Unisys Corporation

Burroughs, Inc.

Gerald R Dunn

Robert V Hutchison

Kenneth Walter Economy

Kenneth N Abel

John A Nelson

Dean R Haagenson

Michael J Pirozzoli

Thomas A Snodgrass

A machine for bonding leads from a chip to a substrate having top and bottom surfaces that are non-coplanar is comprised of a carrier for the substrate which includes a frame having a set of stops that terminate in a single plane and which are arranged in a pattern with a central opening. Also included in the carrier is a forcing mechanism which pushes on the bottom surface of the substrate such that the top surface of the substrate is pinned directly against all of the stops simultaneously and a portion of that top surface is exposed through the opening. This causes the exposed portion of the substrate's top surface to be aligned with the plane of the stops regardless of the degree of non-coplanarity that exists between the substrate's top and bottom surfaces. Further included in the machine are bonding blades which lie parallel to the single plane of the stops, and they move perpendicular to that plane through the opening to bond leads to the exposed top surface portion of the substrate as it is pinned to the stops.

Machine for bonding leads to non-coplanar substrates

A method of soldering component leads to I/O pads on a printed circuit board, without desoldering any other circuit components which were previously soldered to the board near the pads, includes the steps of: forming a mechanical assembly in which respective joints of the pads and the leads and respective solder mounds are mechanically held together; moving the assembly at a predetermined speed on a conveyor such that the joints, but not the previously soldered components, sequentially pass through a target area which is small relative to the total number of joints; and melting and then hardening the solder mounds, without desoldering the previously soldered components, by directing a focused stream of hot gas at the target area as the joints move therethrough on the conveyor.

Method of soldering joints by moving them through a target area on which

A method is disclosed for removing an integrated circuit package that has multiple leads which are soldered into respective metal plated holes in a printed circuit board. The board is of the type that has internal metal lines which make joints with the metal plating, and the method is adapted to remove the package from the board without overstressing the joints. The method includes the steps of: flowing a liquid on the leads at a temperature higher than the melting temperature of the solder without pulling on the package for a time period .DELTA.t.sub.1 ; and pulling on the package immediately after the end of the .DELTA.t.sub.1 period with a force F.sub.1 =F.sub.3 +(25 to 75)% F.sub.2. Force F.sub.2 is the minimum force that will extract a single soldered lead from the board under the condition the solder is below but within 5.degree. C. of melting; F.sub.3 is the minimum force that will lift the package from a pool of the liquid; and .DELTA.t.sub.1 is the time it takes to pull the package from the board with force F.sub.1 being continuously applied while the liquid is flowing on the package leads to melt the solder plus one to three seconds.

Method of removing a soldered integrated circuit package from a printed

A unique contact pin configuration for an electrical connector provides an advantageous connection with a leadless semiconductor device package and a printed circuit board on which the connector is to be mounted. Each contact pin includes an elongated shaft portion, a resilient contact portion and a crossbar portion which offsets the contact portion from the shaft portion of the contact pin. Each contact pin is alternately situated 180.degree. in cavities disposed on two opposed sides of the connector. Consequently, the contact portions of the contact pins provide internal electrical connection to a leadless semiconductor device package with a small contact pad spacing, while providing an external electrical connection via the contact pin shaft portions with a larger spacing therebetween. Also described herein are distinctive stand-off bumps which are coaxial with the shaft portions of the contact pins to insure level mounting onto a printed circuit board.

Growing community of inventors

Carlsbad, CA, United States of America

Gerald R Dunn