Hello all,

We have a failed high pressure (0-40 MPa) gauge (copper internals), manufactured by Ambit which we suspect has been operated outside the recommended temperature range (operating at 80+ C when design dictates temps less than 65C).

The gauge failed at where the bourdon tube is attached to the tube anchor. We found that a lead tin solder (exact composition) was used to initially secure the tube.

My question is, what are the signs of a high temperature soldered joint failure? Is there a typical appearance? Would you expect to see certain features using electron microscopy? Or are there better techniques of determining this?

We have performed some preliminary SEM but we were unable to interpret the results correctly - we saw what looked like fatigue striations but nothing which we thought would be characteristic of high temp failure/melting.

Any feedback from knowledgeable soldering people would be much appreciated.

Thanks in advance.