Intel Core i5-9400F reverts to thermal paste instead of solder

A delidding of the Intel Core i5-9400F reveals this new CPU, which lacks integrated graphics, also doesn't feature a soldered heatspreader. Tom's Hardware reports that on these new F-series models, Intel returns to thermal grease instead of solder TIM (sTIM). Enthusiasts love solder for its superior thermal performance, but Intel thinks thermal grease is better because it results in lower failure rates.

Intel has also long preached the perils of solder TIM, which can lead to shorter lifespans due to microcracks in the solder TIM that form during heat-induced expansion and contraction. That's more of a concern with smaller die, such as the six-core die on the -9400F.

These same effects also can break the solder bumps that connect the substrate and the PCB, leading to premature chip death. Intel has never officially disclosed solder-induced chip failure rates (to the authors' knowledge), but the increase in the failure rates is thought to be within a single percentage point. Of course, when you punch out north of a million die per day like Intel does, even a 1% increase in failure rates equates to a huge hit to the bottom line.

It's unknown whether other F-series chips, like the Core i9-9900KF, will feature solder or thermal grease.