Exposing a Chip on Board (COB)

In a previous post I had described my efforts to build (or should I say extract) a DCF77 clock radio receiver from an old radio clock. The remaining part of the board has undergone another surgery to take a look at the chip on board (COB) technology (German Wikipedia entry). The process of removing the covering epoxy resin with a scalpel was rather destructing, but I did not want to use aggressive chemicals. As a result, the bonding wires (between the silicon chip and the conductor tracks) were destroyed.

The following video shows the process of removing the epoxy resin using a scalpel and a heat gun (fired up to 200°C). The whole process took about 10 Minutes. The last minute of the video also shows some close-ups done with a cheap webcam, which was modified for magnification.

I also added some close-up pictures of the exposed silicon die, taken with my DSLR and a reverse-mounted lens.