The copper/tungsten heat spreaders are soldered on with silver alloy braze. They easily fall off when free of grease and stickers and the chip is allowed to soak in dilute nitric acid. You end up with gold foils from the lid, a clean tungsten plate, a ceramic cpu housing, kovar plated gold legs, a cpu die, gold bonding wires (if present), and a solution containing copper and silver nitrate. Remove the gold plated bottom lids if you are working with cpus that have them (P60/75/90, etc). For ceramic bottom lidded cpus simply fracture the bottom lid enough to allow the acid into the core/bonding wire area of the cpu (expose the core).
Once everything falls apart, pull the tungsten plates out and rinse them with fresh water.
Processing the housings, foils, and remaining parts is straight forward.
I have routinely run 75 pound batches of these with ease in less than 1 week at room tempersture from raw cpus to cast Au bars. With active heating the process can be completed in 2-3 days.
Heating/Sweating the spreaders off is a poor course to take. The tungsten/copper spreader takes a ton of heat to get off, plus they fracture quite often and even worse the Au foil and Ag braze will alloy into the copper of the primarily tungsten spreader and make the rest of the process very tiresome. Additionally, the heating further complicates the recovery of the legs, cpu dies/cores and bonding wires.
Follow my protocol and you will be able to completely reverse engineer the entire chip without damaging the tungsten spreader, insoluble internal parts, or making recovery of the precious metals any more complicated than it needs to be. My method works for any gold top cpu with a raised heat spreader. I sort them by similar make and process each make together.
Direct treament in AR either with or without crushing results in a mix of ceramic shards bonded to tungsten pieces with a silver chloride passvation layer. The AR routes also lead to yellow tungsten oxide, ring around the bucket, false positive stannous chloride tests, and tungsten coprecipitation with your gold powder. It is never wise to process tungsten containing scrap directly in AR unless it is unavoidable. Remove the tungsten first.
I have literally run thousands of pounds of these types of cpus in the last 5 years. My method is the most direct route to the precious metals. As an added bonus you get nice large 99+% purity tungsten plates as one of your by products.
I hope this helps. You will likely see new youtube videos on this process after I post this. Remember you read it here first.
I have photos of these processes, but they are scattered across several cameras, sd cards, smart phones, and computers. I can try to locate some if any is interested in seeing chemically diseceted "gold topped" cpus (ones with integrated tungsten heat spreaders).
Steve
