Lubricated vs. Unlubricated Probes

While direct component contact is important to conductivity, sliding metallic contact will induce wear and degrade performance. QA Technology probes use a thin film of strategically placed lubricant on moving parts to minimize wear and extend probe life without any increase in contact resistance. Removing the lubricant will significantly reduce probe life and should only be used in applications outside of the probe operating temperature specifications.

Cleaning probes with a solvent is not recommended because it dissolves the lubricant on the internal parts. The use of solvents is also likely to wash tip contamination into the critical internal contact areas of the probe. For more information see Probe Maintenance.

QA Technology’s standard test probes are lubricated to increase their life. The lubricant drastically reduces the normal wear from the sliding metal-to-metal contact within the probe. There are significant performance differences between lubricated and unlubricated probes.

Test results from internal testing found that unlubricated 100-25 series probes had electrical resistance greater than 50 milliohms as early as 8,000 cycles. Three probes out of sixteen had failed by 30,000 cycles. (Note that cycle counts on a tester in a controlled laboratory environment are considerably higher than those in a production environment).

The lubricated probes were tested to 250,000 cycles with no measurements greater than 24 milliohms. Lubricated probes are routinely tested to one million cycles with electrical resistance below 50 milliohms.

Wear of the unlubricated probes generated a considerable amount of wear particles. The black wear particles were not only evident on the plunger shanks, but also formed piles around the socket bases. This wear not only results in electrical failure, but the particles also cause the probes to stick down and fail. By the end of the test, six out of the sixteen unlubricated probes (38%) exhibited stroke failures, the earliest at 40,000 cycles.

There is a significant increase in the amount of force required to compress an unlubricated probe. This observation is based on the relative condition of the contact platen after the test. The marks made by lubricated probes were almost unnoticeable, but the platen had obvious indents and damage from the crown points of the unlubricated probes. This is probably not an issue on solder pads for single board tests, but may damage gold or otherwise delicate contact surfaces. Also, the increased force may cause fixture actuation problems.