Robust titanate-modified encapsulants for high voltage potting application of multichip module/hybrid IC

High-voltage gated-diode-crosspoint (GDX) devices (operation at 375-V) for AT&Ts No. 5 electronic switching system (ESS), which require exceptional protection, are considered. Heat-curable silicone elastomer appears to be the ideal material for this application. The material formulation includes small amounts of a silane coupling agent which increases material adhesion to the potted multichip module (MCM)/hybrid integrated circuit (HIC) structure. However, residual silicone coupling agent tends to defuse to outer casings, thereby contaminating leads and preventing further lead attach assembly. Titanate modified silicone elastomer was developed which prevents silane coupling agent contamination and also further improves adhesion within the potted structure. Fourier-transform infrared (FT-IR) and gas chromatography mass spectrometry (GC/MS) analyses of contaminants are described. A solution that achieves a robust potted GDX MCM HIC is described. Laser ionization mass spectrometry (LIMA) analysis was used to elucidate the additional titanate interaction with the potting compound