JPH0549760B2 - - Google Patents
Info
- Publication number
- JPH0549760B2 JPH0549760B2 JP3415685A JP3415685A JPH0549760B2 JP H0549760 B2 JPH0549760 B2 JP H0549760B2 JP 3415685 A JP3415685 A JP 3415685A JP 3415685 A JP3415685 A JP 3415685A JP H0549760 B2 JPH0549760 B2 JP H0549760B2
- Authority
- JP
- Japan
- Prior art keywords
- plating
- bath
- tin
- seconds
- energization
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000007747 plating Methods 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 19
- 229910001174 tin-lead alloy Inorganic materials 0.000 claims description 15
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 9
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 230000002159 abnormal effect Effects 0.000 description 16
- 238000001556 precipitation Methods 0.000 description 14
- 239000002253 acid Substances 0.000 description 4
- 210000001787 dendrite Anatomy 0.000 description 4
- 239000002243 precursor Substances 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000009499 grossing Methods 0.000 description 3
- WHOZNOZYMBRCBL-OUKQBFOZSA-N (2E)-2-Tetradecenal Chemical compound CCCCCCCCCCC\C=C\C=O WHOZNOZYMBRCBL-OUKQBFOZSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229940044654 phenolsulfonic acid Drugs 0.000 description 2
- 238000002203 pretreatment Methods 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- -1 tin and lead Chemical class 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、有機スルホン酸浴を用いる錫−鉛合
金メツキ方法の改善に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in the method of plating tin-lead alloys using an organic sulfonic acid bath.
［従来の技術］
かつて電子部品の露出金属部には防錆及び半田
付け性を目的に電気錫メツキが施されていたが、
このメツキはホイスカーと称されるひげ状の結晶
が発生するため電気回路の短絡等のトラブルがあ
り、近年小型化、精密化された電子部品、例えば
ICパツケージのアウターリード等においてはホ
イスカーの発生の少ない錫−鉛合金メツキが施さ
れている。このような錫−鉛合金メツキの浴とし
て従来最も多く用いられているのはホウフツ化物
浴であるが、この浴を用いた場合排水中のホウフ
ツ化イオンを除去する必要がある。しかし、ホウ
フツ化イオンを十分に除去することは困難である
ため、ホウフツ化物浴に代わるメツキ浴が求めら
れ、そのような錫−鉛合金メツキ浴として有機ス
ルホン酸浴が発表され、実用化されるに至つてい
る。[Prior Art] In the past, exposed metal parts of electronic components were electrolytically plated for the purpose of rust prevention and solderability.
This plating produces whisker-like crystals called whiskers, which can cause problems such as short circuits in electrical circuits.
The outer leads of the IC package are plated with a tin-lead alloy that produces fewer whiskers. The most commonly used bath for such tin-lead alloy plating is a borofluoride bath, but when this bath is used, it is necessary to remove borofluoride ions from the waste water. However, it is difficult to remove borofluoride ions sufficiently, so a plating bath to replace the borofluoride bath is required, and an organic sulfonic acid bath was announced and put into practical use as such a tin-lead alloy plating bath. It has reached this point.
ところでこの有機スルホン酸浴を用いた場合、
メツキ被覆表面に針状又は糸状の異常析出が発生
することがある。この異常析出発生のメカニズム
についてはいまだ明らかでないが、カソード表面
の結晶構造、結晶の異方成長性、化学的親和力等
が原因となつてデンドライト前駆体が生成し、こ
の前駆体に局部的に高電流密度の電流が流れ、加
速度的に成長するためと考えられる。この異常析
出は前記した錫メツキの場合のホイスカーと同様
に電気回路の短絡の原因となり電子部品等の信頼
性を損うので、これを確実に防止することが信頼
性確保の上からも、又メツキ製品歩留り向上のた
めからも強く要請されていた。 By the way, when using this organic sulfonic acid bath,
Abnormal needle-like or thread-like precipitation may occur on the plating surface. Although the mechanism behind this abnormal precipitation is not yet clear, dendrite precursors are formed due to the crystal structure of the cathode surface, anisotropic crystal growth, chemical affinity, etc. This is thought to be because a current with a current density flows and grows at an accelerated rate. Similar to the whiskers in the case of tin plating, this abnormal precipitation causes short circuits in electrical circuits and impairs the reliability of electronic components, so it is important to prevent this from the standpoint of ensuring reliability. This was also strongly requested in order to improve the yield of Metsuki products.
従来、上記のような有機スルホン酸浴を用いる
錫−鉛合金メツキにおける異常析出を防止するた
めに、被メツキ物の酸浸漬、電解脱脂又は化学研
磨等の前処理を施したり、下地メツキを施したり
する方法があるが作業工程が増して製造工程が煩
雑になる上、異常析出を必ずしも十分に抑制する
ことができない。また、平滑化剤をメツキ浴に添
加して活性点を不活性化する方法も知られている
が異常析出を効果的に防止するには平滑化剤の選
択やメツキ浴の管理などが厳しく要求されるため
事実上実施が困難な方法である。 Conventionally, in order to prevent abnormal precipitation in tin-lead alloy plating using an organic sulfonic acid bath as described above, pretreatment such as acid immersion, electrolytic degreasing, or chemical polishing of the object to be plated, or undercoat plating has been carried out. Although there is a method to do this, it increases the number of work steps and makes the manufacturing process complicated, and it is not always possible to sufficiently suppress abnormal precipitation. Another known method is to add a smoothing agent to the plating bath to inactivate the active sites, but in order to effectively prevent abnormal precipitation, strict selection of the smoothing agent and control of the plating bath are required. This is a method that is difficult to implement in practice.
［発明が解決しようとする問題点］
本発明の目的は、上述の従来技術が有する、前
処理や下地メツキのような追加の工程が必要であ
るという問題、あるいは困難な平滑化剤の選択や
管理が必要であるという問題を解決することであ
る。換言すると、本発明の目的は、有機スルホン
酸浴を用いる錫−鉛合金メツキ法における上記異
常析出発生のトラブルを、前処理、下地メツキ等
の追加工程や添加剤等の手段によらずに解消し、
安定的にかつ廉価に錫−鉛合金メツキを行ない得
る方法を提供することにある。[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems of the above-mentioned prior art, which require additional steps such as pre-treatment and base plating, or the difficult selection of a smoothing agent. The purpose is to solve the problem of the need for management. In other words, the purpose of the present invention is to eliminate the trouble of abnormal precipitation occurring in the tin-lead alloy plating method using an organic sulfonic acid bath without resorting to additional steps such as pretreatment or base plating, or by means of additives. death,
The object of the present invention is to provide a method for stably and inexpensively plating tin-lead alloys.
［問題点を解決するための手段］
本発明によれば、錫−鉛合金メツキ用有機スル
ホン酸浴を用いる電気錫−鉛合金メツキ法におい
て、メツキ形成のための順方向の通電を間欠的に
停止しながら行なうとともに、該通電は、20〜80
秒を一単位として行われ、且つ該通電の間欠的停
止は、３〜20秒を一単位として行われることを特
徴とする電気錫−鉛合金メツキ法が提供される。[Means for Solving the Problems] According to the present invention, in an electric tin-lead alloy plating method using an organic sulfonic acid bath for tin-lead alloy plating, the forward direction of current for plating formation is intermittently applied. While stopping, the energization should be carried out for 20 to 80 minutes.
An electric tin-lead alloy plating method is provided, which is characterized in that the energization is carried out in units of seconds, and the intermittent stopping of the energization is carried out in units of 3 to 20 seconds.
本発明方法においては、メツキ形成の順方向の
通電と該通電の停止を間欠的に行うことにより、
前述した異常析出の防止を有効に行うことに成功
したものである。この異常析出防止の効果の点か
らは、通電の時間は短い程よく、また停止時間は
長い程よい。例えば、通電時間が80秒を超えた
り、停止時間が３秒未満と短過ぎると、異常析出
を十分に防止することが困難となる。一方、通電
時間が短か過ぎたり、停止時間が長過ぎたりする
と、メツキ形成の能率が低下する。従つて、本発
明においては、前記通電は、20〜80秒を一単位と
して行われ、且つ該通電の間欠的停止は、３〜20
秒を一単位として行われる。また通電及び間欠的
停止の特に好適な時間は、被メツキ物の材質、メ
ツキ浴組成、電流密度等により異なるので一概に
は言えないが、通常の電流密度である2A／ｄm2
においては、通電を20〜60秒を一単位として行
い、通電の停止を５〜20秒を一単位として行うこ
とが好ましい。 In the method of the present invention, by intermittently performing energization in the forward direction of plating formation and stopping the energization,
This has succeeded in effectively preventing the abnormal precipitation mentioned above. From the viewpoint of the effect of preventing abnormal deposition, the shorter the energization time, the better, and the longer the stopping time. For example, if the energization time exceeds 80 seconds or the stop time is too short, such as less than 3 seconds, it becomes difficult to sufficiently prevent abnormal precipitation. On the other hand, if the energization time is too short or the stop time is too long, the efficiency of plating formation will decrease. Therefore, in the present invention, the energization is performed in units of 20 to 80 seconds, and the intermittent stopping of the energization is performed for 3 to 20 seconds.
This is done in units of seconds. Moreover, the particularly suitable time for energization and intermittent stopping cannot be stated unconditionally because it varies depending on the material of the object to be plated, the composition of the plating bath, the current density, etc., but it cannot be stated unconditionally, but it is 2 A/dm 2 which is the normal current density.
In this case, it is preferable that the energization is carried out in units of 20 to 60 seconds, and the energization is stopped in units of 5 to 20 seconds.
上記のように通電を間欠的に停止させることに
よる電流の波形は特に限定されず、例えば矩形
波、ステツプ波、三角波、鋸波など何れでもよ
い。 The waveform of the current caused by intermittent cessation of energization as described above is not particularly limited, and may be any one of, for example, a rectangular wave, a step wave, a triangular wave, a sawtooth wave, and the like.
本発明の方法に用いられる錫−鉛合金メツキ用
有機スルホン酸浴は、錫および鉛の、アルカノー
ルスルホン酸、フエノールスルホン酸等の有機ス
ルホン酸の塩を主成分とするメツキ浴として知ら
れ、例えば石原薬品(株)製のアルカノールスルホン
酸はんだメツキ浴（AS浴）、フエノールスルホン
酸はんだメツキ浴（PS浴）；西独マツクスシユレ
ツター社製のスロツトレツトＫ浴等を挙げること
ができる。 The organic sulfonic acid bath for tin-lead alloy plating used in the method of the present invention is known as a plating bath mainly containing salts of organic sulfonic acids such as tin and lead, alkanol sulfonic acid, phenolsulfonic acid, etc. Examples include alkanolsulfonic acid solder plating bath (AS bath) and phenolsulfonic acid solder plating bath (PS bath) manufactured by Ishihara Pharmaceutical Co., Ltd.; and Throttletz K bath manufactured by Maxschuletzter, Germany.
［作 用］
本発明の方法により異常析出が効果的に防止さ
れる理由は必ずしも明らかではないが、次のよう
に推定される。前述したように諸要因により形成
されたデンドライト前駆体が異常析出へと成長す
る過程にはカソードの近傍に形成される拡散二重
層が重要な役割を果すと考えられる。即ち、カソ
ード近傍のカチオンが電着により消費されて拡散
二重層の濃度勾配が大きくなる結果デンドライォ
前駆体が突起状に成長し、この突起に高電流密度
の電流が流れて突起が加速度的に成長し異常析出
になるものと推定される。本発明の方法により通
電を間欠的に停止すると停止時間中にカソード沖
合から拡散二重層へカチオンの移動が起つて拡散
二重層の濃度勾配が緩和され、その結果デンドラ
イト前駆体の成長が抑制されるものと考えられ
る。[Function] The reason why abnormal precipitation is effectively prevented by the method of the present invention is not necessarily clear, but it is presumed as follows. As mentioned above, the diffusion double layer formed near the cathode is thought to play an important role in the process in which dendrite precursors formed due to various factors grow into abnormal precipitation. In other words, the cations near the cathode are consumed by electrodeposition and the concentration gradient of the diffused double layer increases, resulting in the growth of dendrite precursors into protrusions.A current with high current density flows through these protrusions, causing the protrusions to grow at an accelerated pace. It is estimated that this will lead to abnormal precipitation. By the method of the present invention, when the current supply is stopped intermittently, cations move from the offshore of the cathode to the diffused double layer during the stopped period, and the concentration gradient of the diffused double layer is relaxed, and as a result, the growth of dendrite precursors is suppressed. considered to be a thing.
［実施例］
以下、本発明の方法を実施例により具体的に説
明する。[Example] Hereinafter, the method of the present invention will be specifically explained with reference to Examples.
実施例 １
揺動カソードラツクを備えたメツキ装置にAS
−Ｓ（アルカノールスルホン酸第１錫）200ｇ／
、AS−Ｐ（アルカノールスルホン酸鉛）20ｇ／
、MS−Ａ（アルカンスルホン酸）70ｇ／を
主成分として含有するメツキ浴（石原AS浴、商
品名）を充填し、錫−鉛合金板を陽極に用い、通
電と停止の時間をそれぞれ60秒及び５秒とし、極
間距離200mm、陰極電流密度2A／ｄm2、温度20℃
で12分間、カソードラツクに取付けた42アロイテ
ストピースにメツキしたが、異常析出は認められ
なかつた。Example 1 AS plating equipment equipped with a swinging cathode rack
-S (Stannous alkanol sulfonate) 200g/
, AS-P (lead alkanol sulfonate) 20g/
, a plating bath (Ishihara AS bath, trade name) containing 70 g of MS-A (alkanesulfonic acid) as the main component was filled, a tin-lead alloy plate was used as the anode, and the energization and stopping times were 60 seconds each. and 5 seconds, distance between electrodes 200mm, cathode current density 2A/dm 2 , temperature 20℃
A 42 alloy test piece attached to the cathode rack was plated for 12 minutes, but no abnormal deposition was observed.
実施例 ２
スロツトレツトSN（錫）180ｇ／、スロツト
レツトPB（鉛）７ｇ／、スロツトレツトＡ（酸）
150ｇ／を主成分として含有するメツキ浴（ス
ロツトレツトＫ浴、商品名）を用い、通電と停止
の時間をそれぞれ20秒及び５秒とし、実施例１と
同様にメツキした結果、異常析出は認められなか
つた。Example 2 Slottletz SN (tin) 180g/, Slottletz PB (lead) 7g/, Slottletz A (acid)
As a result of plating in the same manner as in Example 1, using a plating bath (Slottorett K bath, trade name) containing 150 g/ml as the main component, and setting the energization and stop times to 20 seconds and 5 seconds, respectively, no abnormal precipitation was observed. Nakatsuta.
比較例
実施例２と同じメツキ浴を用い、通常の直流電
源により12分間メツキを行なつた。テストピース
上に長さ約100μ程度の針状析出が認められた。Comparative Example Using the same plating bath as in Example 2, plating was carried out for 12 minutes using a normal DC power source. Acicular deposits with a length of approximately 100 μm were observed on the test piece.
［発明の効果］
本発明により電気錫−鉛メツキにおける針状、
糸状の異常析出が効果的に防止され、メツキ物の
信頼性向上、製品歩留向上に大きく寄与できた。
また、本発明によれば、メツキのメツキ厚、組成
等のバラツキも小さくできる利点もある。[Effect of the invention] According to the present invention, the needle shape in electric tin-lead plating,
Abnormal filamentous precipitation was effectively prevented, making a significant contribution to improving the reliability of plated products and improving product yield.
Further, according to the present invention, there is an advantage that variations in plating thickness, composition, etc. of plating can be reduced.
さらに、本発明の方法は被メツキ物の前処理や
下地メツキが不要であり、また特別の添加剤を使
用しないのでその管理なども不要であり、簡便、
低廉でかつ安定した実用性の高い方法である。 Furthermore, the method of the present invention does not require pre-treatment of the object to be plated or base plating, and since no special additives are used, there is no need to manage them.
This is an inexpensive, stable and highly practical method.
Claims (1)
る電気錫−鉛合金メツキ法において、メツキ形成
のための順方向の通電を間欠的に停止しながら行
なうとともに、該通電は、20〜80秒を一単位とし
て行われ、且つ該通電の間欠的停止は、３〜20秒
を１単位として行われることを特徴とする電気錫
−鉛合金メツキ法。1. In the electric tin-lead alloy plating method using an organic sulfonic acid bath for plating tin-lead alloys, the current flow in the forward direction for plating formation is stopped intermittently, and the current flow is continued for 20 to 80 seconds. 1. An electric tin-lead alloy plating method characterized in that the process is carried out in one unit, and the intermittent stopping of energization is carried out in units of 3 to 20 seconds.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3415685A JPS61194196A (en) | 1985-02-22 | 1985-02-22 | Electroplating method of tin-lead alloy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3415685A JPS61194196A (en) | 1985-02-22 | 1985-02-22 | Electroplating method of tin-lead alloy |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61194196A JPS61194196A (en) | 1986-08-28 |
| JPH0549760B2 true JPH0549760B2 (en) | 1993-07-27 |
Family
ID=12406339
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3415685A Granted JPS61194196A (en) | 1985-02-22 | 1985-02-22 | Electroplating method of tin-lead alloy |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61194196A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63118093A (en) * | 1986-11-05 | 1988-05-23 | Tanaka Electron Ind Co Ltd | Method for tinning electronic parts |
| JP2697773B2 (en) * | 1991-03-11 | 1998-01-14 | 日本エレクトロプレイテイング・エンジニヤース 株式会社 | Plating method |
| US5750017A (en) * | 1996-08-21 | 1998-05-12 | Lucent Technologies Inc. | Tin electroplating process |
| GB0106131D0 (en) * | 2001-03-13 | 2001-05-02 | Macdermid Plc | Electrolyte media for the deposition of tin alloys and methods for depositing tin alloys |
| JP4725145B2 (en) * | 2005-03-17 | 2011-07-13 | 日本電気株式会社 | Alloy plating method and alloy plating apparatus |
| JP5168555B2 (en) * | 2008-04-01 | 2013-03-21 | 三菱マテリアル株式会社 | Anode material for solder plating |
-
1985
- 1985-02-22 JP JP3415685A patent/JPS61194196A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61194196A (en) | 1986-08-28 |
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