The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 21, 1995
Filed:
Jan. 27, 1994
Moses Khazam, Lexington, MA (US);
Steven M Blumenau, Royalston, MA (US);
GenRad, Inc., Concord, MA (US);
Abstract
In a method for testing whether a pin (12) of an electronic component (14) on a circuit board under test (18) has been properly connected to a circuit-board track (16), a source (20) drives the track (16), and a capacitive probe (34) located above the component (14) generates a resultant output. The pin (12) is determined to be connected correctly if that output exceeds a threshold determined for that pin (12) during a training process in which similar measurements have been made on a known good board for that pin and other pins on the same electronic device. The threshold is determined by dividing the capacitance measurement made during the training process for that pin into connection-dependent and connection-independent parts, the latter being the part that would result even in the absence of a proper pin connection. Determination of the pin-independent part is made, without disconnecting the pin in question, by operations that take advantage of symmetries in the pattern of lead-frame conductors predominately responsible for the connection-dependent component of the measured capacitance. The threshold is the sum of the connection-independent part and a percentage of the connection-dependent part.