using a hot plate.
Then, it cooled to room temperature and measured the amount of curvature of an Invar board with calipers.
ここで、基板としてインバー基板を用いたのは、インバー基板の熱膨張率が０〜２ｐｐｍ／℃であり、Ｃｕの熱膨張率１７ｐｐｍ／℃と比較して差が大きいため、はんだ接合時に平角Ｃｕ線とインバー基板が固着してから、室温に下がるまでの間に大きな熱応力が発生し、反りの測定が容易にできるためである。この試験方法によれば、融点の異なるはんだや、液相線と固相線の温度が大きく異なるはんだにおいても、熱応力の大きさを相対的に比較することができる。 Here, the Invar substrate was used as the substrate because the thermal expansion coefficient of the Invar substrate was 0 to 2 ppm / ° C., and the difference was larger than the thermal expansion coefficient of Cu of 17 ppm / ° C. This is because a large thermal stress is generated from the time when the wire and the Invar substrate are fixed to when the temperature is lowered to room temperature, and the measurement of the warp can be easily performed. According to this test method, it is possible to relatively compare the magnitudes of thermal stress even in solders having different melting points and solders having greatly different liquidus and solidus temperatures.
（２）金属間化合物の分析
断面観察を行い、はんだ／Ｃｕ界面に形成される金属間化合物の分析を行った。
(2) Analysis of intermetallic compound Cross-sectional observation was performed and the intermetallic compound formed in a solder / Cu interface was analyzed.
（３）温度サイクル試験におけるクラック長さの測定（耐疲労特性の評価）
各種組成のはんだ合金について温度サイクル試験を行ない、疲労強度を比較した。試料は、インバー基板の両面にはんだめっき平角Ｃｕ線をはんだ接合し、基板の反りを抑制した点を除き、上記「（１）反り量の測定」で作製した試料と同じである。当該試料を用いることにより、はんだ接合時及び温度サイクル試験中の熱応力を反りで解放させずに、はんだに効率的に与えることができる。温度サイクル試験は、−４０／９０℃、１０００サイクルの条件で行い、試験後の試料の断面観察により、試料の両側から入ったはんだ接続部のクラック長さを測定し、合計した。
(3) Measurement of crack length in temperature cycle test (evaluation of fatigue resistance)
Temperature cycle tests were performed on solder alloys having various compositions, and fatigue strengths were compared. The sample is the same as the sample prepared in the above “(1) Measurement of warpage” except that solder-plated rectangular Cu wires are soldered to both sides of the Invar substrate and the warpage of the substrate is suppressed. By using the sample, thermal stress during soldering and during the temperature cycle test can be efficiently applied to the solder without being released by warping. The temperature cycle test was performed under the conditions of −40 / 90 ° C. and 1000 cycles, and the crack lengths of the solder joints entered from both sides of the sample were measured and totaled by observing the cross section of the sample after the test.
表１に記載の「（１）反り量の測定」における測定結果（参考例１〜８）から、Ｂｉは添加量が増えるほど、反り量が小さくなり２０質量％以上の添加で従来の有鉛はんだ合金（Ｓｎ−３７質量％Ｐｂ）の反り量より小さくなることが分かった。反り量は４０質量％Ｂｉ〜６０質量％Ｂｉの領域で最小となることを確認した。 From the measurement results (Reference Examples 1 to 8) in “(1) Measurement of warpage amount” shown in Table 1, the amount of Bi becomes smaller as the addition amount is increased, and the conventional leaded lead with the addition of 20% by mass or more. It turned out that it becomes smaller than the curvature amount of a solder alloy (Sn-37 mass% Pb). It was confirmed that the amount of warpage was minimized in the region of 40 mass% Bi to 60 mass% Bi.
また、はんだ／Ｃｕ界面の金属間化合物を分析した結果、Ｎｉを添加していない従来例、参考例１〜８及び比較例１は、クラックの発生しやすいＣｕ６Ｓｎ５が形成されていた。また、Ｐ／Ｎｉ質量比が１／４を超えるようにＮｉとＰを添加した比較例２も、クラックの発生しやすいＣｕ６Ｓｎ５が形成されていた。それに対し、ＮｉとＰを添加し、Ｐ／Ｎｉ質量比が１／４以下である実施例１〜５は、クラックが生じにくい（Ｃｕ,Ｎｉ）６Ｓｎ５が形成されていた。 Moreover, as a result of analyzing the intermetallic compound at the solder / Cu interface, Cu 6 Sn 5 in which cracks are likely to occur was formed in the conventional examples in which Ni was not added, Reference Examples 1 to 8, and Comparative Example 1. Further, in Comparative Example 2 in which Ni and P were added so that the P / Ni mass ratio exceeded 1/4, Cu 6 Sn 5 in which cracks were likely to occur was formed. In contrast, in Examples 1 to 5 in which Ni and P were added and the P / Ni mass ratio was ¼ or less, (Cu, Ni) 6 Sn 5 was hardly formed.
「（３）温度サイクル試験におけるクラック長さの測定」における測定結果から、Ｐ／Ｎｉ質量比が１／４以下である実施例１〜５は、クラックが抑制されていることが分かった。さらにＴｉを添加した実施例４〜５は、実施例１〜３よりも更にクラックが抑制されていることが分かった。 From the measurement results in “(3) Measurement of crack length in temperature cycle test”, it was found that cracks were suppressed in Examples 1 to 5 having a P / Ni mass ratio of ¼ or less. Furthermore, it turned out that the cracks were suppressed further in Examples 4-5 which added Ti further than Examples 1-3.
以上より、本発明の無鉛はんだ合金は、従来の有鉛はんだと比較し、はんだ接合時の基板反り量を抑制しつつ、耐疲労特性を向上できることが分かった。
From the above, it has been found that the lead-free solder alloy of the present invention can improve the fatigue resistance while suppressing the amount of warpage of the substrate at the time of soldering, as compared with the conventional leaded solder.
Claims (8)
A joined body in which a joined article and an article to be joined are joined using the joining material according to claim 6.
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| CN105750757A (en) * | 2016-03-22 | 2016-07-13 | 苏州虎伏新材料科技有限公司 | Welding material for surfacing to obtain Sn-based babbitt alloy wear-resisting layer |
| CN106624432A (en) * | 2016-11-30 | 2017-05-10 | 安徽华众焊业有限公司 | Low-melting-point tin bismuth solder alloy |
| CN106695162A (en) * | 2016-12-29 | 2017-05-24 | 安徽华众焊业有限公司 | Lead-free solder for micro-electronics industry and preparation method thereof |
| CN109175771A (en) * | 2018-10-22 | 2019-01-11 | 南京航空航天大学 | Epoxy resin composite S n-Bi lead-free solder paste |
| CN108971794A (en) * | 2018-10-22 | 2018-12-11 | 深圳市汉尔信电子科技有限公司 | A kind of composite S n-Bi lead-free solder paste containing epoxy resin |
| PT3828294T (en) | 2019-04-11 | 2023-01-26 | Nihon Superior Co Ltd | Lead-free solder alloy and solder joint part |
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| JP2002178191A (en) * | 2000-12-06 | 2002-06-25 | Hitachi Ltd | Low temperature system lead-free solder composition and electronic parts-packaged structure using the same |
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