JPH02155727A - Manufacture of thermocuring resin laminated sheet - Google Patents

Abstract

PURPOSE:To eliminate the uneveness from the surface of a substrate and thereby increase drilling processing efficiency by using woven glass cloth which is made brittle as an intermediate layer and using a specific weight of unwoven glass cloth on the surface of the woven glass cloth. CONSTITUTION:Epoxy resin which is made brittle so that the bending strength of a laminated plate reaches 50 kg/mm<2> both in vertical and horizontal directions is impregnated with thermocuring resin varnish such as epoxy resin, then a dried prepreg is used as an intermediate layer and the prepreg which is impregnated with thermocuring resin varnish and dried is applied, as a surface layer, on the unwoven glass cloth weighing 100 to 150g/m<2>. After this, a desired number of these surface layers and intermediate layers are laminated and copper foil is placed together. These are thermally molded under pressure. To make the woven glass cloth brittle, a variety of methods are available which are heat-cleaning at high temperatures of 400 deg.C or higher for a comparatively long time, soaking in an acid or alkali liquid and opening the fibers of a glass cloth mechanically. The unwoven glass cloth should preferably be of 7 to 12 mum monofilament in dia. and 9 to 19mm fiber length. The unwoven glass cloth also should preferably be heat-resistant and less water-absorptive for binder and coupling processes.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a novel thermosetting resin laminate for industrial equipment and electronic equipment, and its purpose is to improve the surface smoothness of the substrate. The object of the present invention is to obtain a thermosetting resin laminate having excellent drill workability, especially small-diameter drill hole position accuracy.

[Conventional technology]

Conventionally, woven glass fabric has been mainly used as a base material for electrical insulating boards and copper-clad laminates for printed circuits used in industrial equipment, electronic equipment, etc. that require high quality. This is because laminates based on woven glass fabric have dimensional stability, mechanical strength,
This is because it has excellent properties such as electrical properties, heat resistance, and chemical resistance.

However, in recent years, electronic components have become smaller and more reliable, and in particular, the advent of flat packages has led to rapid progress in surface mounting, which has led to rapid increases in the density of printed wiring boards. . Along with this, the diameter of through-holes has become smaller, the number of via holes has increased, and productivity has improved and costs have been reduced. Even in small-diameter drilling (0.5aφ or less), conventional two-ply processing has been changed to three-ply processing. As demands have increased, problems such as hole position accuracy, drill blade wear, and hole wall roughness have emerged.

Furthermore, as the circuit width and circuit spacing become thinner due to higher density, the smoothness of the substrate surface has become a problem in order to improve the adhesion between the etching resist and the laminate.

Traditionally, glass woven fabrics used for thermosetting resin laminates for industrial equipment and electronic devices have a thickness of 25 to 180 μm and a weight of 19 to 220 g/rrf, which is correlated with the bending strength of the laminate. Tensile strength is 80-100 kg in longitudinal direction
/25peng, 60-80kg/25m in the lateral direction.

In the case of laminated plates obtained using such glass woven fabric, when three-ply processing is performed instead of the conventional small-diameter drilling (0.5 m or less) two-ply processing, the accuracy of the drill hole position is significantly improved. 3. Drill blade wear decreased significantly and drill blade wear increased significantly.
It is not possible to satisfy the requirements for layer processing.

In addition, there are gaps between warp and weft threads in glass woven fabric.
The entire glass woven fabric has a non-uniform shape with glass fibers in some areas and voids in others. For this reason, a laminate using glass woven fabric has unevenness on its surface. This causes disconnection or thinning of the circuit due to poor adhesion with the etching resist.

Drilling with a drill also causes the drill to slip during machining, especially when using a small diameter drill.

Therefore, in order to improve this surface unevenness, a method of thickening the resin layer on the surface has been considered, but this method
Constructing a resin layer with a thickness of 0 μm or more has disadvantages such as occurrence of slippage during pressing, resin content flowing out during pressing, and reduction in plate thickness accuracy.

[Problem B to be Solved by the Invention] In order to improve the above-mentioned drawbacks, the object of the present invention is to provide a glass fabric which has been subjected to embrittlement treatment so that the bending strength of the laminated plate is 50 kg/w' or less in both the longitudinal and transverse directions. To provide a laminate with improved drillability and improved surface irregularities by using cloth as an intermediate layer and glass woven cloth with a weight of 110 to 150 g/rrf on the surface thereof.

[Means to solve the problem]

In the present invention, the bending strength of the laminated plate is 50 in both the longitudinal and lateral directions.
A glass woven fabric that has been embrittled to a weight of 100 to 150 g/rr is impregnated with a thermosetting resin press such as epoxy resin, and dried prepreg is used as the intermediate layer.
A heating method characterized in that a prepreg obtained by impregnating and drying the thermosetting resin press is used as a surface layer on the glass nonwoven fabric of f, and a predetermined number of these surface layers and an intermediate layer are laminated, copper foil is layered, and heat and pressure molding is performed. This is a method for manufacturing a curable resin laminate.

The feature of the present invention is that the bending strength of the laminated plate is 50 in both the vertical and horizontal directions.
A glass woven fabric that has been embrittled to a weight of 110 to 150 kg/nl is used as the intermediate layer, and the surface is
The purpose is to use glass non-woven fabric.

In order to reduce the strength of the laminate, the strength of the glass woven fabric is mainly reduced.

Generally, the strength of a glass woven fabric is indicated by the tensile strength of the glass threads constituting the glass woven fabric immediately before lamination and molding. However, the tensile strength of glass thread usually depends on the amount of adhesive applied, the type and amount of coupling agent used to strengthen the bond with the epoxy resin, and the temperature and time of heat cleaning. For this reason, even if base materials with the same tensile strength are used, the bending strength values of the obtained laminates differ. It is believed that the accuracy of the position of a small-diameter drill hole is determined by whether or not the drill blade is bent by the base material due to the difference in rigidity between the base material (glass woven fabric) and the resin.

As shown in FIG. 1, there is a clear correlation between the positional accuracy of small-diameter drill holes and the bending strength of the laminate.

(Figure 1 shows a diameter of 0.4 amφ, 3 sheets stacked, rotation speed = 60
．． 000 rpm, feed: 1.2 m/min. )
As is clear from FIG. 1, as the bending strength of the laminate decreases, the large bend N (average value of the large bend distance) decreases. If the bending strength of the laminate is 50 kg/am2 or more, it will not be effective against large bends.

Furthermore, if the weight is less than 20 kg/+m+'', there is a risk of reducing productivity due to breakage of the base material during the coating process and press/heat molding, so care must be taken in the manufacturing process.

In order to reduce the temporary bending strength of the product, it is necessary to obtain a embrittled glass fabric.The usual embrittlement treatment is 400°
Examples include a method of performing heat cleaning at a high temperature of C or higher for a relatively long time, a method of immersing in an acid or alkaline solution, a method of mechanically opening a glass cloth, but the method is not particularly limited.

When a glass non-woven fabric is used for the surface layer, the distribution of glass fibers and resin in the surface layer is much more uniform compared to a glass woven fabric, which alleviates the unevenness of the glass woven fabric in the intermediate layer and improves the surface smoothness of the substrate. . Therefore, the laminated plate manufactured by the conventional method with this configuration has improved adhesion with the etching resist, and during small-diameter drilling, the slippage of the drill is reduced, resulting in good hole position accuracy.

As the glass nonwoven fabric, monofilament 7 to 12 μm
It is necessary to select a fiber having a fiber length of 9 to 9 mm, and for the binder and coupling treatment to improve heat resistance, it is necessary to select a fiber with low heat resistance and water absorption.

Further, the thermosetting resin used in the present invention is not particularly limited and may be an epoxy resin, a polyimide resin, a phenol resin, a polyester resin, or the like.

〔Example〕

The present invention will be explained by examples.

Example 1 In order to obtain the longitudinal bending strength of the laminate of 40 kg/1, the monofilament was 9 νm and the vertical driving loss was 41/2501.
A glass woven fabric with a thickness of 180 μm and a weight of 205 g/rtr was heat-cleaned in a heating furnace at 400° C. for 20 hours to burn off the adhesion sizing agent.

Furthermore, this was continuously passed through a high temperature furnace at 600'C,
Next, epoxy disilane was applied as a coupling agent and dried.

The tensile strength of the glass woven fabric thus treated was 35 kg/25 m+a in the longitudinal direction and 25 kg/25 m+a in the transverse direction.

Separately, epoxy resin (oiled shell epoxy ■Product name E
p5045) 100 parts by weight (hereinafter referred to as parts), 4.7 parts of curing agent dicyandiamide, curing accelerator 2-ethyl-
An epoxy resin varnish consisting of 4-methylimidazole and a solvent was prepared, and the glass woven fabric was impregnated with the varnish and dried to obtain a prepreg having a resin content (RC) of 40 to 42%.

Subsequently, for the surface layer, a glass nonwoven fabric (Ep-4050 manufactured by Nippon Vilene Co., Ltd.) weighing 50 g/rrf was impregnated with the same varnish as described above and dried to obtain a prepreg having a resin content of 53 to 55%.

Next, the eight sheets of glass woven prepreg were laminated as an intermediate layer, and the glass nonwoven prepreg was laminated as the upper and lower surface layers, and then 1i! Fli (18 μm) was overlapped and molded under heat and pressure to obtain an epoxy resin copper-clad laminate having a thickness of 1.6 mm.

Example 2 Seven glass woven prepregs similar to those in Example 1 were laminated as an intermediate layer, and glass nonwoven prepregs with a resin content of 65 to 67% were laminated on the upper and lower surface layers, and the same treatment as in Example 1 was performed. A 1.6 inch epoxy resin copper clad laminate was obtained.

Comparative Example 1 Monofilament diameter 9μm, number of 1 strokes 41/25■,
Number of horizontal strokes: 32/25, thickness: 180μm, weight: 1205
g/% glass woven fabric was impregnated with the same resin as in the example and dried to obtain a prepreg with a resin content of 39 to 41%, and 8 sheets of this prepreg were laminated and W4 foil (18 μm) was layered on both sides. An epoxy resin copper-clad laminate having a thickness of 1.6 mm was obtained by heat-pressing molding.

Comparative Example 2 Eight woven glass fabric prepregs similar to those in Example 1 were laminated, copper foil (18 μm) was layered on both sides, and heat and pressure molded to form an epoxy resin copper-clad laminate with a thickness of 1.6 mm. Obtained.

The drill workability and surface roughness of the laminates obtained in Example 1.2 and Comparative Example 1.2 were measured, and the results were compared to the first
Shown in the table.

As is clear from Table 1, the drill workability and surface roughness of the laminate of the present invention are extremely superior to those of conventional laminates.

Table 1 Note: Measurement method (1) Drill diameter 0.4-φ 3-ply rotation speed 60
000r, p, ■ Feed rate 1.2m/5in Average value up to 5000 shots (2) Drill diameter 11aφ 3-ply rotation speed 65000r, pom Feed rate 5. Average value up to 10,000 shots (3) Maximum roughness of the laminate surface [Effects of the invention] According to the method of the present invention, drilling with a small diameter drill can be
It is now possible to stack three sheets instead of the conventional two-layer stack, greatly improving productivity. In addition, the surface irregularities, which were defects of conventional glass woven laminates, have been improved, resulting in better smoothness, improved adhesion with resist, and the ability to form fine patterns. A resin laminate can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the large bending amount of a small diameter drill and the bending strength of a laminate.

Claims (1)

[Claims] (1) The bending strength of the laminate is 50 kg in both the vertical and horizontal directions.
/mm^2 or less, glass woven fabric has been subjected to embrittlement treatment,
A prepreg impregnated with thermosetting resin varnish such as epoxy resin and dried is used for the intermediate layer, and the weight is 10 g/m^2 ~
A glass non-woven fabric of 150 g/m^2 is impregnated with the thermosetting resin varnish, the dried prepreg is used as a surface layer, a predetermined number of these surface layers and an intermediate layer are laminated, copper foil is layered, and heat and pressure molding is performed. A method for producing a characteristic thermosetting resin laminate.