An electron microscopic study of an epoxy bonded silicon strain gage system for stress transducers

A specimen of epoxy bonded silicon strain gage was photographed at various angles and localities using a Qwik Scanning Electron Microscope. The specimen was magnified up to 5,000 times. Epoxy fillet size variation, epoxy filler particles and metal surface texture were recorded. Relatively large dust particles were also found on the specimen surface. Consequently, an energy dispersion elemental analysis was performed on two arbitrarily selected dust particles and it was found that their predominant composition was aluminum. The specimen was then ground in successive planes perpendicular to the length of the silicon gage. Ten such specimen cross sections were photographed at 500X magnification. These photographs were analyzed for the magnitude and variation of epoxy thickness, gage thickness and gage width. The experimental technique demonstrated in this effort is also useful for investigating some potential stress transducer manufacturing problems related to diaphragm surface texture, epoxy filler particle size and silicon/leadwire contact.