Patent ID: 6076726
Filing Date: 2000-06-20
Classification: B23K,H05K,Y02P

Abstract:
A process for establishing an electrical attachment between a module having contact surfaces and a printed circuit board (PCB) having plated via holes therethrough which are aligned with said module contact surfaces and present via capture pads with contact surfaces at the confronting board surface surrounding and extending from the via hole plating comprisingapplying a first solder paste at the via capture pad contact surfaces, said first solder paste comprising an Sn/Pb alloy and particles of a third metal that forms at least one intermetallic phase which increases the upper end of the melting point temperature range of the solder paste mixture when reflowed;reflowing said first solder paste, whereupon the liquid solder to be wicked into the associated via hole is caused to form said at least one intermetallic phase and create a stable plug at the melting temperature of eutectic Sn/Pb solder;applying a second solder paste of Sn/Pb solder to said capture pad contact surfaces;engaging said module contact surfaces with said second solder paste applications at said via capture pad contact surfaces; andreflowing said second solder paste to bond said solder mixture with said contact surfaces to bond and electrically connect said module to said PCB.