Understanding gap fillers as a thermal management solution in electric vehicles

by Eric Wyman, Senior Scientist, Automotive, Industrial, and Electronics Assembly and Electronic Materials Group, LORD Corporation


Eric Wyman of LORD Corporation

Eric Wyman

Extending the life of your power electronics requires the maintenance of low thermal resistance as well as protection from shock, moisture, and debris.

Although the traditional thermal interface material solution selected for use between a heat generating device and a heat sink is a gap pad, thermally conductive gap fillers are growing in popularity as a means to fill all those nooks and crannies. Best suited for large volume applications, gap fillers can be quickly dispensed and the pattern can be modified to suit part tolerances. They are a stay-in-place solution and cure as a gel, easing the stresses caused by thermal differences and flex.

Although gap fillers have already been accepted as a solution for microelectronic applications, there is a great market need for products used in between battery modules and cooling plates in a variety of Electric Vehicle (EV) applications.

For example, gap fillers used in battery packs solve the need for effective heat transfer between cells and the cooling plate – a great option if you do not need adhesion between the two substrates. Typically more economical than gap pads, gap fillers have recently been used in large-format power electronics as a thermal interface material between switching electronics and the cooling plate. One technical advantage of gap fillers is that they can exhibit a high thixotropic index, allowing for easier and faster dispensing. Further, they offer excellent isolation and vibration dampening. Of note, though electrically isolative, gap fillers do not include an isolation film as some gap pads do, so depending on the design (bare metal) and the area (small), a gap pad may be the better choice.

In response to this market need, LORD has developed gap filler solutions specifically for large volume automotive applications. For example, LORD ThermosetTM GF-1400 thermally conductive silicone gap filler is a two-component system designed to provide excellent thermal conductivity for electronic applications, while retaining desirable properties associated with silicones. It exhibits low shrinkage and stress on components as it cures, is composed of an addition-curing polydimethyl siloxane polymer that will not depolymerize when heated in confined spaces, and provides excellent thermal shock resistance.

LORD application engineers are available to help you select the correct solution that aligns with your budget and optimize your process to improve performance. Contact us here.

Click here for a video on LORD thermal management gap filler being dispensed by Scheugenpflug equipment at IPC APEX Expo 2017 in San Diego.

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