Method and apparatus for testing of electrical interconnection networks
First Claim
1. A method for testing rigid or flexible electrical interconnection network boards including at least two networks including terminal points and interconnecting conductors, said method comprising the steps of:
- establishing an electrically conductive reference means in a predetermined electrical and geometrical position with respect to the surface containing the interconnecting conductors of the networks, and separated therefrom by a dielectric;
making measurements from terminal points of the interconnection board being tested includingat least one impedance measurement from a terminal point of each network to said reference means, andat least a measurement of the end-to-end resistance of each network;
with either the impedance or the resistance measurement(s) being made first;
comparing said measured impedance and resistance values with the respective pre-established values for an interconnection board with no electrical faults;
and indicating faults when either(a) said impedance measurement value is above said respective established value by more than a predetermined amount;
(b) said impedance measurement value is below said respective established value by more than a predetermined amount; and
/or(c) said resistance measurement value departs from said respective predetermined value.
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Accused Products
Abstract
A method and apparatus for testing circuit boards using two or a small number of probes for making resistive and radio frequency impedance measurements e.g. capacitive measurements. The combination of resistive and impedance measurements substantially reduces the number of tests required to verify the integrity of a circuit board. The impedance or capacitive "norm" values used in testing the circuit boards can be obtained by operating the system in a learning mode. Analysis of the data provides not only fault detection but also can indicate approximate fault location.
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Citations
33 Claims
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1. A method for testing rigid or flexible electrical interconnection network boards including at least two networks including terminal points and interconnecting conductors, said method comprising the steps of:
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establishing an electrically conductive reference means in a predetermined electrical and geometrical position with respect to the surface containing the interconnecting conductors of the networks, and separated therefrom by a dielectric; making measurements from terminal points of the interconnection board being tested including at least one impedance measurement from a terminal point of each network to said reference means, and at least a measurement of the end-to-end resistance of each network; with either the impedance or the resistance measurement(s) being made first; comparing said measured impedance and resistance values with the respective pre-established values for an interconnection board with no electrical faults; and indicating faults when either (a) said impedance measurement value is above said respective established value by more than a predetermined amount; (b) said impedance measurement value is below said respective established value by more than a predetermined amount; and
/or(c) said resistance measurement value departs from said respective predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for testing rigid or flexible electrical interconnection network boards including at least two networks and a plurality of terminal points interconnected by electrical conductors to form a predetermined pattern, comprising
at least two independently movable probes for contacting selective terminal points of the said interconnection board being tested; -
positioning means associated with at least one of said probes for positioning the same to contact selected terminal points on the interconnection board; conductive reference means spaced from said conductor network of the interconnection board by a dielectric; impedance measuring means connected to at least one of said probes to measure impedance between the probe connected thereto and said reference means; resistance measuring means connected to said probes to measure electrical resistance between said probes; and control means for moving said probes and for activating said measuring means to obtain; (a) at least one impedance measurement from a terminal point of each network to said reference means; and (b) at least a measurement of the end-to-end resistance of each network. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of testing interconnection boards including at least two networks including terminal points and interconnecting conductors comprising the steps of:
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establishing a conductive reference means in a predetermined electrical and geometrical position with respect to the surface containing the interconnecting conductors of the networks, and separated therefrom by a dielectric; making at least one impedance measurement from a terminal point of each network and to said reference means for a plurality of interconnection boards in a sample lot; determining the mean impedance value for each measured terminal point; discarding measured impedance values which deviate from said average impedance values by more than a predetermined amount and determining the average impedance values for the remaining measurements to derive a respective reference value; similarly measuring impedance values for other like interconnection boards and rejecting as circuit faults any measurements higher than said reference value by more than a predetermined amount, and rejecting as circuit faults any measurements lower than said respective reference value by more than a predetermined amount. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A method for testing interconnection boards including terminal points and interconnecting conductor networks and for indicating locations of faults therein comprising the steps of:
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establishing a conductive reference plane parallel to the plane of the terminal points and interconnecting conductor networks, and separated therefrom by a dielectric; measuring the capacitance between a particular terminal point and said reference plane; comparing said measured capacitance value with the known correct value for an interconnection board with no faults present; indicating an open circuit fault if said measured capacitance value is less than said known correct value by a predetermined amount; and determining the fault location for any such open circuit fault relative to said measuring point in accordance with the magnitude of deviation from said known correct value. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for testing interconnection boards including terminal points and interconnecting conductor networks comprising the steps of:
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establishing a conductive reference plane parallel to the plane of the terminal points and interconnecting conductor networks and separated thereform by a dielectric; measuring the capacitance between at least one terminal point of each network and said reference plane; comparing said measured capacitance value with the known correct value for interconnection boards with no faults therein; indicating as a short circuit fault for any measured capacitance which is higher than the respective known correct value by more than a predetermined amount; and indicating as shorted together any networks showing similar high values. - View Dependent Claims (29, 30, 31, 32, 33)
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Specification