Thermally conductive and humidity-resistant adhesive for power semiconductors

04-06-2020 | DELO | Subs & Systems

DELO has produced a new electronic adhesive that is thermally conductive and electrically insulating, showing excellent strength even after standardised humidity tests with subsequent reflow cycles. DELO MONOPOX TC2270 assures fast heat transfer and long-term stable operation of semiconductors in power electronics.

The new electronic adhesive is a one-component, heat-curing epoxy resin. Due to its ceramic filler, aluminium nitride, it gives very high thermal conductivity of 1.7W/(m∙K) (measured by the criteria of ASTM D5470). This is comparable with silver-filled isotropic conductive adhesives (ICA), that has a thermal conductivity of ~1.5-2W/(m∙K).

DELO MONOPOX TC2270 provides an advantage over ICA in that it also gives electrical insulation. The adhesive, therefore, assures both reliable heat dissipation and electrical insulation of assemblies. Adopting the new electronic adhesive further enables proportionate component costs to be lessened.

In cured condition, the adhesive has a compression shear strength of 34MPa on the FR4 composite material and of 11MPa on high-performance LCP plastics. When bonding microchips, the electronic adhesive reaches values of 60N in the die shear test (1 x 1mm2 silicon dies on gold surface). Even after standardised humidity tests, the adhesive displays good strength. To ascertain the moisture sensitivity level (MSL 1), silicon dies were bonded to different PCB materials, stored for one week at 85C and 85% air humidity, and then subjected to three consecutive reflow cycles. Even with these loads, the adhesive held its high strength level.

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