In the universe of automatic dispensing applications, the process of applying adhesives for attaching surface-mount components to circuit boards is a radically different animal. Production speeds are faster, accuracy requirements are stricter, and the quantities dispensed are significantly smaller. The size of a typical adhesive dot ranges from 0.7 to 1.5 millimeters in diameter. A dot for a very small component, such as an 0402, might be only 0.3 millimeter in diameter. Most components require only one dot, but a large part, such as an S016, might require two or three. "The big challenge today is to make smaller dots," says Gary Helmers, vice president of Creative Automation Co. (Sun Valley, CA). "The problem is, a lot of materials, especially silver-filled epoxies used in photonics applications, are extremely compressible. If you compress more material than you want to dispense, you have to find a way to relieve that pressure."
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