US 5,491,424 A · System for measuring contamination resistance

Abstract

A test fixture is provided for testing the resistance associated with contamination material on the surface of electrical contacts mounted to a printed circuit board. A probe used to engage the contacts consists of first and second conductive probe segments which form a sandwich about a layer of insulating material. A current source provides a constant alternating current which is applied across the first and second probe segments. Circuitry is provided for amplifying the alternating current voltage developed across the first and second probe segments in response to the constant current. Circuitry is provided for rectifying the amplified alternating current voltage to provide a direct current voltage which is proportional to the measured resistance of the contact engaged by the probe. Data corresponding to the bulk and contact resistance associated with the clean contact is stored in memory of a computer. The bulk resistance represented by the stored data is subtracted from the measured resistance represented by the DC voltage of the contact under test in order to determine the contamination resistance.

Claims18

Dependent claims

In an electronic apparatus that tests contamination resistance of electrical contacts contained in a connector assembly mounted to a printed circuit board (PCB), the improvement comprising:

probe means for engaging said contacts, the probe means comprising a first and second conductive probe segment that form a sandwich about a layer of insulating material;
constant current source of alternating current (AC) applied across the first and second probe segments;
means for amplifying and rectifying the AC voltage developed across the first and second probe setments in response to said constant current applied across said first and second probe segments to produce a direct current (DC) voltage proportional to the resistance at the contact engaged by the probe means;
memory means for storing data corresponding to the DC voltage measured by the probe means for a clean contact, said data representing the total bulk resistance associated with the apparatus and the clean contact;
means for subtracting the bulk resistance from the resistance represented by the DC voltage of a contact under test in order to determine the contamination resistance.

2 more elements

In an electronic apparatus that tests contamination resistance of electrical contacts contained in a connector assembly, the improvement comprising:

probe means for engaging said contacts, the probe means comprising a first and second conductive probe segment that form a sandwich about a layer of insulating material;
constant current source of alternating current (AC) applied across the first and second probe segments;
means for amplifying and rectifying the AC voltage developed across the first and second probe segments in response to said constant current applied across said first and second probe segments to produce a direct current (DC) voltage proportional to the resistance at the contact engaged by the probe means;
a computer including:
means for converting said DC voltage into a digital value having a magnitude corresponding to the resistance at the contact engaged by the probe means;
memory means for storing data corresponding to the total bulk resistance associated with the apparatus;
means for subtracting the bulk resistance from the resistance represented by the digital value to determine the contamination resistance;
means for displaying the measured contamination resistance.

5 more elements

Dependencies are inferred from the claim text.

System for measuring contamination resistance

Life of this patent

System for measuring contamination resistance

Life of this patent

Abstract

Claims18