Hello All,
We need your support on below query.
We are following the worksurface STM4.1 standard to measure the all jig’s/fixtures. However sometimes the surface of small fixtures/jigs is not sufficient to keep the resistance meter electrode for Point to Point & Point to ground measurement.
Your advice and support required for how we can measure and qualify those fixtures where the PCBA resting area is too small to perform PTP & PTG measurement by using electrode equipment.
Rahul,
You could clamp a conductive plate to the small fixture and then use the 5 lb probe.
You could also use alligator clips or bull nose clips to attach to the fixture. Although the amount of contact to the fixture would be less, it may be good enough to pass your testing limits.
Hello Mr. Andy,
We have been using alligator clips, but most of the time, we have observed variations in the measurement readings, and sometimes the readings are showing out of limit.
Are there any guidelines in the ANSI/ESD standards regarding this ? I have reviewed all the reference ESD standards but couldn’t find any.
Your support is always appreciated.
Rahul,
Sorry, I don’t know of any ESDA documents that give guidance on using clips for bonding. Thanks.
Hello,
Greetings of the day from India
In my view for small areas where neither the two 5 lbs probes nor the concentric probe could be used , two-point probe per ANSI/ESD STM 11.13 would be applicable per ANSI / ESD TR53-01-22 (7.4.3) and IEC 61340-2-3 (10.2.1)
However, ESDA expert’s views will be good to consider
Thank you
I agree with GN if you are trying to measure the resistance of the fixture itself at the place you put the probe. If you are trying to measure the point to ground resistance of the fixture, the two-point probe won’t do this.
Thank You Mr. Andy .
Please let me know your views on my following views
” Can we not Rg test with two-point probe by connecting one lead of the resistance meter to Gnd like we do with one 5 lb probe on surface and the other from the meter to gnd as the built in second probe may get by passed? “
Maybe it would work but I can’t quite picture what you are saying. Thanks
The two point probe might work as long as the probe connected to ground did not touch anything else. If it did touch the mat or another part of the fixture then the ground connection could be bypassed.
I might try using copper tape to the fixture and then use a clamp or an alligator clip to the copper tape and the other end to ground. Not exaclty the same measurement but it should work.
Mr. Andy & Mr. John K ,
Respected Sir/s,
What I want to say is that, “on the small area of the testing surface the two point probe is placed and one port of the two point probe is connected to one port of the resistance meter and the lead from another port of the meter to ground” Can this not work for Rg test of the surface as the second port of the two point probe is open and it may bypass the second contact point on test surface ?
Regards
That may work if you have a two-point probe with two leads that can independently connect to the resistance meter. My two point probe couldn’t do that.
If you are able to independently connect each point, you would then either shunt the two points together or leave one point floating. I am not sure you would get much more of a contact area than an alligator clip, but it may be worth trying if you have the right equipment
Greetings of the day from India
Thank you Andy Sir for your suggestion
Thank you Andy.
Just wanted to confirm if there are any specific alligator clips for ESD measurement, as the standard mentions using two-point probes for packaging trays.
Rahul,
There is no suggested alligator clips that I know of, likely because it is not preferred to get good contact. Like John said above, “try using copper tape to the fixture and then use a clamp or an alligator clip to the copper tape and the other end to ground.” This should give you the best chance to make the measurement
Thanks a lot Andy for support and clarity on measurement.