Underfill epoxy offers thermal conductivity and electrical insulation

26-11-2019 | Masterbond | Subs & Systems

Master Bond EP29LPTCHT is a two-component, low viscosity epoxy compound that can be effectively employed for underfill and encapsulation applications. It does not require excessive heat for curing and has a long working life at room temperature. This solution is electrically insulative and thermally conductive with very fine particle size filler material. The compound can be readily dispensed into tiny gaps, and when employed as an adhesive, it forms thin bond lines from 5 to 15 microns, resulting in a significantly low thermal resistance of 12-15 x 10-6K•m2/W.


The compound provides exceptional flow properties with an initial mixed viscosity of 5,000-15,000cps. It provides a long working life after mixing, for example, a 100g batch at 75F will produce an open time of 10-12 hours. The compound has a thermal conductivity of 9-10BTU•in/(ft2•hr•F), and a volume resistivity of more than 1015Ohm-cm, both measured at 75F.


The recommended cure schedule is overnight at room temperature followed with 4-5 hours at 160F-180F. This processing characteristic makes it excellent for substrates which are heat sensitive. After curing the compound features a particularly low coefficient of thermal expansion of 22-24 x 10-6 in/in/C along with a compressive strength of 24,000-26,000psi and a hardness of 80-90 Shore D. It is offered in premixed and frozen syringes, 1/2 pint kits, pint kits, and quart kits. The colour of Part A is off white, and the colour of Part B is white.

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