Failure Analysis Lab performs Electronic Failure Analysis

Array of Pogo Pins

Top of Pogo Pin at Mag. 30 X

Cross sectioned Pogo Pins at Mag. 5 X

Read Consulting Failure Analysis Labs often perform electronic failure analysis for various manufacturers. The objective is to determine the root cause of the failure and help the manufacturer correct the problem.In this case, a company that assembles an array of Pogo connector pins into an instrument for multiple contacts. Some of the Pogo pin arrays are hand soldered into the equipment; other arrays are assembled using a wave solder machine. The wave soldered arrays had poor contact. Initially we were told that there were two shipment lots of Pogo pin arrays, and it was thought that  one was bad. Read Consulting tested a representative sample from both lots and could find no difference:
1. Through the optical microscope the pins from both lots were found to have good gold plating. On the upper left is a  photomicrograph of the surface of a "bad" pin.
2. In both cases testing the Pogo pins with a needle showed good contact all through the instrument.
3. Samples were cross sectioned and both lots showed good plating on the interior of the Pogo pins. Center photomicrograph.

The client was advised that there was no bad lot. It was suggested that the Pogo pins be wiped with isopropyl alcohol and retested. This test was successful; therefore one must conclude that a contaminant film settled on the contact surfaces during the wave solder operation. The alcohol wipe was added to the procedure.

California Failure Anal

California Failure Analysis lab performed an electronic failure analysis on Pogo pin spring loaded contacts (Pogo connector pins) to determine the cause of intermittent open circuits. Electronic testing had detected that there were times when the spring loaded pin was depressed, the circuit would open and there would be an interruption of the signal. The cross section of a single Pogo (upper left) showed that the  the structure was entirely made of gold plated parts (pin, spring and outer
 case).  However, there was some concern that the inner wall of the case
was defective. For additional failure analysis, a sample case was split open (photo-micrograph on the right) and the inner surface was found to have horizontal machining marks,  not be plated, to be corroded and contaminated with plating salts. These plating defects indicate that the intermittent contact problem will worsen with time. These results are not surprising since the case is really a deep blind hole, and this makes it impossible to properly clean and plate  the interior. The vendor being analyzed is an overseas vendor that was to replace a reliable US supplier. These parts are unusable.