International Business Machines Corporation

John Gregory Stephanie

Joseph Paul Kuczynski

Stephen L Buchwalter

Paul George Rickerl

Pei C Chen

Thomas E Kindl

Mark J Schadt

Mark Kenneth Hoffmeyer

David J Braun

James Aloysius Hagan

Miles Frank Swain

Timothy Charles Daun-Lindberg

Steven Dennis Keidl

Charles J Guenther

Vincent W Ting

A cleavable epoxy resin composition suitable for encapsulating electronic chips comprising the cured reaction product of a diepoxide containing a cyclic anhydride curing agent or and an amine promoter.

Cleavable acetal-containing diepoxide and anhydride curing agent for removable epoxy compositions

A cleavable epoxy resin composition suitable for encapsulating electronic chips and a method for making the composition comprises the cured reaction product of a diepoxide; a cyclic dicarboxylic anhydride curing agent mixture; a 1,3-diaza compound having two nitrogen atoms present with one nitrogen atom doubly bonded to the central carbon and singly bonded to one other carbon, and the other nitrogen atom singly bonded to the central carbon and singly bonded to another carbon and singly bonded to a hydrogen. The 1,3-diaza compound serves either as the sole catalyst or in combination with a tertiary amine catalyst different from the diaza compound. The composition may include an optional hydroxy functional compound capable of reacting with the cyclic anhydrides to form a half ester thereby initiating the reaction between the diepoxide and the cyclic dicarboxylic anhydride curing agent. The resin can be used for the encapsulation of electronic parts, but can be removed by a solvent. This feature allows electronic components to be recycled.

Cleavable diepoxide for removable epoxy compositions

A system for removing protective coatings from a circuit board assembly. The system includes a tool for removing protective coatings from a circuit board assembly. The tool has a flow head, which includes a support, having an opening which is adapted to contact the circuit board assembly and flow solvent to the surface of the circuit board. The flow head may also include a solvent nozzle positioned within the support. The solvent nozzle has an opening adapted to apply solvent to the circuit board assembly. The flow head also includes a solvent recovery volume positioned beneath the support and adjacent to the nozzle. The system also includes a second solvent reservoir, a mechanism for applying heat to the reservoir, and a mechanism for circulating solvent from the reservoir to the flow head and back to the reservoir.

Tool for removing protective encapsulants

Disclosed is a circuit board and a process for the manufacture thereof providing a circuit board comprising a metal core having parallel first and second major faces and exhibiting high thermal and electrical conductivity. The circuit board includes electrical insulating layers of thermally conductive, dielectric material applied to the first and second major faces of the metal core. Protecting the dielectric layer and copper conductors is a solder mask layer applied to the dielectric layers and forming outward facing major surfaces. A plurality of insulated and grounded vias having electrically conductive interior rings connecting the major surfaces are provided through the board. Conductive sleeves within the vias are either electrically insulated from the metal core by dielectric material or in electrical contact to the metal core for grounding.

Metal substrate double sided circuit board

An improved method of laminating a metal foil or sheet to a polyimide material is provided. A solution of a precursor of an intractable (i.e. thermosetting) polyimide is applied to a substrate and the solvent is removed to form a dry tack-free film. Thereafter, a solution of a precursor of a thermoplastic polyimide is applied onto the first film of polyimide and the solvent is removed to form a dry tack-free second film. Both films are then cured concomitantly at a sufficiently rapid rate and low temperature to effect substantial imidization of the polyimide precursors of both films without substantial crosslinking or densification of the polyimides in either of the films. Thereafter, a metal sheet or foil is laminated onto the thermoplastic polyimide film according to the following process. The thermoplastic film is contacted with the sheet or foil of metal to be laminated thereto. A first pressure is applied to the metal sheet and the polyimide substrate composite, which pressure is sufficiently low to permit outgassing of any gases trapped or generated within the polyimides and the temperature is increased. The temperature is raised to a level to essentially complete imidization of the polyimides and also to expel any gases contained or generated by said polyimide films. Thereafter, the pressure is increased to a second level or value and the temperature is controlled to a value which temperature is above the T.sub.g of the thermal plastic film. This second pressure is sufficiently high to complete the lamination of the metal sheet or foil to the thermoplastic polyimide.

Method of laminating polyimide to thin sheet metal

An improved method of laminating a metal foil or sheet to a polyimide material is provided. A solution of a precursor of an intractable (i.e. thermosetting) polyimide is applied to a substrate and the solvent is removed to form a dry tack-free film. Thereafter, a solution of a precursor of a thermoplastic polyimide is applied onto the first film of polyimide and the solvent is removed to form a dry tack-free second film. Both films are then cured concomitantly at a sufficiently rapid rate and low temperature to effect substantial imidization of the polyimide precursors of both films without substantial crosslinking or densification of the polyimides in either of the films. Thereafter, a metal sheet or foil is laminated onto the thermoplastic polyimide film according to the following process. The thermoplastic film is contacted with the sheet or foil of metal to be laminated thereto. A first pressure is applied to the metal sheet and the polyimide substrate composite, which pressure is sufficiently low to permit outgassing of any gases trapped or generated within the polyimides and the temperature is increased. The temperature is raised to a level to essentially complete imidization of the polyimides and also to expel any gases contained or generated by said polyimide films. Thereafter, the pressure is increased to a second level or value and the temperature is controlled to a value which temperature is above the T.sub.g of the thermoplastic film. This second pressure is sufficiently high to complete the lamination of the metal sheet or foil to the thermoplastic polyimide.

Growing community of inventors

Rochester, MN, United States of America

John Gregory Stephanie