Browse Prior Art Database

TRANSISTOR CLAMP

IP.com Disclosure Number: IPCOM000006036D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2001-Nov-28
Document File: 2 page(s) / 69K

Publishing Venue

Motorola

Related People

David Moore: AUTHOR [+2]

Abstract

The RFPA is the next generation Power Amplifier for the Motorola GSM Base Station Infrastructure. The following design of Transistor Clamp solves a number of initial problems during development, namely: -to produce mechanical support for a printed circuit board at right angles to the mounting face; - to transfer the thermal output of a number of TO.220 style transistors to a heatsink (up to 30 Watts maximum); - to insulate each transistor; - to operate without degradation in temperatures in excess of 100 degrees C; - to provide constraint to cableforms to prevent trapping; -to be manufacturable within the constraints of reflow solder techniques; -to reduce the parts count and improve assembly time.

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MOlYlROLA Technical Developments Volume 11 October 1990

  TRANSISTOR CLAMP by David Moore and Graham Bell The RFPA is the next generation Power Amplifier for the Motorola GSM Base Station Infrastructure. The following design of Transistor Clamp solves a number of initial problems during development, namely:

-to produce mechanical support for a printed circuit board at right angles to the mounting face; - to transfer the thermal output of a number of TO.220 style transistors to a heatsink (up to 30 Watts maximum); - to insulate each transistor;
- to operate without degradation in temperatures in excess of 100 degrees C;
- to provide constraint to cableforms to prevent trapping;
-to be manufacturable within the constraints of reflow solder techniques;
-to reduce the parts count and improve assembly time.

The initial prototype consisted of wnventional aluminum riveted brackets with individual insulated bushes and scmws The solution is an injection molded plastic using Zytel 70G-30HSL (DuPont) material.

The clamp exerts a contact pressure of 435 Psi using individual 'fingers' to allow for tolerance differences, with a contact area of approximately 5.5 square mm.

   Initial tooling has produced prototypes that have been tested and produce sufficient clamping force at elevated temperatures. Long term creep may be a problem as the temperature cycles over a ten year life and accelerated life tests have yet to be performed.

The clamp rivets or bonds onto the printed circuit...