Component Registration Using Photosensitive Dielectric
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Figs. 1 and 2 illustrate the use of Photosensitive Dielectric, to provide Surface-Mounted Component (SMC) registration-orientation and restriction of movement during solder reflow. First, dielectric layer 1 acts as solder mask. After solder deposition on the pads, a second layer 2 of photosensitive dielectric is deposited and developed, providing a cavity for component placement. The cavity also acts as orientation guide due to the notched corner 3. The arrangement has several advantages: 1. The "pick-n-place" tolerance can be relaxed since the cavity acts as guide and the component has a self-centering action. 2. The component is restricted in the x and y directions, thereby movement due to mechanical vibration is eliminated.