JPH01189987A - Electrical laminate - Google Patents

Abstract

PURPOSE:To improve finish at the time of cutting by composing at least part of a bonding material layer of a prepreg and containing a nonwoven base material such as a nonwoven fabric, paper, etc. as a base material in at least one part of the prepreg. CONSTITUTION:An electrical laminate is constituted of a thin wiring board 1, on both the surface and the rear of which circuits are formed, prepregs 2 as bonding material layers and a backup board 3. Nonwoven fabric base materials are used as base materials in at least one parts of the prepregs 2 organizing the bonding material layers, thus inhibiting the generation of a hachure, then increasing the speed of cutting and largely improving cutting workability. Since constitution having the backup board 3 is shaped, the thickness of the wiring board 1 is thinned, thus relatively reducing the quantity of thermal expansion, then maintaining reliability on a through-hole. Accordingly, superior cutting workability is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrical laminate used in electronic equipment and the like.

[Conventional technology]

In recent years, electronic devices have become increasingly smaller, thinner, lighter, and more multifunctional, and the parts used are rapidly becoming denser and more sophisticated. Correspondingly, requirements for laminates used as materials for printed wiring boards constituting these electronic devices are becoming increasingly strict.

Specifically, high-density wiring on printed wiring boards.

Due to the need for surface mounting and high-speed signal transmission, electrical properties such as insulation properties and dielectric properties and heat resistance8
Improvement in dimensional stability, etc. is strongly desired. In response to this, new glasses with high 3i0* content such as Q glass, D glass, and S glass, organic fibers such as aromatic polyamide, or quartz glass fibers, etc. are used as substrate materials to achieve low thermal expansion. Attempts have been made to produce laminates with low dielectric constants and low dielectric constants. As the -ring, for example, heat resistance 0
An electrical laminate that uses aromatic polyamide fiber cloth, which has excellent dimensional stability, tensile properties, and light weight, as part of the base material, by subjecting it to surface plasma treatment and impregnating it with a normal thermosetting resin. Boards and multilayer printed wiring boards have already been developed (Japanese Unexamined Patent Publications No. 125690/1983;
125689, Japanese Patent Application Laid-Open No. 125698), here, the surface plasma treatment improves the adhesive strength of the resin-impregnated aromatic polyamide fiber cloth and reduces the peeling between the eyebrows that occurs during punching and drilling of the laminate. This is done to solve problems such as

[Problem to be solved by the invention]

Incidentally, the thermal expansion coefficient of the substrate differs greatly in the XY force direction and the Z direction. As is clear from the coefficient calculation formula, the thermal expansion in the XY force direction is largely contributed to by the thermal expansion coefficient of the reinforcing fibers. Therefore, by using the above-mentioned low thermal expansion fibers as a base material, , this X
It is possible to suppress the thermal expansion in the Y force direction to a low level. On the other hand, the thermal expansion in the Z direction is greatly influenced by the thermal expansion coefficient of the impregnated resin and the amount of resin, so the problem of thermal expansion in the thickness direction remains unresolved. This is a factor that reduces the reliability of through-hole connections. In other words, the characteristic difference between the coefficient of thermal expansion in the thickness direction of the base material and that of the through-hole plating material such as copper causes cracks to occur in the plating part due to repeated stress due to heat and humidity, leading to connection failure. It is.

On the other hand, as mentioned above, plasma treatment of aromatic polyamide fibers is an important process for improving interlayer adhesion and ensuring through-hole reliability, but there is also the problem that the treatment cost is high. .

Furthermore, the aromatic polyamide fiber cloth that is normally used as a base material has the disadvantage of poor cuttability, which causes fuzz to occur during cutting, resulting in a poor finish when cutting the outer mold. There has been a strong desire to improve this point in prepregs that use material cloth.

In view of the above circumstances, it is an object of the present invention to provide a low thermal expansion, low dielectric constant electrical laminate that can overcome these problems.

[Means to solve the problem]

In order to solve the above-mentioned problem, the present invention arranges a backup board for supporting the wiring board on the back surface of a thin wiring board having two or more conductor layers via an adhesive layer, Furthermore, at least a portion of the adhesive layer is made of prepreg, and at least a portion of the prepreg includes a nonwoven substrate such as nonwoven fabric or paper.

[For production]

In the electrical laminate according to the present invention, the required thickness of the entire laminate is covered by the provision of a supporting backup board. Therefore, the thickness of the wiring board can be reduced while maintaining the thickness of the entire laminate as before. That is, a base material required to constitute a wiring board.

Specifically, the number of prepreg sheets can be reduced.

Furthermore, as the above-mentioned backup board, one (balancer) consisting of the same structure as the insulating material layer in the thin wiring board.
By disposing the adhesive layer and paying attention to the structure of the adhesive layer, the structure of the entire laminate can be made symmetrical in the thickness direction.

Furthermore, since the base material of the prepreg constituting the adhesive layer includes a nonwoven base material such as a nonwoven fabric or paper, good cutting workability can be obtained even when a thick base material is used.

〔Example〕

Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings.

Both FIG. 1 and FIG. 2 each show an embodiment of the electrical laminate according to the present invention. The electrical laminate (schematic cross-sectional view) shown in Figure 1 consists of a thin wiring board 1. It is composed of a prepreg 2 serving as an adhesive layer and a backup board (including a balancer) 3, and the prepreg 2 is made of a nonwoven base material. FIG. 2 shows an electrical laminate (schematic sectional view) in which a woven fabric base material prepreg 2' is used in combination with the prepreg 2 as the prepreg constituting the adhesive layer.

The thin wiring board 1 is equipped with two or more conductor layers, and for example, a metal foil such as copper, aluminum, or nickel is pasted on both sides of an insulating material layer made of prepreg or the like, or is coated by plating or the like. A double-sided board formed with the above metal layer, or a circuit inside the insulating material layer (inner layer circuit)
It consists of a multilayer board (not shown) having conductor layers. Of these conductor layers, the layer that will eventually be placed on the surface of the laminate is optional, but it is recommended to form a predetermined circuit in advance as necessary for the other conductor layers and connect them through through holes. .

As the base material constituting the prepreg for the thin wiring board 1, it is preferable to use a material having the characteristics of a low coefficient of thermal expansion and a low dielectric constant.As such a base material, for example, various aromatic polyamides are used. fiber (aramid fiber),
Examples include new glass fibers with a high silicon dioxide content (for example, about 60 wt% or more) such as Q glass, D glass, and S glass, woven fabrics, nonwoven fabrics, cloaks, and papers made of quartz glass fibers and the like. The number of sheets to be used is arbitrary, but it goes without saying that the number can be kept small compared to conventional wiring boards.The above aramid fibers are manufactured by the product names "Keplar 29.49J and R Nomex" (both manufactured by DuPont). , handled by DuPont Far East Japan Branch), ``Technora'' and ``Conex J'' (both manufactured by Kijin ■) can be used.As mentioned above, these aramid fibers are coated with surface plasma to improve interlayer adhesion. It is preferable to use a treated material because the surface of the base material is roughened by plasma treatment, and an anchoring effect can be expected.
The treatment method is not particularly limited, such as ordinary dry treatment.

The thermosetting resin to be impregnated into the base material is not particularly limited, and may include phenol resin, cresol resin, epoxy resin, and unsaturated polyester resin.

Melamine resin, fluororesin, silicone resin, yurya resin,
BT resin, polyimide resin, polybutadiene resin,
Common things such as modified products of these resins alone,
Or multiple types are used together. Impregnation of the resin into the base material, drying, etc. are performed according to a normal prepreg manufacturing method.

The material constituting the insulating material layer in the thin wiring board 1 is not limited to the prepreg obtained by impregnating the base material with the resin, and includes, for example, a prepreg having electrical insulation properties, heat resistance, etc. Weldable plastic films can also be used. Examples of such film materials include polyphenylene oxide, polyphenylene sulfide, epoxy resin, polyimide resin, and the like.

The adhesive layer for adhering the thin wiring board 1 and the backup board 3 described below can be made of the above-mentioned prepreg, heat-fusible plastic film, etc. In addition, conventionally commonly used natural fibers can be used. A prepreg made of a base material such as fiber, synthetic fiber, or E-glass fiber may be used, provided that at least a portion of the prepreg 2 is made of a nonwoven base material such as nonwoven fabric or paper. The number and structure of these laminated sheets are not particularly limited, but for example, when the nonwoven base material prepreg 2 and the woven fabric base material prepreg 2' are used together, the second
As shown in the figure, it is preferable that the combined structure be symmetrical in the thickness direction, since this can eliminate warping and twisting of the entire laminate. Note that the constituent elements of the bank-up board 3, which do not require plasma treatment on the aramid fibers, are made of a base material with low thermal expansion and low dielectric constant, similar to those constituting the insulating material layer of the thin wiring board 1. It is preferable that the configuration be the same as that of the insulating material layer of the thin wiring board 1 as a balancer, and the configuration of the adhesive layer as described above should also be taken into consideration. For example, the structure of the entire electrical laminate can be made symmetrical in the thickness direction. Note that the aramid fibers may not be subjected to plasma treatment.

Next, more specific examples and comparative examples will be described.

(Example 1) A curing agent-containing epoxy resin (the composition of which is shown below) was applied to a 0.1-thick surface plasma-treated aromatic polyamide fiber cloth (the surface of Duposis Kevlar cloth was plasma-treated). It was impregnated to a concentration of 50% by weight and dried to obtain a prepreg (hereinafter referred to as prepreg A).
.

*Composition of hardening agent-containing epoxy resin Next, the same hardening agent-containing epoxy resin as above was used as the impregnating resin, and a 0.1u thick aromatic polyamide fiber cloth (same Kevlar cloth, not plasma treated) was used as the base material. prepared prepreg (this is referred to as prepreg B), and
Prepregs (referred to as Prepreg C) were prepared in the same manner using an aromatic polyamide fiber nonwoven fabric (Kevlar cloth as above, untreated with plasma) having a thickness of 0.2 mm as a base material.

Two sheets of the obtained prepreg A are stacked, and both sides have a thickness of 0.
A laminate consisting of 0.18 m of copper foil was sandwiched between metal plates and laminated for 10 minutes at a molding pressure of 50 kg/cd and a molding temperature of 170°C to obtain a metal foil-clad laminate with a thickness of 0.2 fi. Ta. A circuit board was formed on both sides of this laminate to obtain a wiring board.

Next, a laminate in which two sheets of prepreg B were stacked and release films were placed on both sides was sandwiched between metal plates, and lamination molding was performed in the same manner as described above. After molding, the release film was peeled off to obtain a backup board with a thickness of 0.2 mvs.

Finally, as shown in FIG. 1, the bank-up board 3 is arranged on the back side of the wiring board 1 through four prepregs C (2 in the figure), and this is sandwiched between metal plates. An electrical laminate having a thickness of 1°211 mm was obtained by lamination molding (hereinafter referred to as laminate X).

(Example 2) Aromatic polyamide fiber cloth with a thickness of 0.2 M (
A prepreg was prepared in the same manner as above using the same Kevlar cloth (not plasma treated) (this was prepared using prepreg D
).

As shown in Fig. 2, two sheets of the above prepreg C (2 in the figure) are stacked, and the obtained prepreg D (2'
), and further laminated the wiring board 1 on one side and the backup board 3 on the other side, and laminated and molded them in the same manner to obtain an electrical laminate with a thickness of 1.2 mm. (
(hereinafter referred to as laminate Y).

(Comparative Example 1) As shown in Fig. 3, four sheets of the prepreg D (2') are stacked, the wiring board l is laminated on one side, and the backup board 3 is laminated on the other side, and these are similarly molded. and thickness 1
．． An electrical laminate of two cranes was obtained (hereinafter referred to as laminate Z).
.

The obtained electrical laminate x-2 was cut with a diamond cutter, and the appearance of the cut surface (presence or absence of fuzz) and cutting speed were evaluated.

The above results are shown in Table 1.

As shown in Table 1, it was found that the laminates of the examples using prepreg with a nonwoven fabric as the base material suppressed the occurrence of fluff, and also had faster cutting speeds and improved workability. .

〔Effect of the invention〕

In the electrical laminate according to the present invention, since a nonwoven base material is used as the base material for at least a part of the prepreg constituting the adhesive layer, generation of fluff is suppressed and cutting speed is improved. The cutting processability has been greatly improved. Furthermore, since the configuration includes a backup board, the following effects are also obtained.

- Since the thickness of the wiring board becomes thinner, the amount of thermal expansion in the Z direction of that part becomes relatively small, and through-hole reliability can be maintained.

■ Reduce the number of prepregs that make up the wiring board,
Costs can be reduced by suppressing the amount of expensive plasma treatment required for the prepreg.

■ By making the overall structure of the electrical laminate symmetrical in the thickness direction, the overall balance can be ensured and the laminate will not warp or twist.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic sectional views showing one embodiment of the electrical laminate according to the present invention, and FIG. 3 is a schematic sectional view showing a comparative example of the electrical laminate described above. l... Thin wiring board 2... Prepreg (adhesive layer) 3... Backup board agent Patent attorney Takehiko Matsumoto Figure 1 Figure 2 2222222222nini22 ? 2 Figure 3 Procedural Amendment (0-1, Incident Indication 1985 Tokuhi Division No. 015168 Address 1048 Kadoma, Kadoma City, Osaka Prefecture Name)
Name (583) Representative of Matsushita Electric Works Co., Ltd. Between and rjJO,
Insert r, 149J. ■ On page 8 of the specification, lines 6 to 7, it is stated that “the surface of the base material is
...can be expected," was corrected to read, "impurities on the surface will be removed and the adhesion to the resin will improve."

Claims (1)

[Claims] (1) An electrical laminate in which a backup board for supporting the wiring board is disposed on the back surface of a thin wiring board having two or more conductor layers via an adhesive layer, the adhesive At least a part of the material layer is composed of prepreg,
An electrical laminate characterized in that a nonwoven base material is used as a base material for at least a portion of the prepreg.