Hughes Aircraft Company

Raytheon Company

Delco Electronics Corporation

Hughes Electronics Corporation

Other

Sierracin Corporation

Hughes Aircraft

Ralph D Hermansen

Steven E Lau

Henry M Sanftleben

James M Rosson

Brian M Punsly

E Dean Johnston

Wai-Cheng Seetoo

Samuel R Wennberg

Theresa Renee Lindley

Norman Bilow

David L Voss

Gary R Shelton

Richard F Davis

Petrina L Schnabel

Deborah S Huff

William Albert Miller

Dennis T Baird

David J Vachon

Douglas C Smith

Thomas H Sutherland

Roamer Predmore

Flexible epoxy-based adhesive compositions which remain Theologically stable at room temperature in an uncured state comprise: (a) at least one flexible polyepoxide resin having a hardness not exceeding a durometer Shore D reading of 45 when cured with a stoichiometric amount of diethylene triamine (&ldquo;DETA&rdquo;); and (b) a substantially stoichiometric amount of at least one latent epoxy resin curing agent. Optionally, the adhesive composition may also incorporate one or more semi-flexible resins. Other optional components include fillers, thixotropic agents, and flexibilizers. The adhesive composition provicdes an epoxy-based adhesive composition that is storable for weeks as a single component mixture at room temperature, curable at temperatures ranging from about 100&deg; C. to 125&deg; C. in less than two hours, and flexible upon curing to temperatures as low as minus 50&deg; C., exhibiting a durometer Shore A of less than about 95.

Adhesive of flexible epoxy resin and latent dihydrazide

An adhesive and method for attaching a heat sink to a printing wiring assembly that provides a thermal path from electronic components on the printing wiring assembly to the heat sink. The adhesive is flexible and accommodates thermal expansion stresses and is readily reworkable. The adhesive comprises a filler material that is disposed between the heat sink and the printing wiring assembly, and an impregnant that impregnates the filler material, which impregnated filler material is cured. The filler material may comprise alumina particles that have a spherical shape. The impregnant comprises a polymer, typically selected from a group of epoxy resins and their curatives that form a flexible material when cured. In practicing the method, a heat sink is positioned adjacent to and spaced apart from a printing wiring assembly to provide an appropriate spacing between them. The periphery of the printing wiring assembly is sealed. A cavity that is formed between the heat sink and the printing wiring assembly is filled with a filler material. The filled assembly is vibrated to maximize packing density of the filler material. The filler material is then impregnated with a flexible epoxy impregnant. The impregnant is then cured to form the flexible adhesive. This produces a structure wherein the heat sink is bonded to the printed wiring assembly.

Reworkable, thermally-conductive adhesives for electronic assemblies

A flexible thermally-conductive epoxy-based adhesive composition and method for making the same are provided. The present adhesive composition comprises (a) a polymer mixture comprising at least one polyepoxide resin having a hardness not exceeding a durometer Shore D reading of about 45, when cured with a stoichiometric amount of diethylene triamine ('DETA'), and a substantially stoichiometric amount of at least one latent epoxy resin curing agent; and (b) a thermally-conductive filler. Optional components include secondary epoxy resins, non-reactive flexibilizers, diluents, and processing aids. The present adhesive composition is rheologically stable for weeks or even months at room temperature and is curable in less than one hour at a temperature ranging from about 100.degree. C. to 140.degree. C., whereupon the cured adhesive composition exhibits a durometer Shore A of less than about 90 and a thermal conductivity exceeding 0.4 BTU/hr-ft-.degree. F. (0.7 W/m-K).

Room-temperature stable, one-component, thermally-conductive, flexible

A solid, one-component, flexible epoxy-based composition and method for making the same are provided. The present compositions comprise: (a) an epoxy-terminated prepolymer formed by reacting at least four moles of a polyepoxide resin with approximately one mole of a diamine compound, wherein at least one of the polyepoxide resin and diamine compound is solid at room temperature, and wherein the prepolymer is rheologically stable for weeks as a single component mixture at room temperature and, and (b) a substantially stoichiometric amount of an epoxy resin curing agent selected from the group consisting of a heat-curable, latent epoxy resin curing agent and a room temperature-curable ketimine curing agent. Optional components include thixotropic agents, diluents, fillers, anti-oxidants, and processing aids. The present uncured epoxy-based compositions upon cure, exhibit a durometer Shore D of less than about 45 (or a durometer Shore A of less than about 100).

Epoxy-terminated prepolymer of polyepoxide and diamine with curing agent

A flexible, electrically-conductive, one-component epoxy adhesive composition and method for making the same are provided. The present adhesive composition comprises: (a) at least one polyepoxide resin having a hardness not exceeding a durometer Shore D reading of about 45 when cured with a stoichiometric amount of diethylene triamine; (b) a substantially stoichiometric amount of curing agent including at least one amine-terminated butadiene-acrylonitrile polymer; and (c) an electrically-conductive filler. The epoxy adhesive, upon cure, has a volume resistivity not exceeding about 10.sup.-3 ohm-cm at room temperature and a drop resistance such that a 6-mil-thick (0.015 cm) bond effected by the adhesive can withstand at least six 60-inch (152 cm) drops onto a hard surface. Optional components in the epoxy adhesive include secondary rigid and semi-rigid epoxy resins, secondary amine curing agents, non-reactive flexibilizers, diluents, and processing aids. The adhesive bonds achieved using these epoxy adhesives are non-brittle, flexible, resilient, and drop-resistant, while also exhibiting strong adhesion and good processing characteristics.

Adhesive of epoxy resin, amine-terminated ban and conductive filler

An adhesive is provided for bonding cyanate ester composite parts together which is also plateable with metal once chemically etched. The adhesive comprises a polymeric matrix and a filler of cyanate ester polymer. The polymeric matrix comprises at least one polyepoxide resin and a curing agent, while the cyanate ester polymer filler is present in the adhesive as a powder. In practice, the present adhesive is applied to the surface of cyanate ester composite articles to be bonded and is allowed to cure at room temperature. Thereafter, the surface of the assembly is chemically etched and then plated with metal. The present adhesive enable the complete coverage of the cyanate ester composite assembly with the plated metal, including the adhesive bondlines. A cyanate ester resin structure assembled with the present adhesive composition may, upon plating, replace certain metallic components in such applications as aircraft, spacecraft, and automobiles given its highly conductive and comprehensive metallic coating.

Plateable structural adhesive for cyanate ester composites

A method and encapsulation material are provided for processing an electronic circuit assembly having surface mount integrated circuit packages mounted with soldered leads to its substrate, in which encapsulation of the soldered lead joints serves to enhance the fatigue life of the solder joints. The encapsulation material is a reactive hot melt epoxy that is curable at temperatures significantly lower than that required for previous epoxy-based encapsulation materials. As such, processing of the circuit assembly is greatly facilitated, while the benefit of encapsulated solder joints is achieved for the assembly. The encapsulation material further includes a latent curative and a filler material for lower the coefficient of thermal expansion of the encapsulation material.

Solder joint encapsulation material

Hot melt epoxy encapsulation material

An adhesive material is provided which is particularly suitable for potting a sensing element within a container. The adhesive material is characterized by mechanical and physical properties which enable the adhesive material to maintain its adhesive and structural integrity under intense thermal cycling conditions, so as to exclude foreign elements from the sensing element when potted within a container with the potting material. The adhesive material can be formulated so as to be sufficiently adherent for use with containers formed from materials such as polybutylene terephthalate, polyethylene terephthalate, and E-coated steel, by including additions of a flexibilized polyol/polyepoxide epoxy novolac in an amount of up to about 15 parts by weight.

Polybutadiene urethane potting material

A flexible electrically-conductive epoxy-based adhesive composition and method for making the same are provided. The present adhesive composition comprises: (a) a polymer mixture comprising at least one polyepoxide resin having a hardness not exceeding a durometer Shore A reading of 45, when cured with a stoichiometric amount of diethylene triamine ('DETA'), and a substantially stoichiometric amount of at least one latent epoxy resin curing agent; and (b) an electrically-conductive filler comprising a metal. Optional components include secondary epoxy resins, non-reactive flexibilizers, diluents, and processing aids. The present adhesive composition is rheologically stable for weeks as a single component mixture at room temperature and is curable in less than two hours at a temperature ranging from about 100.degree. C. to 140.degree. C., whereupon the cured adhesive composition exhibits a durometer Shore A of less than 95 and a volume resistivity less than about 10.sup.-2 ohm-cm at room temperature.

Room-temperature stable, one-component, electrically-conductive,

Conformal coating materials are provided for forming a protective conformal coating on the surface of an electronic assembly. The conformal coating materials are characterized by being hot melt materials, in that they are each initially a solid or semisolid at approximately room temperature, a liquid at an elevated temperature at which the coating material is applied to the electronic assembly, and solidify upon cooling to a temperature corresponding to a service temperature of the electronic assembly. As such, the coating systems can be rapidly applied through various highly controllable techniques associated with hot melt dispensing equipment. In addition, the coating systems quickly solidify upon cooling to allow handling of the electronic assembly. The conformal coating systems may be nonreactive, indicating that the system can be remelted, or reactive, indicating that a post-application curing process occurs over time at a temperature less than the elevated application temperature.

Hot melt conformal coating materials

Encapsulant compositions which provide both dry heat and humid heat stability comprise: (a) a first liquid epoxy resin comprising either:

Encapsulant of amine-cured epoxy resin blends

Adhesives and sealants, based on polyurethane reactants, are provided. The one-component frozen premix material of the invention comprises: (a) up to about 60 vol % of at least one filler; (b) about 0.5 to 5 wt % of a thixotrope comprising hydrophobic fumed silica; and (c) the balance a urethane matrix. The urethane matrix comprises at least one polyol that includes at least one carbon-carbon double bond in its backbone and has less than 20 wt % of ether and ester moieties, at least one aliphatic polyisocyanate in stoichiometric amount relative to the polyol, and about 0.01 to 0.1 wt % of an organo-metallic catalyst. The urethanes of the invention can be stored as one-component, frozen, premix materials for a minimum of three months, and, when thawed, can be applied with a spatula or trowel to form non-sag fillets. The cured elastomers are free of voids, tears, or bubbles.

Frozen premix, fillet-holding urethane adhesives/sealants

A superior thermal transfer film adhesive comprises the following composition: (a) at least one aliphatic epoxy resin; (b) a stoichiometric amount of at least one aliphatic polyamine curative; (c) an effective amount of a thixotropic agent, such as fumed silica; and (d) about 20 to 50 volume percent of at least one filler, such as alumina, based on the total of the epoxy resin and the curative. The aliphatic epoxy resin has aliphatic pendant chains of 6 to 20 carbon atoms in length. The curative comprises a long chain aliphatic or cycloaliphatic curing agent for the epoxy resin. Since aliphatic moieties, which are flexible, are used, the glass transition temperature of the resulting cured material is lower than epoxies and plasticizers employing rigid moieties. The adhesive of the invention is novel in attaining high volume resistivity (at least 10.sup.14 ohm-cm at 25.degree. C.), low temperature flexibility (-55.degree. C.), excellent adhesion for maximum thermal transfer, and ease of reworkability.

Growing community of inventors

Northridge, CA, United States of America

Ralph D Hermansen