JP2004269998A - Electroless copper plating liquid, and method of producing printed circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroless copper plating liquid which is excellent in adhesion between inner layer copper foil and through hole plating after a soldering stage on component packaging in the production process of a printed circuit board. <P>SOLUTION: The electroless copper plating liquid comprises copper salt, a complexing agent for copper ions, a pH adjuster, a reducing agent and an additive. Gaseous hydrogen in a film after electroless copper plating is desorbed at ≤150°C. The production method for the printed circuit board comprises an electroless copper plating treatment stage using the electroless plating liquid and a stage of performing annealing treatment at ≤150°C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００１０】
アニール処理は、１５０℃以下で２時間程度、さらに好ましくは、１３０℃以下で２時間程度行う。
【００１１】
本発明の無電解銅めっき液を用いることにより、１５０℃以下のアニール処理によって皮膜中の水素を除去可能な無電解銅めっき被膜を得ることが出来る。また、本発明を用いることにより、内層接続信頼性に優れたプリント配線板を得ることが出来る。
【００１２】
【実施例】
以下、実施例を用いて本発明を説明するが、本発明はこれらに限定されるものではない。
実施例１として、多層プリント配線板に、高速ドリリングマシンにより所定の位置にスルーホールとなる穴を開け、スミア処理を施した基板を試料として用いた。めっき前処理として、クリーナーコンディショナであるＣＬＣ−６０１（日立化成工業株式会社製、商品名）に、浸漬処理して表面の清浄化及びコンディショニングをした後、銅箔表面のソフトエッチング及び穴内壁の増感処理液であるＨＳ−２０１（日立化成工業株式会社製、商品名）に浸漬し、更に密着促進処理液であるＡＤＰ−６０１（日立化成工業株式会社製、商品名）で浸漬処理を行った。このような前処理を行った試料を、以下の組成の無電解銅めっき液に、以下の組成の添加剤を加えためっき液を用い、めっき温度４０℃で５分間めっきを行った。更に電気めっきにより、約２０ μｍの銅を析出させ、試験用プリント配線板を作成した。作成した試験用プリント配線板を１３０℃において２時間アニール処理を施した。
（無電解銅めっき液の組成）
ＣｕＳＯ_４・５Ｈ_２Ｏ ： １０ ｇ／ｌ
ＥＤＴＡ・４Ｎａ ： ５０ ｇ／ｌ
３７％ＨＣＨＯ ： １２ ｍｌ／ｌ
ＮａＯＨ ： ５．５ ｇ／ｌ
（添加剤）
メルカプトコハク酸 ： １ ｍｇ／ｌ
２−２’ ジピリジル ： ３ ｍｇ／ｌ
ポリエチレングリコール（分子量 ： ６００）： ２０ ｍｇ／ｌ
【００１３】
比較例１として、実施例１と同じ組成の無電解銅めっき液を用い、添加剤は添加せず、実施例１と同じめっき前処理、めっき条件にてめっきを行い、同様のアニール処理を施した。
【００１４】
無電解銅めっき皮膜中の水素ガスの検出結果は以下の通りである。無電解銅めっき皮膜中の水素ガスの検出は、昇温脱離ガス分析装置（電子科学（株）製 ＥＭＤ−ＷＡ１０００Ｓ）を用いて検出した。実施例１および比較例１に記載のめっき前処理、めっき条件において、それぞれの無電解銅めっき皮膜をＳＵＳ（４３０）板に生成し、剥離した皮膜を試験片とした。試験片を室温から７００ ℃まで、６０ ℃・ｍｉｎ^−１の昇温速度で加熱し、水素の質量数２におけるスキャンスペクトルを測定した。
この結果を図１、２に示した。
【００１５】
内層接続信頼性の評価は下記の様に行った。作成した試験用プリント配線板を、２６０℃の半田槽に２０秒間フロート後、常温にて放冷する作業を５回行い、内層銅とめっき銅との接続が良好なものを○、劣るものを×と評価した。この結果を表１に示した。
【００１６】
【表１】

【００１７】
表１から明らかなように、実施例１の処理方法は、内層接続信頼性に優れる方法である。
【００１８】
【発明の効果】
本発明では、内層接続信頼性に優れたプリント配線板の製造方法を得ることができる。
【図面の簡単な説明】
【図１】実施例１の条件により作製した無電解銅めっき皮膜の測定結果。
【図２】比較例１の条件により作製した無電解銅めっき皮膜の測定結果。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electroless copper plating solution and a method for manufacturing a printed wiring board using the same.
[0002]
[Prior art]
The method most frequently used as an interlayer connection method for a multilayer printed wiring board is a plating through-hole method. In general, a through hole penetrates the entire thickness of a printed wiring board, and a partial via hole that connects a part of layers is used for a large number of layers. The plating through-hole method is a method in which a hole is made in order to make a through-hole connection, and the inside of the hole is made conductive by electroless copper plating or electrolytic copper plating.
[0003]
The electroless copper plating solution used in the production of the above-mentioned multilayer printed wiring board includes a divalent copper salt such as cupric sulfate, an alkali-soluble complexing agent of a divalent copper ion such as ethylenediaminetetraacetic acid, and formaldehyde. Although a reducing agent and a pH adjuster such as sodium hydroxide are the main components, a stabilizer such as sodium cyanide is generally added as a stabilizer because the stability of the solution is poor. However, in the case of electroless copper plating for a base, the physical properties of the plating film itself are not given much importance.
[0004]
[Problems to be solved by the invention]
Generally, electrical characteristics, mechanical characteristics, thermal characteristics, and the like are required as the performance of a printed wiring board. In particular, as for the thermal characteristics, it must be able to satisfy the connection reliability between the inner-layer copper foil and the through-hole plating even after the soldering step at the time of component mounting, which is one of the printed wiring board manufacturing steps. However, in the case of the above electroless copper plating solution, although the stability of the solution itself is sufficient, there is a problem that the reliability of the inner layer connection is low due to poor adhesion between the inner layer copper foil and the through-hole plating after the soldering process. is there.
[0005]
Accordingly, the present invention provides an electroless copper plating solution that provides excellent inner layer connection reliability, and a method for manufacturing a printed wiring board using the same.
[0006]
[Means for Solving the Problems]
(A) The present invention includes a copper salt, a complexing agent for copper ions, a pH adjuster, a reducing agent and an additive, and hydrogen gas in the electroless copper plating film after the electroless copper plating is heated and desorbed. The present invention relates to an electroless copper plating solution that desorbs at a temperature of 150 ° C. or less as measured by a gas analyzer.
(B) The present invention also relates to an electroless copper plating solution wherein the reducing agent according to (a) is formaldehyde or paraformaldehyde.
(C) The present invention also provides a method for manufacturing a printed wiring board, comprising the steps of: performing an electroless copper plating process using the electroless copper plating solution described in (a); and performing an annealing process at a temperature of 150 ° C. or lower. About the method.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described.
[0008]
The electroless copper plating solution is an aqueous solution containing a copper salt, a complexing agent for copper ions, a pH adjusting agent such as an alkali hydroxide, and a reducing agent. Copper salts include copper sulfate, copper oxide, and copper hydroxide, and are not particularly limited as long as they contain copper ions. The complexing agent for copper ions is not particularly limited as long as it forms a complex with copper ions such as ethylenediaminetetraacetic acid or a salt thereof, tartaric acid or a salt thereof. The pH adjuster is not particularly limited as long as it is a hydroxide of an alkali metal or alkaline earth metal such as sodium hydroxide or potassium hydroxide. Examples of the reducing agent include formaldehyde, potassium tetrahydroborate, dimethylamine borane, glyoxylic acid, and the like, and preferably formaldehyde or paraformaldehyde.
[0009]
The electroless copper plating solution of the present invention can be obtained by further adding an additive to the above basic composition. The additive referred to here is an additive that makes it possible to remove hydrogen from the film by an annealing treatment at 150 ° C. or less after the electroless copper plating by being added. Examples of the additive include, for example, a combination of 2-2 ′ dipyridyl, a surfactant having a polyoxyethylene chain (— (CH ₂ CH ₂ O) _n −) in the molecule, and mercaptosuccinic acid. Can be Examples of the surfactant having a polyoxyethylene chain in the molecule described above include those having the following structure.
Embedded image

[0010]
The annealing treatment is performed at 150 ° C. or lower for about 2 hours, and more preferably at 130 ° C. or lower for about 2 hours.
[0011]
By using the electroless copper plating solution of the present invention, it is possible to obtain an electroless copper plating film capable of removing hydrogen in the film by annealing at 150 ° C. or lower. Further, by using the present invention, a printed wiring board having excellent inner layer connection reliability can be obtained.
[0012]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
Example 1 In Example 1, a hole was formed as a through hole at a predetermined position on a multilayer printed wiring board by a high-speed drilling machine, and a smear-treated substrate was used as a sample. As a pre-plating treatment, after cleaning and conditioning the surface by immersion treatment in CLC-601 (trade name, manufactured by Hitachi Chemical Co., Ltd.) which is a cleaner conditioner, soft etching of the copper foil surface and inner wall of the hole. It is immersed in HS-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) which is a sensitizing treatment solution, and further immersed in ADP-601 (trade name, manufactured by Hitachi Chemical Co., Ltd.) as a treatment solution for promoting adhesion. Was. The sample subjected to such pretreatment was plated at a plating temperature of 40 ° C. for 5 minutes using a plating solution obtained by adding an additive having the following composition to an electroless copper plating solution having the following composition. Further, about 20 μm of copper was precipitated by electroplating to prepare a test printed wiring board. The prepared test printed wiring board was annealed at 130 ° C. for 2 hours.
(Composition of electroless copper plating solution)
_{CuSO 4 · 5H 2 O: 10} g / l
EDTA · 4Na: 50 g / l
37% HCHO: 12 ml / l
NaOH: 5.5 g / l
(Additive)
Mercaptosuccinic acid: 1 mg / l
2-2 'dipyridyl: 3 mg / l
Polyethylene glycol (molecular weight: 600): 20 mg / l
[0013]
As Comparative Example 1, an electroless copper plating solution having the same composition as in Example 1 was used, no additives were added, plating was performed under the same plating pretreatment and plating conditions as in Example 1, and the same annealing treatment was performed. did.
[0014]
The detection results of hydrogen gas in the electroless copper plating film are as follows. The detection of hydrogen gas in the electroless copper plating film was detected using a thermal desorption gas analyzer (EMD-WA1000S manufactured by Electronic Science Co., Ltd.). Under the plating pretreatment and plating conditions described in Example 1 and Comparative Example 1, each electroless copper plating film was formed on a SUS (430) plate, and the peeled film was used as a test piece. The test piece was heated from room temperature to 700 ° C. at a heating rate of 60 ° C. · min ⁻¹ , and a scan spectrum at a hydrogen mass number of 2 was measured.
The results are shown in FIGS.
[0015]
The inner layer connection reliability was evaluated as follows. The test printed wiring board thus prepared was floated in a solder bath at 260 ° C. for 20 seconds, and then allowed to cool at room temperature five times. X was evaluated. The results are shown in Table 1.
[0016]
[Table 1]

[0017]
As is clear from Table 1, the processing method of Example 1 is a method having excellent inner layer connection reliability.
[0018]
【The invention's effect】
According to the present invention, it is possible to obtain a method for manufacturing a printed wiring board having excellent inner layer connection reliability.
[Brief description of the drawings]
FIG. 1 is a measurement result of an electroless copper plating film produced under the conditions of Example 1.
FIG. 2 shows a measurement result of an electroless copper plating film produced under the conditions of Comparative Example 1.

Claims (3)

An electroless copper plating solution containing a copper salt, a complexing agent for copper ions, a pH adjuster, a reducing agent, and an additive, in which hydrogen gas in a film after electroless copper plating is desorbed at a temperature of 150 ° C. or less. An electroless copper plating solution, wherein the reducing agent according to claim 1 is formaldehyde or paraformaldehyde. A method for manufacturing a printed wiring board, comprising a step of performing an electroless copper plating treatment using the electroless copper plating solution according to claim 1 and a step of performing an annealing treatment at a temperature of 150 ° C. or lower.

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