Method for determining coplanarity of electrical contact of BGA type packages prior to electrical characterization

摘要

A method of performing electrical characterization of a chip scale package in which impressionable material, such as copper tape, is applied on a contact surface of an isolation plate of a test fixture. The isolation plate is placed on the tops of an array of electrical contacts of a chip scale package and then pressed against the array of electrical contacts so that at least some of the electrical contacts make an impression in the impressionable material. By examining the impressions in the impressionable material, the coplanarity of the tops of the electrical contacts in the array is determined. This provides a measure of how well grounded the electrical contacts in the array will be when placed in a test fixture with an isolation plate placed on the contacts.