Stoic
Starting to get Involved
I've seen at least two firms take the position that a manual soldering process does not require validation because the only identified CTQ - electrical continuity - is either verified on 100% of devices produced or simply considered 100% verifiable. (To muddy the waters, one of those firms has also validated a soldering process on at least one occasion, possibly in response to a customer request.)
On the other side of the argument, there's a passing mention of soldering in the 1997 FDA Guide to Inspections of Medical Device Manufacturers as a type of process requiring validation, but I've seen nothing more explicit or recent. The MDSAP Audit Model (Ch. 6, §7) still just lists the big four from the QSR preamble, including welding. And while there are of course manufacturers that are validating soldering processes, I've found no warning letters yet for any that failed to validate one. Likewise, while there are several past threads on the subject in various sub-forums, I've not yet seen a detailed explanation of why "100% verification; no validation" is out of the question for any type of soldering process.
Those focused solely on electrical continuity emphasize that the solder joints in question are not considered mechanical connections, i.e. the forces they are subjected to are negligible, and destructive testing is not necessary. Is this a valid argument, or are they missing the point about reliability failure modes associated with thermal cycling, transport vibration, shock, etc? Are there any other publicly available data points to consider?
On the other side of the argument, there's a passing mention of soldering in the 1997 FDA Guide to Inspections of Medical Device Manufacturers as a type of process requiring validation, but I've seen nothing more explicit or recent. The MDSAP Audit Model (Ch. 6, §7) still just lists the big four from the QSR preamble, including welding. And while there are of course manufacturers that are validating soldering processes, I've found no warning letters yet for any that failed to validate one. Likewise, while there are several past threads on the subject in various sub-forums, I've not yet seen a detailed explanation of why "100% verification; no validation" is out of the question for any type of soldering process.
Those focused solely on electrical continuity emphasize that the solder joints in question are not considered mechanical connections, i.e. the forces they are subjected to are negligible, and destructive testing is not necessary. Is this a valid argument, or are they missing the point about reliability failure modes associated with thermal cycling, transport vibration, shock, etc? Are there any other publicly available data points to consider?
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