Wevo launches low-viscosity silicone gap filler for EV battery pack thermal management

German potting and adhesives manufacturer Wevo-Chemie has introduced a new thermally conductive silicone gap filler for compact assemblies such as high-voltage battery packs and power electronics.

Wevo’s WEVOSIL 26040 FL gap filler is rated at 4 W/m·K and can be applied at bondlines of less than 70 µm. The material has a thermal conductivity of 3 W/m·K and a density of 2.22 g/cm³.

Wevo says conventional paste-like gap fillers with high viscosity quickly reach their limits when gaps measure only a few millimeters, and that the new material can be applied reliably in tight spaces. It can be laid down as a bead and compressed into place under low pressure. If no free areas need to be connected, it can also be injected into the gap, and Wevo says its high sag resistance keeps it from flowing back out.

The gap filler can be processed using standard dosing systems, such as those used for potting compounds, including both piston and eccentric screw pumps. Wevo says the extruders and barrel or drum extrusion stations that many highly filled gap fillers require aren’t necessary, and that its sedimentation-optimized formulation can be stirred back to a uniform consistency with simple mixing tools in a few minutes even after prolonged storage. The choice of filler and the low viscosity also help prevent abrasion in the dosing systems and the maintenance costs that come with it, the company says.

The material cures without by-products or volume shrinkage, and the cured surface stays tacky. Wevo says the density is significantly lower than that of many highly filled gap fillers of comparable thermal conductivity, which supports weight-optimized assembly designs.

Wevo says compact high-performance batteries or electronic components in humanoid robots can be thermally bonded to the outer skin in narrow areas with layers of 1 to 2 mm to support rapid, uniform heat dissipation. Wevo also names batteries for electric vehicles and industrial environments among the applications.

Source: Wevo-Chemie