A customer came to Paragon with a switch plate assembly consisting of several custom, lighted switches wired together and terminating into a 12 position plug.
The LEDs which illuminated the switches would frequently stop working and would present random false illumination issues. Activating one switch could cause the LED on a different switch to light. The switches themselves would also seem to activate intermittently without having been pressed.
In our analysis of these issues, Paragon discovered that the offshore switch manufacturer our customer was using had employed a dropping resistor that was rated for less than 1/5th of the required power dissipation. The under-rated resistors were getting hot enough to re-flow the solder joints within the switch causing the issues with intermittent LED illumination. To correct this, Paragon was able to source the custom switches through an alternate domestic switch manufacturer which solved the issue while also improving the switch’s overall quality and reducing the cost.
The intermittent activation or malfunction of some assemblies were then quickly identified to be caused by nylon cable ties being cinched too tightly on Teflon insulated wires during harnessing. The excessive pressure of the cable ties over time would cause the Teflon insulation to cold flow to the point that some wires could form intermittent shorts inside the harness. At Paragon’s suggestion, the design was changed from the use of nylon cable ties to using lacing tape, eliminating the pressure on the wires.
In the end, Paragon was able to reduce the failure rate from nearly 15% to less than 1%, and reduce the per assembly cost by almost 6%.