【発明の詳細な説明】[Detailed description of the invention]
本発明は、均一厚みの電気めつきが得られる如
く改良した電気めつき方法に関するものである。
ここ数年来、技術的優秀性と省力化の観点よ
り、精度の要求される印刷配線板の製造にも電気
めつき方法が利用され、これについての各種の改
良改善が施されてきた。
ところで、印刷配線板を製造するにさいして
は、絶縁基板に無電解めつきを施し、次いで電気
めつきを施し、回路形成を行なうのであるが、こ
の回路形成法の一つにテンテイング法と称せられ
ている形成の仕方があり、これは絶縁基板にスル
ーホールと称している貫通孔を穿設し、全面に無
電解めつきを施してなる印刷配線板用基板を陰極
にして電解槽中で全面に電気銅めつきを施した
後、貫通孔の両端および回路となる部分にエツチ
ングレジストを施し、エツチングにより回路を形
成し、エツチングレジストを除去して印刷配線板
を製造する仕方である。
ところで上述の如き、印刷配線板用基板に電気
めつきを行なつた場合、該基板の端縁部あるいは
貫通孔の入口近く（エツジ部）に電気めつきが多
く析出し、均一な厚みのめつき膜を得ることが困
難であつた。
かかる欠点を改善するために、厚さが１〜５mm
程度のプラスチツク絶縁板に円形の穴を穿設した
整流板を陰極と陽極との間に設置して電気めつき
を行なう試みもなされてはいるが、未だ均一効果
が少ないのみならず、電流整流板の穴以外の部分
のために電極間の電気抵抗が増大し、このため浴
電圧を上げねばならず、消費電力が大きくなると
いう欠点があり、また陰極室と陽極室との分割分
離のため、陽極における金属イオンへの変化速度
が低下し、スラツジの発生が生ずるなどの避け得
ない難点なり欠陥があつた。
本発明は、かかる現状に鑑み、電解槽中の陰極
と陽極との間に、陰極と陽極とに面して開口し、
かつ個々の大きさが20mm以下で、空隙率が陰極へ
の正射影で90％以上で、長さが極間隙の1/3以上
であるハニカム状の多数の貫通孔が施された電流
整流板を配置して電気めつきを施すことにより、
均一な厚みの電気めつきを大きな消費電力を要す
ることなく行なうことができ、スラツジの発生の
ない電気めつき方法を提供するものであつて、以
下本発明を印刷配線板の製造に適用した図示の実
施例に従つて詳細に説明することとする。
図において、１はハニカム状の多数の貫通孔２
を有する電流整流板にして、例えば塩化ビニル樹
脂等の合成樹脂で形成される正六角柱状の管３の
集合（ハニカムチユーブ）よりなつている。貫通
孔２の長さは電極間の1/3以上であつて、その大
きさ（六角形の大きさ）は20mm以下のものであつ
て、製作上の制限内で小さければ小さいほど好ま
しい。貫通孔２の形状を以上のようにすることに
より、陽極から陰極までの電流を効果的にしぼる
ことができ、電気めつきを均一な厚みとすること
ができる。
また、電流整流板１の貫通孔部分の占める割
合、すなわち空隙率は陰極への正射影で90％以上
であることが必要であつて、これにより電気めつ
きの抵抗増加が抑えられ、浴電圧を上げずに電気
めつきを均一に行なうことができると共に、陰極
室と陽極室とが分割分離することなく、スラツジ
の発生を防止することができる。
電流整流板１は、第３図に示す如く電解槽（め
つき槽）４内のめつき液５中に適宜の間隔をおい
て配せられた印刷配線板用基板などの陰極６と陽
極７との間に、貫通孔２がこれらに面するように
配置せられる。電流整流板１と陰極６や陽極７と
の位置関係は、電流整流板１と陽極７との間隔が
電極間隔の1/3以下で、電流整流板１と陰極６と
の間隔が20mm以上で電極間隔の1/3以下であるこ
とが望ましい。
第３図において、８は電流整流板１の支持台で
あり、９は電解槽４内におけるめつき液の循環用
パイプの開口端、１０は陰極近傍のめつき液を撹
拌するための空気供給用パイプの開口端、１１は
めつき液循環用ポンプ、１２はめつき液のオーバ
ーフロー用液だめ、１３はめつき液のオーバーフ
ローによる流れの方向を示す。なお、めつき液と
しては、例えばピロリン酸銅水溶液、硫酸銅水溶
液等が用いられる。
直径1.0mmの貫通孔を有する絶縁基板を無電解
銅めつきした印刷配線板用基板を３、６、９、
12A／ｄm2の各めつき速度で銅めつきしたとこ
ろ、基板表面での銅めつき膜厚の分布、および貫
通孔部分への銅めつきの分布は以下のようにな
り、電流整流板を使用した場合（本法）は、使用
しない場合（従来法）に比べて非常に均一となつ
た。
The present invention relates to an improved electroplating method that enables electroplating with a uniform thickness. Over the past few years, electroplating methods have been used to manufacture printed wiring boards that require precision from the viewpoint of technical excellence and labor saving, and various improvements have been made in this regard. By the way, when manufacturing printed wiring boards, electroless plating is applied to an insulating substrate, and then electroplating is applied to form a circuit. One of the circuit forming methods is called the tenting method. There is a method of forming the printed wiring board, which is made by drilling through holes in an insulating substrate and applying electroless plating to the entire surface, and using the printed wiring board substrate as a cathode in an electrolytic bath. After applying electrolytic copper plating to the entire surface, etching resist is applied to both ends of the through hole and the portion that will become the circuit, a circuit is formed by etching, and the etching resist is removed to produce a printed wiring board. However, when electroplating is performed on a printed wiring board substrate as described above, a large amount of electroplating is deposited on the edge of the substrate or near the entrance of the through hole (edge portion), making it difficult to maintain a uniform thickness. It was difficult to obtain a coated film. In order to improve this drawback, the thickness is 1 to 5 mm.
Attempts have been made to perform electroplating by installing a rectifier plate with circular holes bored in a plastic insulating plate between the cathode and anode, but this method not only has little uniformity effect but also has difficulty in rectifying the current. The electric resistance between the electrodes increases due to the parts other than the holes in the plate, which requires increasing the bath voltage, which increases power consumption.Also, because the cathode chamber and anode chamber are separated, the electric resistance between the electrodes increases. However, there were unavoidable drawbacks and defects, such as a decrease in the rate of conversion to metal ions at the anode, and the generation of sludge. In view of the current situation, the present invention provides an opening between a cathode and an anode in an electrolytic cell, facing the cathode and anode,
and a current rectifying plate with a large number of honeycomb-shaped through holes, each of which has an individual size of 20 mm or less, a porosity of 90% or more when orthogonally projected onto the cathode, and a length of 1/3 or more of the electrode gap. By arranging and applying electroplating,
An object of the present invention is to provide an electroplating method that can perform electroplating to a uniform thickness without requiring large power consumption and does not generate sludge. This will be explained in detail according to an embodiment. In the figure, 1 is a large number of honeycomb-shaped through holes 2
The current rectifying plate is made of a set of regular hexagonal columnar tubes 3 (honeycomb tubes) made of synthetic resin such as vinyl chloride resin. The length of the through hole 2 is 1/3 or more between the electrodes, and its size (hexagonal size) is 20 mm or less, and the smaller the better within manufacturing limitations. By configuring the shape of the through hole 2 as described above, the current flowing from the anode to the cathode can be effectively restricted, and the electroplating can be made to have a uniform thickness. In addition, the proportion of the through-holes in the current rectifier plate 1, that is, the porosity, needs to be 90% or more when orthogonally projected onto the cathode. Electroplating can be performed uniformly without raising the temperature, and the generation of sludge can be prevented without separating the cathode chamber and the anode chamber. The current rectifying plate 1 includes a cathode 6 and an anode 7, such as a printed circuit board substrate, which are arranged at appropriate intervals in a plating solution 5 in an electrolytic bath (plating bath) 4, as shown in FIG. A through hole 2 is arranged between and facing these. The positional relationship between the current rectifying plate 1 and the cathode 6 and anode 7 is such that the distance between the current rectifying plate 1 and the anode 7 is 1/3 or less of the electrode spacing, and the distance between the current rectifying plate 1 and the cathode 6 is 20 mm or more. It is desirable that the distance be 1/3 or less of the electrode spacing. In FIG. 3, 8 is a support for the current rectifying plate 1, 9 is the open end of a pipe for circulating the plating solution in the electrolytic cell 4, and 10 is an air supply for stirring the plating solution near the cathode. 11 indicates a pump for circulating the plating solution, 12 indicates a reservoir for overflowing the plating solution, and 13 indicates the direction of flow due to overflow of the plating solution. Note that as the plating solution, for example, a copper pyrophosphate aqueous solution, a copper sulfate aqueous solution, etc. are used. 3, 6, 9, printed wiring board substrates with electroless copper plating on insulating substrates with through holes of 1.0 mm in diameter.
When copper plating was performed at various plating speeds of 12 A/dm 2 , the distribution of the copper plating film thickness on the board surface and the distribution of copper plating on the through hole part was as shown below. When it was used (this method), it was much more uniform than when it was not used (conventional method).
【表】【table】
【表】
以上の説明から明らかなように、本発明におい
ては、電気めつきを均一に行うことができ、特に
印刷配線板を製造するに際して無電解めつきが施
された印刷配線板用基板に電気めつきを施し回路
形成を行なう場合に極めて有効であり、また消費
電力も増大することなく、スラツジの発生も防止
することができるなどの実用上における優れた作
用効果が得られる。[Table] As is clear from the above description, in the present invention, electroplating can be performed uniformly, and especially on printed wiring board substrates that have been subjected to electroless plating when manufacturing printed wiring boards. It is extremely effective when electroplating is performed to form a circuit, and excellent practical effects such as being able to prevent the generation of sludge without increasing power consumption can be obtained.
【図面の簡単な説明】[Brief explanation of drawings]
図面は本発明を実施するための電流整流板等の
一例を示すものにして、第１図は電流整流板の正
面図、第２図はその側面図、第３図は電流整流板
の使用状態を示す説明図である。
１：電流整流板、２：貫通孔、３：管、４：電
解槽、５：めつき液、６：陰極、７：陽極、８：
支持台、９：循環用パイプの開口端、１０：空気
供給用パイプの開口端、１１：めつき液循環用ポ
ンプ、１２：オーバーフロー用液だめ、１３：め
つき液のオーバーフローの流れ方向。
The drawings show an example of a current rectifier plate, etc. for carrying out the present invention, and FIG. 1 is a front view of the current rectifier plate, FIG. 2 is a side view thereof, and FIG. 3 is a state in which the current rectifier plate is used. FIG. 1: Current rectifier plate, 2: Through hole, 3: Pipe, 4: Electrolytic bath, 5: Plating solution, 6: Cathode, 7: Anode, 8:
Support stand, 9: Opening end of the circulation pipe, 10: Opening end of the air supply pipe, 11: Plating liquid circulation pump, 12: Overflow liquid reservoir, 13: Flow direction of overflow of the plating liquid.