With the increasing usage of powerful ICs in Motherboard designs, heat dissipation of these high power ICs becomes more and more critical. Heatsinks provide an increasingly important role in dissipating the heat of these densely populated high power ICs. There are two common methods for fastening heatsinks to IC’s, mechanical attachment (such as spring clip, rivet, or screw connections), and adhesive bonding. Adhesive bonding has distinct advantages over mechanical methods, since it only uses the IC surface, and saves valuable area on the board for trace wiring and components, maximizing the space utilization on densely populated board designs. A good adhesive bond should have low thermal resistance, and provide strong, reliable attachment between a heatsink and IC during its life time. Meanwhile, a good adhesive bond process should be easily assembled on the production line, and easily disassembled as required for rework. Based on these requirements, a series of experiments has been conducted to investigate the key factors for good adhesive bonding. The investigation includes incoming heatsink material and surface finish, heatsink adhesive bonding process, and rework temperature impact on the as-bonded heatsink.
The conclusion from this paper will show how heatsink surface, pre-cure application force, load dwell time, activator contact time before weight application, adhesive pattern, and rework temperature influence heatsink performance after assembly.