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Electroformed Copper Flexible Waveguides are cracking

We have problems with cracking electroformed copper waveguide (sometimes silver plated). We've evaluated thickness, microstructures, hardness, etc. and can't find anything unusual. Seems that the cracks are spotted after vibration testing. But simulated vibe coupons are difficult to crack. Is it the material or the testing?

Gary Wos
User of parts with all types of finishes (Satellite manufacturer - El Segundo, California
August 27, 2008

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September 2, 2008

Gary,
You mentioned hardness testing, microstructure and hardness examination. You left out what type of testing method was used. Having performed mil-spec copper plating for many years (obviously much less thickness requirements than electroforming) elongation, tensile and purity testing had to be performed by a certified lab on a monthly basis.
As you may know, the higher the elongation percentage ductility of the copper deposit is improved. Your copper supplier will have the elongation and purity parameters you should abide by. A good material testing lab can perform the tests and analysis for you. If you have had waveguides that passed vibration testing on a regular basis in the past and have not changed techniques, your problem could very well be with the copper deposit. Good Luck to you.

Mark Baker
process engineer - Malone, New York