Yeah, I think everyone knows the letters are laser engraved and I think everyone knows the vast majority of the letters' area lies below the surface. The only question in my mind is if there is a "ridge" around the periphery of the letters. If not, what is the image seen on so many heat sinks?
As a footnote for Bill, I know of one source for plastic deformation on the copper: My brother (also an engineer
). He bought himself an Asus mobo, XP2100, and Thermaltake heat sink. He didn't use compound ("I thought that was only for the retail heat sink") and slid the heat sink after fastening the clip. It was so bad that he sheared a couple of the rubber pads off the chip. When he brought the system to me to diagnose, the slivers of copper and missing rubber made it pretty easy. He actually had a couple of furrows in the base of the heat sink from the edges of the die. Definitely a little plastic deformation going on there.