Stock material or miscellaneous articles – Composite – Of epoxy ether
Patent
1997-10-03
1999-10-12
Gulakowski, Randy
Stock material or miscellaneous articles
Composite
Of epoxy ether
428418, 525 92B, 525 92H, 525112, 525486, 525526, 525530, 525930, 524408, 524409, B32B 2738
Patent
active
059652691
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an insulating adhesive, an adhesive film and an adhesive-backed metal foil, which are useful for printed wiring boards.
BACKGROUND ART
Recent advancement of electronic instruments has been accompanied by increasingly strict requirements of wiring boards for packaging semiconductor (hereinafter, will be referred to as semiconductor-packaging wiring boards), such as PGA (pin grid array) or BGA (ball grid array) packages, for high wiring density, moisture resistance and heat resistance. Also, the heat generated per unit area has been increased due to increasing electronic component mounting density and increasing integration of semiconductor devices, requiring efficient heat dissipation from the semiconductor-packaging wiring boards. Common means for accelerating the dissipation of heat generated by electronic components mounted on semiconductor-packaging wiring boards are the use of wiring boards which are composed of a metal plate bonded with copper foil by insulating adhesives, or printed wiring boards bonded to radiation plates of high heat conductivity, such as aluminum plates, copper plates or steel plates.
To meet these requirements, these wiring boards require complicated shape-processing, such as multilayering, formation of cavities or installation of radiation plates.
Bonding materials commonly used to produce semiconductor-packaging multilayer wiring boards or to bond radiation plates are glass cloth-epoxy resin prepregs containing glass fibers base materials, and rubber-epoxy resin adhesives. When radiation plates are bonded with semiconductor-packaging wiring boards by using glass cloth-epoxy resin prepregs, the wiring boards tend to warp or form CAF (Conductive Anodic Filaments), which occur due to migration of copper ion along the interface between glass fibers and resin, and, on moisture absorption, become poor in soldering heat resistance and electrolytic corrosion resistance. Further, the use of glass cloth-epoxy resin prepregs in the production of wiring boards requiring complicated shape-processing, such as formation of cavities or installation of radiation plates, causes the disadvantage that epoxy resin powder is scattered during drilling to coat connecting surfaces, causing connecting error in wire bonding, or the resin flows in large quantities and even into cavities by the heat and pressure applied during lamination, so that the cavities lose necessary spaces.
Rubber-epoxy resin adhesives are mixtures of epoxy resins with various rubbers components, such as acrylic rubbers or acrylonitrile-butadiene rubbers, which are added to improve the adhesives in strength, flexibility and adhesion. Because of their relative excellency in properties, such as electrical properties, heat resistance and solvent resistance, these conventional acrylic rubber-containing adhesives have been used in the production of flexible boards.
Typical examples of acrylic rubber-containing adhesives are adhesive sheets made of mixtures of acrylic rubber with thermosetting resins, such as epoxy resins, which, however, exhibit insufficient properties at high temperatures due to the low epoxy resin content of about 30% by weight. Further, these adhesives composed mainly of acrylic rubbers have the defects that though the loss of adhesion strength after a long term treatment at high temperatures is relatively small, the adhesion strength at high temperatures is poor, and that the properties, such as heat resistance and electric properties, are considerably deteriorated on moisture absorption. Adhesives composed mainly of acrylonitrile-butadiene rubbers have the defect that the loss of adhesion strength after a long term treatment at high temperatures is considerable and they are inferior in electrical corrosion resistance. The deterioration is particularly significant when they are subjected to tests for moisture resistance under today's severe conditions to which electronic instruments are exposed, such as PCT (pressure cooker test) treatments.
As adhesives improved
REFERENCES:
patent: 5278259 (1994-01-01), Futakuchi et al.
patent: 5403869 (1995-04-01), Arike et al.
patent: 5461112 (1995-10-01), Masse et al.
Inada Teiichi
Kumashiro Yasushi
Shimada Yasushi
Yamamoto Kazunori
Gulakowski Randy
Hitachi Chemical Company Ltd.
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