Method and apparatus for testing of electrical interconnection networks

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.

A method of testing interconnection boards including at least two networks including terminal points and interconnecting conductors comprising the steps of:

• 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.

A method for testing interconnection boards including terminal points and interconnecting conductor networks and for indicating locations of faults therein comprising the steps of:

• 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.

A method for testing interconnection boards including terminal points and interconnecting conductor networks comprising the steps of:

• 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.