JPH0253834A - Production of laminated sheet for printed circuit - Google Patents

Abstract

PURPOSE:To improve light transmission preventing ability while maintaining appearance and mechanical characteristics by using an epoxy resin impregnated glass (non)woven fabric containing a specific amount of fluorescent dyestuff as an intermediate layer in obtaining printed circuit laminates by subjecting an epoxy resin impregnated glass nonwoven fabric to lamination molding. CONSTITUTION:A prepreg obtained by impregnating a varnish obtained by blending a fluorescent dyestuff (preferably cumarin derivative or oxazole derivative) capable of absorbing ultraviolet rays and visible rays (300-420nm wavelength) with an epoxy resin at an amount of 0.1-10wt.% based on the epoxy resin into a glass nonwoven fabric and a prepreg obtained by impregnating a varnish without blending the above-mentioned fluorescent dyestuff with epoxy resin into a glass (non)woven fabric are each laminated as an intermediate layer and both outer layers and molded to provide the printed circuit laminates.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a printed circuit laminate having an extremely excellent effect of preventing ultraviolet light transmission.

[Conventional technology]

Printed wiring boards usually have a conductor pattern layer on the outermost layer,
During soldering, a solder resist is formed to prevent solder bridges between conductors or to permanently protect conductor patterns.

There are two methods for forming a solder resist: a screen printing method and a photoprinting method using a photosensitive resin.

Traditionally, screen printing was the most commonly used method, but as electronic components become smaller and more chip-based, the mounting density on printed wiring boards has become higher, so screen printing has become less precise and easier to work with. It is becoming less practical. Therefore, instead of the screen printing method, photo printing using a negative or positive mask using a photosensitive resin (photoresist) has come to be carried out by a method.

However, according to the photo printing method, when both sides of a photoresist are simultaneously exposed on a circuit printed on both sides of a laminate, the light that has passed through the photoresist during exposure is further transmitted through the laminate.
It has become known that photoresists on opposite sides of each other are also exposed, resulting in insufficient accuracy of the solder resist, which is the original purpose. Especially when the thickness of the laminate is 1.
It is known that the light transmittance is high when the thickness is 6 mm or less.

For this reason, the thickness of the photoresist is increased (50 to 80 μm).
), or a laminate using a polyimide-modified resin as the outermost surface of the laminate, as disclosed in Japanese Patent Publication No. 54-34140. However, when the thickness of the photoresist is increased, extra curing time is required after the exposure phenomenon in order to fully exhibit its performance as a solder resist. On the other hand, the use of polyimide-modified resin for a part of the laminate increases the cost and has the disadvantage that the prevention of light transmission is still insufficient. In order to eliminate these drawbacks, a method has been considered in which a light-shielding substance is included in the laminate to prevent light transmission.

(Japanese Unexamined Patent Publication No. 54-32769).

As a result of examining various light-shielding substances, the present inventors found that among organic ultraviolet absorbers, those with a specific ultraviolet wavelength absorption region are effective in preventing light transmission. When the content is increased, there are disadvantages such as a decrease in performance as a printed circuit board, such as discoloration due to heating, decrease in solvent resistance, and thermal deterioration of various performances.

Further, when the content is reduced, the effect of preventing light transmission is small, especially in a laminate having a thickness of 1.2 mm or less. Furthermore, it has been found that oxides are particularly effective among inorganic UV-screening agents, but when coating and impregnating the resin with a sufficient amount to prevent light transmission, the difference in specific gravity between the resin and the inorganic oxide However, it is difficult to impregnate uniformly, and the resulting laminate has the disadvantage of causing variations in light transmittance.

Furthermore, as the precision of photo solder resists has recently improved, the conventional ultraviolet range (360 to 380 nm)
Therefore, a laminate plate that blocks light up to an even higher wavelength region (near 420 nm) is desired, and it is difficult to satisfy this demand with conventional ultraviolet absorbers.

As a solution to this problem, dyes or pigments have been added to the laminates when they are manufactured, but this method has the disadvantage that the appearance of the laminates differs greatly from the conventional color tone, and the problem is that the solvents used during circuit formation are There is also the disadvantage that pigments and dyes elute and contaminate the solvent.

[Problems to be Solved by the Invention] The present invention was carried out in an effort to obtain a laminate that maintains the performance and appearance (color tone) of conventional printed circuit laminates, while also having an excellent effect of preventing light transmission. As a result, the present invention was completed by blending a fluorescent dye that absorbs light in the ultraviolet and visible regions into a conventional laminate resin and laminating the resulting prepreg as an intermediate layer. .

[Means to solve the problem]

The present invention relates to a method for manufacturing a printed circuit laminate in which glass woven fabric or glass nonwoven fabric substrate impregnated with epoxy resin and dried is laminated and molded.
A glass woven fabric or glass non-woven fabric is impregnated with a varnish containing 0.1 to 10% by weight of a fluorescent dye that absorbs light of 420 nm) to an epoxy resin as an intermediate layer to absorb the fluorescent dye. This is a method for manufacturing a laminate board in which a prepreg containing no dye is laminated and molded as the outermost layer.

The fluorescent dyes used in the present invention are mainly diaminostylhene disulfonic acid derivatives, imidazole derivatives, oxazole derivatives, coumarin derivatives, and other derivatives such as triazole, carbazole, pyridine, naphthalic acid, and imidasilone. Can be done. All exhibit a light absorption peak in the wavelength range of 300 to 450 nm. Suitable for use in the present invention are coumarin derivatives and oxazole derivatives.

The manufacturing method of the present invention is characterized by adding 0.1 to 1% of the fluorescent dye to the resin content in the commonly used epoxy resin varnish.
It dissolves 0% by weight and is used only for the intermediate layer.

[Effect]

In a laminate obtained by using eight prepregs containing fluorescent dyes, the fluorescent dyes elute and contaminate the solvent during cleaning with a solvent (especially methylene chloride) during circuit formation. By laminating an unblended prepreg as the outer layer and one or more prepregs containing fluorescent dye as the intermediate layer, elution of the fluorescent dye into the solvent can be prevented, and the effect of preventing light transmission can be maintained. be able to.

(Example〕 Examples and comparative examples are shown below.

Example 1 100 parts by weight of Epicote EP-1046 (brominated bisphenol A epoxy resin manufactured by Yuka Shell Co., Ltd.), 4 parts by weight of dicyandiamide, 0 parts by weight of 2-ethyl-4methylimidazole
．． 15 parts by weight, as a fluorescent dye, rNe of Chuo Synthesis of Coumarin Derivatives.

A varnish solution was prepared by blending 3 parts by weight of 5upper HR-IJ, dissolving it in a solvent of methyl ethyl ketone and methyl cellosolve, and stirring uniformly so that the total solid content was 50% by weight. A glass woven fabric was impregnated with this varnish and dried to obtain a glass prepreg with a resin content of 45%.

One layer of this prepreg is layered as the middle layer, one layer of prepreg containing no fluorescent dye is layered as the outermost layer, and one layer of 18 μm copper foil is layered on both sides of the prepreg, heated at 165°C.
A double-sided copper-clad laminate with a thickness of 0.6 mm was obtained by heat-pressing molding at a pressure of 60 kg/cIfl for 90 minutes.

Example 2 One prepreg containing a fluorescent dye mixed in the same manner as in Example 1 (however, the blending amount was 4 parts by weight) was used as the intermediate layer, and three prepregs each containing no fluorescent dye were placed on both sides of the intermediate layer. A double-sided copper-clad laminate with a thickness of 1.6 mm was obtained by stacking 4 sheets.

Comparative Examples 1 and 2 All prepregs containing fluorescent dye (the amount of compounding was 1 part by weight in Comparative Example 1 and 0.5 part by weight in Comparative Example 2) (Comparative Example 1 (thickness 0.5 parts by weight)) Double-sided copper sheets with thicknesses of 0.6 mm and 1.6 mm were laminated in the same manner as in the example, except that 3 sheets were laminated in the case of 6 mm) and 8 sheets were laminated in the case of Comparative Example 2 (thickness 1.6 mm). A stretched laminate was obtained.

Comparative Examples 3 and 4 Except that all prepregs containing no fluorescent dye were laminated.
In the same manner as in the example, the thickness was 0.6 mm and the thickness was 1.6 ffl.
A double-sided copper-clad laminate of I11 was obtained.

Next, the obtained copper-clad laminate was etched to remove the copper, and the substrate was tested using an ultraviolet spectrophotometer (Shimadzu self-recording spectrophotometer UV).
-260 type), the light transmittance of the substrate was measured. Furthermore, this substrate was immersed in methylene chloride for 3 minutes, and the presence or absence of elution of the fluorescent dye was examined.

FIGS. 1 and 2 show the ultraviolet transmittance curves of Examples and Comparative Examples, and Table 1 shows the presence or absence of fluorescent dye elution.

Table 1 In addition, as a fluorescent dye, 'Neo-5upper 0R-
IJ t7, rUVITEX OBJ (oxazoline, Ciba Geigy), 'Kayalight
OSRJ (oxazole type, manufactured by Nippon Kayaku Co., Ltd., rH
akkol SP J (4,4°-diaminostilbendisulfonic acid type, Halakol Chemical Co., Ltd.) and the like were used, but the results were generally similar to those of the Examples.

The copper-clad laminate used in the examples had performance as a printed circuit board, that is, electrical properties, heat resistance, and machinability equivalent to those of conventional laminates.

〔Effect of the invention〕

The printed circuit laminate obtained by the present invention has the following characteristics.

(1) It has a large shielding effect against light of 300 to 420 nm, and when photoresists coated on both sides of a laminate are exposed simultaneously, it is possible to prevent the trouble of exposing the photoresists on the other side.

(2) By using a prepreg containing a fluorescent dye only in the intermediate layer, solvent contamination during circuit formation can be prevented, and it can be used in the same way as a conventional laminate.

(3) Since the amount of fluorescent dye added to the varnish for laminates is small, the electrical properties, heat resistance, machinability and appearance (
The color tone) is also the same as that of conventional laminates.

[Brief explanation of the drawing]

The drawings are graphs showing the relationship between the wavelength of ultraviolet rays and the transmittance in Examples and Comparative Examples. This is the case.

Claims (1)

[Claims] (1) A method for manufacturing a printed circuit laminate in which a glass woven fabric or a glass non-woven fabric substrate impregnated with an epoxy resin and dried is laminated and molded.
The intermediate layer is a prepreg made by impregnating glass woven fabric or glass non-woven fabric with a varnish containing 0.1 to 10% by weight of epoxy resin of a fluorescent dye that absorbs light (20 nm);
A method for manufacturing a laminate, in which prepregs containing no fluorescent dye are laminated as both outer layers.