VAX 9000 bonding failure

Extended case study. TAB-bonded chips made in Cupertino, then outer-lead bonded three to four weeks later in Arizona, well past the one-hour cleanliness window. With 400 I/O bonds per chip, yield was near zero. Tom uses this as the consequential example of the "bond within an hour" rule from §6–§7. The technical failure compounded Digital Equipment's bankruptcy.

In a good shop, this occurs within an hour of cleaning the copper for the circuit board and then maybe plating it. Now, twenty-four years ago, in the manufacturing program at MIT, I had three of the four students I was supervising that year working in a partnership to build the VAX 9000 computer. This was Digital Equipment, and Motorola, or maybe Rogers Corporation — two firms down in Arizona. They wanted to bond Digital Equipment's latest and greatest type of chip — like this little Intel chip — and it was on a TAB bonding tape. We haven't really talked about this; we'll probably talk about it Monday.