Abstract:
A printed wiring board having a layered composite of metal planes and dielectric layers. At least one of the dielectric layers has a modulus lower than the modulus of the remaining dielectric material layers. A plating, extending through the layered composite, has a first land on a first external surface of the layered composite, a second land on a second external surface of the layered composite, and a barrel extending between the first land and the second land. The lower modulus dielectric material layer deforms during thermal excursions of the printed wiring board in such a way as to reduce the strains imposed on both the lands and the barrel of the plated through holes.
Abstract:
Reliability of circuit packaging while accommodating larger chips and increased temperature excursions is achieved by use of compliant pads only at the locations of connections between packaging levels, preferably between a laminated chip carrier and a printed circuit board. The invention allows the coefficient of thermal expansion of the chip carrier to be economically well-matched to the CTE of the chip and accommodation of significant differences in CTEs of package materials to be accommodated at a single packaging level. The compliant pads are preferably of low aspect ratio which are not significantly deflected by accelerations and can be formed on a surface or recessed into it. Connections can be made through surface connections and/or plated through holes. Connection enhancements such as solder wettable surfaces or dendritic textures are provided in a conductive metal or alloy layer over a compliant rubber or elastomer layer which may be conductive or non-conductive.
Abstract:
The present invention provides an interconnection scheme having complaint contacts arranged in an array to connect conductive surfaces on a microelectronic device and a supporting substrate, such as a printed circuit board. This invention accommodates for the difference in thermal coefficients of expansion between the device and the supporting substrate. Typically, an area array of conductive contact pads are connected into rows by conductive leads on a flexible, intermediate substrate. Each of the conductive leads bridges a bonding hole in the intermediate substrate which is situated between successive contact pads. Each of the conductive leads further has a frangible portion within or near each bonding hole. A stand-off between the intermediate substrate and the device is create by compliant dielectric pads, typically composed of an elastomer material, positioned under each contact pad. The frangible portions allow the leads to be cleanly broken, bent and secured into electrical contact with chip contacts on the device. Each of these connections may be supported by a compliant layer, typically an uncured elastomer which fills the area around the compliant dielectric pads and is then cured.
Abstract:
The subject matter of the invention is a base sheet for the preparation of a flexible printed circuit board which is a three-layered laminate consisting of (a) an electrically insulating film of a plastic resin such as a polyimide, (b) an epoxy resin-based adhesive layer and (c) a copper foil bonded to the film (a) with intervention of the adhesive layer (b). The base sheet can exhibit excellent performance in respect of peeling resistance, soldering heat resistance, dimensional stability and solvent resistance as well as workability into a printed circuit board only when each of the layers (a), (b) and (c) has a specified thickness in a narrow range of 10-30 nullm, 5-15 nullm and 5-15 nullm, respectively.
Abstract:
A wiring substrate with reduced thermal expansion stress. A wiring substrate, such as a laminated PWB, thin film circuit, lead frame, or chip carrier accepts an integrated circuit, such as a die, a flip chip, or ball grid array package. The wiring substrate has a thermal expansion stress reduction insert, void, or constructive void in a thermal expansion stress region proximate to the integrated circuit. The thermal expansion stress reduction insert or void may extend a selected distance from the edge or edges of the integrated circuit attachment area. The thermal expansion stress reduction insert or void improves the flexibility of the wiring substrate in the region that is joined to the integrated circuit, thus reducing thermal stress between components of the wiring substrate-integrated circuit assembly. In another embodiment, layers of a laminated wiring substrate are intentionally not bonded beneath the chip attach area, thus allowing greater flexibility of the upper layer of the laminate.
Abstract:
A heat-active adhesive for a connecting circuit which is used for electrically connecting circuit electrodes facing each other in the pressing direction by heating and pressing the electrodes. The adhesive has an elastic modulus of 100-2,000 MPa at 40° C. after adhesion. The adhesive can contain at least an epoxy resin, acrylic rubber, and a latent curing agent. An acrylic rubber having a glycidryl ether group as a molecule is preferably used as the acrylic rubber.
Abstract:
The invention relates to a flexible strip conductor connection, by means of which electrical connections between an electrical device (2) and an external component (1) can be made, wherein the strip conductors (8) are located in or on a flexible foil (3), which is clamped on the electrical device (2) as well as the external component (1). In a predetermined area in the course of the strip conductors (8), the flexible foil (3) has a loop (6), which can be filled with an elastic material perpendicularly in relation to the foil plane, or the strip conductors (8) in the plane of the foil respectively have a loop-shaped deviation (9) perpendicularly to the course of strip conductor.
Abstract:
To produce a conductive epoxy resin composition with improvement in the characteristics of rapid-curability, heat resistance and moisture resistance, adhesion reliability, storage properties and low-temperature curability that can be used effectively for production of conductive adhesive films. The conductive epoxy resin composition comprises an alicyclic epoxy resin, optional diols, a styrenic thermoplastic elastomer with an epoxy group in the molecule, an ultraviolet activated cationic polymerization catalyst, an optional tackifier having an aromatic ring in the molecule, and conductive particles.
Abstract:
A wiring substrate equipped with a rerouted wiring having one end connected to an electronic-part mounting pad for electrically connecting an electronic part and another end connected to an external-connection terminal. In the wiring substrate, a low-elasticity underlayer made of a material having a lower modulus of elasticity than that of a base material of the wiring substrate is disposed between the base material of the wiring substrate and each of the electronic-part mounting pad and the rerouted wiring. A method of manufacturing the wiring substrate and a semiconductor device using the wiring substrate are also disclosed.
Abstract:
Method of producing a multi-layered wiring board comprising the steps of subjecting the photosensitive resin to exposure- and development-treatment to form the holes having a predetermined size and shape; depositing and forming the curable resin to the insulating layer having the holes formed therein in such a manner as to bury the holes, and conducting heat-treatment to form the cured thin film of the curable resin on the surface of the insulating layer; and so removing the curable resin as to leave the cured thin film to obtain the via-holes having the reduced opening size by the cured thin film.