【発明の詳細な説明】
本発明は高密度、高信頼性の厚膜フアインパタ
ーンの製法に関するものである。
厚膜フアインパターンは、電流値が必要とされ
る小型コイル、高密度コネクター、高密度配線な
どの分野で要求されている。コイルの製造法とし
ては、通常、巻き線方式が用いられているが、こ
の方法では小型のコイルを製造する事は困難であ
り、かつ巻き線の状態にバラツキが生じる。ま
た、35μｍ銅箔をエツチングしたいわゆるプリン
トコイルは、サイドエツチングの為、導電体間隔
が10〜100μｍの厚膜フアインパターンは得られ
ず、たかだか２〜３本／mmのパターンしか得られ
ず、この方法も小型のコイルを製造する事はむつ
かしい。しかしながら、近年モーターの小型化に
ともない、５〜25本／mmのフアインパターンを有
するフアインコイル即ち導電体間隔が10〜100μ
で厚膜のフアインパターンを有するコイルの開発
が要望されている。
しかしながら、厚膜フアインパターン（５本／
mm以上で膜厚58μｍをこえるもの、特に68μｍを
こえるもの）の所望する回路部の膜厚まで、無電
解メツキで厚付けすると、膜厚以上に幅方向に太
りが生じる為、フアインパターンは得られない。
また、電解メツキで厚付けを行う場合、通常の電
流密度で電解メツキを行うと、膜厚方向以上に幅
方向への太りが生じ、かつメツキ膜厚が不均一に
なつてしまい、フアインパターンを得る事はむつ
かしい。
この問題を解決する為に、鋭意研究した結果、
まず最初に陰極電流密度が大きい程、幅方向への
太りが少なくなり膜厚方向へのメツキの選択性が
向上することを見出した。しかしながら、余り陰
極電流密度を上げ過ぎると通常の電解メツキでは
メツキ厚を58μｍをこえて厚くすると（特に68μ
ｍをこえると顕著に）やけが大きくなり、それ程
陰極電流密度が上げれなかつた。そこで、更に研
究した結果、例えばパルスメツキなどにより、や
けを生じる事なく従来より陰極電流密度が上げら
れる様になり、はじめて従来不可能とされていた
68μｍをこえる膜厚を有する厚膜フアインパター
ンが得られることを見出し、本発明の新規で有用
な厚膜フアインパターンの製法を完成させた。
即ち、本発明は、基板上に、導電体膜厚0.1〜
10μｍの薄膜導電体を形成した後、該薄膜導電体
上にピロリン酸銅メツキ液を用い陰極電流密度が
20A／ｄm2を超える値でパルス電解メツキにより
導体厚が58μｍを超える厚付けを行うことを特徴
とする導電体の線密度５本／mm以上の厚膜フアイ
ンパターンの製法である。
このような厚膜フアインパターンの製法は、ま
ず、導電体間隔10〜100μｍもしくはその近傍の
所定の巾に膜厚0.1〜10μｍの薄膜導電体を形成し
た後、20A／ｄm2をこえる陰極電流密度で、パル
スメツキして厚付けすることにより、形成され
る。
本発明の厚膜フアインパターンの製法は、基板
の片面だけに形成しても良いが、必要に応じて両
面に形成しても良く、両面に形成する場合は基板
に穴あけし、スルーホール接続を必要に応じて行
う。１枚の基板の上に複数のパターンを形成する
場合は、基板の両面にパターンを形成し、スルー
ホール接続した方がつなぎ込みが容易であり好ま
しい。
本発明に使用される基板としては、フイルム状
のものが好ましく、例えばポリエステルフイル
ム、エポキシフイルム、ポリイミドフイルム、ポ
リパラバン酸フイルム、トリアジンフイルムなど
フイルム状のものはすべて使用出来るが、可撓
性、耐熱性の点からポリイミドフイルム、ポリパ
ラバン酸フイルム、トリアジンフイルムが好まし
い。基板の膜厚は、高密度化という意味では出来
るだけ薄いものが好ましいが、余り薄すぎると作
業性が悪くなり、膜厚としては５〜50μｍ、特に
10〜25μｍが好ましい範囲である。
また必要に応じて、基板と導電体の接着性を向
上する為に、基板上に接着層を設けても良い。接
着剤としては、ポリエステル−イソシアネート
系、フエノール樹脂−ブチラール系、フエノール
樹脂−ニトリルゴム系、エポキシ−ナイロン系、
エポキシ−ニトリルゴム系などがあり、耐熱性、
耐湿性、接着性の優れたものが好ましく、特にフ
エノール樹脂−ニトリルゴム系、エポキシ−ニト
リルゴム系接着剤が好ましい。接着剤の膜厚は高
密度化、接着性の点から、１〜20μｍ、特に２〜
10μｍが好ましい範囲である。
本発明に使用される薄膜導電体としては、導電
性のものであれば何でも良いが、銀、金、銅、ニ
ツケル、スズなどが好ましく、特に導電性、経済
性の点から銅が好ましい。本発明の厚膜フアイン
パターンを形成するための膜厚0.1〜10μｍの薄膜
導電体を形成する方法としては、蒸着、スパツタ
リング、イオンプレーテイングなどの方法、無電
解メツキによる方法、銅薄膜を貼る方法などがあ
り、この薄膜導電体は、従来公知のフオトエツチ
ング法などにより、電解メツキ前にフアインパタ
ーン状にパターニングされていても良く、また薄
膜導電体上にフオトレジストでマスクを形成し
て、フアインパターンに電解メツキを行つた後、
フアインパターン以外の薄膜導電体をエツチング
などにより除去しても良い。
薄膜導電体の膜厚は、0.1μｍ以下ではメツキ時
電圧降下が起こり均一な電解メツキがむつかし
く、10μｍ以上ではエツチング時サイドエツチン
グの為フアインパターンの製造が困難であり、特
に0.2〜5μｍが好ましい範囲である。
電解メツキの種類としては、銅が好ましい。銅
の電解メツキとしては、ピロリン酸銅メツキが好
ましい。フアインパターンを電解メツキする場合
重要なことは陰極の電流密度を20A／ｄm2を超え
る値で、かつ、パルスメツキを行うことであり、
これによつて膜厚方向に選択的にメツキされる。
電流密度が20A／ｄm2以下でのパルスメツキでは
線密度５本／mm以上で導体厚58μｍを超える導体
を得ることが出来ない。電解メツキ膜厚は、設計
値により異るが、58μｍをこえて200μｍ以下、特
に68μｍをこえるものが好ましい範囲である。
また、より信頼性を向上する為に、必要に応じ
て、電解メツキ後熱処理或いはポリマーから成る
保護層を設けるなどの処理が行われる。
本発明により、厚膜フアインパターンの回路、
例えば５本／mm以上、58μｍをこえる膜厚更には
68μｍをこえる膜厚を有する今まで不可能視され
ていた回路を提供することができる。
以下に本発明の態様を一層明確にする為に、実
施例を挙げて説明するが、本発明は以下の実施例
に限定されるものではなく、種々の変形が可能で
ある。
実施例 １
デユポン社製ポリイミドフイルム「カプトン」
（膜厚25μｍ）上に、表面処理、無電解銅メツキ
（膜厚5μｍ）、フオトエツチングで導体間隔約20μ
ｍ、膜厚5μｍの薄膜導電体パターンを形成し、
次いで、ハーシヨウ村田社製ピロリン酸銅メツキ
液を用いて、陰極電流密度25A／ｄm2の条件で銅
を75μｍ厚パルスメツキを行つて、膜厚80μｍで
導体間隔15μｍの12.5本／mmのフアインパターン
を得た。
実施例 ２
エツソ化学社製ポリパラバン酸フイルム「トラ
ドロン」（膜厚25μｍ）の両面に、ボスチツク社
製エポキシ−ニトリルゴム系接着剤「XA−564
−９」を乾燥後、片面膜厚が5μｍ塗布し、穴あ
け、銅蒸着して得られた膜厚0.3μｍの薄膜導電体
を、フオトレジスト（膜厚5μｍ）でパターン以
外をマスクし、次いで、ハーシヨウ村田社製ピロ
リン酸銅メツキ液を用いて、陰極電流密度30A／
ｄm2の条件で銅を150μｍ厚パルスメツキを行い、
その後、パターン以外の薄膜銅をエツチング除去
して、膜厚150μｍで導体間隔55μｍで10本／mmの
フアインパターンを得た。
比較例 １〜５
通電方法と陰極電流密度を下記表に示す如く変
化させる以外は、実施例１と同様の処理を行つ
た。その結果を下記表に示す。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thick film fine pattern with high density and high reliability. Thick film fine patterns are required in fields such as small coils, high-density connectors, and high-density wiring that require high current values. A wire winding method is normally used as a method of manufacturing a coil, but it is difficult to manufacture a small coil with this method, and variations occur in the state of the winding wire. In addition, so-called printed coils made by etching 35 μm copper foil cannot obtain thick film fine patterns with a conductor spacing of 10 to 100 μm because of side etching, and can only obtain patterns with 2 to 3 conductors/mm at most. This method is also difficult to manufacture small-sized coils. However, in recent years, with the miniaturization of motors, fine coils with a fine pattern of 5 to 25 wires/mm, that is, conductor spacing of 10 to 100 μm, have become more compact.
Therefore, there is a demand for the development of a coil with a thick film fine pattern. However, thick film fine pattern (5 pieces/
If the film is thickened by electroless plating to the desired thickness of the circuit part of a film with a film thickness of 58 μm or more (particularly a film thickness of 68 μm or more), the fine pattern will thicken in the width direction beyond the film thickness. I can't get it.
In addition, when electrolytically plating is performed, if electroplating is performed at a normal current density, the thickness will increase in the width direction more than in the thickness direction, and the plating film thickness will become uneven, resulting in a fine pattern. is difficult to obtain. In order to solve this problem, as a result of intensive research,
First, it was discovered that the larger the cathode current density, the less thickening in the width direction and the higher the selectivity of plating in the film thickness direction. However, if the cathode current density is increased too much and the plating thickness becomes thicker than 58 μm (especially 68 μm) in normal electrolytic plating,
(m), the burn became significant and the cathode current density could not be increased to that extent. As a result of further research, it became possible to increase the cathode current density using pulse plating, for example, without causing burns, which was previously thought to be impossible.
It was discovered that a thick film fine pattern having a film thickness exceeding 68 μm could be obtained, and the novel and useful method for producing a thick film fine pattern of the present invention was completed. That is, the present invention provides a conductor film with a thickness of 0.1 to 0.1 on a substrate.
After forming a 10 μm thin film conductor, a cathode current density was set using a copper pyrophosphate plating solution on the thin film conductor.
This is a method for producing a thick film fine pattern with a conductor line density of 5 lines/mm or more , which is characterized in that the conductor thickness is increased to more than 58 μm by pulse electrolytic plating at a value exceeding 20 A/dm 2 . The method for producing such a thick film fine pattern is to first form a thin film conductor with a thickness of 0.1 to 10 μm in a predetermined width at or near a conductor interval of 10 to 100 μm, and then apply a cathode current exceeding 20 A/ dm2 . It is formed by pulse plating and thickening at a high density. In the method of manufacturing a thick film fine pattern of the present invention, it may be formed on only one side of the substrate, but it may be formed on both sides as necessary. If it is formed on both sides, holes are made in the substrate and through-hole connections are made. Perform as necessary. When forming a plurality of patterns on one substrate, it is preferable to form the patterns on both sides of the substrate and connect them through through holes because connection is easier. The substrate used in the present invention is preferably a film. For example, any film such as polyester film, epoxy film, polyimide film, polyparabanic acid film, triazine film, etc. can be used; From this point of view, polyimide film, polyparabanic acid film, and triazine film are preferred. The film thickness of the substrate is preferably as thin as possible in the sense of high density, but if it is too thin, workability will deteriorate, so the film thickness should be 5 to 50 μm, especially
The preferred range is 10 to 25 μm. Furthermore, if necessary, an adhesive layer may be provided on the substrate in order to improve the adhesiveness between the substrate and the conductor. Adhesives include polyester-isocyanate-based, phenolic resin-butyral-based, phenolic resin-nitrile rubber-based, epoxy-nylon-based,
There are epoxy-nitrile rubber types, etc., which have heat resistance,
Adhesives having excellent moisture resistance and adhesive properties are preferred, and phenolic resin-nitrile rubber adhesives and epoxy-nitrile rubber adhesives are particularly preferred. The film thickness of the adhesive should be 1 to 20 μm, especially 2 to 20 μm, from the viewpoint of high density and adhesive properties.
A preferred range is 10 μm. The thin film conductor used in the present invention may be any conductive material, but silver, gold, copper, nickel, tin, etc. are preferred, and copper is particularly preferred from the viewpoint of conductivity and economy. Methods for forming a thin film conductor with a film thickness of 0.1 to 10 μm for forming the thick film fine pattern of the present invention include methods such as vapor deposition, sputtering, ion plating, electroless plating, and pasting a copper thin film. The thin film conductor may be patterned into a fine pattern before electrolytic plating by a conventionally known photoetching method, or a mask may be formed on the thin film conductor using a photoresist. , after performing electrolytic plating on the fine pattern,
The thin film conductor other than the fine pattern may be removed by etching or the like. If the film thickness of the thin film conductor is less than 0.1 μm, a voltage drop occurs during plating and uniform electrolytic plating is difficult, and if it is more than 10 μm, it is difficult to produce a fine pattern due to side etching during etching, so 0.2 to 5 μm is particularly preferable. range. As for the type of electrolytic plating, copper is preferred. As the electrolytic plating of copper, pyrophosphate copper plating is preferred. When electrolytically plating fine patterns, it is important to set the cathode current density to a value exceeding 20A/dm 2 and to perform pulse plating.
This allows selective plating in the film thickness direction.
Pulse plating at a current density of 20 A/dm 2 or less cannot produce a conductor with a linear density of 5 lines/mm or more and a conductor thickness exceeding 58 μm. The electrolytic plating film thickness varies depending on the design value, but is preferably in the range of more than 58 μm and 200 μm or less, particularly more than 68 μm. Further, in order to further improve reliability, heat treatment after electrolytic plating or treatment such as providing a protective layer made of a polymer are performed as necessary. According to the present invention, a thick film fine pattern circuit,
For example, film thickness of 5 lines/mm or more, film thickness exceeding 58 μm, and
It is possible to provide a circuit that has a film thickness exceeding 68 μm, which was considered impossible until now. EXAMPLES In order to further clarify aspects of the present invention, examples will be described below, but the present invention is not limited to the following examples, and various modifications are possible. Example 1 Polyimide film “Kapton” manufactured by DuPont
(film thickness 25μm), surface treatment, electroless copper plating (film thickness 5μm), and photo etching conductor spacing of approximately 20μm.
m, forming a thin film conductor pattern with a film thickness of 5 μm,
Next, pulse plating of copper to a thickness of 75 μm was performed using a copper pyrophosphate plating solution manufactured by Hershyou Murata under conditions of a cathode current density of 25 A/dm 2 to form a fine pattern of 12.5 wires/mm with a film thickness of 80 μm and a conductor spacing of 15 μm. I got it. Example 2 Epoxy-nitrile rubber adhesive "XA-564" manufactured by Bostik Co., Ltd. was applied to both sides of polyparabanic acid film "Tradron" (film thickness 25 μm) manufactured by Etsuo Chemical Co., Ltd.
-9" was dried, one side was coated with a film thickness of 5 μm, holes were made, and copper was deposited to form a thin film conductor with a film thickness of 0.3 μm. The area other than the pattern was masked with a photoresist (film thickness of 5 μm), and then, Using a copper pyrophosphate plating solution made by Hershyou Murata Co., Ltd., the cathode current density was 30A/
Copper was pulse plated to a thickness of 150 μm under dm 2 conditions,
Thereafter, the thin copper film other than the pattern was removed by etching to obtain a fine pattern with a film thickness of 150 μm, conductor spacing of 55 μm, and 10 conductors/mm. Comparative Examples 1 to 5 The same treatments as in Example 1 were performed except that the current application method and cathode current density were changed as shown in the table below. The results are shown in the table below. 【table】