Spectrol Electronics Corporation

Bradley D Turner

Richard E Riley

A method of trimming a resistance element is disclosed which comprises cutting transversely into one side of the element until the measured total resistance of the element increases by a fraction 1/N of a fixed percentage of a desired total resistance value. The fraction 1/N is approximately equal to the path length of the resistance element divided by the designed width of the transverse cut and the fixed percentage is equal to the percent deviation of the initial total resistance of the element from a nominal, desired resistance value. After the transverse cut is made, a longitudinal-type cut is made at a distance, equal to the length of the transverse cut, from the edge of the element having the transverse cut to isolate a portion of the element from the remainder of the element so that the isolated portion has the desired total resistance. This method is particularly suitable for use with computer controlled laser trimming systems used to mass produce resistance elements.

Method of trimming a resistance element

An electrical resistance element for a variable resistance device, such as a thick film resistance element, and a method of making the element and a device utilizing the element, such as a potentiometer, is described. The resistance element comprises a single resistance material for use as a resistance path for a contact wiper in a variable resistance device and has a selected series of generally transverse cuts made in at least one section of the resistance material of the element. The cut section(s) provides an increased current path length through the element whereby the total resistance of the element is increased. Also, the cut section(s) provides the resistance element with a resistance function which can be adjusted to vary over a wide range of resistance values depending on the length, width, and number of the cuts.

Variable resistance device having a resistance element with laser cuts

A cermet resistor element utilizing a silver-gold alloy to improve the contact resistance variations and the method of making the element are disclosed. A gold resinate and a silver resinate are mixed with the noble metal resinates and glass frit to make a cermet material. The mixture is heated to drive off the organic resinate materials and to alloy the silver and gold. The resultant material is ground to a powder, reheated and reground. The powder is mixed with a volatile material to form a paste which can be applied to a substrate to form the resistance element. The element is heated to drive off the volatile material and fuse the glass into a solid mass. The silver and gold form a silver-gold alloy during the process and settle on the top surface of the element in globules and improve the contact resistance variations of the element.

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Covina, CA, United States of America

Bradley D Turner