Merced. Steel, or platinum film on copper?
Chemist sends us his conclusions
Updated A metallurgical reader of The Register has sent us facts and figures about different metals Intel may be using in its cartridge Merced design. And now, an electronic engineer has chipped in with his conclusions, which he thinks may be a thin film of platinum deposited on copper. The photographs, developed by Boots the Chemist in the St Ann's Centre in Harrow, are here. When we questioned Stephen Smith, who runs the Merced programme in the US, he told us he had no metallurgical knowledge and so therefore could not explain which metal was on the backside of the cartridge. However, the reader said Smith's comments were "most interesting" and sent us a set of numbers. The ratio is between material, heat conductivity and density. Here are his conclusions. Ag: 420:10.5 Cu: 395:8.93 Au: 310:19.26 Al: 200:2.7 Fe: 50: 7.88 Si: 0.7: 3? He thinks the backplate has got to be a copper alloy although we still favour steel, because of the weight. After all, the silicon is pretty light and even given the 560 gold contacts, there's something hefty there... And even given the metallurgy, Stephen Smith, the Merced programme manager, told us there was a pretty hefty heatsink on the back too. At this point, the chemist left us and gave some figures for both Cork, an organic substance, and rock, an indeterminate substance. Cork: 0.05:0.01 Rock:3: 2? If by rock he meant quartz, we think that Intel buys in its crystals and cork is so light it can float like a Kyocera mobile phone. We conclude from his observations that the backplate must be steel, as we first thought, thus making the package very heavy. It is, after all, pretty conductive. An electrical engineer, howver, doubts the chemist's conclusions. In an email, he wrote: "I doubt that the heat sink of the Merced CPU is made of steel. Your chemist has confused thermal capacity with thermal resistance, or its reciprocal, thermal conductivity. "Aluminum has a low thermal resistance (or high thermal conductivity) and copper has an even lower thermal resistance. "Here's where it gets funky. Silver has an even lower thermal resistance than copper, and platinum yet lower than silver. However, due to both the cost as well as the mechanical strength, these metals aren't used for heat sinks...directly. "However, I remember reading several years ago of a vapour deposition process designed for radiators, like you would find in a home, that deposits a microfine layer of platinum onto a less expensive metal to improve its thermal conductivity. "My guess, which is based strictly upon your photos and physical description of the weight -- platinum deposited upon copper. I haven't heard much about this method being used in electronics, but with the power dissipation of the Merced chip (which needs to be conducted away), it wouldn't surprise me one bit if this is what Intel is doing." ® Intel Developer Forum coverage