Traditionally, electronics are cooled using a heat sink that transfers the heat generated by the electronic system into the air or a liquid coolant. For the heat sink to work, it has to be attached to the CPU or the graphics processor via a thermal interface material such as thermal paste. It helps facilitate the transfer of heat by bridging microscopic gaps between the heat sink and the chip.
With conventional processors, the first layer of the thermal interface material attaches the processor to the lid and a second thermal interface material attaches the lid to the heat sink. Even though the thermal interface material cools better than leaving air gaps between the heat sink and the chip, that thermal interface material impedes heat flow and leads to higher chip temperatures.
A manufacturing technique was developed that will keep electronics cooler by 10 °C (18 °F), allowing for faster, more efficient computation. Those 10 degrees are vital when it comes to saving power and reducing toxic electronic waste. Lower operating temperatures will improve the energy efficiency of data centers by about five percent, which can save $438 million dollars in electricity and can prevent 3.7 billion pounds of carbon dioxide from being emitted per year. It can also reduce toxic electronic waste by about 10 million metric tons because of the lower rates of heat-based device failure.
The technique prints microchannels on the chip to make spirals or mazes that the coolant can travel through directly on the chip instead of using the thermal paste as the connection between the heat sink and the chip. A tin-silver-titanium alloy was used that rapidly forms a thin bonding layer — about 1,000 times thinner than the diameter of a human hair — in the form of a titanium-silicide that acts as a glue between the silicon chip and the metal alloy. This alloy solidifies at a low temperature, leading to lower thermal stress from thermal contraction during cooling. By laser processing, the time to create this silicide bond was reduced to microseconds, which is sufficiently fast to allow additive manufacturing of metal directly onto silicon.
This solution removes both the lid and two thermal interface materials by printing the heat sink directly onto the silicon, giving heat a shortcut and lowering chip temperatures.