IBM stainless steel high-purity semiconductor piping rejection

IBM would reject $15,000 stainless steel gas piping trains if any heat-tint colors appeared on weld surfaces — concerned about contamination reaching gallium arsenide semiconductor processes.

People also see these same types of colors not just on titanium but on stainless steels. About ten or fifteen years ago I used to get people coming through on a regular basis welding stainless steel piping for high-purity semiconductor crystal growth piping. For the gases — if you're going to make gallium arsenide or something, you actually use arsine, which is arsenic hydride gas. IBM would purchase some gas system of stainless steel piping and they might pay $15,000 for this little gas train, which is not very big. They would just cannibalize it and cut it open if they saw anything like those colors on the side on the stainless steel. They would reject everything you built, because they didn't want the contamination to get into their semiconductor. In their opinion it would destroy their process. Well, some of that contamination is oxide, but some of it is not. Some of it is just stainless steel vapor deposited on the side, and you get what we call interference colors, or Newton's rings — just different layers of vapor-deposited material.