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US 5,402,505 AGranted
Semiconductor device lead inspection system
AssigneeTexas Instruments Incorporated
InventorsRajiv Roy, Charles K. Harris
Life of this patent
Estimating the term…
Abstract
The invention is to a system and apparatus for determining the planarity of leads on a semiconductor device. An image system is used to locate the leads with reference to a reference plate on which the device is mounted, and a real-time reference which is used to provide a known correlation between image pixels and linear measurement such as mils.
Claims11
A method, using an imaging system, for automatically measuring the coplanarity of lead ends of a surface-mounted semiconductor device;
- said device having at least two sides and a plurality of leads along each of said device sides;
- and said method comprising the steps of:
- providing a rotatable platform having a planar top surface and at least two sides;
- said platform sides respectively corresponding to said device at least two sides;
- and each platform side having a face with features respectively defining x- and y-axis directions;
- providing a reference member fixed in spaced position relative to said platform;
- said member having a feature defining a straight line which is parallel to said plane of said platform top surface, and having at least a feature of known y-axis direction linear dimensional extent;
- providing an imaging system, including a camera having a field of view simultaneously encompassing said rotatable platform and said reference member;
- mounting said device on said top surface of said platform;
- rotating said platform to successively present each side of said mounted device toward said camera so that, for each device side presented, said camera field of view simultaneously encompasses said presented device side, said platform side corresponding to said presented device side, and said reference member;
- for each presented device side, grabbing an image of said camera field of view in pixel image form;
- for each grabbed image, locating positions of said lead ends relative to positioning of said straight line;
- from a pixel form image of said reference member known linear dimensional extent feature, identifying a scale factor relating pixels to linear dimensional measurement units;
- and
- using said position locations and said scale factor for the grabbed images, determining the coplanarity of said lead ends of said sides.
12 more elements
A method, using an imaging system, for automatically measuring the coplanarity of lead ends of a surface-mounted semiconductor device;
- said device having four sides and a plurality of leads along each of said device sides;
- and said method comprising the steps of:
- providing a rotatable platform having a planar top surface and four sides;
- said platform sides respectively corresponding to said device four sides;
- and each platform side having a fiat face with adjacent edges respectively defining x- and y-axis directions;
- providing a reference frame fixed in spaced position above said platform top surface;
- said frame having a bottom edge defining a straight line which is parallel to said plane of said platform top surface, and having a plurality of apertures with first and second sets of opposite edges, respectively spaced apart in known x- and y-axis direction linear dimensional extents;
- providing an imaging system, including a camera having a field of view simultaneously encompassing said rotatable platform and said reference frame;
- mounting said device on said top surface of said platform, with said device sides generally aligned with said platform sides;
- rotating said platform to successively present each side of said mounted device toward said camera so that, for each device side presented, said camera field of view simultaneously encompasses said presented device side, said platform side corresponding to said presented device side, and said bottom edge and plurality of apertures of said reference frame;
- for each presented device side, grabbing an image of said camera field of view in pixel image form;
- for each grabbed image, locating positions of said leads relative to positions of said straight line and said apertures;
- from a pixel form image of said apertures, identifying a scale factor relating pixels to linear dimensional measurement units;
- and
- using said position locations and said scale factor for the grabbed images, determining coplanarity and displacements of said leads of said sides.
12 more elements
Dependencies are inferred from the claim text.