Also forgot to mention, the thicker the coating the worse the adhesion. 5um is about the limit where the internal stress of the coating start to cause adhesion failures.
Also areas that have relatively thin coating can indicate regions that didn't get plasma etched enough and also be a...
We have had many issues with DLC(diamond-like coating) from many different vendors. The coating varies from batch to batch and from part to part. The one big factor we found was the same you did which is what other parts were in the batch with our parts. All of the vendors do a plasma etch...
