Microscale Self-Assembled Electrical Contacts.

摘要

Self-assembly, or the spontaneous organization of parts into larger structures via energy minimization, is an attractive solution to overcome packaging and integration challenges. Capillary forces from a molten alloy can be used to both bond microscale components and make electrical connections between them in a self-assembly process. This report presents a systematic study of a number of metal alloys and self-assembly media with the aim of reducing the metal contact size between microscale components. Six different alloys or pure metals with melting points below 160 degrees C and nine different fluids with boiling points over 160 degrees C are considered. Tin- based alloys were generally found to be highly susceptible to corrosion at elevated temperatures above the alloy melting point, with Sn being the primary component to corrode and react with the underlying base metal. Using a eutectic Sn-Bi alloy and glycerol at 180-200 degrees C, the self-assembly of 1500 100- micrometers parts and 500 40-micrometers parts was demonstrated, each in about 2.5 min. Thus, 40 micrometers square, 4 micrometers high contacts were shown to remain functional for self-assembly. The electrical conductance of self- assembled 20 micrometers diameter, 2.5 micrometers high alloy contacts based on this Sn-Bi-glycerol system was measured at 1.9 /m-Omega-sq cm.