JPH06255013A - Thermosetting resin laminated sheet - Google Patents

Abstract

PURPOSE:To provide a laminated sheet wherein migration phenomena of silver are hardly caused by specifying the rate of swelling in the direction of thickness of the laminated sheet when it is treated in a pressure cooker. CONSTITUTION:In a paper base thermosetting resin laminated sheet having a thickness of 0.6-1.6mm, after the laminated sheet is treated at 121 deg.C and 2 atmospheric pressure for 8 hours in a pressure cooker, the rate of swelling in the direction of thickness of the laminated sheet is regulated within the range shown by formula I when thickness of the laminated sheet is shown in x mm and the rate of swelling is shown in y %. The laminated sheet is applied regardless of an impregnation method such as one-stage impregnation method and two-stage impregnation method. The paper base thermosetting resin laminated sheet having excellent resistance to migration properties of silver is obtained by sufficiently penetrating resin into the inside of paper fiber especially in a primary treatment of the two-stage impregnation method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper base thermosetting resin laminated plate (hereinafter referred to as a laminated plate) in which a silver migration phenomenon is less likely to occur (hereinafter referred to as "excellent silver migration resistance"). ) Is provided.

[0002]

2. Description of the Related Art Conventionally, a laminated board is prepared by impregnating a varnish containing a thermosetting resin compound into a kraft paper or a linter paper, laminating a plurality of the impregnated papers, and copper with an adhesive on one or both sides depending on the application. It is manufactured by stacking foils and then heat-pressing. The laminated plate thus obtained shows a migration phenomenon of silver over time when a voltage is applied between two silver electrodes (silver jumpers, silver through holes, etc.) formed on the laminated plate under temperature and humidity conditions. It is well known to occur.
In recent years, the trend toward lighter, thinner, shorter, and smaller electronic products requires higher density of printed circuit wiring boards, and the pitch between silver through holes is 2.5.
It has been narrowed down to ~ 2.0 mm, and now even a 1.5 mm pitch is about to be put to practical use. Therefore, a short circuit due to the migration phenomenon of silver is likely to occur, and in order to secure the reliability of the printed circuit wiring board, there is an increasing demand for a laminated board having more excellent silver migration resistance.

It is known that the silver migration phenomenon in a laminated plate occurs by the following mechanism. Ag ⇔ Ag ⁺ + e ^- Ag ⁺ + OH ^- ⇔ AgOH
(1) 2AgOH⇔Ag ₂ O + H ₂ O
_{(2) Ag 2 O + H} 2 O⇔2AgOH⇔2Ag + + 2OH -
(3) As described above, since the ionization of silver is the main factor, it is indispensable for water to enter the laminate. Further, the elution of ionic impurities into the invading water deteriorates the electrical characteristics of the laminate, particularly promotes the ionization of silver, and significantly reduces the resistance to silver migration. For this reason, the method of improving the moisture resistance of the laminate by making the resin hydrophobic or improving the impregnation of the resin by two-stage impregnation or the ionization of silver by adding an ion collector to the resin Methods have been adopted to suppress this.

[0004]

SUMMARY OF THE INVENTION The present invention provides a laminate having excellent silver migration resistance. That is, the inventors have found that a laminate having a small swelling ratio in the thickness direction of the laminate when subjected to pressure cooker treatment has excellent silver migration resistance, and completed the present invention.

[0005]

The present invention has a thickness of 0.6 to
In a 1.6 mm laminated plate, the swelling ratio in the thickness direction of the laminated plate 8 hours after pressure cooker treatment at 121 ° C. and 2 atm was 8 (x) (mm), and the swelling ratio was y (mm). %), It is within the range represented by the following formula: a paper-based thermosetting resin laminate.

[Equation 1]

The present invention will be described in detail below. The silver migration phenomenon occurs inside paper fibers in the laminate due to moisture absorption. Therefore, it is possible to suppress the silver migration phenomenon by preventing the laminated plate from absorbing moisture by sufficiently impregnating the paper fibers with the resin. When the laminate absorbs moisture, the paper fibers swell, which causes silver migration. Although it is difficult to measure the swelling of paper fibers under normal use conditions, the degree of swelling of paper fibers can be quantified by swelling the laminated plate by pressure cooker treatment. That is, the quality of silver migration can be determined by measuring the swelling ratio in the thickness direction of the laminate 8 hours after pressure cooker treatment at 121 ° C. and 2 atmospheres. A laminated plate having a swelling ratio after 8 hours from the pressure / cooker treatment outside the range of the above formula will not be a laminated plate having excellent silver migration resistance because the swelling of paper fibers due to moisture absorption becomes large.

The laminated plate 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.
In the primary treatment of the stepwise impregnation method, the resin is sufficiently permeated into the inside of the paper fiber to provide excellent silver migration resistance. Examples of the paper base material used in the present invention include kraft paper and linter paper. As the thermosetting resin, a phenol resin, an epoxy resin, an unsaturated polyester resin, a melamine resin, or a dry resin such as tung oil, tall fatty acid, cashew oil, linseed oil, castor oil, linolenic oil, linole oil, and epoxidized vegetable oil can be used. Oil, semi-drying oil,
Examples thereof include those modified with a flexibilizing agent such as glyceride, epoxidized polybutadiene, polyethylene glycol, polyester and polyether, and these may be used alone or in combination.

[0008]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto. Example 1 Water 50 parts by weight, methanol 40 parts by weight, water-soluble low molecular weight phenolic resin varnish (solid content 50% by weight)
The primary treatment varnish consisting of 10 parts by weight was impregnated with a paper base material consisting of kraft pulp for 30 seconds to perform the primary treatment, and thereafter,
A prepreg a was obtained by impregnating with a dry oil-modified phenol resin varnish (solid content: 50% by weight) so that the resin amount was 50% by weight. <Example 2> 50 parts by weight of water, 40 parts by weight of methanol, and 10 parts by weight of a water-soluble low-molecular weight phenolic resin varnish were used, and 50 parts by weight of the paper substrate was added to the primary treatment varnish used in Example 1.
It was impregnated for a second and subjected to a primary treatment, and then impregnated with the drying oil-modified phenol resin varnish so that the resin amount was 50% by weight to obtain a prepreg b.

Example 3 A drying oil-modified phenolic resin varnish containing 10 parts by weight of water and 20 parts by weight of the water-soluble low-molecular weight phenolic resin varnish was added to the paper base with a resin amount of 5 parts.
Impregnation was carried out for 60 seconds so that the prepreg c became 0% by weight. Comparative Example 1 A prepreg d was obtained by impregnating the paper base material with the drying oil-modified phenol resin varnish for 20 seconds so that the resin amount was 50% by weight.

Eight pieces of each prepreg thus obtained and one set of copper foil with adhesive are heat-pressed to form four types of laminated plates A1, B1, C having a thickness of 1.6 mm.
1 and D1 were obtained. Similarly, each prepreg 6
Four types of laminated plates A2, B2, C2, D2 with a thickness of 1.2 mm, which are heat-pressed as a set of a sheet and a copper foil with adhesive.
Got Further, four pieces of each prepreg and a copper foil with an adhesive were set as a set and heat-pressed to obtain four kinds of laminated plates A3, B3, C3, D3 having a plate thickness of 0.8 mm. Table 1 shows the characteristics of the laminated plate obtained by the above method.

[0011]

[Table 1]

(Test method) 1. Swelling ratio in the thickness direction For a laminated plate having a size of 50 × 50 mm, 121 ° C.
The pressure cooker treatment was performed for 8 hours under the condition of 2 atm, the thickness of the laminated plate before and after the treatment was measured, and the swelling ratio was calculated from the difference. 2. Resistance to silver migration Two circuits with 100 continuous silver through-holes with a land diameter of 1.5 mm and a through-hole diameter of 0.7 mm are arranged adjacent to each other with a pitch between the through-holes of 2.0 mm. The test pattern was created. Using this test pattern, the insulation resistance between circuits was measured after 1000 hours of treatment under the conditions of an applied voltage of 50 VDC, a temperature of 40 ° C. and a relative humidity of 93%.

[0013]

As is clear from the above results, the laminate according to the present invention has extremely excellent resistance to silver migration.

Claims (1)

[Claims] 1. A paper-based thermosetting resin laminate having a thickness of 0.6 to 1.6 mm has a swelling ratio in the thickness direction of the laminate after 8 hours of pressure cooker treatment at 121 ° C. and 2 atm. A paper-based thermosetting resin laminate, characterized in that when the thickness of the laminate is x (mm) and the swelling ratio is y (%), it is within the range represented by the following formula. [Equation 1]