Celanese Gmbh

Hoechst Celanese Corporation

Hoebbst Celanese Corporation

Nancy C Eickman

Hyun-Nam Yoon

Charles E McChesney

Gary E Williams

Robert Dix

Walter Fabisiak

Arie A Hochberg

Frank Haimbach, Iv

A flame-resistant polybutylene terephthalate molding composition has vastly improved fatigue strength and improved melt flow by incorporating therein a halogenated epoxy flame retardant represented by the general formula: ##STR1## wherein an n is the degree of polymerization and the halogenated epoxy resin has a molecular weight of at least about 20,000 to 40,000; X is a chlorine or bromine atom, and i is an integer of from 1-4.

Flame retardant polybutylene terephthalate

An improved thermoplastic molding composition is provided which is particularly suited for use in the impervious void-free encapsulation on a relatively expeditious basis of an electronic component wherein the preformed electronic component is positioned in a mold cavity prior to the introduction of the molding composition via injection molding. The molding composition comprises a melt processable thermotropic liquid crystalline polymer which is of a relatively low weight average molecular weight of approximately 4,000 to 25,000 (e.g. approximately 4,000 to 10,000) and which is substantially incapable of further chain growth upon heating. Uniformly dispersed within the liquid crystalline polymer is approximately 40 to 80 percent by weight (e.g. approximately 50 to 75 percent by weight) of a particulate inorganic material (preferably of silicon dioxide) which serves to advantageously decrease its volumetric coefficient of thermal expansion and to advantageously increase its thermal conductivity. In a preferred embodiment the electronic component which is encapsulated is a semiconductor device, such a relatively delicate quad or dual-in-line integrated circuit device which is assembled onto a flat prestamped lead frame or other conductive device having a plurality of leads which extend outside the area which is encapsulated. The resulting encapsulated electronic component is well protected in spite of the relatively low molecular weight of the liquid crystalline polymer and is capable of satisfactory service for an extended period of time even if adverse environmental conditions are encountered. A rugged commonly nonburning and relatively inexpensive package is provided.

Electronic component encapsulated with a composition comprising a

Encapsulation of electronic components

An improved thermoplastic molding composition is provided which is particularly suited for use in the impervious void-free encapsulation on a relatively expeditious basis of an electronic component wherein the preformed electronic component is positioned in a mold cavity prior to the introduction of the molding composition via injection molding. The molding composition comprises a melt processable thermotropic liquid crystalline polymer which is of a relatively low weight average molecular weight of approximately 4,000 to 25,000 (e.g. approximately 4,000 to 10,000) and which is substantially incapable of further chain growth upon heating. Uniformly dispersed within the liquid crystalline polymer is approximately 40 to 80 percent by weight (e.g. approximately 50 to 75 percent by weight) of a particulate inorganic material (preferably of silicon dioxide) which serves to advantageously decrease its volumetric coefficient of thermal expansion and to advantageously increase its thermal conductivity. In a preferred embodiment the electronic component which is encapsulated is a semiconductor device, such as relatively delicate quad or dual-in-line integrated circuit device which is assembled onto a flat prestamped lead frame or other conductive device having a plurality of leads which extend outside the area which is encapsulated. The resulting encapsulated electronic component is well protected in spite of the relatively low molecular weight of the liquid crystalline polymer and is capable of satisfactory service for an extended period of time even if adverse environmental conditions are encountered. A rugged commonly non-burning and relatively inexpensive package is provided.

Encapsulation of electronic components with anisotropic thermoplastic

A process for producing bundles of high modulus polyethylene fibers for reinforcement in composites wherein the matrix is a brittle material such as cement, concrete, plaster of Paris or the like. The process involves passing high modulus polyethylene yarn through high pressure nip rolls to deform the individual filaments and to form a loosely adhering unitary mass or bundle of filaments which is then chopped into short lengths for use as fibrous reinforcement in composites. In a preferred embodiment, the yarn is twisted prior to being passed through the nip rolls.

High modulus polyethylene fiber bundles as reinforcement for brittle

A thermotropic liquid crystalline polymer matrix having wollastonite fibers incorporated therein for reinforcement to prepare a molding compound. The wollastonite fibers have an average aspect ratio of greater than 3 to 1, and may be coated on their surface with a coupling agent to produce better bonding between the fibers and the thermotropic liquid crystalline polymer. The surface abrasion of an article produced from a blend of wollastonite with a thermotropic liquid crystalline polymer is reduced as compared to that of unfilled polymer.

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Mountainside, NJ, United States of America

Nancy C Eickman