KELVIN CONTACT FAILURES

Guest

Would like to know from this forum if anyone have experienced problems on KELVIN CONTACT FAILURES. The failure is denoted by a resistance reading above the set Kelvin limits.

If yes, what are the possible known causes.... hope you could help me...
i'm quite new on this....

KELVIN Jr. Twisted Evil

Guest

Kelvin Jr.,

In a Kelvin contact system, there are 4 contacts involved - two for forcing the excitation (the 2nd one is the return path) and two for sensing the response (the 2nd one is again for the return path).

Ideally, the contact resistance between these contacting points and the DUT pins is zero. If the resistance exceeds a certain limit, then you get the failure. Anything that can make the resistance go high at any of these 4 points will lead to failure.

Worst case is open circuit at any of these 4 points. This is easy to analyze. Possible causes: broken wire, broken contact finger, broken board trace, EOS, loss of contact due to total misalignement, etc. - anything that can open up the path.

If none of the 4 Force/Sense paths are open, then check which one has a high resistance and why. Possible causes: dirt, oxidation, wear-out, reduced contact due to misalignment, condensation, etc.

Note than errors in your excitation and measurement instruments can also lead to failures.

To summarize: 1) measure the resistance of each of your 4 paths so you'll know which one is failing; 2) determine what's causing the high resistance.

Good luck, mah friend!

Testing 123