JP3837446B2 - Microsphere solder plating method - Google Patents
Microsphere solder plating method Download PDFInfo
- Publication number
- JP3837446B2 JP3837446B2 JP09495897A JP9495897A JP3837446B2 JP 3837446 B2 JP3837446 B2 JP 3837446B2 JP 09495897 A JP09495897 A JP 09495897A JP 9495897 A JP9495897 A JP 9495897A JP 3837446 B2 JP3837446 B2 JP 3837446B2
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- Prior art keywords
- solder
- plating
- solder plating
- hydrogen
- tin
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- 238000007747 plating Methods 0.000 title claims description 50
- 229910000679 solder Inorganic materials 0.000 title claims description 38
- 238000000034 method Methods 0.000 title claims description 23
- 239000004005 microsphere Substances 0.000 title claims description 18
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 23
- 229910052739 hydrogen Inorganic materials 0.000 claims description 17
- 239000001257 hydrogen Substances 0.000 claims description 17
- 150000002500 ions Chemical class 0.000 claims description 14
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 12
- 238000009713 electroplating Methods 0.000 claims description 10
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims 1
- -1 phenol sulfone Chemical class 0.000 claims 1
- 239000002184 metal Substances 0.000 description 8
- 239000000758 substrate Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005219 brazing Methods 0.000 description 2
- 239000008199 coating composition Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229940044652 phenolsulfonate Drugs 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 2
- WHOZNOZYMBRCBL-OUKQBFOZSA-N (2E)-2-Tetradecenal Chemical compound CCCCCCCCCCC\C=C\C=O WHOZNOZYMBRCBL-OUKQBFOZSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910020598 Co Fe Inorganic materials 0.000 description 1
- 229910002519 Co-Fe Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910020220 Pb—Sn Inorganic materials 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000833 kovar Inorganic materials 0.000 description 1
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 1
- RVPVRDXYQKGNMQ-UHFFFAOYSA-N lead(2+) Chemical compound [Pb+2] RVPVRDXYQKGNMQ-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- HXTSPGYEPSIZKP-UHFFFAOYSA-N phenol;tin Chemical compound [Sn].OC1=CC=CC=C1 HXTSPGYEPSIZKP-UHFFFAOYSA-N 0.000 description 1
- 229940044654 phenolsulfonic acid Drugs 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910001174 tin-lead alloy Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/341—Surface mounted components
- H05K3/3431—Leadless components
- H05K3/3436—Leadless components having an array of bottom contacts, e.g. pad grid array or ball grid array components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3457—Solder materials or compositions; Methods of application thereof
- H05K3/3473—Plating of solder
Description
【０００１】
【発明の属する技術分野】
この発明は、直径が０．１〜１．０ｍｍ程度の微小球、特に金属球の外周面にハンダめっき被膜を設けるハンダめっき法の改良に係り、高イオン濃度のめっき液を用いて、極めて低い電流密度で電気めっきを行い、微小球表面に所定厚みの水素含有量の少ないハンダめっき被膜を設けた微小球のハンダめっきに関する。
【０００２】
【従来の技術】
従来、ＢＧＡ（Ｂａｌｌ Ｇｒｉｄ Ａｒｒａｙ）タイプの半導体パッケージのパンプ芯材として用いられる微小球は、直径が０．１ｍｍ〜１．０ｍｍ程度で、材質としては所定組成のハンダの他、最近では、電気特性や機械的特性を考慮して、コバール（Ｎｉ−Ｃｏ−Ｆｅ合金）、Ｃｕ、４２Ｎｉ−Ｆｅ合金などの金属球を芯材としてろう材を被覆したチップキャリアーが提案（特開昭６２−１１２３５５号）されている。
【０００３】
前記微小球の製造方法として、溶融金属を所定温度の液体中に滴下し、溶融金属自体の表面張力にて球形化してそのまま凝固するいわゆる液体中滴下方法（特開平７−２５２５１０号）、金型によるフォーミング等のいわゆる機械的塑性加工方法（特開平４−３５４８０８号）、金属粒又は金属片を非酸化性雰囲気中で平板上に載置して振動を加えながら加熱溶融してその表面張力で球形化してそのまま凝固する振動加熱方法（特公平２−５０９６１号）などが提案されている。
【０００４】
このように製造された微小球の外周面のろう材としては、要求される寸法精度や半導体パッケージとプリント基板との固着強度などにより適宜選定される。例えば、厚み５〜５０μｍの種々の組成からなるハンダ（Ｐｂ−Ｓｎ系）が被覆され、必要に応じてＮｉなどの下地層を形成することもある。
【０００５】
通常のハンダめっき方法は、バレル方式を用いる場合、イオン濃度が５〜１３ｇ／ｌ、電流密度０．５〜３．０Ａ／ｄｍ2で行われる。（例えば、めっき教本電気鍍金研究会編、日刊工業新聞（１９８６年刊、１９９６年第９版重版 Ｐ１３２〜Ｐ１３７）に記されている。）
【０００６】
【発明が解決しようとする課題】
このようにして外周面にハンダめっき被膜を設けた微小球は、パッケージボードに加熱溶着する際に、ハンダめっき被膜に膨れが生じ、この膨れが破裂する際にボールが該基板から剥離飛散する問題、あるいは加熱装着後のハンダめっき被膜内にボイド（空隙）ができる問題があった。
【０００７】
そのため従来は、パッケージボードの加熱装着する前に、予め真空中または不活性ガス中で加熱して、脱ガス処理を行う必要があった。また、この処理を行うとハンダが一部溶融してめっき被膜厚さが不均一になるという問題もあった。
【０００８】
また、発明者らは、従来のこれらの問題について種々検討し、微小球のハンダめっき被膜中に吸蔵される水素ガス量と相関関係があり、問題解決にはハンダめっき被膜中に吸蔵される水素ガス量を極力低減する必要があることを知見し、ハンダめっき被膜中に吸蔵される水素ガス量を低減できるめっき方法として、めっき浴に不活性ガスを導入してバブリングしながらめっきを行う方法（特願平８−１８８８３４号）や、めっき浴槽全体を減圧に保持する方法（特願平８−２１５４２９号）を提案した。
【０００９】
しかし、上記方法は、新たな処理工程を追加する必要があったり、めっき反応時にいろいろな付帯反応設備を取り付ける必要があり、作業性が劣るという問題があった。
【００１０】
この発明は、上述の問題に鑑み、工程が簡単で、ハンダめっき被膜中に吸蔵される水素ガス量を低減できる微小球のめっき方法の提供を目的としている。
【００１１】
【課題を解決するための手段】
発明者らは、めっき反応を詳細に解析し、発生する水素ガスを除去するのではなく、水素の発生そのものをめっき処理中で抑制する方法について鋭意検討した結果、総イオン濃度を高濃度にし、かつ低い電流密度で電気めっきを行うことにより、水素の発生を抑制でき、水素量を０．０５ｐｐｍ以下、特に０．０３ｐｐｍ以下に低減したハンダ被膜を生成できることを知見し、このめっき方法にて微小球、特に金属球にハンダめっき被膜を設けると、前述した被膜の膨れにて微小球が基板から剥離飛散する問題や被膜内にボイドができる問題を解消できることを確認し、この発明を完成した。
【００１２】
すなわち、この発明は、バレル方式を用いる電気めっき法にて直径が 0.1mm 〜 1.0mm の微小球にハンダ被膜を生成する方法において、錫と鉛の総イオン濃度が20〜50g/lであるアルカノールスルホン酸浴又はフェノールスルホン酸浴を用い、かつ0.03〜0.3A/dm2の電流密度範囲で電気めっきを行うことにより、ハンダ被膜中の水素量を0.05ppm以下に低減したことを特徴とする微小球のハンダめっき法である。
【００１３】
【発明の実施の形態】
この発明によるめっき法は、めっき浴中の錫と鉛の合計イオン濃度を通常条件の５〜１３ｇ／ｌよりも増加させて、２０〜５０ｇ／ｌの高イオン濃度のめっき液を用いることによって、錫−鉛析出電位が貴な側へ移行することを利用し、かつ０．０３〜０．３Ａ／ｄｍ2の低電流密度に設定することによって、ハンダ（錫−鉛合金）の析出電位を水素の発生電位よりも貴に保つことができ、水素の発生量を著しく抑制することができるものである。
【００１４】
この発明において、めっき浴中の錫と鉛の合計イオン濃度は、２０ｇ／ｌ未満では水素発生電位より貴な電位が得られ難く、水素の発生を伴い、また５０ｇ／ｌを越えるとハンダ被膜組成（錫と鉛の比率）のコントロールが難しくなるため、めっき浴のイオン濃度を２０〜５０ｇ／ｌに限定した。好ましい濃度範囲は２５〜３５ｇ／ｌである。
【００１５】
なお、めっき浴中の錫と鉛の合計イオン濃度中の錫、鉛イオン濃度は、所望するハンダめっき組成及びめっき条件によって異なるが、例えば錫６０％、鉛４０％のハンダ被膜組成を得るためには、アルカノールスルホン酸浴を用いて総イオン濃度を３０ｇ／ｌ、０．１Ａ／ｄｍ2でめっきする場合、錫（Ｓｎ2+）イオン濃度２４〜２７ｇ／ｌ、鉛（Ｐｂ2+）イオン濃度３〜６ｇ／ｌに調整することが好ましい。
【００１６】
また、陰極電流密度については、０．０３Ａ／ｄｍ2未満では生産性が著しく悪くなる上、被膜表面がザラつき良好なめっき被膜が得られない。また０．３Ａ／ｄｍ2を越えるとめっき反応時の水素発生量が増大し、めっき被膜中の水素含有量が増大し目的とする製品が得られない。従って、陰極電流密度を０．０３〜０．３Ａ／ｄｍ2に限定した。さらに好ましい陰極電流密度範囲は０．０６〜０．１５Ａ／ｄｍ2である。
【００１７】
この発明のめっきに使用するハンダめっき液としては、アルカノールスルホン酸錫、アルカノールスルホン酸鉛、フェノールスルホン酸錫、フェノールスルホン酸鉛などを含むめっき液を使用することができ、電気めっき方法としては各種形状のバレル方式を用いることができる。
【００１８】
また、この発明において、微小球は、従来技術として先に詳述した各種製法で得られる直径が 0.1mm 〜 1mm のCu、ハンダなどの金属球のほかに、プラスチックス球に金属被膜した球であっても同様にめっきすることができる。
【００１９】
【実施例】
実施例１
直径が０．６ｍｍのＣｕ線をプレスマシンによって定寸切断し、直径Ｄ＝０．６ｍｍ、長さＬ＝０．６４ｍｍの円柱状個片（Ｌ／Ｄ＝１．０７）としたＣｕ個片を作製し、これらを高級アルコールで脱脂した後、カーボン製の平板状個片配置治具に形成されている穴内に振り込み配置した後、水素雰囲気中で１１５０℃の電気炉内に２０分配置して加熱溶融した後、２５℃／分の冷却速度で冷却して凝固させ直径０．７ｍｍのＣｕボールを作製した。
【００２０】
ハンダめっき浴として、錫（Ｓｎ2+） ２５．２ｇ／ｌ、鉛（Ｐｂ2+） ４．８ｇ／ｌを含んだアルカノールスルホン酸、半光沢剤を含むｐＨ＜１のめっき液を用い、浴温２４℃にて電気めっきを開始した。電気めっきは、水平バレルを用い、陰極電流密度０．０６Ａ／ｄｍ2、陰極板としてＳｎ／Ｐｂ＝６／４にて電気めっきを２２時間めっきを行い、Ｃｕボール外周面に膜厚み３７μｍの共晶ハンダめっき層を被覆した。
【００２１】
得られたこの発明によるハンダめっき層を有するＣｕボールを、２００℃、２１０℃、各１０秒間、各条件１０００個を溶着した時の膨れ発生率及び基板からの剥離飛散率を測定した。表１にその結果を示す。また、ＴＣＤ検出器法により、室温から６００℃間で温度を上昇させながら水素ガスの放出量を測定温度におけるピークごとに測定した。表２にその結果を示す。
【００２２】
比較例１
実施例１と同様に作製したＣｕボールを用い、Ｓｎ2+ ８．３ｇ／ｌ、Ｐｂ2+１．５ｇ／ｌ以外は実施例と同一組成のめっき液を用い、実施例と同一条件でＣｕボール外周面に膜厚み３７μｍの共晶ハンダめっき層を被覆した。その後、実施例１と同様に膨れ発生率、基板からの剥離飛散率、水素ガス放出量をそれぞれ測定した。その結果を表１，２に示す。
【００２３】
【表１】
【表２】
【発明の効果】
この発明は、電気めっきにてハンダ被膜を生成するにおいて、錫と鉛の総イオン濃度が２０〜５０ｇ／ｌのめっき液を用い、かつ０．０３〜０．３Ａ／ｄｍ2の極めて低い電流密度範囲で電気めっきを行うことにより、ハンダめっき被膜中に吸蔵される水素量を０．０５ｐｐｍ以下に低減できるもので、当該方法にて微小球にハンダめっき被膜を設けると、実施例に明らかなようにハンダめっき被膜を設けた微小球がパッケージボードに加熱溶着した際に被膜の膨れが激減し、基板から微小球が剥離飛散する問題が解消される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a solder plating method in which a solder plating film is provided on the outer peripheral surface of a microsphere having a diameter of about 0.1 to 1.0 mm, particularly a metal sphere, and is extremely low using a plating solution having a high ion concentration. The present invention relates to solder plating of microspheres in which electroplating is performed at a current density and a solder plating film having a small thickness of hydrogen content is provided on the surface of the microsphere.
[0002]
[Prior art]
Conventionally, a microsphere used as a bump core material of a semiconductor package of BGA (Ball Grid Array) type has a diameter of about 0.1 mm to 1.0 mm, and the material is not only solder of a predetermined composition, but recently electrical characteristics. In consideration of the mechanical properties, a chip carrier is proposed in which a metal ball such as Kovar (Ni—Co—Fe alloy), Cu, or 42Ni—Fe alloy is coated with a brazing material (Japanese Patent Laid-Open No. 62-112355). )
[0003]
As the method for producing the microspheres, a so-called liquid dropping method (Japanese Patent Laid-Open No. 7-252510), in which molten metal is dropped into a liquid at a predetermined temperature, spheroidized by the surface tension of the molten metal itself, and solidified as it is, mold A so-called mechanical plastic working method such as forming (Japanese Patent Laid-open No. 4-354808), placing metal particles or metal pieces on a flat plate in a non-oxidizing atmosphere, heating and melting them while applying vibrations, and using the surface tension A vibration heating method (Japanese Patent Publication No. 2-50961) that forms a sphere and solidifies as it is proposed.
[0004]
The brazing material on the outer peripheral surface of the microspheres manufactured in this way is appropriately selected depending on the required dimensional accuracy, the bonding strength between the semiconductor package and the printed circuit board, and the like. For example, solder (Pb—Sn series) having various compositions having a thickness of 5 to 50 μm is coated, and an underlayer such as Ni may be formed as necessary.
[0005]
How conventional solder plating, the case of using a barrel type, ion concentration 5~13g / l, performed at a current density 0.5~3.0A / dm 2. (For example, it is written in the Nikkan Kogyo Shimbun, published in 1986, published in 1986 and published in 9th edition, 1996, P132-P137).
[0006]
[Problems to be solved by the invention]
The microspheres with the solder plating film provided on the outer peripheral surface in this way have a problem that the solder plating film swells when heated and welded to the package board, and the balls peel off from the substrate when the swell bursts. Alternatively, there is a problem that voids (voids) are formed in the solder plating film after heat mounting.
[0007]
For this reason, conventionally, it is necessary to perform degassing by heating in a vacuum or in an inert gas in advance before heat mounting the package board. In addition, when this treatment is performed, there is a problem in that the solder partially melts and the plating film thickness becomes non-uniform.
[0008]
In addition, the inventors have made various studies on these conventional problems and have a correlation with the amount of hydrogen gas occluded in the solder plating film of microspheres. To solve the problem, hydrogen occluded in the solder plating film Knowing that it is necessary to reduce the amount of gas as much as possible, as a plating method that can reduce the amount of hydrogen gas occluded in the solder plating film, introducing an inert gas into the plating bath and performing plating while bubbling ( Japanese Patent Application No. 8-18834) and a method (Japanese Patent Application No. 8-215429) for maintaining the entire plating bath under reduced pressure have been proposed.
[0009]
However, the above method has a problem that workability is inferior because it is necessary to add a new processing step or to attach various incidental reaction equipment during the plating reaction.
[0010]
In view of the above-described problems, an object of the present invention is to provide a method for plating microspheres that has a simple process and can reduce the amount of hydrogen gas occluded in a solder plating film.
[0011]
[Means for Solving the Problems]
The inventors analyzed the plating reaction in detail and did not remove the generated hydrogen gas, but earnestly examined the method of suppressing the generation of hydrogen itself during the plating process. As a result, the total ion concentration was increased to a high concentration, In addition, by performing electroplating at a low current density, it was found that generation of hydrogen can be suppressed and a solder coating with a hydrogen content reduced to 0.05 ppm or less, particularly 0.03 ppm or less, can be produced. It was confirmed that when a solder plating film was provided on a sphere, particularly a metal sphere, it was possible to eliminate the problem that the microspheres were peeled and scattered from the substrate due to the swelling of the film and the problem that voids were formed in the film.
[0012]
That is, the present invention relates to a method for producing a solder coating on microspheres having a diameter of 0.1 mm to 1.0 mm by an electroplating method using a barrel method, and an alkanol having a total ion concentration of tin and lead of 20 to 50 g / l. A small amount of hydrogen characterized in that the amount of hydrogen in the solder coating is reduced to 0.05 ppm or less by electroplating in a current density range of 0.03 to 0.3 A / dm 2 using a sulfonic acid bath or a phenol sulfonic acid bath. This is a solder plating method for balls.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the plating method according to the present invention, the total ion concentration of tin and lead in the plating bath is increased from 5 to 13 g / l under normal conditions, and a plating solution having a high ion concentration of 20 to 50 g / l is used. By utilizing the fact that the tin-lead precipitation potential shifts to the noble side and setting it to a low current density of 0.03-0.3 A / dm 2 , the precipitation potential of the solder (tin-lead alloy) is reduced to hydrogen. The generation potential of hydrogen can be kept noble, and the amount of hydrogen generated can be remarkably suppressed.
[0014]
In the present invention, if the total ion concentration of tin and lead in the plating bath is less than 20 g / l, it is difficult to obtain a noble potential from the hydrogen generation potential, accompanied by hydrogen generation, and if it exceeds 50 g / l, the solder coating composition Since it becomes difficult to control (ratio of tin and lead), the ion concentration of the plating bath is limited to 20 to 50 g / l. A preferred concentration range is 25 to 35 g / l.
[0015]
The tin and lead ion concentrations in the total ion concentration of tin and lead in the plating bath differ depending on the desired solder plating composition and plating conditions. For example, in order to obtain a solder coating composition of 60% tin and 40% lead. When plating with an alkanol sulfonic acid bath at a total ion concentration of 30 g / l and 0.1 A / dm 2 , a tin (Sn 2+ ) ion concentration of 24-27 g / l and a lead (Pb 2+ ) ion concentration It is preferable to adjust to 3-6 g / l.
[0016]
On the other hand, when the cathode current density is less than 0.03 A / dm 2 , the productivity is remarkably deteriorated, and a coating film having a rough surface cannot be obtained. On the other hand , if it exceeds 0.3 A / dm 2 , the amount of hydrogen generated during the plating reaction increases, and the hydrogen content in the plating film increases, so that the intended product cannot be obtained. Thus, with limited cathodic current density 0.03~0.3A / dm 2. A more preferable cathode current density range is 0.06 to 0.15 A / dm 2 .
[0017]
As the solder plating solution used in the plating of the present invention, a plating solution containing tin alkanol sulfonate, lead alkanol sulfonate, tin phenol sulfonate, lead phenol sulfonate, etc. can be used. A barrel method of shape can be used.
[0018]
In addition, in this invention, the microsphere is a sphere in which a plastics sphere is coated with a metal in addition to a metal sphere such as Cu or solder having a diameter of 0.1 mm to 1 mm obtained by the various manufacturing methods described in detail as the prior art. Even if it exists, it can plate similarly.
[0019]
【Example】
Example 1
A Cu piece having a diameter of 0.6 mm and a cylindrical piece (L / D = 1.07) having a diameter D = 0.6 mm and a length L = 0.64 mm, which is cut by a press machine. These were degreased with higher alcohols, then placed in holes formed in a flat plate piece placement jig made of carbon, and then placed in an electric furnace at 1150 ° C. for 20 minutes in a hydrogen atmosphere. After being heated and melted, it was cooled and solidified at a cooling rate of 25 ° C./min to produce a Cu ball having a diameter of 0.7 mm.
[0020]
As a solder plating bath, a plating solution having a pH <1 containing alkanol sulfonic acid containing 25.2 g / l of tin (Sn 2+ ), 4.8 g / l of lead (Pb 2+ ), and a semi-brightening agent was used. Electroplating was started at a temperature of 24 ° C. Electroplating was performed using a horizontal barrel, cathode current density of 0.06 A / dm 2 , and cathode plate of Sn / Pb = 6/4 for 22 hours. A crystal solder plating layer was coated.
[0021]
The resulting Cu balls having the solder plating layer according to the present invention were measured at 200 ° C., 210 ° C., 10 seconds each, and the swelling generation rate and peeling / scattering rate from the substrate when 1000 conditions were welded. Table 1 shows the results. Further, the amount of released hydrogen gas was measured for each peak at the measurement temperature while the temperature was raised between room temperature and 600 ° C. by the TCD detector method. Table 2 shows the results.
[0022]
Comparative Example 1
Using Cu balls produced in the same manner as in Example 1, except for Sn 2+ 8.3 g / l and Pb 2+ 1.5 g / l, a plating solution having the same composition as in the example was used, and Cu was used under the same conditions as in the example. A eutectic solder plating layer having a film thickness of 37 μm was coated on the outer peripheral surface of the ball. Thereafter, in the same manner as in Example 1, the occurrence rate of swelling, the rate of separation and scattering from the substrate, and the amount of hydrogen gas released were measured. The results are shown in Tables 1 and 2.
[0023]
[Table 1]
[Table 2]
【The invention's effect】
The present invention uses a plating solution having a total ion concentration of tin and lead of 20 to 50 g / l in producing a solder film by electroplating, and has an extremely low current density of 0.03 to 0.3 A / dm 2. By performing electroplating in the range, the amount of hydrogen occluded in the solder plating film can be reduced to 0.05 ppm or less. When the solder plating film is provided on the microsphere by this method, it is apparent in the examples. When the microspheres provided with the solder plating film are heat-welded to the package board, the swelling of the film is drastically reduced, and the problem that the microspheres are peeled off and scattered from the substrate is solved.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09495897A JP3837446B2 (en) | 1997-03-27 | 1997-03-27 | Microsphere solder plating method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09495897A JP3837446B2 (en) | 1997-03-27 | 1997-03-27 | Microsphere solder plating method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10270836A JPH10270836A (en) | 1998-10-09 |
| JP3837446B2 true JP3837446B2 (en) | 2006-10-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09495897A Expired - Fee Related JP3837446B2 (en) | 1997-03-27 | 1997-03-27 | Microsphere solder plating method |
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| JP (1) | JP3837446B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4534183B2 (en) * | 2001-02-26 | 2010-09-01 | 日立金属株式会社 | Electronic components |
| DE60325620D1 (en) | 2002-09-27 | 2009-02-12 | Neomax Materials Co Ltd | LOTBESCHICHTETE BALL AND METHOD FOR THE PRODUCTION AND METHOD FOR FORMING A SEMICONDUCTOR CONNECTOR STRUCTURE |
| DE10340197B3 (en) * | 2003-08-27 | 2004-09-23 | Siemens Ag | Process for electrochemical separation of metals from an electrolyte containing the metal ions to be separated and indium ions useful in separation of metal ions from electrolytes with decreased hydrogen build up at the electrodes |
| TW200704789A (en) * | 2005-06-30 | 2007-02-01 | Nippon Mining Co | Sn-plated copper alloy bar having excellent fatigue characteristics |
| WO2021049437A1 (en) | 2019-09-11 | 2021-03-18 | 株式会社新菱 | Sn-bi-in-based low melting-point joining member, production method therefor, semiconductor electronic circuit, and mounting method therefor |
| JP7080939B2 (en) | 2020-09-04 | 2022-06-06 | 株式会社新菱 | Low melting point bonding member and its manufacturing method, semiconductor electronic circuit and its mounting method |
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1997
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| JPH10270836A (en) | 1998-10-09 |
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