Practical Production Uses of SMT Adhesives

Category: Adhesives and Dispensing
Post Date: July 20, 2004
Author(s): Douglass Dixon, Steve Marongelli, Sergio Porcari, Wendy Cummings, Frank Murch, Al Osterhout, GDM Product Team, Universal Instruments

Description
Adhesives are typically used in surface mount PCB assemblies to hold the passive, (and sometimes active), components on to the bottom side of the board during wave soldering. The adhesive is used to bond the surface mount device (SMD) to the PCB, thus forming a joint between the body of the (SMD) and the solder resist or bare FR-4 board between the solder pads. This is necessary to avoid the displacement of components from their sites during high-speed placement of passive components. Dispensing equipment must be able to dispense a precise consistent dot shape with different volumes as appropriate for different size devices. After the SMD is placed, the wet adhesive must have sufficient "wet" or "green" strength to hold the SMD in position until cured.

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