Surface-Mounted Component Lead Co-Planarity Measurement Tool
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
The figure illustrates a fixture which is used to measure the lead co-planarity of surface-mounted components (SMCs). During the reflow process, the liquid solder has a tendency to be sucked up to the lead due to the temperature of the lead frame which gets heated up first. If the co-planarity of the lead exceeds the specified value, a degraded solder joint will be formed. The device will ensure the accurate measurement of lead co-planarity so that only the good components will be used for SMC assembly. Lead co-planarity contributes significantly to the solder joint integrity during the SMC card assembly, especially for Plastic Leaded Chip Carrier (PLCC) components. The J-shaped lead of PLCC has a small contact area on the pad. The copper pad has solder paste screened on it prior to component placement.