Browse Prior Art Database

Active Resistor Position Sensing

IP.com Disclosure Number: IPCOM000059883D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Bartley, GK: AUTHOR [+3]

Abstract

Active resistor position sensing allows for the alignment of thin-film resistor patterns on a substrate without expensive optical alignment equipment. Thick-film processing allows the top-surface circuit patterns to be aligned with the substrate. When a part is further processed, for example, by laser trimming, the alignment is achieved with special carriers that hold each part at its edges. However, using existing laser trim tools the alignment repeatability of thin-film resistors on top of multi-layer ceramic substrates is not adequate for substrate alignment. This technique forms L-shaped alignment resistors in opposite corners of each substrate (Fig. 2). One terminal of each resistor connects to the ground plane, allowing this end of the resistor to make contact through the connection of the substrate ground pin.

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Active Resistor Position Sensing

Active resistor position sensing allows for the alignment of thin-film resistor patterns on a substrate without expensive optical alignment equipment. Thick- film processing allows the top-surface circuit patterns to be aligned with the substrate. When a part is further processed, for example, by laser trimming, the alignment is achieved with special carriers that hold each part at its edges. However, using existing laser trim tools the alignment repeatability of thin-film resistors on top of multi-layer ceramic substrates is not adequate for substrate alignment. This technique forms L-shaped alignment resistors in opposite corners of each substrate (Fig. 2). One terminal of each resistor connects to the ground plane, allowing this end of the resistor to make contact through the connection of the substrate ground pin. The total alignment burden on the substrate is one pin and a little real estate in the corners of the top surface. New parts are made by placing the first part into the laser tool. The positions of each resistor and the alignment resistor corners are loaded by means of a joystick and television monitor system. This part becomes the template for the remaining parts. To begin trimming the next part, the laser is programmed to begin stepping toward one leg of the alignment resistor. When the laser senses a change in the resistor value, the position of the laser is recorded by the system. This position approximates one c...