JPS61252698A - Manufacture of multilayer printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method for manufacturing a multilayer printed circuit board, and in particular, in a simplified manufacturing method called a build-up method, forming a roughened layer is more reliable than K. It's about how to increase your sex.

[Background of the invention]

Conventional 1A manufacturing methods for multilayer printed circuit boards include a lamination adhesive method and a build-up method. Among these, the lamination adhesion method has excellent reliability, but it is difficult to align each layer, and the cost increases because the material cost increases. on the other hand,
Although the build-up method is low in cost, it has the disadvantage of poor reliability, especially poor adhesion between the steel pattern and the insulating layer.

An example of the build-up method is
As described in the publication, a circuit was formed on a through-hole plated copper-clad laminate by etching, masking was performed with an insulating resin leaving a land portion, and a conductive paste ink was printed on it to form a circuit. After that, a chemical steel plating film is formed on the conductive paste ink and on the through holes. However, in this method, since the conductive paste is applied by printing, it is difficult to form fine wiring, and it is also difficult to adhere the conductive paste and the plating film. Regarding adhesion between the base material and the plating film, there is also a printed wiring board manufacturing method using an adhesive mixed with a rubber modified substance, as described in Japanese Patent Publication No. 55-48715, but this method Etching the modified rubber in the adhesive with strong oxidizing power such as chromium sulfuric acid,
This forms a rough surface. Therefore, although this method is effective in terms of adhesive strength, it is unfavorable in terms of safety because it uses chromium sulfate, and furthermore, modified rubber products have problems such as poor heat resistance.

[Purpose of the invention]

The purpose of the present invention is to solve the problems in the conventional build-up method of manufacturing multilayer printed circuit boards,
An object of the present invention is to provide a novel method for manufacturing a multilayer printed circuit board that is easy to manufacture, economical, and of high quality.

[Summary of the invention]

In order to achieve the above object, the present invention has focused on the advantages of the prior art and has also discovered a safe method for increasing the adhesion of the copper film, thereby creating a multilayer printed circuit board that is easy to manufacture and of high quality. It is designed so that it can be manufactured. That is, as mentioned above, in the method of forming multiple layers on a circuit formed by etching with an insulating layer interposed therebetween,
The adhesion between the insulating layer and the pattern formed by chemical copper plating was poor, making it impractical.

Therefore, in the present invention, an insulating layer that can be roughened, that is, a so-called roughened layer, is provided between the circuit and the pattern to improve the adhesive strength, thereby solving the problem.

Additionally, compared to rubber-modified adhesives used in conventional multilayer printed circuit board manufacturing, the present invention forms a roughened layer without using chromium sulfate. That is, in this method, an appropriate amount of acid-soluble filler is added to an insulating resin, the resin containing the filler is printed and cured, and then the resin surface is plasma etched to expose the filler. Then, the filler is dissolved and removed by immersion in 1 acid to form a roughened layer.

Next, the optimal filler and various conditions for improving adhesive strength will be described. In this regard, we conducted the following preliminary study.

That is, (a) Resin composition used: Epoxy novolac resin... River... 1
00 parts by weight 1-0-) Bisphenol A diglycidyl ether modified product of rilbiguanide: 50 parts by weight Thixotropic agent・
・・・・・・・・・・・・・・・・・・・・・ 5 parts by weight Antifoaming agent・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
2 parts by weight 5-butylthrosolve...
...... 10 parts by weight) Curing conditions...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・130C150min(c) Etching method α, oxygen plasma oxygen pressure・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・ 17(b+a Torr input ・・・i・・・・・・・・・・・・・・・・・・
・・・River・・・・・・・Mountain 4ooW etching time・
・・・・・・・・・・・・・・・・・・・・・ 10F
IliF&b, acid 5% hydrochloric acid immersion for 5 minutes (at 20°C)) Drying conditions 100C/3Qty
Figure 2 shows the results of measuring beer strength under the above conditions with varying amounts of calcium carbonate as a filler.

As shown in Figure 2, oxygen plasma etching is performed,
After exposing the filler, dissolve the calcium carbonate with acid,
It has been found that by removing this, the adhesive strength can be made to the same level as copper-clad υ laminates. The amount of calcium carbonate added is 10 parts by weight per 100 parts by weight of the resin.
The effect was significant at parts by weight or more.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. First, through-holes 2 are formed by drilling holes in a so-called copper-clad laminate in which copper is clad on an insulating substrate 1, and then the copper is etched by a method well known to those skilled in the art to form a circuit/'-e tangent. 3 and land foil 4 are formed. Next, an insulating resin 5 is applied to the surface excluding the land foil 4. Furthermore, a roughened layer 6 is provided on the insulating resin 5. Note that this insulating resin 5 is provided to provide a thickness necessary to satisfy electrical characteristics, and does not necessarily have to be provided. Further, the insulating resin 5 may be replaced by a roughened layer 6. The roughening layer 6 is made of a resin to which an acid-soluble filler is added, and in this example, a layer having the following composition was used.

Composition of the roughening layer: Epoxy novolak resin 100 parts by weight 1-0-) Rilbiguanide modified with bisphenol A diglycidyl ether 50 parts by weight Modifier ・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ 5 parts by weight Antifoaming agent ・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ 2 parts by weight - butyl cellosolve・・・・・・・・・・・・・・・・
・10 parts by weight Calcium carbonate (average particle size 10 μm) 60 parts by weight The above composition was applied by screen printing, and then 11C130C/ass
The roughened layer 6 as described above is formed by thermosetting under the following curing conditions. This roughened layer 6 is treated with oxygen plasma (400ji'
, 10mln) to expose the calcium carbonate, and then immersed in 5% hydrochloric acid for 5 minutes (20°C).
Dissolve and remove.

Next, a catalyst serving as a nucleus for plating is deposited on the entire surface, and after chemical steel plating is applied, a pattern 7 consisting of a chemical steel plating layer is formed by an etching method.

Further, by providing a portion on the circuit pattern 3 where the insulating resin 5 and the roughened layer 6 are not applied, a so-called via hole portion 8 connected to the circuit on the insulating resin 5 can be formed.

Furthermore, parts other than the land foil 40 are covered with solder resist 9.

The same material as the above-mentioned insulating resin aI5 was used for this turret resist 9. The multilayer printed circuit board manufactured in this way can be made into a product by printing characters and shaping the board as well known to those skilled in the art.

As can be seen from the above examples, the manufacturing method of the present invention
Since this is a type of build-up method that does not use a laminated press, it is possible to eliminate positional deviations that were a problem with the press method. Furthermore, by using the roughening layer forming method that is a feature of the present invention, it is possible to obtain adhesive strength equivalent to that of conventional copper-clad laminates, and it is possible to improve the adhesion reliability of circuit patterns. Furthermore, according to the present invention, it is possible to easily manufacture a four-layer multilayer printed circuit board by performing chemical steel plating only once.

Although the present invention has been described in detail as above, it is obvious that the present invention is not limited to the above embodiments. That is, instead of using a copper-clad laminate as in the above embodiment, the roughened layer of the present invention is provided on the base material, and chemical steel plating is used.
It should be noted that it is also possible to form a tongue, and furthermore, a multilayer board can be manufactured by repeating this process. Furthermore, the filler in the roughened layer is not limited to calcium carbonate as in this example, and it should be noted that the effects of the present invention can be obtained even better than etching quartz filler with hydrofluoric acid. It is. Furthermore, the same effect can be obtained as long as the gas used for plasma etching is not oxygen but is a gas used for etching organic matter.

〔Effect of the invention〕

As explained above, according to the present invention, multiple layers of electrical circuits can be formed on a single insulating substrate, and not only can material costs be greatly reduced, but also by forming a roughened layer,
It is possible to easily produce a highly reliable multilayer printed circuit board that has a copper coating with greater adhesion than conventional copper-clad laminates.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view showing an example of a multilayer printed circuit board manufactured by the manufacturing method of the present invention, and Fig. 2 shows the relationship between the amount of calcium carbonate added as an example of a filler in the present invention and beer strength. 3 is a graph showing etching conditions. Explanation of symbols 1...Insulating substrate 2...Through hole 3...
・Circuit pattern 4... Land foil 5... Insulating resin 6... Roughening layer 7... Pattern
8... Via hole part 9... Solder resist l"・1; 1.i, - Matter 1:2 is represented by patent attorney Katsuo Ogawa S 1st I21

Claims (1)

[Claims] 1. A step of drilling through holes and forming a pattern on a laminate having steel foil on both sides, a step of printing an insulating resin except for land areas and via hole areas, and a step of roughening the insulating resin. A method for manufacturing a multilayer printed circuit board, comprising sequentially carrying out a step of catalytically treating the roughened surface and insides of the through-holes and forming a pattern on the insulating resin using copper plating, the method comprising: A soluble filler is added to the printed insulating resin, and after the surface of the printed insulating resin is treated with oxygen plasma, the filler portion is dissolved and removed with acid to roughen the insulating resin. A method for manufacturing a multilayer printed circuit board. 2. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein the insulating resin contains 10 parts by weight or more of calcium carbonate as a filler per 100 parts by weight of the resin.