JPH01189190A - Electric laminated bodies - Google Patents

Abstract

PURPOSE:To obtain electric laminated bodies characterized by low thermal expansion and low dielectric constant, by arranging a backup board for supporting a wiring board through an adhesive material layer on the rear surface of a thin film wiring board. CONSTITUTION:Laminated bodies are constituted with a thin film wiring board 1, in which circuits are formed on both upper and rear sources, prepreg 2, which serves as an adhesive material layer, and a backup board 3. The board 1 is formed with multilayered plate comprising the following plates: the plate in which metal foils are stuck on both surfaces of an insulating material layer comprising prepreg and the like; the plate having a conductor layer, which constitutes a circuit, in an insulating material layer; and the like.

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 resistance1
Improvement in dimensional stability, etc. is strongly desired. In response, new glasses with high SiO□ content such as Q glass, D glass, and S glass, organic fibers such as aromatic polyamides, or quartz glass fibers 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. For example, heat resistance and two-dimensional stability.

Electrical laminates and multilayer printing that use aromatic polyamide fiber cloth with excellent tensile properties, light weight, etc., which has been subjected to surface plasma treatment and impregnated with ordinary thermosetting resin, as part of the base material. Wiring boards have already been developed (JP-A-59-125690, JP-A-59-125689).
(See Japanese Patent Application Laid-open No. 125698/1983). Here, surface plasma treatment improves the adhesive strength of resin-impregnated aromatic polyamide fiber cloth, punching processing of laminates,
This is done to solve problems such as glabellar peeling that occurs during drilling.

[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 the thermal expansion coefficient of the reinforcing fiber. Therefore, by using fibers with low thermal expansion as described above for the base material, the thermal expansion in the XY force directions can be suppressed 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 the thermal expansion coefficient 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 through-hole plating made of copper, etc., causes cracks in the plating area due to repeated stress due to heat and humidity, leading to connection failure. be.

Furthermore, 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. .

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

[Means to solve the problem]

In order to solve the above problem 7, the present invention arranges a back-up 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, the backup board has the same structure as the insulating material layer in the thin wiring board.

[For production]

In both inventions described in claims 1 and 2, the thickness of the entire board required for the wiring board can be maintained as before by providing a backup board, so the thickness of the wiring board can be reduced accordingly. can. That is, it is possible to reduce the number of base materials, specifically the number of prepregs, required to constitute the wiring board.

Furthermore, in the invention as claimed in claim 2, by disposing a backup board (hereinafter referred to as a "balancer") having the same structure as the insulating material layer in the thin wiring board, the entire laminate is The configuration can be symmetrical in the thickness direction.

〔Example〕

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

FIGS. 1 and 2 show corresponding embodiments of the electrical laminate according to the invention as claimed in claims 1 and 2, respectively.

That is, the electrical laminate (schematic cross-sectional view) shown in FIG. Prepreg 2 and backup board 3 to serve as adhesive layer
FIG. 2 shows an electrical laminate in which the backup board 3 in FIG. 1 is a balancer 3'.

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. Such base materials include, for example, various aromatic polyamide fibers (aramid fibers),
Examples include woven fabrics, nonwoven fabrics, mats, and papers made of new glass fibers with high silicon dioxide content (for example, about 60 wt% or more) such as Q glass, D glass, and S glass, and quartz glass fibers. Its thickness is usually 1
A crane level is selected. Although the number of boards used is arbitrary, it goes without saying that the number can be kept smaller than that of conventional wiring boards. The above aramid fibers include the product names "Kevlar 29,49" and "Nomex".
(both manufactured by DuPont, handled by DuPont Far East Japan Branch), "Technora J" and "Conex"
(both made by Kijin@) etc. can be used. As mentioned above, it is preferable to use aramid fibers whose surfaces have been subjected to plasma treatment in order to improve interlayer adhesion. This is because the surface of the base material is roughened by the plasma treatment, and an anchoring effect can be expected, and 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, fluorine resin, silicone resin, yurya resin,
BT resin, polyimide resin, polybutadiene resin,
General products such as modified products of these resins can be used alone,
Or multiple types are used together. Impregnation of the base material with these resins, drying, etc. are carried out according to a normal prepreg manufacturing method.The insulating material layer in the thin wiring board 1 is formed by impregnating the base material with the resin. It is not limited to prepreg obtained by
For example, a heat-fusible plastic film having electrical insulation properties, heat resistance, etc. can also be used. Examples of such film materials include polyphenylene oxide,
Examples include polyphenylene sulfide, epoxy resin, polyimide resin, and the like.

As the adhesive layer for adhering the thin wiring board 1 and the backup board 3 (including the balancer 3') described below, the above-mentioned prepreg and heat-fusible plastic film can be used. Prepregs made of base materials such as natural fibers, synthetic fibers, or E-glass fibers may also be used. There are no particular limitations on the number of layers stacked. Note that the aramid fibers do not need to be subjected to plasma treatment.

The constituent elements of the backup board 3 are also preferably 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, but are not particularly limited. However, the structure of the balancer 3' must be the same as the insulating material layer of the thin wiring board 1,
Therefore, by paying attention to the structure of the adhesive layer, the structure of the entire electrical laminate can be made symmetrical in the thickness direction.

Note that as the base material, one having a thickness of about 0.1 tm or more can be used, and the aramid fibers do not need to 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 surface plasma-treated aromatic polyamide fiber cloth (Kevlar cloth manufactured by DuPont, whose surface was plasma-treated) with a thickness of 0.1 +n. It was impregnated in an amount of 50% by weight and dried to obtain a prepreg (hereinafter referred to as prepreg A).

* Composition of epoxy resin containing curing agent Next, a 0.2 tm thick aromatic polyamide fiber cloth (Kevlar cloth as above, non-plasma treated) was used as a base material, and prepreg was produced in the same manner as above. (This is called prepreg B). Furthermore, as a base material, the thickness is 0.
．． A prepreg was similarly produced using a 1 m glass cloth (this was referred to as prepreg C).

Two sheets of the obtained prepreg A are stacked, and both sides have a thickness of 0.
A laminate made of 0180 copper foil was sandwiched between metal plates, molding pressure was 50 kg/cflI, and molding temperature was 170°C.
Lamination molding was carried out for 100 minutes to obtain a metal foil-clad laminate having a thickness of 0.2 mm. After printing the through-hole reliability test pattern shown in Figure 3 on both sides of this laminate, through-holes are drilled at predetermined positions (according to the following conditions), and copper through-hole plating is applied to obtain a wiring board. (hereinafter referred to as wiring board A).

*Through-hole reliability test pattern Next, a laminate consisting of four sheets of prepreg B stacked on top of each other with release films on both sides was sandwiched between metal plates, and laminated and molded in the same manner as above. After molding, the release film was peeled off to obtain a 0.8-thick laminate (hereinafter referred to as a backup board).

Finally, a laminate (see Figure 1) in which a backup board is arranged on the back side of the wiring board A with two sheets of prepreg C interposed therebetween is sandwiched between metal plates, and this is laminated and molded in the same manner.
An electrical laminate having a thickness of 1.2 mm was obtained (hereinafter referred to as laminate X).

(Example 2) A prepreg was produced in the same manner as in Example 1 using a 0.1-thick fin aromatic polyamide fiber cloth (Kevlar cloth as above, non-plasma treated) as a base material (this was referred to as prepreg D). ). Two sheets of the obtained prepreg D were stacked, a release film was placed on both sides, and the sheets were sandwiched between metal plates. Laminate molding was then carried out under the same conditions to obtain a laminate with a thickness of 0.2 mm. (referred to as a balancer).

Next, the wiring board A, the four prepregs B, and the balancer were laminated in this order (see Fig. 2), and these were similarly laminated and molded to obtain an electrical laminate with a thickness of 1.2 mm (hereinafter referred to as (denoted as laminate Y).

(Comparative Example 1) A laminate made by stacking 12 sheets of prepreg A in the above example and placing copper foil with a thickness of 0.018 mm on both sides was sandwiched between metal plates, and laminated molding was performed in the same manner as in the example. A double-sided copper-clad laminate having a thickness of 1.2 fl was obtained. A test pattern similar to that of the example was printed on this and through holes were formed to obtain a wiring board.

The following performance tests were conducted on the obtained electrical laminates of Examples and wiring boards of Comparative Examples.

(a) Through-hole reliability test The three test specimens of Examples and Comparative Examples were immersed in 260°C oil for 10 seconds, 20°C water for 10 seconds, and 20°C trichlorethylene for 10 seconds. One cycle of thermal shock was applied, and the number of cycles until the through-hole part was disconnected was measured, and the through-hole reliability was determined.

(bl Coefficient of Thermal Expansion Thermal expansion coefficient in the X and Y directions (room temperature to 150°C) was measured using a duratometer for the three test specimens of Examples and Comparative Examples.
was measured.

(C) Warp and twist The warp and twist of the laminates X and Y of Examples were measured after lamination molding and after heating at 170° C. for 30 minutes. However, the sample size shall be 250 cranes in height and width.

The above results are shown in Table 1.

As shown in Table 1, it was found that in the electrical laminates of the Examples having a backup board or balancer, the through-hole reliability was significantly improved while maintaining the coefficient of thermal expansion. Further, in the laminate Y in which the backup board is a balancer, almost no warping or twisting occurs.

〔Effect of the invention〕

In the electrical laminate according to both inventions described in claim 1.2, the following common effects can be 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,
The amount of expensive plasma treatment required for the prepreg can be suppressed.

Furthermore, the electrical laminate according to the invention according to claim 2,
It also has the following effects:

■ 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]

1 and 2 are schematic cross-sectional views of an embodiment of the electrical laminate according to the present invention, and FIG. 3 shows a test pattern for evaluating through-hole reliability. . l...Thin wiring board 2...Prepreg (adhesive layer) 3...Backup board agent Patent attorney Takehiko Matsumoto March 1988 Modus operandi

Claims (2)

[Claims] (1) An electrical laminate, characterized in that 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. (2) A backup board for supporting the wiring board is disposed on the back surface of the thin wiring board having two or more conductor layers via an adhesive layer, and the backup board is
An electrical laminate having the same structure as the insulating material layer in the wiring board.