And the second being Breywood (C015):
The Breywood gold top packages are rather easy to decap as the package is simply heated up and the steel cap is lifted off:
This was then masked and dumped with a masked UV attack as done in previous posts:
The F-1 Dream is a glass frit CERDIP which is a little trickier to decap. Glossing over details, the best technique we've come up with is to strongly heat the top to release it. This melts the glass holding it on without melting the glass holding the pins in place. However, this is a delicate operation that can go wrong in many ways.
Here's the die after decap:
Which was masked like on Breywood:
However, the chip did not dump. Closer inspection revealed the leadframe had shifted a bit and had caused some minor bond wire damage, notably one had completely snapped. This is very hard to see in the pictures, but was easily found with a continuity test and some probing. So it was patched with some epoxy:
Even after this, dumps were very flaky. We got a few decent looking dumps but they started getting worse. We suspected bad pin connections and tried to clean up the chip a bit more. However, on closer inspection we noticed microfractures on the die:
So, it seems that we narrowly got this chip dumped before it stopped working. We could have potentially patched some of these up, but this would have gotten complicated quickly.
What happened? In the past we had pre-heated the chip / workholder for longer, but this time didn't wait quite as long. We suspect that the chip was cooled faster than expected, causing the microfractures. Suppose all is well that ends well, but a lesson for the future to be more conservative on these parts.
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