Delidding a CPU involves removing the integrated heat spreader (IHS) that’s put over the bare die and the substrate that it is mounted on. The reason for this is usually to improve cooling performance, as the IHS is effectively a small heatsink between the die and the large heatsink, adding more problematic thermal interfaces. If delidding is done improperly it can cause severe damage to the substrate, as in the case of a very nice 1.3 GHz Tualatin Pentium III CPU that [Bits und Bolts] got in an eBay lot with nasty delidding damage.
With the delidding enthusiast presumably having used brute force and ignorance combined with a prying implement, around a dozen of tiny traces on the substrate got severed, requiring tedious trace repair to fix. After confirming that with the severed traces the CPU is indeed busted, enough of the soldermask is removed to make a repair.
Any traces that were still good got covered with soldermask, while for the remainders the thinnest available copper wire was used to create new traces. Although very much doable with a good microscope and a steady hand, this is definitely one of those things that’s much easier to prevent than to fix.
With IHSes having become standard on CPUs, delidding continues to this day, with increasing risks of severed traces and ripped-off capacitors should it go wrong. Although those newer CPU substrates are probably not repairable, repairing these older CPUs instead of tossing them as e-waste seems plausible at least.
Continue reading “Repairing Traces On A Delidded Pentium III CPU Gone Wrong”



Perhaps the most annoying kinds of faults are those that involve expensive equipment that just sit around in a cupboard, only for them to just stop working at all. Such was the case with the £2,000 Amprobe cable trace kit that [Tom] bought for work-related purposes. After sitting around unused for a few years, the signal generating part of the kit refused to power up at all, with Fluke’s service department wanting at least £600 to even attempt a repair after already having had [Tom] cough up £70 to even get this quote.



