Patent ID: 6567161
Filing Date: 2003-05-20
Classification: G01N,H05K

Abstract:
Apparatus for providing first and second backlit images of a semiconductor device edge and lead extending therefrom, said images representative of first and second viewing angles corresponding to first and second different optical axes as measured in a plane perpendicular to said device edge, comprising:at least one illuminator providing diffuse backlit illumination of said device edge and leads in directions corresponding to said first and second optical axes; a camera arranged on an opposite side of said device edge from said illuminator along said first optical axis and oriented to form a direct image corresponding to said first optical axis; a deflector arranged on an opposite side of said device edge and said leads along said second optical axis for deflecting a backlit image of said device edge and leads in a direction corresponding to said second optical axis toward said camera; and a semiconductor device lead inspection system determining a distance L between a lead tip of a lead and the device edge in the direction of the first optical axis, where L is equal to: L=L1/SIN 2&thgr;âˆ’L2 TAN 2&thgr;and whereL1 is a distance value 1 between the lead tip and the device edge in tile backlit image, L2 is a distance value 2 between the lead tip and the device edge in the direct image, and 2&thgr; is an angle between the first optical axis and the second optical axis.