Browse Prior Art Database

Surface-Mounted Component Lead Co-Planarity Measurement Tool

IP.com Disclosure Number: IPCOM000061296D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Yu, S: AUTHOR

Abstract

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.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 85% of the total text.

Page 1 of 2

Surface-Mounted Component Lead Co-Planarity Measurement Tool

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. During the reflow process, the solder paste melts to form solder joint bonding the lead to the pad. It is critical to ensure that the lead co- planarity of the component is within the specification. The device shown has a rectangular steel block 1 with flat surface 2. The block has a hole 3 at the center where vacuum will suck the component against the flat surface. The fixture with the component is placed under the tool-maker's microscope 4 with the backup light 5 shining through the component 6. The gap 7 between the flat surface and the end of lead can be accurately measured. Two parallel lines with f...