JP2020066041A - Production method of solder joint - Google Patents
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- JP2020066041A JP2020066041A JP2018201476A JP2018201476A JP2020066041A JP 2020066041 A JP2020066041 A JP 2020066041A JP 2018201476 A JP2018201476 A JP 2018201476A JP 2018201476 A JP2018201476 A JP 2018201476A JP 2020066041 A JP2020066041 A JP 2020066041A
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- 229910000679 solder Inorganic materials 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- 238000001816 cooling Methods 0.000 claims abstract description 51
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 36
- 239000000956 alloy Substances 0.000 claims abstract description 36
- 239000013078 crystal Substances 0.000 claims abstract description 35
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 26
- 229910017482 Cu 6 Sn 5 Inorganic materials 0.000 claims description 5
- 229910052709 silver Inorganic materials 0.000 claims description 4
- 229910052787 antimony Inorganic materials 0.000 claims description 3
- 229910052797 bismuth Inorganic materials 0.000 claims description 3
- 229910052738 indium Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 claims 1
- 229910018471 Cu6Sn5 Inorganic materials 0.000 abstract description 31
- 230000009466 transformation Effects 0.000 abstract description 13
- 239000000203 mixture Substances 0.000 abstract description 6
- 238000007711 solidification Methods 0.000 abstract description 4
- 230000008023 solidification Effects 0.000 abstract description 4
- 238000002844 melting Methods 0.000 abstract description 3
- 230000008018 melting Effects 0.000 abstract description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 22
- 239000012071 phase Substances 0.000 description 9
- 238000012360 testing method Methods 0.000 description 8
- 239000010949 copper Substances 0.000 description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 4
- 230000001131 transforming effect Effects 0.000 description 4
- 229910020888 Sn-Cu Inorganic materials 0.000 description 3
- 229910019204 Sn—Cu Inorganic materials 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 229910052718 tin Inorganic materials 0.000 description 3
- 229910006345 η-Cu6Sn5 Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 2
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000004377 microelectronic Methods 0.000 description 2
- 238000005476 soldering Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 229910006413 η′-Cu6Sn5 Inorganic materials 0.000 description 2
- 229910017944 Ag—Cu Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910018082 Cu3Sn Inorganic materials 0.000 description 1
- 229910020882 Sn-Cu-Ni Inorganic materials 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
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Abstract
Description
本発明は、はんだ接合部の製造方法に関し、特に錫銅系はんだ合金を用いたはんだ接合部の製造方法に関するものである。 The present invention relates to a method for manufacturing a solder joint, and particularly to a method for manufacturing a solder joint using a tin-copper solder alloy.
環境上から、ミクロ電子部品の組み立てに用いる大半のはんだ合金は鉛の含有を減少した組成に変わっている。そして、現在では多くのはんだ合金は、Ｓｎ−Ａｇ−Ｃｕや、Ｓｎ−Ｃｕ−Ｎｉ合金を主成分としている。はんだ界面の接合部では、作業中、及び冷却中にＣｕ６Ｓｎ５金属間化合物（以下、単に「Ｃｕ６Ｓｎ５金属間化合物」又は「Ｃｕ６Ｓｎ５」と標記する場合がある。）が形成され、マイクロ電子回路のはんだ信頼性に大きく影響を及ぼす、はんだと界面の間の連続相を形成することになる。したがって、Ｃｕ６Ｓｎ５の結晶構造を安定した状態に維持することは、電子部品の信頼できる製造とサービスに適用するうえで重要である。電子製品のライフサイクルの間で変化する可能性がある様々な結晶構造中に存在するＣｕ６Ｓｎ５金属間化合物を考えた場合、特にこの金属間化合物の安定化は重要な課題である。 From the environmental point of view, most solder alloys used for assembling microelectronic components have been changed to lead-free compositions. And nowadays, most solder alloys are based on Sn-Ag-Cu and Sn-Cu-Ni alloys. A Cu 6 Sn 5 intermetallic compound (hereinafter, may be simply referred to as “Cu6Sn5 intermetallic compound” or “Cu6Sn5”) is formed at the joint of the solder interface during working and cooling, and a microelectronic circuit is formed. Will form a continuous phase between the solder and the interface, which will greatly affect the solder reliability of the. Therefore, maintaining the crystal structure of Cu6Sn5 in a stable state is important for application to reliable manufacture and service of electronic components. When considering Cu6Sn5 intermetallic compounds present in various crystal structures that may change during the life cycle of electronic products, stabilization of the intermetallic compounds is an important issue.
このＣｕ６Ｓｎ５金属間化合物は、１８６℃以下で六方晶から斜方晶の結晶構造に固相変態する。錫銅系の合金を用いてはんだ接合部を形成する場合、通常２３０℃より高い温度まで昇温した後冷却して凝固させる。冷却の際に六方晶のＣｕ６Ｓｎ５金属間化合物が形成され、電子部品に残存すると、その作動時に固相変態が起こる可能性がある。そして、この変態に伴って体積変化等が発生すると金属間化合物そのものに亀裂が発生することで、接合部の強度が低下したり、電気抵抗が増加したりする場合がある。また、はんだリフロー工程を複数回繰り返すと、その度に結晶構造が変化することとなるため、その繰り返しによりＣｕ６Ｓｎ５金属間化合物に亀裂が発生する可能性が生じる。そこで、本発明者は、溶融状態から凝固までのプロセスにおいて冷却温度を制御することによって、凝固した接合部に生成するＣｕ６Ｓｎ５金属間化合物を、それに伴う体積変化が最小限になる温度領域で積極的に安定した状態の斜方晶に変態させ、作動時あるいは製造時に相変態に伴う体積変化、及び体積変化に起因した歪や亀裂の発生などを抑制する方法を提案している（特許文献１）。 The Cu6Sn5 intermetallic compound undergoes solid phase transformation at 186 ° C. or lower into a hexagonal to orthorhombic crystal structure. When forming a solder joint using a tin-copper-based alloy, it is usually heated to a temperature higher than 230 ° C. and then cooled to solidify. When a hexagonal Cu6Sn5 intermetallic compound is formed during cooling and remains in the electronic component, solid phase transformation may occur during its operation. When a volume change or the like occurs due to this transformation, cracks may occur in the intermetallic compound itself, which may reduce the strength of the joint or increase the electrical resistance. Further, if the solder reflow step is repeated a plurality of times, the crystal structure will change each time, so that the repetition may cause cracks in the Cu6Sn5 intermetallic compound. Therefore, the present inventor positively controls the Cu6Sn5 intermetallic compound generated in the solidified joint in the temperature range in which the accompanying volume change is minimized by controlling the cooling temperature in the process from the molten state to the solidification. Has proposed a method of suppressing the volume change associated with the phase transformation during operation or manufacturing, and the generation of strains and cracks caused by the volume change, by transforming into a stable orthorhombic crystal (Patent Document 1). .
特許文献１に記載のように、本発明者は、１８６℃以上で溶融するＳｎ−Ｃｕ二元合金、あるいはこれに対して他の元素を含むがＣｕ６Ｓｎ５金属間化合物を生成する合金では、冷却温度履歴によっては、Ｃｕ６Ｓｎ５金属間化合物の全てが六方晶から斜方晶に変態する場合と、六方晶のうちの一部だけが斜方晶に変態し、六方晶と斜方晶が混在する場合があることを知見した。そして、冷却温度と冷却時間との関係から、冷却履歴とＣｕ６Ｓｎ５金属間化合物の結晶構造の関係を実験により導出した（図１参照）。図１に示すように、Ｘ軸に時間（秒）、Ｙ軸に温度（℃）で示した二次元図において、冷却温度と冷却時間の関係から、（１）１００％安定斜方晶Ｃｕ６Ｓｎ５（η’−Ｃｕ６Ｓｎ５）に変態する領域（単斜晶領域）と、（２）η’−Ｃｕ６Ｓｎ５に変態しない状態の六方晶Ｃｕ６Ｓｎ５（η−Ｃｕ６Ｓｎ５）が混在する領域（斜方晶と六方晶の混合領域）と、（３）比較的短時間で冷却した場合の１００％準安定η−Ｃｕ６Ｓｎ５領域（六方晶領域）が存在し、これらが１８６℃以下の温度において、２つの時間−温度−変態曲線（ＴＴＴ曲線）により区画されることを確認した。そして、図１に基づき、Ｃｕ６Ｓｎ５金属間化合物を安定した状態の斜方晶に変態させる方法として、（ｉ）１４０〜１６０℃程度で４０００秒程度保持することによって、単斜晶領域を通過させ、全てのＣｕ６Ｓｎ５金属間化合物を六方晶から斜方晶に変態させる方法、（ii）１２０〜１７５℃程度で２００秒程度保持することによって、単斜晶と六方晶の混合領域を通過させ、一部のＣｕ６Ｓｎ５金属間化合物を六方晶から斜方晶に変態させる方法を提案した。
As described in
特許文献１に記載の発明では、前記（ｉ）の方法により、全てのＣｕ６Ｓｎ５金属間化合物を斜方晶に変態させることが最善であり、前記（ii）の方法により斜方晶と六方晶との混合状態に変態させることは次善であるという立場であった。これは、作動時のＣｕ６Ｓｎ５金属間化合物の変態をより確実に防止できると考えたためである。
In the invention described in
しかし、（ｉ）の方法では、１４０〜１６０℃程度の温度範囲での経過時間（保持時間とも称する。）として４０００秒程度の時間を必要とすることから、はんだ接合部の製造工程の実情に鑑みるとより短時間の冷却工程が求められる。特に、はんだ接合部の製造工程においては、接合が不十分な可能性がある場合は、はんだ合金を溶融、冷却する工程を複数回行うことが多い。そのため、冷却時間が長いことは生産性の低下、製造コストの上昇を招くことになる。 However, the method (i) requires about 4000 seconds as an elapsed time (also referred to as a holding time) in a temperature range of about 140 to 160 ° C., and therefore, the actual process of the solder joint manufacturing process is not limited. In view of this, a shorter cooling process is required. In particular, in the manufacturing process of the solder joint portion, when there is a possibility that the joint is insufficient, the step of melting and cooling the solder alloy is often performed plural times. Therefore, a long cooling time leads to a decrease in productivity and an increase in manufacturing cost.
また、（ii）の方法に関しては斜方晶と六方晶との混合物であり作動時のＣｕ６Ｓｎ５金属間化合物の変態を避けられず、斜方晶が存在することによる意義は必ずしも十分ではない可能性があると考えられた。そのため、１２０〜１７５℃程度の温度範囲での経過時間（保持時間とも称する。）は２００秒程度ではあっても、その効果は必ずしも十分なものとはならないと考えられた。 Further, regarding the method (ii), a mixture of orthorhombic and hexagonal crystals cannot be avoided because the transformation of the Cu6Sn5 intermetallic compound during operation cannot be avoided, and the significance of the presence of orthorhombic crystals is not always sufficient. Was thought to be. Therefore, even if the elapsed time (also referred to as holding time) in the temperature range of about 120 to 175 ° C. is about 200 seconds, it is considered that the effect is not always sufficient.
そこで、本発明の目的とするところは、はんだ合金の溶融、冷却凝固を複数回行う場合であっても、作動時に相変態に伴う体積変化、及び体積変化に起因した歪や亀裂の発生などを抑制した信頼性の高い接合部を生産性良く形成可能なはんだ接合部の製造方法を提供することにある。 Therefore, the purpose of the present invention is to melt the solder alloy, even when performing cooling and solidification a plurality of times, the volume change accompanying the phase transformation during operation, and the occurrence of strain and cracks due to the volume change, etc. It is an object of the present invention to provide a method for manufacturing a solder joint, in which a suppressed and highly reliable joint can be formed with high productivity.
本発明者は、前述の課題解決のために鋭意検討を行った。その結果、意外にも、Ｃｕ６Ｓｎ５金属間化合物の安定斜方晶と六方晶の混在領域を所定の条件で通過させると、はんだ合金の溶融、冷却凝固を複数回行っても、信頼性の高い接合部を生産性良く形成可能であることを見出し、本発明を完成させるに至った。 The present inventor has earnestly studied to solve the above problems. As a result, surprisingly, when the stable orthorhombic and hexagonal mixed regions of Cu6Sn5 intermetallic compound are allowed to pass under predetermined conditions, even if the solder alloy is melted and cooled and solidified multiple times, highly reliable bonding is achieved. It has been found that the parts can be formed with high productivity, and the present invention has been completed.
本発明は、Ｃｕ：０．３〜７．６重量％、残部がＳｎ及び不可避不純物である合金を１８６℃以上に昇温した後１８６℃以下に冷却する冷却工程を複数回繰り返し行うはんだ接合部の製造方法であって、各冷却工程において、合金を１８６℃以上に昇温した後、合金の温度の経時変化を示す冷却温度線がＣｕ６Ｓｎ５の１８６℃以上で安定な六方晶と、１８６℃以下で安定な斜方晶の混在領域を通過し、かつ、１６０〜１３７℃の温度範囲での保持時間が９６〜３０５秒となるように冷却する、はんだ接合部の製造方法に関する。 The present invention is a solder joint in which Cu: 0.3 to 7.6% by weight, the balance is Sn and alloys which are unavoidable impurities are heated to 186 ° C. or higher and then cooled to 186 ° C. or lower. In each cooling step, after the temperature of the alloy is raised to 186 ° C. or higher, a cooling temperature line showing a change with time of the temperature of the alloy is a stable hexagonal crystal of Cu 6 Sn 5 at 186 ° C. or higher, The present invention relates to a method for manufacturing a solder joint, which passes through a stable orthorhombic mixed region at 186 ° C. or lower and cools so that a holding time in a temperature range of 160 to 137 ° C. is 96 to 305 seconds.
本発明の実施形態では、冷却温度線がＣｕ６Ｓｎ５の安定斜方晶と六方晶の前記混在領域を通過し、かつ、１７５〜１２０℃の温度範囲での保持時間が４，０００秒以下となるように冷却してもよい。 In the embodiment of the present invention, the cooling temperature line passes through the mixed region of stable orthorhombic and hexagonal Cu 6 Sn 5 and the holding time in the temperature range of 175 to 120 ° C. is 4,000 seconds or less. You may cool so that it may become.
本発明の実施形態では、合金が、Ａｇ、Ｂｉ、Ｓｂ、Ｚｎ、Ｇｅ、Ｍｎ、Ｉｎから選択される少なくとも１種の元素を含んでもよい。 In the embodiment of the present invention, the alloy may include at least one element selected from Ag, Bi, Sb, Zn, Ge, Mn, and In.
本発明の実施形態では、Ｎｉの含量が、０．０３重量％以下であってもよい。 In an embodiment of the present invention, the Ni content may be 0.03 wt% or less.
本発明によれば、はんだ合金の溶融、冷却凝固を複数回行う場合であっても、作動時に相変態に伴う体積変化、及び体積変化に起因した歪や亀裂の発生などを抑制した信頼性の高い接合部を、生産性良く、形成可能なはんだ接合部の製造方法を提供することができる。 According to the present invention, even when performing melting and cooling solidification of the solder alloy a plurality of times, the volume change accompanying the phase transformation at the time of operation, and the reliability of suppressing the occurrence of strain and cracks due to the volume change It is possible to provide a method for manufacturing a solder joint capable of forming a high joint with good productivity.
以下、本発明の実施形態について説明する。 Hereinafter, embodiments of the present invention will be described.
本発明に係るはんだ接合部の製造方法の実施形態では、Ｃｕ：０．３〜７．６重量％、残部がＳｎ及び不可避不純物である合金を１８６℃以上に昇温した後１８６℃以下に冷却する冷却工程を複数回繰り返し行う。そして、複数回繰り返し行われる各冷却工程において、合金を１８６℃以上に昇温した後、合金の温度の経時変化を示す冷却温度線が、図１に示す、Ｃｕ６Ｓｎ５金属間化合物の１８６℃以上で安定な六方晶と、１８６℃以下で安定な斜方晶の混在領域を通過し、かつ、１６０〜１３７℃の温度範囲の保持時間が９６〜３０５秒になるように冷却する。 In the embodiment of the method for manufacturing a solder joint according to the present invention, Cu: 0.3 to 7.6% by weight, the balance is Sn and an alloy containing inevitable impurities is heated to 186 ° C. or higher and then cooled to 186 ° C. or lower. The cooling step is repeated a plurality of times. Then, in each cooling step that is repeated a plurality of times, after the alloy is heated to 186 ° C. or higher, the cooling temperature line showing the change with time of the temperature of the alloy is 186 ° C. or higher of the Cu6Sn5 intermetallic compound shown in FIG. The mixture is cooled so that it passes through a mixed region of stable hexagonal crystals and stable orthorhombic crystals at 186 ° C. or lower and the holding time in the temperature range of 160 to 137 ° C. is 96 to 305 seconds.
このように、複数回行われる冷却工程において、特許文献１に記載の発明の場合とは異なり、１６０〜１３７℃での温度保持時間が、９６〜３０５秒であっても、この条件下で、合金の温度の経時変化を示す冷却温度線が、図１に示す、Ｃｕ６Ｓｎ５の安定斜方晶と六方晶の混在領域を通過していれば、信頼性の高い接合部が形成される。これは、（１）１３７〜１６０℃の温度で、例えば４０００秒程度保持すると、Ｃｕ６Ｓｎ５の相変態は起こるものの、結晶が成長することで亀裂（クラック）が発生し、かえってクラックの発生量が増加すること、（２）図１に示す各結晶相の境界を表すＴＴＴ曲線のうち、斜方晶と六方晶の混合領域と１００％準安定η−Ｃｕ６Ｓｎ５領域（六方晶領域）との境界を示すＴＴＴ曲線（以下、「混晶ＴＴＴ曲線」と称する場合がある。）を越すと急激に相変態が起こり短時間でも斜方晶の割合が多くなり得ること、等が要因と考えられる。尚、１３７〜１６０℃での保持時間を長くすることでクラックの発生量が増加すること、短時間で相変態が起こることは、実験により確認している。
In this way, in the cooling step performed a plurality of times, unlike the case of the invention described in
冷却工程では、合金を１８６℃以上に昇温した後は、合金の温度の経時変化を示す冷却温度線がＣｕ６Ｓｎ５の安定斜方晶と六方晶の混在領域を通過し、かつ、１６０〜１３７℃の温度範囲の保持時間が９６〜３０５秒となるように冷却すればよい。信頼性を向上する観点から当該温度範囲での保持時間（経過時間）は、１００秒以上が好ましく、１３０秒以上がより好ましい。この際の温度と時間の関係は、逆進的な昇温をさせない限りは、特に限定はない。漸次降温してもよいし、一定温度に保持する時間を適宜設けてもよい。言い換えると降温速度を一定にしてもよいし、任意に変化させてもよい。また、より効率的な冷却を行う観点から、冷却温度線がＣｕ６Ｓｎ５の安定斜方晶と六方晶の混在領域を通過し、かつ、１７５〜１２０℃の温度範囲の保持時間が４，０００秒以下となるように冷却してもよい。 In the cooling step, after the alloy is heated to 186 ° C. or higher, the cooling temperature line showing the time-dependent change in the temperature of the alloy passes through the mixed region of stable orthorhombic and hexagonal Cu6Sn5, and 160 to 137 ° C. Cooling may be performed so that the holding time in the temperature range is 96 to 305 seconds. From the viewpoint of improving reliability, the holding time (elapsed time) in the temperature range is preferably 100 seconds or longer, more preferably 130 seconds or longer. The relationship between the temperature and the time at this time is not particularly limited as long as the temperature is not increased in the reverse direction. The temperature may be gradually decreased, or a time for maintaining a constant temperature may be appropriately provided. In other words, the cooling rate may be constant or may be changed arbitrarily. Further, from the viewpoint of more efficient cooling, the cooling temperature line passes through a mixed region of stable orthorhombic and hexagonal Cu6Sn5 and the holding time in the temperature range of 175 to 120 ° C. is 4,000 seconds or less. You may cool so that it may become.
また、１８６℃以上に昇温後１６０℃に至るまで及び１３７℃未満になった後は、効率的に接合部を冷却することができれば降温速度は特に限定はない。１８６℃以上に昇温後１６０℃に至るまではＣｕ６Ｓｎ５の安定斜方晶と六方晶の混在領域を通過させる観点から、１８６℃以上に昇温して冷却を開始した後、１４０〜１６０℃で図１に示す混晶ＴＴＴ曲線と効率的に交差するように、逆進的に昇温させることなく合金の冷却温度線を制御するのが好ましい。 Further, the temperature lowering rate is not particularly limited as long as the joint can be efficiently cooled after the temperature is raised to 186 ° C. or higher and reaches 160 ° C. or lower than 137 ° C. From the viewpoint of passing through a mixed region of stable orthorhombic and hexagonal Cu6Sn5 until the temperature reaches 160 ° C after the temperature is raised to 186 ° C or higher, the temperature is raised to 186 ° C or higher and cooling is started, and then at 140 to 160 ° C. It is preferable to control the cooling temperature line of the alloy without increasing the temperature in a backward manner so as to efficiently intersect the mixed crystal TTT curve shown in FIG.
冷却工程の繰り返し回数は、はんだ接合を行う基材等の特性等により適宜決定することができるが、繰り返し回数が多くなると、接合強度が低下する傾向にあるため、極端に回数を多くするのは望ましくない。また、繰り返し時の冷却条件は、同じでもよいし、異なってもよい。 The number of times the cooling step is repeated can be appropriately determined depending on the characteristics of the base material to be soldered and the like.However, as the number of times the soldering is increased, the bonding strength tends to decrease. Not desirable. The cooling conditions at the time of repetition may be the same or different.
合金の成分組成は、Ｃｕ０．３〜７．６重量％、残部がＳｎ及び不可避不純物であってよい。つまり、残部は実質的にＳｎが９９．７〜９２．４重量％で微量の不可避不純部を含み得る。Ｃｕの含量が０．３重量％未満である場合、良好なはんだ接合部を形成することができなくなる傾向にある。７．６重量％を超えると、Ｃｕ３Ｓｎ金属間化合物も形成され、Ｃｕ６Ｓｎ５の生成量が相対的に低下する。そのため、本発明を適用する意義が低下する。 The composition of the alloy may be Cu 0.3 to 7.6% by weight, the balance being Sn and unavoidable impurities. That is, the balance may be substantially 99.7 to 92.4 wt% Sn and may contain a trace amount of unavoidable impurities. If the Cu content is less than 0.3% by weight, it tends to be impossible to form a good solder joint. If it exceeds 7.6% by weight, a Cu3Sn intermetallic compound is also formed, and the amount of Cu6Sn5 produced is relatively reduced. Therefore, the significance of applying the present invention decreases.
合金には、Ｃｕ６Ｓｎ５の生成を大きく阻害しなければ、ＳｎとＣｕ以外に他の金属を含んでもよい。このような金属元素としては、例えば、Ａｇ、Ｂｉ、Ｓｂ、Ｚｎ、Ｇｅ、Ｍｎ、Ｉｎ等が挙げられる。これらは、１種含んでもよいし、２種以上含んでもよい。なお、Ｎｉを０．０３重量％より多く含むと前述のような冷却工程を経ることなく良好な接合部を形成可能である。そのため、前述の冷却工程を意義あらしめる観点からは、Ｎｉの含量は、０．０３重量％以下が望ましく、０．０２重量％以下がより好ましい。 The alloy may contain other metals in addition to Sn and Cu as long as they do not significantly inhibit the production of Cu6Sn5. Examples of such metal elements include Ag, Bi, Sb, Zn, Ge, Mn, and In. These may include one kind or two or more kinds. If Ni is contained in an amount of more than 0.03% by weight, a good joint can be formed without going through the cooling process as described above. Therefore, from the viewpoint of making the above cooling step meaningful, the Ni content is preferably 0.03% by weight or less, and more preferably 0.02% by weight or less.
以上のような実施形態に係るはんだ接合部の製造方法は、Ｓｎ−Ｃｕはんだ合金やＣｕ６Ｓｎ５の生成を大きく阻害しない他の金属を含むＳｎ−Ｃｕ系はんだ合金を用いて行われる各種のはんだ付けにおいて好適に適用可能である。 The solder joint manufacturing method according to the above-described embodiment is applicable to various soldering operations performed using Sn—Cu solder alloys or Sn—Cu based solder alloys containing other metals that do not significantly inhibit the production of Cu6Sn5. It is suitably applicable.
実施例により、本願発明の実施形態をより詳細に説明する。 The embodiments of the present invention will be described in more detail by way of examples.
（試験例１ａ〜４ｃ）
＜はんだ接合部の製造＞
Ｃｕが０．７重量％、残部がＳｎと不可避不純物であるＳｎ−０．７Ｃｕ合金（株式会社日本スペリア社製、ＳＣ０７）を用い、粒子径５００μｍのはんだボールを作製した。銅箔基板の実装箇所に「フラックスＲＭ−５」（株式会社日本スぺリア製）を塗布した後、はんだボールを搭載した。リフロー装置（Ｍａｎｎｃｏｒｐ社製、ＢＴ３００）を用いて、窒素雰囲気下で、以下の温度履歴となるようにはんだ接合部の製造を行った。
(Test examples 1a to 4c)
<Manufacture of solder joints>
A solder ball having a particle diameter of 500 μm was produced using a Sn-0.7Cu alloy (SC07 manufactured by Nippon Superior Co., Ltd.) in which Cu is 0.7% by weight and the balance is Sn and inevitable impurities. "Flux RM-5" (manufactured by Nippon Superior Co., Ltd.) was applied to the mounting locations of the copper foil substrate, and then solder balls were mounted. Using a reflow device (manufactured by Manncorp, BT300), a solder joint was manufactured in a nitrogen atmosphere so as to have the following temperature history.
その後、室温から約５分間で約２４０℃まで昇温した後、表１のような条件で冷却した。リフローを繰り返す場合は、常温まで冷却後、同様の操作を繰り返した。常温に冷却後、ＩＰＡ（イソプロピルアルコール）にて洗浄して、フラックスを除去後、後述する評価を行った。尚、各条件において、はんだボールは２０箇所に実装し、それぞれ下記の評価を行った。また、表１より、試験例１〜４の１６０〜１３７℃の経過時間はそれぞれ、９５ｓ、１５５ｓ、１７４ｓ、３０５ｓである。 Then, the temperature was raised from room temperature to about 240 ° C. in about 5 minutes, and then cooled under the conditions shown in Table 1. When repeating the reflow, the same operation was repeated after cooling to room temperature. After cooling to room temperature, it was washed with IPA (isopropyl alcohol) to remove the flux, and then evaluated as described below. Under each condition, solder balls were mounted at 20 locations and the following evaluations were carried out. Moreover, from Table 1, the elapsed time of 160-137 degreeC of Test Examples 1-4 is 95 s, 155 s, 174 s, and 305 s, respectively.
＜評価＞
各試験例１ａ〜４ｃで得られたはんだ接合部２０箇所をインパクトシェア試験機（ＤＡＧＥ社製 ４０００ＨＳ）にセットし、２，０００ｍｍ／秒でのせん断負荷応力を測定した。せん断負荷応力の最大値の平均値を接合強度とした。評価結果を図２に示す。図２には、接合強度の結果（図２ａ）と、冷却工程を１回行った時の接合強度に対する変化率の算出結果（図２ｂ）を示した。
<Evaluation>
Twenty places of solder joints obtained in each of Test Examples 1a to 4c were set in an impact shear tester (4000HS manufactured by DAGE), and a shear load stress at 2,000 mm / sec was measured. The average of the maximum values of the shear load stress was taken as the joint strength. The evaluation result is shown in FIG. FIG. 2 shows the result of the bonding strength (FIG. 2A) and the calculation result of the rate of change with respect to the bonding strength (FIG. 2B) when the cooling step was performed once.
（試験例５ａ〜８ｃ）
はんだ合金を、Ｃｕが０．５重量％、Ａｇが３．０重量％、残部がＳｎと不可避不純物であるＳｎ−３Ａｇ−０．５Ｃｕ合金（株式会社日本スペリア社製、ＳＡＣ３０５）を用いた以外は、それぞれ試験例１ａ〜４ｃと同様にしてはんだ接合部を製造し、評価を行った。評価結果を図３ａ、ｂに示す。
(Test examples 5a to 8c)
Other than using a solder alloy of 0.5 wt% Cu, 3.0 wt% Ag, and the balance Sn and Sn-3Ag-0.5Cu alloy (SAC305 manufactured by Nihon Superior Co., Ltd.) which is an unavoidable impurity. Was manufactured and evaluated in the same manner as in Test Examples 1a to 4c. The evaluation results are shown in FIGS.
図２、３から分かるように、所定の条件を満たす冷却工程（試験例２〜４）を行うことで、冷却工程を１回のみを行った場合に比べて、複数回行った場合の接合強度の低下を抑制することが可能であることが分かる。
As can be seen from FIGS. 2 and 3, by performing the cooling process satisfying a predetermined condition (Test Examples 2 to 4), the bonding strength when the cooling process is performed a plurality of times as compared with the case where the cooling process is performed only once It can be seen that it is possible to suppress the decrease of
Claims (4)
各冷却工程において、合金を１８６℃以上に昇温した後、合金の温度の経時変化を示す冷却温度線がＣｕ６Ｓｎ５の１８６℃以上で安定な六方晶と、１８６℃以下で安定な斜方晶の混在領域を通過し、かつ、１６０〜１３７℃の温度範囲での保持時間が９６〜３０５秒となるように冷却する、はんだ接合部の製造方法。 Cu: 0.3 to 7.6% by weight, the balance is a method for manufacturing a solder joint in which a cooling step of heating an alloy containing Sn and inevitable impurities to 186 ° C. or higher and then cooling the alloy to 186 ° C. or lower is repeated a plurality of times. There
In each cooling step, after the temperature of the alloy was raised to 186 ° C. or higher, the cooling temperature line showing the change over time of the temperature of the alloy was a hexagonal crystal of Cu 6 Sn 5 stable at 186 ° C. or higher and a stable gradient at 186 ° C. or lower. A method for manufacturing a solder joint, which comprises passing through a mixed region of tetragonal crystals and cooling such that a holding time in a temperature range of 160 to 137 ° C. is 96 to 305 seconds.
The method for manufacturing a solder joint according to any one of claims 1 to 3, wherein the content of Ni is 0.03% by weight or less.
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| JP2005150655A (en) * | 2003-11-20 | 2005-06-09 | Matsushita Electric Ind Co Ltd | Lead frame, semiconductor device using the same, and method for packaging semiconductor device |
| WO2009051255A1 (en) * | 2007-10-19 | 2009-04-23 | Nihon Superior Sha Co., Ltd. | Solder joint |
| WO2013002112A1 (en) * | 2011-06-29 | 2013-01-03 | 株式会社日本スペリア社 | Process for producing solder joint with improved reliability |
| WO2018096917A1 (en) * | 2016-11-22 | 2018-05-31 | 千住金属工業株式会社 | Soldering method |
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| JP2005150655A (en) * | 2003-11-20 | 2005-06-09 | Matsushita Electric Ind Co Ltd | Lead frame, semiconductor device using the same, and method for packaging semiconductor device |
| WO2009051255A1 (en) * | 2007-10-19 | 2009-04-23 | Nihon Superior Sha Co., Ltd. | Solder joint |
| WO2009051181A1 (en) * | 2007-10-19 | 2009-04-23 | Nihon Superior Sha Co., Ltd. | Lead-free solder alloy |
| WO2013002112A1 (en) * | 2011-06-29 | 2013-01-03 | 株式会社日本スペリア社 | Process for producing solder joint with improved reliability |
| WO2018096917A1 (en) * | 2016-11-22 | 2018-05-31 | 千住金属工業株式会社 | Soldering method |
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