Stencil printable phase change material [heatsink applications]

Conventional phase change thermal interface material is in the form of a tape or pad with carrier or backing liner. Such configuration requires the bulk material to be processed into sheets of thin tape, cut to required sizes and either supplied as an individual unit or in a roll before being dispensed and attached onto the heatsink. Pressure is required to hold the tape firmly during the attachment process so as to allow for initial adhesion. All these processes involve various equipment, labour and overhead costs. Yield losses in making the tape as well as in the process of attachment onto the heatsink also increase the cost of the final material. A new process of attaching phase change materials onto heatsinks is by using a stencil printing technique. The phase change material's viscosity was reduced before it was transferred to the heatsink. This stencil printing process provides more flexibility in attaching phase change material onto a heatsink surface with higher yield of attachment. This paper aims to discuss the characteristics of stencil printable phase change materials and the method of stencil printing. The thermal performance of the stencil printable phase change material before and after reliability testing is also discussed.