Chemical apparatus and process disinfecting – deodorizing – preser – With safety feature
Patent
1994-11-29
1997-06-17
Weisberger, Richard
Chemical apparatus and process disinfecting, deodorizing, preser
With safety feature
428156, 428213, 428402, 428901, 422136, 422180, B32B 516
Patent
active
056395442
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a resin-impregnated fabric sheet comprising a fabric sheet in which poly-p-phenylene sulfide resin is impregnated. More particularly, the present invention relates to a resin-impregnated fabric sheet having excellent heat resistance, thermal dimensional stability, high frequency characteristics, mechanical properties and the like, which is suited for circuit boards having small thickness.
BACKGROUND ART
In the fields of electricity and electronics, to attain compaction and high performance of devices, a circuit board having characteristics well balanced at a high level, such as heat resistance, thermal dimensional stability, mechanical properties, low hygroscopicity, fire retardance, high frequency characteristics and the like, is demanded. It is further demanded for the circuit board to attain processing of signals at a high speed and to have small thickness. Therefore, the insulation substrate used for the circuit board also has to satisfy the above-mentioned demands.
Conventional insulation substrates used in this field include substrates comprising a glass cloth in which an epoxy resin is impregnated (hereinafter also referred to as "epoxy resin-impregnated substrate"), polyimide films, fluorine-contained films and the like. However, the epoxy resin-impregnated substrates have high hygroscopicity and poor high frequency characteristics, and it is difficult to make the thickness thereof small. Although polyimide films have good heat resistances, they have high hygroscopicities and poor high frequency characteristics. Fluorine-contained films have poor adhesivenesses, so that it is not easy to mount electro-conductive pastes or to be plated when forming through holes.
To employ a non-oriented sheet of poly-p-phenylene sulfide (poly-p-phenylene sulfide is hereinafter also referred to as "PPS", and non-oriented sheet of poly-p-phenylene sulfide sheet is hereinafter also referred to as "PPS sheet") as the insulation substrate of a circuit board is disclosed in Japanese Laid-open Patent Application (Kokai) No. 56-34426, and to employ a biaxially oriented film of PPS (hereinafter also referred to as "PPS film") as the insulation substrate of a circuit board is disclosed in Japanese Laid-open Patent Application (Kokai) No. 55-36945. These techniques are highly drawing attention recently.
However, although PPS sheets when used alone have satisfactory thermal dimensional stabilities, low hygroscopicities, fire retardances, high frequency characteristics and the like, the temperature to which they can stand is lower than that of biaxially oriented films (i.e., they are likely to thermally deform at temperatures higher than glass transition points). Further, the larger the number of heating steps, the more the crystallization, so that the more the brittleness. In cases where a PPS sheet is used for a printed circuit board, the heat resistance and brittleness are made to be satisfactory to some degree by controlling the crystal size and the like, there is a problem that PPS sheet likely to thermally deform when heated quickly.
PPS films when used alone exhibit dimensional change due to heat shrinkage, so that circuits are likely to be shifted when heat is applied during the manufacturing process of the circuit board. Further, they are easily broken when forming through holes in laminated circuit boards. Thus, their application is limited in the fields wherein thermal dimensional stability is highly demanded.
On the other hand, the following laminates comprising PPS films are known.
(1) A laminate comprising a fabric sheet made of an aromatic polyamide, with which a PPS film is adhered by an adhesive is disclosed in Japanese Laid-open Patent Application (Kokai) No. 60-63158.
(2) A laminate comprising a fabric sheet which is not melted at 300.degree. C. and has a thermal expansion coefficient at 150.degree. C. of not more than 50.times.10.sup.-6 1/.degree. C. and a PPS film is disclosed in Japanese Laid-open Patent Application (Kokai) No. 1-95585.
(3) PPS molded sh
REFERENCES:
patent: 4389453 (1983-06-01), Kitanaka et al.
Kida Kenji
Miyaji Shinichiro
Ueda Toshiaki
Miller Austin R.
Toray Industries Inc.
Weisberger Richard
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