JPH0745220B2 - Composite type laminated board for printed wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composite type laminate for a printed wiring board.

[Conventional technology]

The laminated plate or the copper clad laminated plate is manufactured by laminating a predetermined number of prepregs obtained by impregnating a substrate with a resin and drying, laminating a copper foil on the surface as necessary, and heating and pressing. In the field of printed wiring boards, which is the main application of copper-clad laminates, the requirements for printed wiring board performance have become more stringent with the progress of high-density automatic packaging technology. There is a stricter requirement for stable warpage and less twist.

[Problems to be Solved by the Invention] The cause of the warp / twist of the laminated plate is slightly different depending on the kind of the laminated plate, the manufacturing method and the kind of the material, but the following reason can be considered.

That is, (a) existence of tension difference in the warp direction and weft direction in the manufacturing process, (b) application of pressing pressure, (c) flow of matrix resin during pressing, and (d) temperature difference and linear expansion coefficient. Due to the difference in the amount of expansion or contraction between the base material and the matrix resin, stress and strain mainly act on the base fabric or the fabric and the non-woven fabric that are the stress carriers, and as a result, warp It is considered that twisting occurs, and in the laminated board according to the prior art, since the warp and the screw are large, the automatic device for providing the printed wiring board may be interrupted or inoperable.

The present inventor has found the following causes of warpage and twist in addition to the conventionally known causes. That is, if there is a cause of internal stress / strain in the woven fabric itself which is the base material of the laminated plate, stress from the outside due to the factors (a) to (d)
The strain will be added to the internal stress / strain of the fabric itself in a cohesive form, and as a result, a large stress / strain will appear, resulting in warpage / twisting of the laminate.To reduce this warpage / twisting, the fabric itself It is necessary to reduce the internal stress and strain of the.

[Means for solving problems]

An object of the present invention is to solve the above-mentioned problems of the prior art and to obtain a composite type laminate for a printed wiring board which has good surface smoothness and has little warp and twist. A composite type laminate for a printed wiring board which achieves the object of the present invention, a plurality of layers of non-woven fabric, a layer of fabric superposed on the layers of the non-woven fabric on both sides of the non-woven fabric layer, A non-woven fabric layer and a woven fabric layer, and a compound resin that integrates these layers, the woven fabric is made of glass fiber-based warp yarns and weft yarns, and the twist number of the glass fiber yarns is 0.5 to 2.0. t / 25 mm, and at least the warp yarn and the weft yarn are characterized in that S twist yarns and Z twist yarns are alternately arranged.

The glass fabric used for the base material of the laminated plate was previously the mainstream of the ply-twisted fabric, but now it is a price problem and the resin impregnation property of the woven fabric in the process of making the prepreg, which is one of the laminated plate manufacturing processes. Due to this problem, single yarn fabrics are becoming the mainstream. The single-yarn woven fabric is a woven fabric in which the yarns forming the woven fabric are single-twisted yarns that are sweet twisted (the number of twists is small). The yarn count range of Tex is 5 to 300, preferably 20 to 14
It is 0. No particular limitation is imposed on the shape, thickness, etc. of the filament constituting the yarn, as long as it does not impair the adhesiveness with the resin. Number of twists of thread is 0.5-2.0t / 25mm
Is. If the number of twists of the glass fiber yarn is less than 0.5 t (twist) / 25 mm, the yarn will not be bundled easily, so that good workability cannot be obtained during weaving and fuzz is likely to occur. Particularly, in the case of glass fiber yarn, the filament is broken by ironing and friction, and fuzzing is likely to occur. When a woven fabric made of fibers containing fluffy glass fibers on the surface is impregnated with a resin to form a laminated plate, the roughness of the laminated plate surface increases. In the case of a composite type laminated board for a printed wiring board, since the circuit width is narrowed and the wiring density is increased, the surface smoothness (surface roughness) is a problem of the order of several μm. Therefore, a glass fiber woven fabric having fluffs on the surface can be used as a laminate for FRP in which surface roughness is not a serious problem, but cannot be used for a printed wiring board. On the other hand, when the twist number of the glass fiber yarn is more than 2.0 t (twist) / 25 mm, the handleability of the yarn is deteriorated and the weaving property is adversely affected. In the case of a glass fiber woven fabric for printed wiring boards, a single twisted yarn is used because of problems such as resin impregnation (that is, the glass fiber woven fabric of the single twisted yarn is well impregnated with the resin). Therefore, if the number of twists is greater than 2.0 t (twists) / 25 mm, the yarns may become entangled when the running yarns stop, which may cause cutting and fluffing.

Regarding the composition of the fabric, the shot density is 20-80 pieces / 25 mm,
The weight of the woven fabric is 30 to 400 g / m ^2, preferably 50 to 350 g / m ² , and the weave of the woven fabric may be plain weave, satin weave, twill weave and the like.

Generally, the woven fabric used as the base material of the laminated plate is treated with various treatment agents in order to improve the adhesion with the matrix resin, but the kind and the coating amount thereof are not particularly limited.

Further, the present invention is not particularly limited in terms of uniformity of the woven fabric and warp and weft warp, etc., and if these are improved, the effect of the present invention is further improved.

The thickness of the laminate targeted by the present invention is 0.1 to 5.0 mm, and the effect of the present invention is most prominently 1.0 to 3.0.
It is a laminated board with a thickness of mm. Although the effect of the present invention is theoretically conceivable in the laminated plate outside the thickness range of 0.1 to 5.0 mm, the effect of the constitution of the present invention does not actually occur.

As the matrix resin of the laminate, thermosetting resins such as epoxy resin, phenol resin, melamine resin, unsaturated polyester resin, silicone resin, polyimide resin, and thermoplastic resin such as fluorine resin can be used.
Alternatively, a plurality of these resins may be mixed and used as a matrix resin.

The laminated plate of the present invention, the woven fabric having the above-mentioned structure is treated with a matrix resin by a conventionally known method to form a prepreg,
It is obtained by laminating a plurality of these prepregs, laminating metal foils on both sides or one side as necessary, and heating and pressing.

Furthermore, the composite type laminate of the present invention uses the woven fabric and the nonwoven fabric in combination as a substrate, impregnates these with the resin to form a prepreg, and laminates a plurality of the prepregs, followed by heating. Obtained by pressing.

[Action]

Factors that cause warping and twisting of the laminated plate include, as described above, the gist that occurs during molding and the factor that the base material itself has. The warp / twisting of the base material has been conventionally considered to be the weft bending of the woven fabric. The inventor of the present invention has found that, in addition to the above, there are factors of warpage and twist in the structure itself of the woven fabric. For example, in the case of a glass single yarn woven fabric used for a laminated plate, the yarn is a sweet twisted single-twisted yarn, and the twisting is uneven due to the heat setting effect in the deoiling process during the manufacturing of the laminated plate and the set effect in the subsequent surface treatment process. Since the strain due to the woven fabric is temporarily suppressed, it is considered that the woven fabric itself did not notice the twist deviation as a factor of warping or twisting. In the process of studying the problem of warpage / twist of a laminated plate, the present inventor noticed the twist deviation as a factor of warpage / twist of the woven fabric itself, and at least with respect to at least the warp and the weft of the woven fabric, adjacent two By making the twist directions of the two yarns opposite to each other, that is, S twist yarn and Z
It has been found that the warp and twist of the laminated plate are reduced by alternately disposing the twisted yarns. Further, the present inventor has found that in the case of a single yarn woven fabric used for a laminated plate, the effect of the above temporary pressing is lost in the process of being impregnated with a resin and being heated / pressurized, and the warp / twist factor generated at the time of molding is caused. It was found that warpage and twisting occur due to the interaction of.

Therefore, at least the twist direction of the warp is alternately S twist and Z twist.
By twisting, the strain inherent in the woven fabric due to uneven twist is reduced, and as a result, the warpage and twist of the laminate using this woven fabric as a substrate are reduced.

In the case of the conventional woven fabrics used for laminated boards, the weft yarns are twisted in one direction, which is a factor of distortion of the entire fabric, so that not only the warp yarns but also the weft yarns are alternately twisted in opposite directions. It is preferable that In recent air jet machines, weft yarns can be driven using yarns of different twists, so that in addition to warp yarns, S twists and Z twists are alternately arranged in addition to warp yarns. be able to. As a result, warpage and twist of the laminated plate can be further reduced.

〔Example〕

-Example 1-Two types of glass fabrics of the MIL standard 7628 type were used as the glass fabrics of the composite type laminated board for the printed wiring board of the present invention (that is, two types of the one having the constitution of the present invention and the comparative example). Using the S-twisted and Z-twisted yarns alternately for each warp of each glass fabric and 0.5-
Weaving using warp and weft with twist number of 2.0t / 25mm,
The glass fibers shown in Table 1 were manufactured by deoiling and surface treatment according to known methods. As a comparative example, the same 7628 type glass woven fabric was woven according to the prior art by using only Z-twisted yarn, and the glass fibers shown in Table 1 were similarly produced.

A prepreg was prepared by a known method using each of the two types of glass fibers shown in Table 1 and an epoxy resin (FR-4 type).

Next, a laminate (usually referred to as a composite laminate) was prepared by a known method by combining the prepreg of the glass fiber and the prepreg using glass paper, that is, a glass nonwoven fabric. The manufacturing process was as follows. Use glass paper of 100 g / m ² , make glass paper prepreg with 67% resin amount with this and epoxy resin (FR-4 type), while use glass fabric of 211 g / m ² , With this and epoxy resin (FR-4 type), a glass fabric prepreg is made with a resin amount of 42%, four glass paper prepregs are stacked, and one glass fabric prepreg is placed on each of the upper and lower surfaces, and further on both sides. Layer 18 μm thick copper foil, pressure 30 kg / cm ² , temperature
Two kinds of laminated plates (composite laminated plates) were made by holding at 170 ° C for 90 minutes. The dimensions of this laminate were 45 cm × 45 cm and the thickness was 1.6 mm.

A laminate according to this embodiment of the present invention and a laminate according to a comparative example are
Warpage and twist were measured by the test method specified in JIS C 6481.5.4.3. The results are shown in Table 2.

Sample size: 450 mm x 450 mm with double-sided foil * Heating condition: After press molding, heating at 170 ° C for 30 minutes As apparent from Table 2, in the composite type laminated board for the printed wiring board according to the embodiment of the present invention, It was confirmed that warpage and twist were significantly reduced as compared with the composite laminate for a conventional printed wiring board which is a comparative example.

The 7628 type glass fabric used in this example is ECG 75 1/0 yarn and has a monofilament diameter of 9 μm.
It is a bundle of 400 glass fibers of m. Therefore, when the filaments are cut and fluffed, the glass woven fabric made from the filaments is impregnated with a resin to produce a prepreg, and the fluffed portions become resin pools. The remaining small protrusions are said to be defective as a composite type laminate for a printed wiring board, but since the twist number of 0.5-2.0t / 25mm is used in this embodiment, the glass fiber yarn is used. A composite-type laminate for printed wiring boards, which has no fluffing, has good surface smoothness, and has little warp and twist, could be manufactured.

〔effect〕

In the composite type laminated board for a printed wiring board of the present invention, since the bias in the twisting direction is eliminated with respect to at least the warp of the base fabric made of the glass fiber yarn, the internal stress conventionally present in the base material itself is reduced. However, the laminated plate made by using this base fabric can significantly reduce the warpage and the twist as compared with the laminated plate according to the prior art. As a result, this laminated board was processed as a printed wiring board by a high-density automatic mounting device without trouble. Further, the laminated plate of the present invention has a twist number of the glass fiber yarn, which is a constituent yarn of the base fabric used, of 0.5-2.0 t (times) / 25 mm.
As a result, a laminated board for a printed wiring board having good surface smoothness could be manufactured.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H05K 1/03 7011-4E

Claims (3)

[Claims] 1. A plurality of superposed layers of non-woven fabric, a layer of woven fabric superposed on the non-woven fabric layer on both sides of the non-woven fabric layer, the non-woven fabric layer and the woven fabric layer being impregnated with these layers And a synthetic resin in which the woven fabric is made of glass fiber-based warp yarns and weft yarns, and the twist number of the glass fiber yarns is 0.5-2.0t / 25mm, and at least the warp yarns and the weft yarns are formed. Is a composite type laminated board for a printed wiring board in which S twist yarns and Z twist yarns are alternately arranged. 2. A composite-type laminate according to claim 1, wherein the S twist yarn and the Z twist yarn constituting the warp of the woven fabric have the same number of twists. 3. A copper foil is bonded on both sides or one side,
A composite-type laminate according to claim 1.