International Business Machines Corporation

Motorola Corporation

Janet M Sickler

Barbara L Gutierrez

Everitt W Mace

San-Mei Ku

Rosemary Christie

Bao-Tai Hwang

Varadarajan Srinivasan

High performance semiconductor devices, such as those used to package microprocessor integrated circuits, demand materials with excellent electrical, physical and chemical properties. Polymethylpentene (PMP) compositions provide resin substrates for high performance devices with a material which has a low dielectric constant and a low dissipation factor. In addition, PMP has very low moisture absorption, and good mechanical stability under repeated thermal stress, which will help keep the device from cracking and warping during high temperature assembly processes and constant use.

High performance semiconductor device with resin substrate and method

A no-clean, thermally dissipated soldering flux is shown which includes hydroabietal alcohol as a flux base, an organic activator and an organic diluent. The hydroabietal alcohol provides a tacky medium which holds a precisely aligned chip in place both during placement and reflow. The nature of the formula renders a reducing atmosphere unnecessary. The composition is thermally dissipated during soldering and leaves no undesirable residue which would require a post-cleaning step.

Tacky, no-clean thermally dissipated soldering flux

Water soluble soldering preflux compositions are shown which include gum arabic, modified polysaccharides and other natural resins as a carrier, an oxidation inhibitor and water. The compositions are useful in the assembly of precisely aligned electrical components during multiple step, electronic card assembly techniques. Use of the preflux compositions according to the method of the invention permits a flexible, site-specific method for joining electronic components to a printed circuit board with a fewer number of steps.

Water soluble soldering preflux and method of application

A no clean thermally dissipated soldering flux is shown which includes camphor as a flux base, an organic activator and an organic diluent. The camphor provides a tacky yet fluid medium which is thermally dissipated during the flux operation and leaves no undesirable residue which would require a postcleaning step.

Thermally dissipated soldering flux

A water soluble soldering flux is shown which includes gum arabic, modified polysaccharides and other natural resins as the carrier, an organic activator and water. The carrier provides a tacky, yet fluid medium capable of holding precisely aligned electrical components during solder reflow and allows aqueous removal of the flux after reflow. The flux composition can be used to solder precisely aligned integrated circuit chips onto a circuit board.

Water soluble soldering flux

Disclosed is a method of forming in a monocrystalline silicon body an optimum recessed oxide isolation structure with reduced steepness of the bird's neck. Starting from a monocrystalline silicon body, there is formed thereon a layered structure of first silicon dioxide, polycrystalline silicon, second silicon dioxide and silicon nitride, in that order. The layers are patterned to form openings in the structure at the areas where it is desired to form the oxide isolation pattern within the silicon body. The exposed areas of the silicon body are anisotropically reactive ion etched to an initial portion of the desired depth obtaining the corresponding portion of the trench having substantially vertical walls. Then by chemical etching the trench is extended to a final portion of the desired depth obtaining inwardly sloped walls in the final portion. The body is then thermally oxidized until the desired oxide isolation penetrates to the desired depth within the silicon body.

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Georgetown, TX, United States of America

Janet M Sickler