JPH05104675A - Metallic foil-plated laminate and manufacture thereof - Google Patents

Abstract

PURPOSE:To make a laminate suitable for the material of the printed wiring board for the surface mounting, while the breakage due to cooling and heating cycle does not occur on the interface between the fiber and the resin of the metallic foil-plated laminate of the base material of aromatic polyamide fiber. CONSTITUTION:The resin layer of small elastic modulus such as silicone rubber- modified epoxy resin is formed on the surface of the base material of aromatic polyamide fiber. The upper part of said material is impregnated with thermosetting resin such as epoxy resin and thus a laminate becoming a main body is obtained. In said laminate, base material is first impregnated with the resin of small elastic modulus and is dried, and then the prescribed number of the prepregs as a main body obtained by impregnating with thermo-setting resin and by drying them, are super imposed mutually, and further on its outside, copper foils are super-imposed and its forming is carried out under heating and pressurizing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil-clad laminate suitable for surface mounting printed wiring boards for chip components such as resistors and ICs, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, electronic components to be mounted on printed wiring boards have been rapidly shifting from leaded components to leadless chip components in order to reduce the size and weight of electronic equipment and increase the density. Is becoming mainstream. Against this background, in order to prevent cracks at the solder joints between the mounted leadless chip parts and the printed wiring due to cooling and heating cycles, the vertical and horizontal sides of the metal foil-clad laminate, which is the material of the printed wiring board, There is an increasing demand for making the coefficient of thermal expansion in the direction close to the coefficient of thermal expansion of leadless chip parts ((2 to 7) × 10 to ⁶ / ° C.). In order to meet this demand, metal foil-clad laminates using aromatic polyamide fiber cloth or aromatic polyamide fiber paper with a negative coefficient of thermal expansion as the base material impregnated with thermosetting resin are used for the heat treatment of leadless chip parts. It has been studied as a means of matching the expansion coefficient.

[0003]

The metal foil-clad laminate based on the above aromatic polyamide fiber is a thermosetting resin having a large positive coefficient of thermal expansion (for example, epoxy resin (80- 100) × 10 ~ ⁶ / ℃ movements expansion and contraction of), aromatic polyamide fibers with negative thermal expansion coefficient ((-
6 to -4) × 10 to ⁶ / ° C.) to achieve low thermal expansion as a metal foil-clad laminate. Therefore, due to the thermal shock caused by soldering when mounting components and the cooling / heating cycle of rising and falling of temperature during long-term use
The stress due to the difference in thermal expansion between the fiber and the resin is generated at the resin interface each time, and there is a risk of destruction such as peeling of the fiber-resin interface. The problem to be solved by the present invention is to prevent the fiber-resin interface of an aromatic polyamide fiber-based metal foil-clad laminate from being destroyed by a heat cycle. And it is to make it suitable as a material of the surface mounting printed wiring board.

[0004]

In order to solve the above-mentioned problems, a metal foil-clad laminate of an aromatic polyamide fiber base material according to the present invention has an interface between an aromatic polyamide fiber base material and a thermosetting resin. A resin layer having an elastic modulus smaller than that of the thermosetting resin is formed on all or part of the resin layer. Further, the manufacturing method of the metal foil-clad laminate according to the present invention,
In a method in which one or a plurality of prepregs obtained by impregnating and drying a thermosetting resin on an aromatic polyamide fiber base material are stacked, a metal foil is placed on the surface, and heat / pressure molding is performed to integrate the prepreg, A prepreg obtained by impregnating a fiber substrate with a resin having an elastic modulus smaller than that of the thermosetting resin and drying it, and then impregnating and drying the thermosetting resin is used. The resin having a small elastic modulus is, for example,
It is a silicone rubber modified resin.

[0005]

In general, the surface of the aromatic polyamide fiber is inactive, and the adhesive strength with the resin is lower than that of the glass fiber widely used as the base material of the metal foil-clad laminate.
Various fiber surface treatments have been investigated in order to increase the adhesive strength, but a treatment method having a high effect has not been found yet. Therefore, as described above, in the aromatic polyamide fiber-based metal foil-clad laminate, there is a risk that breakage such as peeling may occur at the fiber-resin interface due to the stress generated due to the difference in thermal expansion between the fiber and the resin. .. However, in the laminated board according to the present invention, since the resin layer having a smaller elastic modulus than the thermosetting resin is formed between the aromatic polyamide fiber and the thermosetting resin, this resin layer is a buffer material. By acting as a layer, the stress generated between the aromatic polyamide fiber and the thermosetting resin can be reduced, and the risk of breaking the interface can be eliminated.

[0006]

EXAMPLES In carrying out the present invention, a resin having a small elastic modulus is a resin having a lower cross-linking density at the time of curing than the thermosetting resin which is a main component. However, in order to enhance the effect, it is preferable to use a rubber-modified resin. Desirably, when a rubber modified resin is used, it is desirable to use a silicone rubber modified resin from the viewpoint of heat resistance. In addition, in use, sufficient consideration should be given to the adhesiveness with the thermosetting resin which is the main component. In the production of prepreg, an aromatic polyamide fiber base material is impregnated with a resin having a small elastic modulus and dried, and then a thermosetting resin as a main component is impregnated and dried. It is desirable that the small resin adhesion amount be 5 to 30 wt% at this stage. If the amount is small, the effect as the cushioning material layer is lowered, and if the amount is large, the cushioning effect is increased, and as a result, the expansion and contraction of the resin are less likely to be restrained by the base material, and the thermal expansion coefficient of the laminated plate is somewhat increased.

EXAMPLE A commercially available aromatic polyamide fiber cloth was impregnated with a silicone rubber-modified epoxy resin so as to have a resin adhesion amount of 15% by weight, dried, and then impregnated with a brominated bisphenol A type epoxy resin and dried, An aromatic polyamide fiber cloth prepreg having a resin adhesion amount of 50 wt% was prepared. Five plies of the obtained prepreg were stacked, a copper foil having a thickness of 35 μm was placed on the surface, sandwiched by a mirror plate, and heated and pressed by a conventional method to obtain a laminated plate having a thickness of 1.0 mm. The characteristics are shown in Table 1.

Comparative Example The aromatic polyamide fiber cloth used in the examples was impregnated with only the brominated bisphenol A type epoxy resin used in the examples, and dried to obtain an aromatic polyamide fiber cloth prepreg having a resin adhesion amount of 50 wt%. It was made. Thereafter, a laminated plate having a thickness of 1.0 mm was obtained in the same manner as in the examples. The characteristics are shown in Table 1.
Shown in.

[0009]

[Table 1]

(Note 1) It was floated in a solder bath at 288 ° C. for 3 minutes, and the occurrence of measling (fine peeling phenomenon between fiber and resin) was examined.

(Note 2) 30 minutes at -65 ° C and 3 minutes at 125 ° C
After 100 cycles of cooling and heating for 0 minutes, the occurrence of measling was examined.

[0012]

As is clear from Table 1, the aromatic polyamide fiber-based metal foil-clad laminate according to the present invention has the above-mentioned structure at the interface between the aromatic polyamide fiber-based material and the thermosetting resin as a main component. Since the resin layer having a smaller elastic modulus than the thermosetting resin is formed, the resin layer having a small elastic modulus acts as a buffer material layer between the aromatic polyamide fiber and the thermosetting resin,
Measling (fiber-shaped by heat shock and cold cycle
The phenomenon of minute peeling between resins is unlikely to occur, and the characteristics of low thermal expansion using an aromatic polyamide fiber base material are not impaired.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H05K 1/03 H 7011-4E // B29K 105: 06

Claims (4)

[Claims] 1. A metal foil-clad laminate in which a substrate is formed by impregnating an aromatic polyamide fiber base material with a thermosetting resin, and the whole or one of the interfaces between the aromatic polyamide fiber base material and the thermosetting resin is used. A metal foil-clad laminate, wherein a resin layer having an elastic modulus smaller than that of the thermosetting resin is formed in the portion. 2. The metal foil-clad laminate according to claim 1, wherein the resin having a small elastic modulus is a silicone rubber-modified resin. 3. A metal in which one or a plurality of prepregs obtained by impregnating and drying a thermosetting resin on an aromatic polyamide fiber substrate are stacked, a metal foil is placed on the surface thereof, and heat / pressure molding is performed to integrate them. In the production of a foil-clad laminate, a prepreg obtained by impregnating an aromatic polyamide fiber base material with a resin having a smaller elastic modulus than the thermosetting resin and drying the impregnated and dried thermosetting resin is used. A method for producing a metal foil-clad laminate, which comprises: 4. The method for producing a metal foil-clad laminate according to claim 3, wherein the resin having a small elastic modulus is a silicone rubber-modified resin.