Products > Test Equipment
TH2830 vs TH2832
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luudee:

--- Quote from: KungFuJosh on July 23, 2023, 04:32:59 pm ---
I did the regular open/close + DCR corrections. There's no option for how many points except if you add manual spot correction.

2832D? Hmm, I wonder if that hardware is any different. 😉🤣

--- End quote ---

Not in the office at the moment, but I am pretty sure that I saw something like "correction lists" ....

Will check in 12h !


luudee
mawyatt:

--- Quote from: mawyatt on July 23, 2023, 04:31:24 pm ---Think the idea of putting anything like a small SMD cap, resistor or inductor on a FR4/Epoxy PCB to use as some "Reference" is unwise. PCBs of FR4/Epoxy or similar material change with humidity, temperature, time, handling and so on, some PCB materials are better tho, and maybe those would be acceptable.

Maybe others can comment about the different PCB materials, and the relative behavior for supporting precision SMD devices.

As mentioned above every mm counts when measuring nH, and that any equipment/cabling moves can cause measurement uncertainty, including Kelvin cables. This is why we don't use Kelvin cables for precision measurements of SMDs, even the Tweezer Kelvin types. We go so far as to do a Open Cal with an LCR SMD fixture by placing the plunger opening distance equal to the expected DUT SMD spacing, this helps capture the fringe capacitance with the plungers at the expected spacing, thus minimizing the fringe capacitance effects on the DUT measurements.

Along this line, for the Short Cal, we often use a Zero Ohm SMD of the same size/type as the expected DUT, altho not certain this is beneficial in all cases. The thinking here is that the Zero Ohm device helps compensate for the expected contact area of the SDM DUT as well as the plunger spacing and tension.

The SMD fixture plunger spacing is an interesting thought regarding inductance measurements (as well as the mentioned capacitance measurements). Since inductance is associated with length and the fixture plunger has a diameter of ~1mm (fixtures we have) and varies in length when engaging a SMD. Then a 1206 SMD that was considered a round "wire" has a self inductance of ~1.14nH (Grover's), an 0603 0.40nH, an 0402 0.22nH. So it seems that when measuring small SMD inductances doing the Short Cal with a Zero Ohm SMD might be useful.

Disclaimer we have no way of knowing if these inductors are accurate per OEMs data sheet, and did a very crude test with a small SMD inductor, 0603 10nH +-0.2nH (Wurth WE-MK type). We see a difference in the ball park as shown by Grover's estimate above relative to if the Short Cal is performed with a Zero Ohm SMD device or not.

Later if time permits we may expand on this crude test, but seems that the concept of utilizing a similar size Zero Ohm SMD for the Short Cal with a SMD fixture is worthwhile for small inductors, and spacing the plungers at the proper spacing for the Open Cal is also beneficial for small capacitances. Does anyone know if "Zero Capacitance" SMD devices exist? We've thought about just using very high resistance SMDs of various sizes for the "Zero Capacitance" equivalent, but haven't do so yet.

Best,

--- End quote ---

We just measured (Hioki IM3536) an 0603 10nH Wurth WE-MK mentioned above, the measured valued was 11.71nH when using the standard Short Cal without Zero Ohm Shunt with the SMD fixture, and with a Zero Ohm Shunt device 10.71nH. These were measured at 1MHz, so we could compare with data sheet.

Also at 100KHz so we could use the TH2830, the IM3536 at 100KHz 11.71nH without and 10.75nH with Zero Ohm Shunt used for Short Cal, the TH2830 at 100KHz produced 11.88nH without and 10.82 with Shunt.

So looks as if the Short Cal use of a Zero Ohm Shunt SMD of the same size as the inductor DUT for small inductance values has merit  :-+

Best
KungFuJosh:
Now you're making me want to try the TH2830 on the board and see if the failures in that respect are the same or not. 🤔
KungFuJosh:
I did some comparison tests with the TH2830, and the ST2832. Except for a couple failures from the ST2832, it actually outperformed the TH2830 firmware.

The largest failure with ST2832 was the 100Ω DCR measurement:


The second biggest fail was the 700mH inductor. According to their accuracy chart, between 100mH to nearly 1H should have excellent accuracy between 1k to 10kHz.



KungFuJosh:
If somebody with a 2830 wants to test, the failures on mine were:
100uF was lower than expected (100uF read as 83uF; 2832 saw it as 90uF).
100nH read as 100.045 on the ST2832, and read as 180.321 on the TH2830.
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