Manufacturing defect analyzer
First Claim
1. A method of detecting open circuits on a printed circuit board populated by a plurality of components, each having a plurality of signal leads and at least one ground lead connected to conductive traces on the printed circuit board, said method comprising:
- a) connecting one terminal of a voltage source to the ground lead and the second terminal of the voltage source to two signal leads and measuring the current flow through the voltage source while applying a predetermined voltage level;
b) connecting one terminal of the voltage source to the ground lead and the second terminal to a first of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level;
c) connecting one terminal of the voltage source to the ground lead and the second terminal to the second of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level;
d) computing an indication of the common mode resistance between the two signal leads and the ground lead; and
e) indicating a defect when the indication of the common mode resistance is outside of a predetermined range.
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Accused Products
Abstract
A method for detecting faults on a printed circuit board populated with semiconductor electronic components. To detect faults, signal pins on the components are taken in pairs. The an indication of the common mode resistance between those pins and ground is computed from a series of current measurements. An error is detected when the common mode resistance is outside of a predetermined range. A "learn mode" is also disclosed in which the pairs of leads used for the test are selected by taking measurements on a known good board without detailed knowledge of the semiconductor components on the board.
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Citations
11 Claims
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1. A method of detecting open circuits on a printed circuit board populated by a plurality of components, each having a plurality of signal leads and at least one ground lead connected to conductive traces on the printed circuit board, said method comprising:
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a) connecting one terminal of a voltage source to the ground lead and the second terminal of the voltage source to two signal leads and measuring the current flow through the voltage source while applying a predetermined voltage level; b) connecting one terminal of the voltage source to the ground lead and the second terminal to a first of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level; c) connecting one terminal of the voltage source to the ground lead and the second terminal to the second of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level; d) computing an indication of the common mode resistance between the two signal leads and the ground lead; and e) indicating a defect when the indication of the common mode resistance is outside of a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of detecting open circuits on a printed circuit board populated by a plurality of components, each having a plurality of signal leads and at least one ground lead connected to conductive traces on the printed circuit board, said method comprising:
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a) connecting one terminal of a voltage source to the ground lead and the second terminal of the voltage source to two signal leads and measuring the current flow through the voltage source while applying a predetermined voltage level; b) connecting one terminal of a voltage source to the ground lead and the second terminal to a first of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level; c) connecting one terminal of a voltage source to the ground lead and the second terminal to the second of the two signal leads and measuring the current flow through the voltage source while applying the predetermined voltage level; d) computing the difference between the current measured at step (a) and the sum of the currents measured at steps (b) and (c); and e) indicating a defect when the computed difference is outside of a predetermined range. - View Dependent Claims (9, 10, 11)
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Specification