Test probes used in production testing will eventually get dirty enough to cause contact problems. The following steps will eliminate contact problems caused by dirty probes:
Some recommendations to help keep test probes clean:
In some cases, especially in high volume production (where the probes see many cycles over a short time) it may be practical to clean the tips of the probes. Virtually all manufacturers of low-resistance, long-life probes use some sort of lubricant to prolong the life of the probe's internal sliding contact surfaces. Cleaning a probe by submerging it in solvent will remove this important lubricant. Even spot-cleaning the probe tips with solvent can wash particles down into the critical internal surfaces where they can drastically affect performance.
To clean probe tips, remove lint, fibers, flux, and other contaminants by gently brushing the probe tips with a small brush and vacuuming away the dislodged particles. A brush with nylon or natural fiber bristles works well; metallic bristles may damage the probe plating and are not recommended.
A practical maintenance program for fixtures can save considerable time and money at the production level. Testing becomes more reliable, thus reducing the chance of false failures and lost rework expense.
Diagnosing contact problems as they arise and replacing test probes one at a time is more expensive than replacing probes on regular intervals. Use cycle counters on test fixtures to help establish a maintenance program, which calls for cleaning or replacing probes after a predetermined number of cycles.
Developing such a program requires some tracking to determine the average life of the probes in a particular application. Since test conditions vary widely, it is difficult to generalize probe life. Some applications call for replacement as often as every few thousand cycles, while probes in clean environments or applications with wide electrical tolerances can last far longer. Better test yields and reduced downtime are the rewards for keeping fixtures and probes in top condition.