A s electronic devices have grown smaller and more complex, the individual components that make up the device have been forced to shrink as well. One category of these complex components is custom spring and electrical contacts.
With the miniaturization of these parts, designers are forced to use tighter tolerances and thinner metals. Leader Tech has extensive experience manufacturing these components and our material of choice is Beryllium Copper Alloy.
While there are several different types of Copper Beryllium alloys, Leader Tech’s standard material is alloy 25 or UNS C17200. The metal is composed of 1.8% Beryllium, 0.2% Cobalt+Nickel, trace amounts of Aluminum and Silicon, and the remainder Copper (ASTM B194 Pg. 2). Alloy 25 provides the right combination of material strength and electrical conductivity needed to produce complex electrical spring contacts (Guide to Beryllium Copper Pg. 4).
In order for the material to gain its spring properties, it must undergo a precipitation heat treat process. The metal is heated to the single phase region and held there long enough to dissolve the existing soluble precipitates and then rapidly quenched. The precipitates become condensed and produce a super saturated solid solution (Connector Engineering IV, 02). In the case of Beryllium Copper, the Beryllium is the precipitate and because it has a higher density, there is a small negative volume change in the material after heat treatment (Connector Engineering IV, 02)
(Connector Engineering IV,02)
The small changes in the material’s volume equate to part dimensions changing during the heat treat process. When designing a part, these changes must be taken into account so that the finished product is within dimensional tolerances. Leader Tech’s engineers and manufacturing team use a variety of methods to mitigate this issue including fine tuning pre-heat treat dimensions that will expand or contract to the correct final dimensions and using heat treat fixtures to prevent parts from moving at all.
Brush Wellman. Connector Engineering Design Guide. Cleveland, Ohio. 1999. Print
ASTM B194-08, “Standard Specification for Copper-Beryllium Alloy Plate, Sheet, Strip and Rolled Bar,” ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
Brush Wellman. Guide to Beryllium Copper. Cleveland, Ohio. Print