JPH08158288A - Laminated board and aromatic polyamide fiber paper for base material of laminated board - Google Patents

Abstract

PURPOSE: To obtain a laminate board preventing the generation of warpage and strain due to the heat of a solder, etc., by adding fibrillated cellulose fibers to aromatic polyamide fibers, processing the mixture into aromatic polyamide fiber paper, impregnating the paper with a thermosetting resin, and subsequently heating and molding the treated paper. CONSTITUTION: Aromatic polyamide fibers are mixed with 5-50wt.%, preferably <=25wt.%, of fibrillated cellulose fibers, and further with a resin binder, and subsequently processed into aromatic polyamide fiber paper prevented in fuzz. The fiber paper is impregnated with a thermosetting resin such as a brominated bisphenol A type epoxy resin to form a prepreg. The prescribed number of the formed prepregs are laminated to each other into a laminated board in which the prepregs are partially or wholly used. Or further, a metal foil such as a copper foil is integrally laminated to the surface of the laminated board to form a metal foil-lined laminate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board or a metal foil-clad laminated board suitable for an insulating substrate of a printed wiring board on which leadless chip parts such as resistors and ICs are surface-mounted, and an aromatic polyamide for a laminated board substrate. It relates to textile paper.

[0002]

2. Description of the Related Art In recent years, a technique of mounting electronic components on a printed wiring board by a surface mounting method has become mainstream in view of downsizing, weight reduction and density increase of electronic devices. Against this background, a laminated board which is an insulating board of a printed wiring board is required to have a small thermal expansion coefficient. This is because the coefficient of thermal expansion of the insulating board of the printed wiring board in the vertical and horizontal directions is the coefficient of thermal expansion (2 to 7
(* 10 to ⁶ / ° C.) As much as possible so that cracks due to repeated cooling / heating cycles do not occur at the solder joints of the leadless chip component and the printed wiring. In response to the above requirements, a laminated sheet or a metal foil-clad sheet made of aromatic polyamide fiber paper having a negative coefficient of thermal expansion as a base material, impregnated with a thermosetting resin (matrix resin), dried, and heat-pressed Laminates have been considered.

[0003]

The above-mentioned conventional laminated plate is
The base material is aromatic polyamide fiber paper in which aromatic polyamide fibers are bonded together only with a resin binder. In the aromatic polyamide fiber paper having such a constitution, the elastic modulus thereof is drastically lowered in a region above the glass transition temperature (about 110 ° C.) of the resin binder. Therefore, as long as such an aromatic polyamide fiber paper is used as a base material, the aromatic polyamide fiber paper may be deformed unevenly under the influence of the flow and pressure of the melted matrix resin in the heat and pressure molding step of the laminate. become. This is because the melting temperature range of the matrix resin is generally 80 ° C. to 140 ° C., which exceeds the glass transition temperature of the resin binder. A printed wiring board using a laminated board whose base material is deformed unevenly as an insulating board may be warped or twisted. Further, the aromatic polyamide fiber paper is a nonwoven fabric similar to the glass fiber nonwoven fabric used as the base material of the composite laminate. Therefore, when a leadless chip component is surface-mounted on a printed wiring board using an aromatic polyamide fiber paper substrate laminate as an insulating substrate, if high heat is applied by a reflow device or the like, the entire substrate uniformly expands or contracts. Instead, it shows non-uniform behavior such as stretching at some parts and shrinking at some parts. Due to such behavior, the printed wiring board may be warped or twisted.
The problem to be solved by the present invention is caused by a laminated board having an aromatic polyamide fiber paper as a base material, due to a flow of matrix resin at the time of heat and pressure molding and heat of soldering at the time of mounting leadless chip parts. To avoid warping or twisting.

[0004]

In order to solve the above problems, the aromatic polyamide fiber paper for a laminate substrate according to the present invention is a mixed paper of aromatic polyamide fiber and fibrillated cellulose fiber, It is characterized in that the content of the cellulose fibers is 5 to 50% by weight. The content of fibrillated cellulose fibers is preferably 25% by weight
It is the following. A resin binder may be contained in these laminated plate base materials. The laminated sheet according to the present invention is a laminated sheet obtained by heating and pressing a sheet-shaped substrate impregnated with a thermosetting resin, wherein a part or all of the sheet-shaped substrate is the aromatic polyamide fiber paper. It is characterized by being. The laminated plate according to the present invention may have a metal foil integrated on the surface.

[0005]

In the aromatic polyamide fiber paper for a laminated board substrate according to the present invention, the fibrillated cellulose fibers are entangled with the aromatic polyamide fibers and exhibit the effect of a binder. And, cellulose fiber has little temperature dependence of elastic modulus,
Aromatic polyamide fiber paper using this as a binder maintains a high elastic modulus even at high temperatures. Therefore, by using this as a base material, it is less likely to be affected by the flow and pressure of the matrix resin melted in the base material in the heating and pressure molding step of the laminated plate. Since it is possible to reduce the uneven deformation of the base material in the heating and pressure molding step, it is possible to suppress the occurrence of warpage and twist of the laminated plate due to this. In addition, since the elastic modulus of the base material does not decrease even at high temperatures, a printed wiring board that uses a laminated board using the base material as an insulating substrate is highly susceptible to soldering when mounting leadless chip components. Since the expansion and contraction of the insulating substrate due to heat can be reduced, it is possible to suppress the occurrence of warpage and twist due to this. However, if the content of the cellulose fibers is less than 5% by weight, the strength of bonding the aromatic polyamide fibers to each other becomes low, so that the warpage and the twist cannot be sufficiently suppressed.
On the other hand, when the content of the cellulose fibers exceeds 50% by weight, the moisture resistance of the cellulose fibers causes a problem of poor moisture insulation and heat resistance of the laminate. Therefore, the content of the cellulose fibers is 5 to 50% by weight. Must be in the range.

The aromatic polyamide fiber paper for a laminated board base material according to the present invention containing a resin binder is a prepreg (thermosetting on a base material when the resin binder suppresses fiber fluffing to produce a laminated board. Of dust from a resin impregnated and dried).

[0007]

【Example】

Example 1 A blending of 95% by weight of aromatic polyamide fiber and 5% by weight of fibrillated cellulose fiber was made into a paper, and the unit weight was 60 g.
An aromatic polyamide fiber paper of / m ² was obtained. Using this aromatic polyamide fiber paper as a base material, brominated bisphenol A type epoxy resin varnish (matrix resin) was impregnated and dried to prepare a prepreg having a resin adhesion amount of 50% by weight. 5 plies of the obtained prepreg, 1 on each side
Place a copper foil of 8 μm and heat and pressure mold 0.5 mm
A thick copper clad laminate was obtained.

Example 2 A copper-clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that 80% by weight of aromatic polyamide fiber and 20% by weight of fibrillated cellulose fiber were blended to produce paper. .

Example 3 A copper clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that 70% by weight of aromatic polyamide fiber and 30% by weight of fibrillated cellulose fiber were blended to produce a paper. .

Example 4 A copper-clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that 50% by weight of aromatic polyamide fiber and 50% by weight of fibrillated cellulose fiber were blended to produce a paper. .

Example 5 The procedure of Example 2 was repeated except that 5% by weight of a water-soluble epoxy binder (glass transition temperature: 110 ° C.) was adhered to the aromatic polyamide fiber paper of Example 2, and a thickness of 0.5 mm was used. A copper-clad laminate was obtained. The prepreg obtained by impregnating and drying a brominated bisphenol A type epoxy resin varnish with an aromatic polyamide fiber paper as a base material in this example has less dust during handling, and has a dent on the copper foil surface of a molded copper-clad laminate. It was confirmed that defects could be reduced.

Example 6 The procedure of Example 2 was repeated except that 10% by weight of a water-soluble epoxy binder (glass transition temperature: 110 ° C.) was adhered to the aromatic polyamide fiber paper of Example 2, and a thickness of 0.5 mm was used. A copper-clad laminate was obtained. It was confirmed that the copper-clad laminate of this example can also reduce dent defects as in Example 5. It is suitable that the amount of the resin binder attached is up to about 15% by weight.

Comparative Example 1 A copper-clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that 97% by weight of aromatic polyamide fiber and 3% by weight of fibrillated cellulose fiber were blended for papermaking. .

Comparative Example 2 A copper-clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that 45% by weight of aromatic polyamide fiber and 55% by weight of fibrillated cellulose fiber were blended to produce paper. .

Conventional Example Aromatic polyamide fiber paper (unit weight 60 g / m ² ) prepared by paper-making only aromatic polyamide fiber and adhering 15% by weight of water-soluble epoxy binder (glass transition temperature: 110 ° C.).
Using as the base material, a copper-clad laminate having a thickness of 0.5 mm was obtained in the same manner as in Example 1.

Table 1 shows the warpage, moisture resistant insulation, solder heat resistance, and coefficient of thermal expansion of the copper clad laminates of Examples 1 to 6, Comparative Examples 1 and 2, and the conventional example. The measurement conditions and evaluation methods for each characteristic are as follows. Warpage: The amount of uplift from the flat surface of the four corners of the sample (8 points on the front and back) was measured and the maximum value was adopted. "War after molding"
Is a laminated plate (500 mm x 500 m after heat and pressure molding)
warp of m). "Warp after component mounting process" is for sample (50 mm
Warp after subjecting (70 mm) to reflow treatment at a maximum temperature of 230 ° C. Moisture resistance: Measure insulation resistance after pressure cooker treatment for 6 hours. Solder heat resistance: The time required for blistering to occur on the surface of a normal laminated plate floated in a solder bath at 300 ° C. Thermal expansion coefficient: Measure the vertical direction of the substrate.

[0017]

[Table 1]

In the above embodiments, the laminated board using only the aromatic polyamide fiber paper as the base material has been described, but it can be used in combination with other base materials such as woven glass fiber cloth.

[0019]

As described above, the laminated sheet or the metal foil-clad laminated sheet based on the aromatic polyamide fiber paper according to the present invention is not warped without damaging the basic characteristics of the laminated sheet shown in Table 1. The twist can be reduced. When the content of the fibrillated cellulose fibers is preferably 30% by weight or less, more preferably 25% by weight or less, the overall characteristics can be maintained in a good balance. Also,
Since the aromatic polyamide fiber paper according to the present invention containing the resin binder generates less dust, it is advantageous in reducing dent defects due to dust in forming a laminate.

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Claims (5)

[Claims] 1. A mixed paper of aromatic polyamide fibers and fibrillated cellulose fibers, wherein the content of the cellulose fibers is 5 to 50% by weight. . 2. The aromatic polyamide fiber paper for a laminated board substrate according to claim 1, wherein the content of the fibrillated cellulose fibers is 25% by weight or less. 3. The aromatic polyamide fiber paper for a laminated board substrate according to claim 1, which contains a resin binder that bonds the fibers together. 4. A laminated plate obtained by heating and pressing a sheet-shaped base material impregnated with a thermosetting resin, wherein part or all of the sheet-shaped base material is defined in any one of claims 1 to 3. A laminated board characterized by being an aromatic polyamide fiber paper. 5. The metal foil is integrated on the surface.
The laminate described.