Burn from Soldering Iron or Measling ??

You're correct. It's a peculiar looking defect.

With measling, we expect to see discrete white spots or crosses just below the surface of the base material. We don't see that here.

We do see a similar condition at almost every PTH in the picture, although not to the degree of the one with the inspection arrow. We're thinking maybe this defect: * Should be called delamination or crazing. [not that we can explain the difference] * Probably is not burnt board, because of the symetry of the appearance of the defect. * Possibly was caused by mechanical damage during component nsertion or lead trimming. The discolored lines appear to be perpendicular to the angle of the lead trim.

If the size of the dicoloration increases during thermal cycles, we'd consider it a defect. If it doesn't increase, we'd probably ship it and investigate it further.

Consider doing sections on this portion of the board to better understand the cause of the problem.

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