Contact Inspection Technique

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A Technique for Visual Inspection of Contact Marks
Robert W. Young
4/21/06

Introduction: The following is a technique used for visual inspection of contact marks. When
investigating intermittent contacts or contact alignment, this technique gives some insight from
visual inspection. This technique is not a substitute for electrical testing but may give insight into
why some connections have a high failure rate. The advantage of this technique is that it does not
leave a contaminant on the connector. The component can be used after the treatment if the
visual inspection is acceptable. The Harness connector can not be re-used and must be discarded.

Equipment needed: Dry Erase Marker (must be dry erase) and a microscope or optics for
magnification.

Technique: Below are the steps and supporting pictures of this technique.
1.Obtain samples for study i.e. general inspection, COV, DOE etc…

Figure 1.A. Electronic Control using RAST Figure 1.B. Sensor (OWI) using RAST
2. Gain access to the contact pads / area to be viewed. Some components may require partial
disassembly.
3. Apply the dry erase marker to the pads to be studied. Best technique is to apply at a right angle
to the PCB land that will be studied.

Figure 3A Application of dry erase marker to PCB lands.
A Technique for Visual Inspection of Contact Marks
Robert W. Young
4/21/06

4. Re-Assemble the electronic assembly into it’s housing.
5. Attach the connection to be used in the appliance.

Figure 5A RAST connection on Board Figure 5B RAST on sensor (OWI) housing.
6. Remove connection, and then remove housing to gain line-of-sight to the PCB lands.

Figure 6A. Treated Contacts on PCB Lands. Figure 6B Clean contact marks (good).
No contact made prior to application of harness. Well centered side to side and in far enough
up on the land to make proper contact.
A Technique for Visual Inspection of Contact Marks
Robert W. Young
4/21/06

Figure 6C Unacceptable contact marks on edge of land and not deep enough on the connector.
Contacts are not centered and not in correct position to withstand normal variation.

Figure 6D Unacceptable marks on edge and some indication that there is the potential for
intermittent contact. Contacts are not centered and not in correct position to withstand normal
variation.

7. All contacts can be cleaned with a cloth or tissue. The harness may not be re-used for normal
operation.