Patent ID: 6541304
Filing Date: 2003-04-01
Classification: B05C,H01L

Abstract:
A method of underfilling a space between a semiconductor flip chip and a substrate to completely encapsulate a plurality of solder bumps and solder pads with a viscous material, comprising:providing a pressurized reservoir for holding the viscous material; coupling a positive displacement pump outside the pressurized reservoir for metering a variable amount of the viscous material from the pressurized reservoir coupled to the pump and through a dispensing element connected to the pump; maintaining the dispensing element at a first substantially constant temperature; maintaining the substrate at a second substantially constant temperature; metering a first variable amount of viscous material dispensed through the dispensing element onto a weigh scale during a time interval and measuring a weight thereof; calculating a flow rate based upon the time interval and the measured weight; and moving the dispensing element along at least one side edge of the flip chip mounted on the substrate and metering a second desired amount of viscous material through the dispensing element based on the calculated flow rate, the second amount of viscous material being sufficient to completely encapsulate the plurality of solder bumps and solder pads without overflowing an upper side of the flip chip.