I was an FAE with Semtech at the time. Diodes Inc. isn't a manufacturer, they're a "brand" and have stuff labeled for them by many companies, mostly in Taiwan and then China, but some come from Microsemi. I first got involved with Magic Chef, I think; they were making microwave ovens for a few different brand names -- memory is a bit hazy as this was back in about 1977-78. They were experiencing a high HV rectifier failure rate, to the point that they had a lot of warranty returns in addition to on-line test failures in the factory. They, and some others, were "fixing" this by upping the number of stacked junctions in the rectifier until they were using 25-30kV rectifiers! Which still failed. We developed a high avalanche energy stacked junction device rated 7kV PIV but it could handle a lot of kickback energy, hundreds of mJ. It worked and that was the end of the problem. We used exactly the same technology to make HV rectifiers for X-ray machines, but those used many more diodes and were rated 200kV (but still high energy designs) which solved a lot of problems for G.E., Picker, Siemens and others at about that same time. The 200kV units hardly needed any insulation since they're always operated in a dielectric oil bath, so they were actually pretty small for their rating.