Loctite 5404 Thermally Conductive Silicone Adhesive
For bonding circuit board substrates, metallic heat sinks, and ceramic chips, Loctite 5404 is an ideal selection for an adhesive. This silicone based adhesive was designed for applications that include bonding numerous different types of devices that generate heat to their corresponding heat sinks. This product offers low resistance to the flow of heat from the power device to the heat sink. Loctite 5404 provides strong bonds for metal enclosures in electronics circuits as well as modules, power semiconductors, graphics processors and other heat generating devices to their heat sinks. This material combines high thermal conductivity and great electrical isolation.
The specific gravity of Loctite 5404 Adhesive is 2.3 to 2.45 LMS at 25°C, and the VOC is 32.1 g/l ASTM D 3960. The glass transition temperature is -40°C, and the coefficient of thermal expansion is 1.04 x 10ˉ⁴. The dielectric breakdown strength is 19.2 IEC 60243-1, kV/mm, and the dielectric strength is 17.1. For additional technical data, please see the Loctite 5404 Technical Data Sheet. It is recommended that the time the fixtured parts are exposed to temperatures lower than 30°C is minimized. This, in turn, helps the conductive filler maintain consistent dispersion within the adhesive matrix.
Either an IR oven or a convection oven can be used when curing Loctite 5404 Silicone Adhesive. It is suggested that the minimum heat cure conditions for either option be 15 minutes at 130°C or 10 minutes at 150°C. These suggested times exclude heat up rate. The proper cure rate depends heavily on the composition, size, and geometry of the parts that are being bonded, as well as the type of oven that is being used. It is vital that the bond lines reach these temperatures for their specified times.
Loctite 5404 Properties:
Glass Transition Temperature
Coefficient of Thermal Expansion
Dielectric Breakdown Strength
32.1 g/l ASTM D 3960
1.04 x 10ˉ⁴
19.2 IEC 60243-1, kV/mm
An adhesive bond line of .13 to .15 mm is produced as the composition of Loctite 5404 contains .13 mm diameter glass spheres. No more adhesive than is necessary to fill the bond should be applied to the heat sink or the part. When applying or dispensing this material, a method that eliminates air entrapment within the bond line should be used. This product should be stored in a dry location in its unopened container. Once the material has been removed, it should not be returned to its original container as contamination may occur. If added storage or application information is required for Loctite 5404, please contact a Krayden Technical Representative.
Loctite 5404 Adhesive is a white to gray silicone adhesive paste designed to bond power devices to their respective heat sinks. This product boosts shock absorbing and load bearing characteristics of the bond area, and has low resistance to the stream of heat that moves from power device to heat sink. When setting your curing conditions for Henkel‘s Loctite 5404, it is imperative to take into consideration that thermal effects from the components, oven, and board may occur. For additional assistance with Loctite 5404 Silicone Adhesive, please contact Krayden, an authorized distributor of Henkel Loctite Adhesives.