Monitors Causing OQA Failures

Guest

Hi, I'm not new in semicon but I'm new as a Test engr. We have testers that have large monitors beside the output rails. Sometimes we get OQA failures which we couldnt explain. Someone said that the monitors might be the cause for the units failing but did not explain why. Is this possible?

DUTcom

Posted: Thu Jul 24, 2026 10:35 am Post subject:

Hello DUTcom,

Welcome to the forum!!! Since you are only asking if monitors (you're referring to CRT's, right?) can damage your units, then I would say that yes, it is possible for CRT's to do some damage. However, I can not tell you how probable or likely that this is really the cause of your problem.

CRT's radiate electric fields that can charge up the various layers of your device circuits to different voltage levels, depending on many factors. Although the net charge inside each of these layers would still be zero, the voltages come from the imbalance of charges that arises when the field attracts charges of one polarity to its side and drives those of opposite polarity to the other side.

Now there are two ways for damage to the circuits to occur. First, the electric field may be so large that it can cause very thin dielectric layers to break down and rupture. This can happen if the dielectric is sandwiched between two layers that have charged up to different voltage levels, resulting in a large potential across the dielectric. An example is when one layer is grounded and the other is floating.

Another possibility is when the units get into contact with a grounded surface after they've charged up inside the electric field. A good candidate for this is when they slide down the output rails you mentioned, which I presume to be grounded.

Note that the two possibilities above assume that the CRT's are close enough to the units to charge them up. This depends largely on how far or how close your CRT's are to the units. If you think that this is really the cause of your problem, then just move your CRT's away from the units. Remember, no charge, no discharge!

Good Luck and keep on posting!!!

EE

Joined: 19 Jun 2026 Posts: 8

dutcom, i doubt dat ur problem's caused by ur monitors. based on our experience, ur test prog is more of a suspect. do FA on ur units and see if there's eos damage.

maximus

Guest

FA found nothing, thats the problem. Failure is just marginal offset. It also isnt there all the time, so its hard to analyze. Maybe its really the monitors. TY to all.

DUTcom

Guest

First what type of device your dealing with.

I think you're refering to LTX synchro tester? That's not close enough to produce what EE had said. Maybe somewhere around the tester is, or maybe the TP.

You can do some experiment on this, but still I insists that CRT will not effect your testing, except if your product is ULTRA LOW VOS, even a simple flourecent lamp will produce such offset.

Flipflop

Guest

i agree with flip-flop. you may want to consider the type of device you're dealing with. if it were an rf device, it's possible that the cause of your device's failure is not the crt, but rather some electromagnetic inteference coming from cell phones and the like. if that were the problem, it can be resolved by proper shielding of your test system.

Guest

even cameras sa production line.... Yung security cams.... nakakaapekto yun