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Algorithm to Locate the Seating Plane of Surface-Mounted Devices

IP.com Disclosure Number: IPCOM000039313D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01

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Blackshear, ED [+details]


An algorithm has been proposed to mathematically establish the seating plane of a surface-mounted semiconductor device. A program can then be written so that automatic optical measuring equipment may be used to give coplanarity readings. This method would replace manual techniques using feeler gages. On surface-mounted semiconductor modules the leads must be coplanar within rigid specifications. The conventional method used to measure coplanarity is to place the module lead down on a surface plate. Feeler gages are then used to determine the distance between the lead surface and the plate. The proposed algorithm would establish a seating plane 1 (Fig. 1) with the module 2 on its back. The object is to determine which three leads 3, 4 and 5 comprise the seating plane.