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Browse Prior Art Database

TRIMMABLE TOP HAT CHIP RESISTOR

IP.com Disclosure Number: IPCOM000005476D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2001-Oct-08
Document File: 1 page(s) / 53K

Publishing Venue

Motorola

Related People

Torleiv Melkeraaen: AUTHOR

Abstract

Hybrid circuits, such as used in channel element designs, make use of top hat resistors to compen- sate for circuit tolerances. Sometimes, during circuit compensation, which is done by using a laser to trim the resistors, the required resistor value is overshot. in other words, the laser overtrims the resistor to a higher than desired value. in this case, the hybrid is no longer usable and it must be scrapped.

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Volume 3 March 1983

TRIMMABLE TOP HAT CHIP RESISTOR

By Torleiv Melkeraaen

    Hybrid circuits, such as used in channel element designs, make use of top hat resistors to compen- sate for circuit tolerances. Sometimes, during circuit compensation, which is done by using a laser to trim the resistors, the required resistor value is overshot. in other words, the laser overtrims the resistor to a higher than desired value. in this case, the hybrid is no longer usable and it must be scrapped.

   The present chip resistor allows for repair of hybrid subassemblies which otherwise would be scrapped. This chip resistor consists of a screened top hat resistor on a ceramic chip carrier and top connecting electrodes 10 and 12 (see figures 1 and 2). The electrodes 10 and 12 on the top side are con- nected to the pads 14 and 16 on the back side of the ceramic carrier by portions of plated-through holes 18 and 20. The electrodes and pads 22 at the other end of the carrier are only used in the illustrated ex. ample to secure the carrier to the hybrid.

   This small chip resistor allows for the repair of extremely dense hybrid circuits that would other. wise be scrapped. To replace an existing mis-trimmed resistor on the circuit with the top hat chip resistor, the existing resistor is either severed or removed with abrasive. The new chip resistor is then placed on the substrate and the connections are made to pads 14 and 16 by using either solder or con- ductive epoxy. The repaired substrat...