JP2606387B2 - Manufacturing method of laminate for additive printed circuit board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a surface roughness which is a problem in the production of a laminate for an additive method printed wiring board.

[Conventional technology]

In order to accurately form a high-density circuit on a laminate by a printing method, its surface roughness needs to be small. If the roughness is large, the ink will drool and bleed when printed, resulting in poor printing.

Heretofore, as a countermeasure, printing has been performed after mechanically polishing the adhesive layer on the surface of the laminated board on which a circuit is to be formed one to several times to achieve a predetermined surface roughness.

2.54mm grid diameter for current printed circuit board circuit density
When a 1.0mm hole is drilled, it is becoming mainstream to provide two circuits between them. When such a circuit is designed, the width of the ink applied to insulate the circuits is 0.15
~ 0.20mm. When the ink dripping or bleeding is 30 μm or more, a failure phenomenon such as disconnection tends to occur when a circuit is formed by electroless plating in a later step.

[Problems to be solved by the invention]

In the pre-printing process of the printed wiring board, the following problem arises when the surface of the laminated board with the adhesive, that is, the surface of the adhesive layer is smoothed by polishing once or several times.

(1) Since the mechanical polishing step is inserted before the printing step, the step becomes complicated. When the number of times of polishing is two or more, it becomes particularly complicated.

(2) The thickness of the adhesive layer is usually several tens of μm, but the adhesive layer remaining after polishing becomes thin, and the adhesiveness between the plated metal and the adhesive layer in the next plating step is significantly reduced.
In addition, since the polishing is performed twice or more to obtain the desired surface roughness, the adhesive layer is removed, and the surface of the laminate under the adhesive layer is exposed, so that the laminate cannot be used as a laminate for a printed wiring board.

In view of the above problems, an object of the present invention is to provide an adhesive layer that does not require polishing for smoothing in the production of a laminate for an additive printed wiring board.

[Means for solving the problem]

A varnish of a thermoplastic resin or a thermosetting resin is impregnated into paper or glass cloth and heated to form a semi-cured prepreg. A predetermined number of these are stacked and heated and pressed to obtain a laminated plate. The solvent content and unreacted components of the varnish remain in this laminate. It is a conventional method to apply an adhesive layer and heat the adhesive to cure the adhesive to form a laminated board with adhesion. However, according to this conventional method, unevenness on the surface of the laminated board as a result of heat curing of the prepreg resin is obtained. When an adhesive is applied along the surface of the resin, and then the adhesive is cured by heating, unevenness increases due to evaporation of a solvent component and unreacted components. The present inventors have focused on this fact and arrived at the present invention.

The present invention volatilizes the solvent component and unreacted components remaining in the laminate by heat-treating the laminate before applying the adhesive, and further smoothes the surface of the laminate by mechanical polishing,
This is a method for producing an additive-processed printed wiring board with an adhesive requiring an adhesive having excellent surface smoothness by applying an adhesive and heating to cure the adhesive.

The heating temperature depends on the type and amount of the solvent and unreacted components, but is set to 100 ° C. or higher, preferably 140 to 180 ° C. The heating time is set so that the solvent and the unreacted components substantially evaporate, and may be shorter if the heating temperature is higher.

[Action]

By heat treatment before polishing the laminate surface,
Residual solvent and unreacted components in the laminate are volatilized. Since the adhesive is applied after removing the irregularities generated at this time by polishing, the surface of the adhesive layer becomes smooth.

〔Example〕

Example 1 A laminate before adhesive application in a manufacturing process of an adhesive-based paper-based epoxy resin laminate for an additive method printed wiring board was subjected to a heat treatment at 100 ° C. for 3 hours, and a surface roughness was obtained by mechanical polishing. Was set to 3 to 4 μm (the surface roughness was measured according to JIS B
0601, based on the 10-point average roughness method). Further, an adhesive having a catalytic activity for electroless plating was applied to this to a thickness of 30 ± 5 μm, and heated at a predetermined temperature and time.

On the surface of the laminate with the adhesive obtained in this manner, ink for insulation between circuits was applied in a width of 0.15 mm and heated,
The bleeding and dripping length of the cured ink were measured. In addition, electroless copper plating was performed on the surface of the laminate with adhesive to deposit copper by 35 μm, and the peel strength and 260 ° C.
(The measurement method conformed to the JIS C6481 test method for copper-clad laminates for printed circuits.)

Example 2 The laminate before application of the adhesive of Example 1 was subjected to a heat treatment at 140 ° C. for 1 hour, and the surface roughness was 3 to 4 μm by mechanical polishing.
And An adhesive was applied and heated to the polished laminate under the same conditions as in Example 1, and the same test as in Example 1 was performed. Table 1 shows the results.

Example 3 The laminate of Example 1 was heated at 170 ° C. for 30 minutes before applying the adhesive, and the surface roughness was 3 to 4 μm by mechanical polishing.
And An adhesive was applied and heated to the polished laminate under the same conditions as in Example 1, and the same test as in Example 1 was performed. Table 1 shows the results.

COMPARATIVE EXAMPLE 1 An adhesive was applied to the laminated plate of the example that had not been subjected to the heat treatment before the application of the adhesive under the same conditions as in the example and heated to obtain a laminated plate with an adhesive. This was polished to a surface roughness of 3 to 4 μm. The obtained sample was tested in the same manner as in the example. Table 1 shows the results.

Comparative Example 2 A laminate not subjected to heat treatment before application of the adhesive in the example was polished to a surface roughness of 3 to 4 μm, and then the adhesive was applied and heated under the same conditions as in the example, and the laminate with the adhesive was applied. I got This was used as a sample and tested in the same manner as in the example. Table 1 shows the results.

[Effects of the Invention] According to the test results shown in Table 1, since the surface of the laminated board with the adhesive according to the method of the present invention is extremely smooth, high-density circuits can be printed even if mechanical polishing in the conventional printing step is omitted. It was confirmed that it could be formed by the method.

Claims (1)

(57) [Claims] 1. A method of manufacturing a laminate for an additive-type printed wiring board, wherein an adhesive layer is provided on both sides of the laminate for fixing metal layers formed by electroless plating. A method for producing a laminate for an additive printed wiring board, comprising heating a board and polishing the surface so as to be smooth, thereby forming an adhesive layer.