Packaging flat micro heat pipe using low melting point alloy

Abstract

Heat pipe based coolers and substrates can spread heat in high efficiency, thus it is widely used in thermal management of the high power electronic devices. The critical issue in fabrication of the flat micro heat pipe (FMHP) is working fluid charge and sealing. Using low melting point alloy (LMPA) to charge and sealing FMHP is presented in this paper. The layout of the charging grooves of FMHP is shown in this paper, the sealing grooves on the silicon substrate and the glass cover plate are discontinuous, but after anodic bonding, channeled through the silicon wafer and glass plate, the grooves are connected to the working area of the FMHP. The detailed charging steps are described in the paper as well. After the working fluid charged, the FMHP keeps a flat contour, which benefits its usage in compacted application. This charge and sealing methods also provide a feasible way to charge a non-metal heat pipe without employ epoxy glue, thus reduced spontaneously leak the non-condensable gas into the working part of the FMHP and promote it performance.