Method and apparatus for dispensing viscous materials

A method for dispensing viscous solder paste onto an apertured stencil in intimate contact with a printed circuit board so that the solder paste will be deposited on areas of the circuit board exposed through the apertures in the stencil comprising the steps of:

• directing solder into a housing beneath a piston slidably mounted therein;
• simultaneously compensating for fluctuations in the pressure of the material during the flow thereof into the housing;
• applying a pressure against the piston to force the solder paste out from the housing through a slot therein;
• confining the solder paste forced from the slot in the housing between a pair of flexible blades mounted to the housing on opposite sides of the opening, the blades extending from the housing toward the stencil so as to be in contact therewith;
• and
• moving the housing across the stencil so that the blades urge the solder paste into the apertures in the stencil and onto the areas on the circuit board in registration therewith.

An apparatus for dispensing viscous material into apertures in a substrate comprising:

• a housing having a first opening therein and a plurality of spaced second openings of successively increasing size;
• a piston slidably mounted within said housing for movement to and from said first opening;
• conduit means, having a successively increasing cross-sectional area in communication with said second openings in said housing for carrying viscous material into said housing while simultaneously compensating for fluctuations in the pressure of the viscous material during the flow thereof;
• means for applying pressure against said piston to cause said piston to force the viscous material out from said first opening in said housing;
• and
• a pair of flexible members depending from the housing on opposite sides of the first opening for confining the viscous material forced from the first opening therebetween.