JP4610027B2 - Electrolytic copper plating solution for forming acicular crystals and method for forming acicular film - Google Patents
Electrolytic copper plating solution for forming acicular crystals and method for forming acicular film Download PDFInfo
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- JP4610027B2 JP4610027B2 JP26593298A JP26593298A JP4610027B2 JP 4610027 B2 JP4610027 B2 JP 4610027B2 JP 26593298 A JP26593298 A JP 26593298A JP 26593298 A JP26593298 A JP 26593298A JP 4610027 B2 JP4610027 B2 JP 4610027B2
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Description
【0001】
【発明が属する技術分野】
本発明は、針状結晶被膜を形成することのできる電気銅めっき液およびこれを利用する針状銅被膜形成方法に関し、更に詳細には、被めっき物に均一針状銅被膜を析出せしめることができ、多層プリント基板等の導体回路上や銅張積層板上等の銅箔と樹脂の接着を始め、多くの金属と樹脂等の接着強度の向上のために使用される、樹脂との接着性が良好な電気銅めっき液および針状銅被膜形成方法並びにこの方法により得られるめっき製品に関する。
【0002】
【従来の技術】
従来、多層プリント基板は、銅張積層板の銅箔を加工してプリント配線を形成することにより内層用銅張積層板を調製し、この銅箔を表面前処理(一般的に脱脂に引続き、過硫酸アンモニウム、過硫酸ナトリウム、塩化第二銅、硫酸−過酸化水素系等に代表されるソフトエッチング処理及び活性化処理)で粗面化処理した後、更に黒化処理またはブラウン処理等に代表される処理で酸化銅または亜酸化銅の針状の被膜を形成せしめ、この内層用銅張積層板に熱硬化性樹脂含浸基材(プリプレグ)を介して外層用銅張積層板又は銅箔を積層接着することにより接着性の高い多層積層板として製造されていた。
【0003】
この様にして製造された多層積層板は各層に通電する必要があり、このため積層板に穴あけを行ない、スルーホールめっきを行なう必要があるが、スルーホールめっきのための触媒付与工程での酸性溶液のしみ込や、無電解銅めっき工程でのめっき液のしみ込により、酸化銅または亜酸化銅被膜が溶解し、ピンクリング(ハローイング)が発生するという欠点があった。
【0004】
一方、あらかじめ粗面化した銅箔を用いた銅張積層板を利用してプリント配線を形成することにより、上記の銅箔の粗面化、酸化被膜形成を省略して多層プリント基板を形成することも行なわれているが、この方法によると銅箔表面が粗化されているため印刷エッチングレジストや、紫外線焼き付け方法によるエッチングレジストのパターン精度が劣るという問題があった。
【0005】
近年、銅張積層板のこのような欠点を解決し、接着強度を向上させる方法として、特定の無電解銅めっき方法を利用させる方法が開発されている(特開昭61−15980号、同61−15981号、同61−41775号)。
しかし、上記の無電解銅めっきは、実際上還元剤としてホルマリンが必須であり、このホルマリンは、▲1▼樹脂上に銅が異常析出したり、▲2▼浴が不安定であったり、▲3▼臭気が強く発ガン性の恐れがあるという問題があった。
【0006】
最近、本発明者らは、接着性に優れた均一針状の銅被膜を無電解銅めっきにより形成する方法を開発した(特開平4−116176号、WO97/46731)。 この技術によれば、前記した欠点のない、接着性の高い銅張積層板が得られるが、基本的に無電解めっきであり、析出速度が遅く、また、液の寿命もあまり長くないという問題があった。
【0007】
【発明が解決しようとする課題】
電気めっきは無電解めっきに比べ、被膜の形成速度が速く、しかも浴管理が容易であるから、電気めっき法により、接着性に優れた均一針状の銅被膜を得ることができれば技術的にも、経済的にも極めて有利である。
本発明は、このような要望を満たすもので、電気めっき法による、接着性に優れた均一針状の銅被膜を得ることができる技術を提供することを課題とするものである。
【0008】
【課題を解決するための手段】
本発明者は、銅被膜析出速度の速い酸性銅めっき浴に着目し、この浴で均一な針状結晶の銅被膜を得る可能性およびその条件について鋭意検討を行っていたところ、遷移金属元素と、イオウ系化合物との両者を存在させることにより均一針状の銅被膜が得られることを見出し、本発明を完成した。
【0009】
すなわち本発明は、酸性銅めっき液に、遷移金属元素と、イオウ系化合物とを添加したことを特徴とする針状結晶形成用電気銅めっき液を提供するものである。
また本発明は、被めっき物を、上記針状結晶形成用電気銅めっき液中で電気めっきする針状銅被膜形成方法およびこの方法で得られるめっき製品を提供するものである。
【0010】
【発明の実施の形態】
本発明の針状結晶形成用電気銅めっき液(以下、「本発明銅めっき液」という)は、通常の酸性銅めっき液に、遷移金属元素およびイオウ系化合物の両者を添加することにより調製される。
【0011】
本発明銅めっき液において使用される酸性銅めっき液としては、硫酸銅めっき液、ピロリン酸銅めっき液等が挙げられる。このうち、硫酸銅めっき液としては、一般に使用される範囲の組成で良く、例えば、硫酸銅として60〜120g/l、硫酸として150〜250g/l、塩酸は塩素イオンとして30〜100ppm程度の濃度のものを利用することができる。
【0012】
また、この酸性銅めっき液に添加される遷移金属元素としては、ニッケル、コバルト、鉄等の周期表VIII族元素等が挙げられる。この遷移金属元素の添加量は、金属の種類によっても相違するが、周期表VIII族元素の場合は、200〜10,000mg/l程度とすることが好ましい。
【0013】
更に、酸性銅めっき液に添加されるイオウ系化合物としては、チオ硫酸や、チオ硫酸ナトリウム、チオ硫酸カリウム、チオ硫酸カルシウム、チオ硫酸鉄、チオ硫酸銅カリウムなどのチオ硫酸塩等が挙げられ、その添加量は100〜10,000mg/l程度とすることが好ましい。
【0014】
本発明銅めっき液には、上記した遷移金属元素およびイオウ系化合物の他、本発明の効果を阻害しない範囲において公知の添加剤、例えば光沢剤や界面活性剤等を添加することができる。
【0015】
次に、本発明銅めっき液を用いる針状銅被膜形成方法(以下、「本発明方法」という)について説明する。
【0016】
本発明方法は、基本的には従来の酸性銅めっき液によるのとほぼ同じ条件で実施することができる。すなわち、20〜40℃程度の浴温、0.1〜5A/dm2程度の電流密度で、空気あるいは攪拌下実施することができる。
【0017】
本発明方法で目的とする均一な針状結晶を有する銅被膜を得るには、約0.2μm以上の厚みの銅被膜が必要であり、めっき時間は1分以上とすることが好ましい。
【0018】
また、本発明方法の実施に必要な装置や電源も、従来の酸性銅めっきと同じものが使用できる。
【0019】
【作用】
本発明は、電気銅めっきでの異状析出の解析を元に開発されたものである。すなわち、針状結晶のめっき皮膜の形成は、異常析出の一種であり、光沢被膜を得るためには避けるべきものであった。
【0020】
これに対し、粗面化処理に代わるめっき方法においては、異常析出である針状結晶の析出が必須であるので、以前経験したトラブルのうち、異常析出の原因を遡って調べ、遷移金属元素と、イオウ化合物を見出したのである。つまり、忌避すべき異常析出を別の観点から価値を認めた点に本発明の特徴がある。
【0021】
【実施例】
次に実施例および試験例を挙げ、本発明を更に詳しく説明するが、本発明はこれら実施例等になんら制約されるものではない。
【0022】
実 施 例 1
下記組成の基板用硫酸銅めっき液に、硫酸ニッケル20g/l、チオ硫酸ナトリウム1.5g/lを加え、本発明銅めっき液を調製した。この銅めっき液中で、銅張積層板(両面基板;銅箔18μm)に電気めっきを行った。めっき条件は、電流密度1A/dm2、めっき時間1〜5分で、浴温は25℃であった。また同様に、前記銅張積層板上に常法によりパターンニングして得たパターンニング基板にも電気めっきを行った。
【0023】
得られた両基板について、その表面状態を電子顕微鏡で観察したところ、銅張積層板両面基板、パターンニング基板とも、1分間のめっきで針状結晶の銅皮膜が析出していた。
また、めっきの密着強度も、ガムテープ剥離で確認したところ剥離する所はなく密着良好との結果を得た。
【0024】
(本発明めっき液組成)
CuSO4・5H2O 75g/l
H2SO4 180g/l
Cl− 60ppm
NiSO4・6H2O 20g/l
Na2S2O3・5H2O 1.5g/l
光沢剤* 2ml/l
* Cu−Brite TH−MI(荏原ユージライト(株)製)
【0025】
【発明の効果】
本発明によれば、短い処理時間で、しかもコスト的にも安く、針状結晶のめっき皮膜を得ることができる。
本発明により得られる針状結晶のめっき皮膜は、銅と樹脂との接着、例えば多層プリント配線板等の回路形成、銅張積層板等の銅箔と樹脂の接着等に有利に利用することができる。
以 上[0001]
[Technical field to which the invention belongs]
The present invention relates to an electrolytic copper plating solution capable of forming a needle-like crystal coating and a method for forming a needle-like copper coating using the same, and more specifically, a uniform needle-like copper coating can be deposited on an object to be plated. It can be used to improve the adhesive strength of many metals and resins, including the adhesion of copper foil and resin on conductor circuits such as multilayer printed circuit boards and copper-clad laminates. The present invention relates to an electrolytic copper plating solution and a method for forming a needle-like copper film, and a plated product obtained by this method.
[0002]
[Prior art]
Conventionally, a multilayer printed circuit board prepares a copper clad laminate for an inner layer by processing a copper foil of a copper clad laminate to form a printed wiring, and this copper foil is subjected to surface pretreatment (generally following degreasing, After roughening with a soft etching treatment and activation treatment represented by ammonium persulfate, sodium persulfate, cupric chloride, sulfuric acid-hydrogen peroxide, etc., it is further represented by blackening treatment or brown treatment. In this process, a needle-like film of copper oxide or cuprous oxide is formed, and a copper-clad laminate or copper foil for outer layers is laminated on this copper-clad laminate for inner layers via a thermosetting resin-impregnated substrate (prepreg). It was manufactured as a multi-layer laminate having high adhesion by bonding.
[0003]
The multilayer laminate produced in this way needs to be energized to each layer. Therefore, it is necessary to make holes in the laminate and perform through-hole plating. Due to the penetration of the solution and the plating solution in the electroless copper plating step, the copper oxide or cuprous oxide film is dissolved, and pink rings (haloing) are generated.
[0004]
On the other hand, by forming a printed wiring using a copper clad laminate using a previously roughened copper foil, the multilayered printed circuit board is formed by omitting the roughening of the copper foil and the formation of an oxide film. However, according to this method, since the surface of the copper foil is roughened, there is a problem that the pattern accuracy of the printing etching resist and the etching resist by the ultraviolet baking method is inferior.
[0005]
In recent years, a method of utilizing a specific electroless copper plating method has been developed as a method for solving such drawbacks of the copper clad laminate and improving the adhesive strength (Japanese Patent Laid-Open Nos. 61-15980 and 61). -15981, 61-41775).
However, in the above electroless copper plating, formalin is indispensable as a reducing agent. This formalin has (1) abnormal precipitation of copper on the resin, (2) unstable bath, 3 There was a problem that the smell was strong and there was a risk of carcinogenicity.
[0006]
Recently, the present inventors have developed a method for forming a uniform needle-like copper film having excellent adhesion by electroless copper plating (Japanese Patent Laid-Open No. 4-116176, WO 97/46731). According to this technique, a copper-clad laminate having high adhesion without the above-mentioned drawbacks can be obtained, but it is basically electroless plating, the deposition rate is slow, and the life of the liquid is not so long. was there.
[0007]
[Problems to be solved by the invention]
Compared to electroless plating, electroplating has a faster film formation rate and easier bath management, so if a uniform needle-like copper film with excellent adhesion can be obtained by electroplating, technically, It is also very advantageous economically.
An object of the present invention is to satisfy such a demand and to provide a technique capable of obtaining a uniform needle-like copper coating having excellent adhesion by electroplating.
[0008]
[Means for Solving the Problems]
The present inventor has paid attention to an acidic copper plating bath having a high copper film deposition rate, and has been diligently examining the possibility of obtaining a uniform acicular crystal copper coating in this bath and the conditions thereof. The present inventors have found that a uniform needle-like copper film can be obtained by the presence of both a sulfur-based compound and the present invention.
[0009]
That is, the present invention provides an electrolytic copper plating solution for forming needle crystals, wherein a transition metal element and a sulfur compound are added to an acidic copper plating solution.
The present invention also provides a method for forming a needle-like copper film by electroplating an object to be plated in the above-mentioned electrolytic copper plating solution for forming a needle-like crystal, and a plated product obtained by this method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The electrolytic copper plating solution for forming needle crystals of the present invention (hereinafter referred to as “the copper plating solution of the present invention”) is prepared by adding both a transition metal element and a sulfur compound to a normal acidic copper plating solution. The
[0011]
Examples of the acidic copper plating solution used in the copper plating solution of the present invention include a copper sulfate plating solution and a copper pyrophosphate plating solution. Of these, the copper sulfate plating solution may have a composition in a generally used range, for example, 60 to 120 g / l as copper sulfate, 150 to 250 g / l as sulfuric acid, and hydrochloric acid at a concentration of about 30 to 100 ppm as chlorine ions. Can be used.
[0012]
Moreover, as a transition metal element added to this acidic copper plating solution, periodic table group VIII elements, such as nickel, cobalt, iron, etc. are mentioned. The amount of the transition metal element added varies depending on the type of metal, but in the case of a Group VIII element of the periodic table, it is preferably about 200 to 10,000 mg / l.
[0013]
Furthermore, examples of the sulfur compound added to the acidic copper plating solution include thiosulfate, thiosulfate such as sodium thiosulfate, potassium thiosulfate, calcium thiosulfate, iron thiosulfate, and copper potassium thiosulfate. The amount added is preferably about 100 to 10,000 mg / l.
[0014]
In addition to the transition metal elements and sulfur compounds described above, known additives such as brighteners and surfactants can be added to the copper plating solution of the present invention as long as the effects of the present invention are not impaired.
[0015]
Next, a method for forming a needle-like copper film using the copper plating solution of the present invention (hereinafter referred to as “the method of the present invention”) will be described.
[0016]
The method of the present invention can basically be carried out under substantially the same conditions as with conventional acidic copper plating solutions. That is, it can be carried out with air or stirring at a bath temperature of about 20 to 40 ° C. and a current density of about 0.1 to 5 A / dm 2 .
[0017]
In order to obtain a target copper film having uniform needle-like crystals in the method of the present invention, a copper film having a thickness of about 0.2 μm or more is required, and the plating time is preferably set to 1 minute or more.
[0018]
Moreover, the apparatus and power supply required for implementation of the method of this invention can use the same thing as the conventional acidic copper plating.
[0019]
[Action]
The present invention was developed based on analysis of abnormal precipitation in electrolytic copper plating. That is, the formation of the acicular crystal plating film is a kind of abnormal precipitation and should be avoided to obtain a glossy film.
[0020]
On the other hand, in the plating method that replaces the roughening treatment, the precipitation of needle crystals, which are abnormal precipitation, is essential. And found a sulfur compound. That is, the present invention is characterized in that the value of abnormal precipitation that should be avoided is recognized from another viewpoint.
[0021]
【Example】
EXAMPLES Next, although an Example and a test example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by these Examples.
[0022]
Example 1
Nickel sulfate 20 g / l and sodium thiosulfate 1.5 g / l were added to a copper sulfate plating solution for a substrate having the following composition to prepare the copper plating solution of the present invention. In this copper plating solution, electroplating was performed on a copper clad laminate (double-sided substrate; copper foil 18 μm). The plating conditions were a current density of 1 A / dm 2 , a plating time of 1 to 5 minutes, and a bath temperature of 25 ° C. Similarly, electroplating was performed on a patterned substrate obtained by patterning the copper-clad laminate by a conventional method.
[0023]
When the surface state of both the obtained substrates was observed with an electron microscope, a copper film of needle-like crystals was precipitated by plating for 1 minute on both the copper-clad laminate double-sided substrate and the patterning substrate.
Also, the adhesion strength of the plating was confirmed by peeling the gum tape.
[0024]
(The present plating solution composition)
CuSO 4 · 5H 2 O 75g / l
H 2 SO 4 180 g / l
Cl - 60ppm
NiSO 4 · 6H 2 O 20g / l
Na 2 S 2 O 3 · 5H 2 O 1.5g / l
Brightener * 2ml / l
* Cu-Brite TH-MI (manufactured by Sugawara Eugleite Co., Ltd.)
[0025]
【The invention's effect】
According to the present invention, an acicular crystal plating film can be obtained in a short processing time and at a low cost.
The acicular crystal plating film obtained by the present invention can be advantageously used for adhesion between copper and resin, for example, circuit formation such as multilayer printed wiring boards, adhesion between copper foil and resin such as copper clad laminates, etc. it can.
more than
Claims (2)
Priority Applications (1)
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JP26593298A JP4610027B2 (en) | 1998-09-21 | 1998-09-21 | Electrolytic copper plating solution for forming acicular crystals and method for forming acicular film |
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JP26593298A JP4610027B2 (en) | 1998-09-21 | 1998-09-21 | Electrolytic copper plating solution for forming acicular crystals and method for forming acicular film |
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JP4610027B2 true JP4610027B2 (en) | 2011-01-12 |
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JP2001335986A (en) | 2000-05-30 | 2001-12-07 | Matsuda Sangyo Co Ltd | Palladium plating liquid |
JP2002069691A (en) * | 2000-08-31 | 2002-03-08 | Nippon Denkai Kk | Method for manufacturing copper foil for printed circuit board |
TWI577523B (en) | 2011-06-17 | 2017-04-11 | 三菱麗陽股份有限公司 | Mold having an uneven structure on its surface, optical article, and manufacturing method thereof, transparent base material for surface light emitter, and surface light emitter |
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