JPH09143288A - Prepreg sheet for multilayer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare the subject prepreg sheet useful for multilayer printed circuit board and excellent in dimentsional stability by impregnating a specific resin material into a reinforcing substrate and preliminarily drying the reinforcing substrate. SOLUTION: A resin composition obtained by mixing 0.5-30 pts.wt. crosslinked nitrile rubber with 100 pts.wt. epoxy resin and containing a curing agent of the epoxy resin is impregnated into a reinforcing substrate (glass fabric, etc.) and preliminarily dried. Thereby, dispersion of dimensional changing ratio can be lowered without lowering heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg sheet used in a multilayer printed wiring board and having excellent dimensional stability.

[0002]

2. Description of the Related Art A multilayer printed wiring board is generally manufactured by the following procedure. First, a reinforcing base material such as glass cloth or glass nonwoven cloth is impregnated with epoxy resin or polyimide resin.
Stack the pre-dried prepreg to a specified thickness,
A copper foil is placed on one side or both sides and heated and pressed to form a copper clad laminate. Next, a predetermined copper foil circuit pattern is formed on this copper clad laminate by an etching method to obtain an inner layer circuit board. The circuit pattern at this time has a dimensional change due to the influence of the next heating and pressurizing step. Therefore, when the dimensional change is large, the circuit pattern is preliminarily estimated.
Next, place a prepreg on one side or both sides of this inner layer circuit board, further place a copper foil on it, heat and pressurize it to make a copper clad laminate with inner layer circuit, drill hole → through hoe plating → outer layer etching → permanent A multilayer printed wiring board is obtained through the resist process. Multilayer printed wiring boards are becoming denser and thinner year after year, and therefore their patterns are required to be finer and denser. Above all, the dimensional change of the inner layer when forming multiple layers is the most important issue.
Regarding the point that a pattern that takes into account the dimensions of the inner layer circuit is formed in advance, the rate of change varies depending on the board thickness, the state of the circuit, the nature and number of prepregs used, and so it is decided each time. There is. Further, even if the multilayer printed wiring boards have the same specifications, if the variation in the variation rate is large, the drill hole and the inner layer circuit cannot be aligned with each other, which may cause disconnection. Reducing this variation has become a particularly important issue for miniaturization of circuit patterns. The present invention has been made in view of such circumstances, and an object thereof is to provide a multilayer printed wiring board having excellent dimensional stability.

[0003]

In order to solve the above problems, a prepreg sheet for a multilayer printed wiring board according to the present invention comprises an epoxy resin, a curing agent for the prepreg sheet, and a crosslinked nitrile rubber as essential components, and a crosslinked nitrile rubber as an epoxy. Resin 10
A resin composition containing 0.5 to 30 parts by weight relative to 0 parts by weight is impregnated into a reinforcing base material and preliminarily dried. The epoxy resin (A) in the present invention is not particularly limited, but is bisphenol A type epoxy resin, modified bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin. , Naphthalene skeleton epoxy resin, biphenyl type epoxy resin, dicyclopentadiene skeleton epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, etc.,
Furthermore, there are epoxy resins obtained by brominated them. These are used alone or in combination of two or more. As a particularly frequently used example, a combination of 100 to 70 parts by weight of a brominated bisphenol A type epoxy resin and 0 to 30 parts by weight of a cresol novolac type epoxy resin is widely adopted because it conforms to the JIS standard GE4F grade. These two types may be used alone, or may be used in which a novolac component and a bisphenol A component are preliminarily reacted at the time of forming an epoxy resin. The curing agent (B) for the epoxy resin in the present invention is not particularly limited, but various known agents such as various amines, phenol resins, acid anhydrides and polyamides can be used. From the viewpoint of storage stability, dicyandiamide, diaminodiphenylsulfone or novolac phenol resin is often used for a multilayer printed wiring board. In the present invention, the crosslinked nitrile rubber (C) reduces the curing shrinkage of the epoxy resin during heat molding,
Therefore, it has the effects of reducing the dimensional change rate due to heating and reducing variations. It is a well-known fact that liquid nitrile rubber is blended for the purpose of imparting toughness to the epoxy resin, but in our experiments, there was no effect on the dimensional change rate. On the other hand, the cross-linked nitrile rubber itself is cross-linked, so even after the epoxy resin is cured, for example, there is an independent rubber island in the sea of epoxy resin. It was possible to alleviate the strain of curing shrinkage without impairing the original properties of the resin. However, the compounding amount is 0.5
If the amount is less than or equal to parts by weight, the effect is scarce, and if the amount is greater than or equal to 30 parts by weight, the heat resistance is deteriorated. A more appropriate range is 5
It is desirable that the amount is ˜15 parts by weight.

[0004]

Example 1 22% brominated bisphenol A type epoxy resin (epoxy equivalent 520) 85 parts by weight cresol novolac epoxy resin (epoxy equivalent 220) 15 parts by weight dicyandiamide 2.5 parts by weight 2E4MZ as a curing accelerator 0.1 parts by weight Crosslinked nitrile rubber ... 5 parts by weight The above resin composition is dissolved in a solvent such as MEK, DMF, acetone, methyl cellosolve, and toluene to form a varnish,
A 0.18 mm thick plain woven glass cloth was impregnated and pre-dried to obtain a 0.2 mm thick prepreg. A copper foil having a thickness of 35 μm is laminated on both sides of the six prepregs, and a molding pressure of 40 is applied.
kgf / cm ^2, and 1.2mm thickness of the double-sided copper-clad laminate by applying 1 hour heating at 170 ° C. After the gelation at a temperature 0.99 ° C., it was evaluated. A copper foil of another double-sided copper-clad laminate obtained in the same manner is formed into a predetermined circuit by an etching method to form an inner layer circuit board, and one 0.2 mm-thick prepreg is provided on each side of the circuit board. And a copper foil with a thickness of 18 μm were stacked, and heated and pressed under the same conditions as above to obtain a substrate for a 4-layer multilayer printed wiring board having a thickness of 1.6 mm and evaluated.

[0005]

Example 2 Example 1 was repeated except that the amount of the crosslinked nitrile rubber was changed to 15 parts by weight.

[0006]

Comparative Example 1 The procedure of Example 1 was repeated except that the cross-linked nitrile rubber was changed to liquid nitrile rubber.

[0007]

Comparative Example 2 The procedure of Example 1 was repeated except that the amount of the crosslinked nitrile rubber was 0 part by weight.
Table 1 shows the measurement results.

[0008]

Comparative Example 3 The procedure of Example 1 was repeated, except that the amount of the crosslinked nitrile rubber was 35 parts by weight.

Table 1 shows the evaluation results of Examples 1 and 2 and Comparative Examples 1, 2, and 3.

[0010]

[Table 1]

[0011]

【Test method】

(1) The average value of the dimensional change rate of the double-sided copper-clad laminate is JI
It was based on Section 5.16 of S C-6481. n = 10,
The heating condition was 170 ° C. for 30 minutes. (2) The variation width of the dimensional change rate of the double-sided copper clad laminate is
The absolute value of the difference between the maximum value and the minimum value of the dimensional change rate under the same conditions was used. (3) The solder heat resistance of the double-sided copper-clad laminate was measured by boiling a 50 mm × 50 mm sample in which the copper foil was entirely removed by etching for 2 hours, and then measuring the time until swelling of solder occurred at 260 ° C. (4) The average value of the dimensional change rate of the four-layer multilayer printed wiring board substrate is a 330 mm square 1.2-thick double-sided copper clad laminate,
After etching the circuit pattern provided with the reference marks, the distance between the reference marks was measured and used as the normal value. The distance between the reference marks was about 300 mm, and both vertical and horizontal measurements were made on one plate at two locations. With this circuit board as the inner layer,
After heat-press molding on the multilayer plate, the mark-to-mark dimension after the reference mark was countersunk was measured to determine the rate of change with respect to the normal value. n = 10. (5) The variation width of the dimensional change rate of the four-layer multilayer printed wiring board substrate is the absolute value of the difference between the maximum value and the minimum value of the dimensional change rate. (6) Solder heat resistance of the 4-layer multilayer printed wiring board is 50 mm x 50 mm obtained by etching the entire surface of the multilayer copper foil.
After boiling for 2 hours, the sample was floated on the solder at 260 ° C. and the time until blistering occurred was measured.

[0012]

INDUSTRIAL APPLICABILITY The multilayer printed wiring board using the prepreg sheet according to the present invention has an excellent dimensional change rate and is very useful.

Claims (1)

[Claims] 1. A reinforcing base material is impregnated with a resin composition comprising an epoxy resin, a curing agent thereof, and a crosslinked nitrile rubber as essential components, and 0.5 to 30 parts by weight of the crosslinked nitrile rubber mixed with 100 parts by weight of the epoxy resin. A prepreg sheet for a multilayer printed wiring board, which is preliminarily dried.