JPH0841222A - Production of thermosetting resin laminate board - Google Patents

Abstract

PURPOSE:To obtain the paper-based laminate board excellent in silver migration resistance, enhanced the reliability, and useful for silver through-hole printed circuit boards by impregnating raw paper having a specific density with a thermosetting resin. CONSTITUTION:This laminate board is obtained by impregnating raw paper having a density of 0.51-0.60g/cm<3> (e.g craft paper or linter paper having a density of 0.52-0.56g/cm<2>) with (B) a thermosetting resin such as a (flexibilizer- modified) phenolic resin, a (flexibilizer-modified) epoxy resin or a (flexibilizer- modified) melamine resin. The flexibilizing agent for modifying the component B includes drying oils and semi-drying oils such as tung oil, tall oil fatty acid, cashew oil and linseed oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a method of manufacturing a silver through-hole printed wiring board, in which a silver migration phenomenon which causes deterioration of reliability is less likely to occur (excellent silver migration resistance). It is a thing.

[0002]

2. Description of the Related Art Conventionally, a paper-based thermosetting resin laminated board is obtained by impregnating a base paper with a thermosetting resin compound varnish, laminating a plurality of the impregnated papers, and adhesive on one or both sides depending on the application. It is manufactured by stacking coated copper foils and then heat-pressing. It is well known that, after silver through-hole processing is applied to the laminated plate thus obtained, a silver transfer phenomenon occurs with time when a voltage is applied between the silver through-holes under high temperature and high humidity conditions. There is. In particular, in a place where the silver through-holes are close to each other, a silver migration phenomenon occurs so as to connect the through-holes inside the laminated plate, and eventually a short circuit occurs. In order to prevent the silver migration phenomenon inside such a laminated plate from occurring easily, the present inventors have filed Japanese Patent Application No. 5-469.
No. 15, Japanese Patent Application No. 5-48376, Japanese Patent Application No. 5-6977
No. 0, Japanese Patent Application No. 6-33938 and other methods have been used to increase the resin impregnation inside the paper fiber.

However, due to the development of the evaluation method as described in Japanese Patent Application No. 6-27789 and Japanese Patent Application No. 6-32678, there is a bias of resin impregnation into the inside of the paper fiber inside the laminated plate. It was found to be a major factor in the occurrence of the silver migration phenomenon.

[0004]

The present invention has been completed as a result of various studies based on the knowledge of such a silver migration phenomenon, and provides a method for producing a laminated plate in which the silver migration phenomenon is less likely to occur. To do.

[0005]

The present invention has a density of 0.51.
A method for producing a paper-based thermosetting resin laminated plate (hereinafter, referred to as a laminated plate), characterized by impregnating a base paper having an amount of to 0.60 g / cm ³ with a thermosetting resin (hereinafter referred to as a resin) Is.

In order to suppress the occurrence of the silver migration phenomenon, the key is how much resin can be impregnated inside the base paper fiber. By taking measures against the resin, the resin can be impregnated inside the base paper fiber. It is possible to increase ability. As a matter of course, when the resin is completely permeated and filled between the base paper fibers and the resin and the base paper fibers are in firm contact,
The impregnation ability of the resin into the fiber of the base paper is most efficiently exhibited.

Conventionally, it has been considered that the base paper used for the laminated board is preferably low in density and swells in the thickness direction during the coating process in order to enhance the resin permeability between the base paper fibers. In such a raw paper, the void volume existing between the raw paper fibers is large, and the void volume existing between the raw paper fibers becomes excessive with respect to the required amount of the resin impregnated into the raw paper. For this reason, the penetration of the resin into the fibers of the base paper becomes non-uniform, and uneven distribution of the resin impregnation inside the fibers of the base paper occurs.

Therefore, a base paper having a higher density than the conventional one,
That is, 0.51 to 0.60 g / cm ³ , preferably 0.
By using a base paper of 52 to 0.56 g / cm ³ ,
It became possible to reduce the void volume between the base paper fibers during the coating process, eliminate the uneven distribution of the resin into the base paper fibers, and effectively reduce the occurrence of the silver migration phenomenon. The base paper density here is measured based on JIS P-8118.

When the density is lower than the above range, the deviation of the resin permeation into the fibers of the base paper becomes large, and when the density is high, the permeation between the fibers of the base paper is hindered, and the phenomenon of silver migration easily occurs. The production method of the present invention can be applied regardless of the impregnation method such as the one-step impregnation method and the two-step impregnation method.

Examples of the base paper used in the present invention include kraft paper and linter paper. As the resin, phenol resin, epoxy resin, unsaturated polyester resin, melamine resin, or the like, or a dry oil such as tung oil, tall fatty acid, cashew oil, linseed oil, castor oil, linolenic oil, linole oil, and epoxidized vegetable oil. , Semi-drying oils, glycerides thereof, epoxidized polybutadiene, polyethylene glycol, polyesters, polyethers and the like modified with a flexibilizing agent, and these may be used alone or in combination.

[0011]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 The base paper density is 0.52 g / cm.
^A prepreg a was obtained by impregnating the base paper of No. ³ with a resol type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50%. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate A was obtained.

Example 2 Base paper density is 0.54 g / cm.
^The base paper of No. ³ was impregnated with a resole-type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50% to obtain a prepreg b. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate B was obtained.

Example 3 Base paper density is 0.60 g / cm.
^The base paper of No. ³ was impregnated with a resole-type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50% to obtain a prepreg c. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate C was obtained.

Comparative Example 1 Density of base paper is 0.63 g / cm.
^The base paper of No. ³ was impregnated with a resole-type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50% to obtain a prepreg d. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate D was obtained.

Comparative Example 2 Density of base paper is 0.50 g / cm.
^The base paper of No. ³ was impregnated with a resole-type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50% to obtain a prepreg e. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate E was obtained.

Comparative Example 3 Density of base paper is 0.48 g / cm.
^The base paper of No. ³ was impregnated with a resole-type phenol resin having a tung oil modification rate of 35% so as to have an adhesion amount of 50% to obtain a prepreg f. Eight sheets of this prepreg and copper foil with an adhesive were superposed on both the front and back sides, and heat-press molded to obtain a plate thickness of 1.
A 6 mm laminated plate F was obtained.

The characteristics of the laminate obtained by the above method are shown in Table 1.

[Table 1]

(Test method for silver migration resistance) Land diameter 1.2 m
m, through hole diameter 0.5 mm, 10 silver through holes
Create a test pattern in which two circuits with 0 holes are arranged adjacent to each other so that the distance between the centers of the through holes is 1.5 mm. Under the conditions of a temperature of 40 ° C and a humidity of 93% RH, the through holes are In the meantime, the voltage (50 VDC) was continuously applied for a predetermined time. After that, the insulation resistance between through holes is measured.

[0020]

As is clear from the above results, the laminated sheet obtained by the present invention has extremely excellent silver migration resistance.

Claims (2)

[Claims] 1. A method for producing a paper-based thermosetting resin laminate, which comprises impregnating a base paper having a density of 0.51 to 0.60 g / cm ³ with a thermosetting resin. 2. The method for producing a laminated board according to claim 1, wherein the thermosetting resin is a phenol resin.