Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1994-06-03
1995-11-07
Rosenberger, Richard A.
Optics: measuring and testing
By polarized light examination
With light attenuation
356237, G01B 1100
Patent
active
054651522
ABSTRACT:
A method for determining coplanarity with 3-D sensing means of substrates for ball grid array, column grid array, and similar surface mount integrated circuit chips, in which opaque fiducials are provided as index pads. Heights of the index pads are correlated with signal pad heights in a neighborhood about the index pads. The index pads are opaque to incident radiation from the 3-D sensor. The index pads reflect sufficient radiation to be detected easily by the 3-D sensor. The index pads are disposed in a prearranged pattern over a domain of ball grid array signal pads. The index pads are restricted to a predetermined range of heights.
REFERENCES:
Cammarano et al "Optical Testing of Solder Pads" IBM Technical Disclosure Bulletin, vol. 21, No. 7, Dec. 1978, pp. 2914-29-15.
Bilodeau Steve
Cain James
Cameron Joanne
Jacovino Frank
Fogiel Max
Robotic Vision Systems Inc.
Rosenberger Richard A.
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