Application: WACKER® SILICONE PASTE P 12 is used especially in semiconductor technology as a heat sink paste. Wherever it is important to have good heat transfer from a semiconductor to a cooling element, it is advisable to apply a thin coating of WACKER® SILICONE PASTE P 12. In the assembly of semiconductors, e. g. diodes, transistors and thyristors, microscopic elevations exist on the mating surfaces of the semiconductor and the cooling surface if they have not been grounded and polished. When these surfaces are placed together, a firm metal-tometal contact will result only where there are these elevations. 40 - 60% of the surface is thus not in direct contact, depending on the roughness. This means that the hollow spaces in between these elevations are filled with air, which has relatively poor thermal conductivity. By coating the contact surfaces with WACKER® SILICONE PASTE P 12, the thermally insulating air is replaced by the heat sink silicone paste when the semiconductor is screwed on. The thermal conductivity of WACKER® SILICONE PASTE P 12 is about 20 times better than that of air. By using WACKER® SILICONE PASTE P 12, the heat transfer resistance from the semiconductor housing to the cooling elements is reduced by 50%. WACKER® SILICONE PASTE P 12 can be applied with a brush, spatula or by screen printing. Best results are achieved when a uniform, thin coat is applied to the mating surfaces. Paste squeezed out when the semiconductor is tightened should be removed.

Information provided by Wacker Chemie AG.