JP2004022645A - Printed circuit board having through hole for wet processing - Google Patents
Printed circuit board having through hole for wet processing Download PDFInfo
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- JP2004022645A JP2004022645A JP2002172710A JP2002172710A JP2004022645A JP 2004022645 A JP2004022645 A JP 2004022645A JP 2002172710 A JP2002172710 A JP 2002172710A JP 2002172710 A JP2002172710 A JP 2002172710A JP 2004022645 A JP2004022645 A JP 2004022645A
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- wet processing
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Abstract
Description
【0001】
【発明の属する技術分野】
本発明は、プリント配線板に関し、特にウェット処理工程を経て製造されるプリント配線板に関する。
【0002】
【従来の技術】
近年、電子機器の小型、軽量、高速化の要求が高まり、プリント配線板の高密度化が進んでいる。このプリント配線板は、製造過程においては「ワークサイズ」と呼ばれる、一般に300mm〜1000mm四方程度の大きさを有しており、最終的にはこれを切断し、製品とする場合が多い。
【0003】
そして、このような比較的大きなサイズのプリント配線板に対し、めっきやエッチング等のいわゆるウェット処理を施す場合、基板に対し高圧噴霧にて処理溶液を供給するスプレー法や基板を処理溶液に浸漬するディップ法により行うことが一般的であるが、その際、処理溶液の基板面内における濃度の均一性は大変重要である。
【0004】
【発明が解決しようとする課題】
しかしながら、ワークサイズが大きくなればなるほど、液だまりが基板中心付近に発生し易くなり、処理溶液の基板面内における濃度の均一性が損なわれる。つまり、エッチングの際はエッチング量のばらつき、めっきの際はめっき厚ばらつき等が発生しやすいといった不具合が生じ易くなるため、プリント配線板の寸法加工精度が落ち、さらなる高密度化に対応することが困難であった。
【0005】
上記を鑑みて、本発明は、ウェット処理工程時に生じうる加工寸法精度のばらつきが生じ難く、高密度化に好適なプリント配線板を提供することを目的とする。
【0006】
【課題を解決するための手段】
上記課題を解決するために、本発明は、ウェット処理工程を経て製造されるプリント配線板において、ウェット処理時における基板面内の処理溶液の液流を確保するために、基板に貫通穴が1つ以上形成されているプリント配線板を提供することをその特徴としている。
【0007】
上記特徴によれば、ウェット処理時において、プリント配線板の適当な箇所に通常では空いていない貫通穴が形成されているために、基板面内における処理溶液の液流が確保され、その面内の濃度を均一とすることが可能となった。
【0008】
本発明において「ウェット処理」とは、プリント配線板製造時、めっき液またはエッチング液といった処理溶液を用いて基板や配線を加工処理すること、さらにはレジスト剥離や基板洗浄等の液体を使用しうる工程での処理をも含む。
【0009】
また、本発明において「貫通穴」とは、従来の層間接続のための貫通穴、位置合わせや製品を固定するための貫通穴などは含まず、これらとは別に形成した本発明の目的を達成するためのものを指す。
【0010】
また、本発明は、上記特徴において、基板の縦方向と横方向のサイズがいずれも50mm以上であるプリント配線板であることが好ましく、この場合、貫通穴が形成されていることによる効果がより顕著に表れる。
【0011】
さらに、本発明は、上記特徴において、貫通穴の直径が100μm以上50mm以下であることが好ましい。
【0012】
以上のような本発明によれば、ウェット処理工程時に生じうる加工寸法精度のばらつきが生じ難く、高密度化に好適なプリント配線板を提供することが可能となる。
【0013】
【発明の実施の形態】
以下、本発明を、図1のプリント配線板の製造方法に沿って、詳細に説明する。ただし、該記載は実施の一例であり、本願特許請求の範囲を限定するものではない。
【0014】
(a)まず、基板の両側に銅箔を有するプリプレグを作製する。ここで用いる基板としては、従来公知のものであれば特に限定されず、そのサイズも特に限定されないが、基板の縦方向と横方向のサイズがいずれも50mm以上である場合には、本発明による効果が顕著に表れ、好ましい。また、銅箔付きプリプレグにはエポキシ樹脂含浸ガラスクロスの上下に銅箔を積層したMCL−E−679(日立化成工業株式会社製、商品名)等が好適である。
【0015】
(b)次に、銅箔の上からドリル若しくはCO2レーザー等を用いて層間接続用貫通穴を形成する。
【0016】
(c)次に、層間接続用貫通穴の他に、ウェット処理の処理溶液の液流を確保するための貫通穴を形成する。穴あけは小径であれば公知のレーザー、ドリルを用い、径が大きければパンチング等を用いることができ、回路形成に支障のない箇所に所望の個数を1個づつ形成しても、同時に形成しても良い。また、貫通穴の直径は100μm以上50mm以下であることが好ましい。直径が100μmより小さいと貫通穴としての効果を有効に発揮することができなくなり、直径が50mmより大きいと経済的ではない。さらに、貫通穴の数は、処理溶液の液流を確保でき、液だまり等の不具合が発生しなければ特に限定せず、例えば、直径5mmの貫通穴であれば10個/dm2程度でよい。さらに、貫通穴を形成した時に発生する樹脂かすを除去するために過マンガン酸処理を行うことが好ましい。
【0017】
(d)次にPd等の核触媒付与後、層間接続のための無電解銅めっきを行う。無電解めっきには、例えば、CUST2000(日立化成工業株式会社製、商品名)やCUST201(日立化成工業株式会社製、商品名)等の市販の無電解銅めっきが使用できる。これらの無電解銅めっきは硫酸銅、ホルマリン、錯化剤、水酸化ナトリウムを主成分とする。めっき方法、条件等は従来公知の方法により行えば良く、形成する無電解銅めっき層の厚さは次の電気めっきが行うことができる厚さであればよく、0.1〜1μm程度で十分である。
【0018】
(e)次に電気めっきにより層間接続を行う。電気めっきには、通常プリント配線板で使用される硫酸銅電気めっき等が使用できる。めっき方法、条件等は従来公知の方法により行えば良く、形成する電気銅めっき層の厚さは、1〜100μmの範囲である事が好ましく、5〜50μmの範囲である事がより好ましい。めっき液の攪拌は通常のエアレーション、カソードロッキング、噴流等あるが、特に限定されない。
【0019】
(f)次に電気めっきを行った上にめっきレジストを形成する。めっきレジストの厚さは、特に限定されないが、5〜40μm程度が好適である。めっきレジストとして使用できる樹脂には、限定されないが、例えば、PMER P−LA900PM(東京応化株式会社製、商品名)のような液状レジストや、HW−425(日立化成工業株式会社、商品名)、RY−3025(日立化成工業株式会社、商品名)等のドライフィルムがある。このようなレジストを使用してめっきレジストを形成する方法としては、従来公知の方法でよく、例えば、形成したい層上にレジストをラミネートし、露光、現像して形成することができる。
【0020】
(g)次に塩化鉄、塩化銅等のエッチング液で導体回路となる部分以外のエッチングを行う。エッチング方法としては、ディップ法、スプレー法等により行うことができるが、スプレー法で行うとエッチングばらつきが少なく好ましい。その他の条件としては、適宜実験により決定すればよいが、エッチング液の液温は30〜60℃、スプレー法におけるスプレー圧は0.5〜3.0kgf/cm2で行うのが好適である。
【0021】
(h)最後にアルカリ性剥離液や硫酸あるいは市販のレジスト剥離液を用いてレジストの剥離を行う。
【0022】
以上のように、本発明によれば、処理溶液の液流を確保するための貫通穴を基板に形成するため、液だまり等が生じることもなく、基板面内の処理溶液濃度は常に均一に保たれる。その結果、得られるプリント配線板は、エッチング量のばらつき、めっき厚ばらつき等の不具合が生じ難く、回路形成性が良好なため、高密度化に好適なものとなる。
【0023】
【実施例】
実施例1
図2(a)に示すように、絶縁基材9に厚さ18μmの銅箔8を両面に貼り合わせた厚さ0.2mmのガラス布基材エポキシ銅張積層板であるMCL−E−679(日立化成工業株式会社製、商品名)を寸法300×500mmに切断し、SAKAI MINI DILL−1(サカイスペシャルカメラ株式会社製、商品名)を用いて、液流を確保するための直径5mmの貫通穴10を10個/dm2面内均一に形成した。その後、図2(b)に示すように、ドライフィルムフォトレジストであるRY−3025(日立化成工業株式会社製、商品名)を、銅箔の表面にラミネートし、フォトマスクを介して露光機EMX−1201−F02(オーク製作所株式会社、商品名)を用いて100mJ/cm2で露光した後、現像機TG11203(東京エンジニアリング株式会社製、商品名)を用いて10vol%炭酸ナトリウム水溶液により55℃、30秒の条件で現像し、レジスト11を形成した。図2(c)に示すように、40℃の塩化第二鉄水溶液を用い、オシレーション式のスプレーにより1.5kgf/cm2の条件でエッチングを行った。最後に図2(d)に示すように、水酸化ナトリウム水溶液でレジスト11の除去を行い、図3に示すような回路導体幅/回路導体間隔(L/S)=40/40μmの櫛型基板を作製した。
【0024】
実施例2
基板に炭酸ガスレーザー穴あけ機L−500(住友重機械工業株式会社製、商品名)を用いて直径100μmの貫通穴を100個/dm2面内均一に形成した他は、実施例1と同様に基板を作製した。
【0025】
実施例3
基板のサイズを50×50mmとした他は実施例2と同様に基板を作製した。
【0026】
比較例1
貫通穴を形成しなかった以外は実施例1と同様に基板を作製した。
【0027】
実施例1〜3、比較例1で作製した基板の配線のライン幅(トップ)を任意に20点測定し、平均を算出した。なお、ライン幅は光学顕微鏡で基板上部から撮影し、画像処理を行い、測定したものである。その結果を表1に示す。
【0028】
【表1】
【0029】
実施例1〜3で作製した基板は、導体トップ幅がほぼ設計値通りに仕上がっており、かつばらつきもほとんどなく回路形成性が良好であった。一方、比較例1の配線はばらつきが大きかった。
【0030】
【発明の効果】
以上に示したように、本発明によれば、ウェット処理時に生じうる加工寸法精度のばらつきが生じ難く、高密度化に好適なプリント配線板を提供することが可能となる。
【図面の簡単な説明】
【図1】ウェット処理用の貫通穴を有するプリント配線板の製造過程の一例を示す模式図。
【図2】ウェット処理用の貫通穴を有する基板の製造過程の一例を示す模式図。
【図3】実施例1により作製された直径5mmの貫通穴を有するくし型基板の写真。
【符号の説明】
1、8 銅箔
2、9 プリプレグ
3 層間接続用貫通穴
4、10 液流を確保するための貫通穴
5 無電解銅めっき層
6 電気銅めっき層
7、11 レジスト[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printed wiring board, and more particularly, to a printed wiring board manufactured through a wet processing step.
[0002]
[Prior art]
In recent years, demands for smaller, lighter, and faster electronic devices have increased, and the density of printed wiring boards has been increasing. This printed wiring board has a size generally called a "work size" of about 300 mm to 1000 mm square in a manufacturing process, and is often cut into a product in the end.
[0003]
When a so-called wet process such as plating or etching is performed on a printed wiring board having such a relatively large size, a spray method for supplying a processing solution to the substrate by high-pressure spraying or immersing the substrate in the processing solution In general, the dip method is used. In this case, the uniformity of the concentration of the processing solution in the substrate surface is very important.
[0004]
[Problems to be solved by the invention]
However, as the work size increases, liquid pools are more likely to occur near the center of the substrate, and the uniformity of the concentration of the processing solution within the substrate surface is impaired. That is, defects such as variations in the amount of etching during etching and variations in plating thickness during plating are likely to occur, so that the dimensional processing accuracy of the printed wiring board is reduced, and it is possible to cope with higher densities. It was difficult.
[0005]
In view of the above, it is an object of the present invention to provide a printed wiring board that is less likely to have variations in processing dimensional accuracy that may occur during a wet processing step and is suitable for high density.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a printed wiring board manufactured through a wet processing step, in which a through hole is formed in a substrate in order to secure a flow of a processing solution in a substrate surface during the wet processing. It is characterized by providing a printed wiring board having at least one formed thereon.
[0007]
According to the above feature, at the time of wet processing, a through hole that is not normally opened is formed at an appropriate place of the printed wiring board, so that the liquid flow of the processing solution in the substrate surface is ensured, and the in-plane Can be made uniform.
[0008]
In the present invention, the term "wet processing" refers to processing a substrate or wiring using a processing solution such as a plating solution or an etching solution at the time of manufacturing a printed wiring board, and further using a liquid such as resist peeling or substrate cleaning. Including processing in the process.
[0009]
In the present invention, the term "through hole" does not include a conventional through hole for interlayer connection, a through hole for positioning or fixing a product, etc., and achieves the object of the present invention separately formed therefrom. To do something.
[0010]
Further, according to the present invention, in the above-described feature, it is preferable that the printed wiring board has a size of 50 mm or more in both the vertical and horizontal directions of the substrate. In this case, the effect of forming the through holes is more effective. Appears noticeably.
[0011]
Further, according to the present invention, in the above-described feature, it is preferable that the diameter of the through hole is not less than 100 μm and not more than 50 mm.
[0012]
According to the present invention as described above, it is possible to provide a printed wiring board that is less likely to have variations in processing dimensional accuracy that may occur during a wet processing step and that is suitable for high density.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the method of manufacturing the printed wiring board of FIG. However, the description is an example of the embodiment and does not limit the scope of the claims of the present application.
[0014]
(A) First, a prepreg having copper foil on both sides of a substrate is prepared. The substrate used here is not particularly limited as long as it is a conventionally known substrate, and its size is not particularly limited. However, when both the vertical and horizontal sizes of the substrate are 50 mm or more, the substrate according to the present invention is used. The effect is remarkable and is preferable. For the prepreg with copper foil, MCL-E-679 (trade name, manufactured by Hitachi Chemical Co., Ltd.) in which copper foil is laminated on and under an epoxy resin-impregnated glass cloth is suitable.
[0015]
(B) Next, through holes for interlayer connection are formed from above the copper foil using a drill or a CO 2 laser.
[0016]
(C) Next, in addition to the through-holes for interlayer connection, through-holes for securing the flow of the treatment solution for the wet treatment are formed. For drilling, a known laser or drill can be used if the diameter is small, and punching or the like can be used if the diameter is large. Even if a desired number is formed one by one at a place where there is no hindrance to circuit formation, it can be formed simultaneously. Is also good. Further, the diameter of the through hole is preferably 100 μm or more and 50 mm or less. If the diameter is smaller than 100 μm, the effect as a through hole cannot be effectively exhibited, and if the diameter is larger than 50 mm, it is not economical. Further, the number of through holes is not particularly limited as long as a liquid flow of the processing solution can be secured and no problem such as a pool is generated. For example, a through hole having a diameter of 5 mm may be about 10 holes / dm 2. . Further, it is preferable to perform a permanganate treatment in order to remove resin residues generated when the through holes are formed.
[0017]
(D) Next, after applying a nuclear catalyst such as Pd, electroless copper plating for interlayer connection is performed. For the electroless plating, for example, commercially available electroless copper plating such as CUST2000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) or CUST 201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) can be used. These electroless copper platings contain copper sulfate, formalin, a complexing agent, and sodium hydroxide as main components. The plating method, conditions and the like may be performed by a conventionally known method, and the thickness of the electroless copper plating layer to be formed may be a thickness capable of performing the next electroplating, and about 0.1 to 1 μm is sufficient. It is.
[0018]
(E) Next, interlayer connection is performed by electroplating. For the electroplating, copper sulfate electroplating or the like usually used for a printed wiring board can be used. The plating method, conditions and the like may be performed by a conventionally known method, and the thickness of the formed electroplated copper layer is preferably in the range of 1 to 100 μm, and more preferably in the range of 5 to 50 μm. Stirring of the plating solution includes ordinary aeration, cathode locking, and jet flow, but is not particularly limited.
[0019]
(F) Next, after performing electroplating, a plating resist is formed. The thickness of the plating resist is not particularly limited, but is preferably about 5 to 40 μm. The resin that can be used as the plating resist is not limited. For example, a liquid resist such as PMER P-LA900PM (trade name, manufactured by Tokyo Ohka Co., Ltd.), HW-425 (Hitachi Chemical Co., Ltd., trade name), There is a dry film such as RY-3025 (trade name of Hitachi Chemical Co., Ltd.). As a method for forming a plating resist using such a resist, a conventionally known method may be used. For example, a plating resist may be formed by laminating a resist on a layer to be formed, exposing and developing.
[0020]
(G) Next, etching is performed on portions other than the portions that will become conductor circuits with an etchant such as iron chloride or copper chloride. As an etching method, a dipping method, a spray method, or the like can be used. However, it is preferable to use a spray method since etching variation is small. Other conditions may be appropriately determined by experiments, but it is preferable that the temperature of the etchant is 30 to 60 ° C. and the spray pressure in the spray method is 0.5 to 3.0 kgf / cm 2 .
[0021]
(H) Finally, the resist is stripped using an alkaline stripper, sulfuric acid, or a commercially available resist stripper.
[0022]
As described above, according to the present invention, since a through hole is formed in the substrate to secure the flow of the processing solution, no liquid pool or the like occurs, and the processing solution concentration in the substrate surface is always uniform. Will be kept. As a result, the resulting printed wiring board is less likely to cause problems such as variations in the amount of etching and variations in plating thickness, and has good circuit formability, and thus is suitable for high density.
[0023]
【Example】
Example 1
As shown in FIG. 2A, MCL-E-679 which is a glass cloth base epoxy copper clad laminate having a thickness of 0.2 mm in which a
[0024]
Example 2
Same as Example 1 except that 100 holes / dm 2 through-holes were uniformly formed in the substrate using a carbon dioxide laser drilling machine L-500 (trade name, manufactured by Sumitomo Heavy Industries, Ltd.) on the substrate. A substrate was prepared.
[0025]
Example 3
A substrate was produced in the same manner as in Example 2 except that the size of the substrate was changed to 50 × 50 mm.
[0026]
Comparative Example 1
A substrate was produced in the same manner as in Example 1, except that no through hole was formed.
[0027]
The line widths (tops) of the wirings of the substrates prepared in Examples 1 to 3 and Comparative Example 1 were arbitrarily measured at 20 points, and the average was calculated. The line width was measured by taking an image from above the substrate with an optical microscope, performing image processing, and measuring. Table 1 shows the results.
[0028]
[Table 1]
[0029]
The substrates produced in Examples 1 to 3 had a conductor top width almost finished as designed, and had almost no variation and good circuit formability. On the other hand, the wiring of Comparative Example 1 had large variations.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a printed wiring board that is less likely to have variations in processing dimensional accuracy that may occur during wet processing and that is suitable for high density.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a manufacturing process of a printed wiring board having a through hole for wet processing.
FIG. 2 is a schematic view illustrating an example of a manufacturing process of a substrate having a through hole for wet processing.
FIG. 3 is a photograph of a comb-shaped substrate having a through-hole having a diameter of 5 mm manufactured in Example 1.
[Explanation of symbols]
1, 8
Claims (3)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP2002172710A JP2004022645A (en) | 2002-06-13 | 2002-06-13 | Printed circuit board having through hole for wet processing |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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JP2002172710A JP2004022645A (en) | 2002-06-13 | 2002-06-13 | Printed circuit board having through hole for wet processing |
Publications (1)
Publication Number | Publication Date |
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JP2004022645A true JP2004022645A (en) | 2004-01-22 |
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JP2002172710A Pending JP2004022645A (en) | 2002-06-13 | 2002-06-13 | Printed circuit board having through hole for wet processing |
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JP (1) | JP2004022645A (en) |
-
2002
- 2002-06-13 JP JP2002172710A patent/JP2004022645A/en active Pending
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