Measurements in the nanohenry range. Tweezer FNIRSI ST2 and others.

[mawyatt]

A 5nH measurement isn't really believable with such an instrument, at any test frequency.

And what's the minimum inductance that LCR tweezers can or should measure?

As we've tried to help you over and over again, as many others have, low Z and high Z components are difficult with tweezers. The tweezer data sheet should show a error graph like Grandchuck has shown, or at minimum should state the lower and upper ranges of measurement.

5nH inductive reactance at 100kHz is 0.003Ω, at 10kHz it's 0.0003Ω, at 1kHz it's 0.000003Ω

Would think a reasonable measurement Z range for quality tweezers and measurements would be 0.1Ω and above with careful attention to detail, this equates to 160nH @ 100kHz, 1.6uH @ 10kHz and 16uH @ 1kHz.

You always bring a  when you show the 5nH Inductance Tweezer measurement with 100 femto Henry resolution (yes that's femto Henries!!), see post #18. Here's the image

Please spend some serious time studying the physics of components, the methods of measurement, the instruments and the range of such. Then and apparently only then will you begin to understand the ridiculous tweezer measurements you keep claiming. Listen to what folks here are trying to say and help you with, instead of ignoring such!!

Best   

[iet]

Here is the error/accuracy chart for the East Tester ET4401 LCR meter.

I made myself three test boards with inductors. This makes it possible to test the range, various values, and resolution of any meter at any frequency up to 100 kHz. This way, I solved the problem of measuring the L parameter.

[mtwieg]

A 5nH measurement isn't really believable with such an instrument, at any test frequency.

And what's the minimum inductance that LCR tweezers can or should measure?

The ST2 specs for inductance measurement are shown in the attached image. It doesn't even provide any accuracy specifications for inductances below 1uH, at any test frequency, which should be a hint.

That doesn't mean the meter can't/shouldn't display values lower than 1uH or precision less than 1nH. But it doesn't mean you should actually believe those measurements are accurate or that precision is valid.

Depending on your purposes, you might not need accuracy on the nanohenry scale, just repeatability. And if you're very careful, it might be possible to make measurements repeatable on the order of +/-5nH from day to day and week to week (probably not possible with the kelvin leads though).

[iet]

The ST2 specs for inductance measurement are shown in the attached image. It doesn't even provide any accuracy specifications for inductances below 1uH, at any test frequency, which should be a hint.

All these tweezers like FNIRSI, ZOYI, and others don't even list resolution in their tables. Although the LCR Pro1 and LCR Reader do.
It's time for these companies to quickly get up to the standard of high-end tweezers.

[iet]

That doesn't mean the meter can't/shouldn't display values lower than 1uH or precision less than 1nH. But it doesn't mean you should actually believe those measurements are accurate or that precision is valid.

Depending on your purposes, you might not need accuracy on the nanohenry scale, just repeatability. And if you're very careful, it might be possible to make measurements repeatable on the order of +/-5nH from day to day and week to week (probably not possible with the kelvin leads though).

Therefore, to be confident in the measured value, I checked the result with other devices.
You're right. I need repeatability. And I don't need to measure nanohenries every day. I just need to be confident that when such measurements are needed, I can count on them, even if there are no other devices nearby.
The ST1 usually does a good job of measuring inductances up to 100 nH.

[iet]

To check the nanohenry range, you don't need to search for or buy inductors. This can be done another way. Take, for example, a copper wire with a diameter of 1 mm. Cut the following pieces (mm): 5, 10, 15, 20, 25. This should correspond to the values ​​in nH (100 kHz, 1 V).
5-10 nH
10-20 nH
15-30 nH
20-40 nH
25-50 nH

[mawyatt]

2X ranges in inductance doesn't build much confidence in a "reference" component to use for evaluations/comparisons!!

How are tweezers going to connect to a 25mm long wire, you will need to bend the wire....how does this effect inductance!!

You need to get quality inductors and get quality measurements of such (not tweezers) with quality fixtures before considering them as "references"!!

Instead of wasting time with all this, consider using such time in studying the physics of components, their measurements, and the instruments that make such measurements. Then and only then will you begin to understand what everyone is telling you here....forget nanohenry inductance measurements with tweezers

Best

[iet]

Now the results of measuring the inductance of these pieces of wire. FNIRSI ST2 tweezers.

[mawyatt]

You need to contact NIST, CERN, and WMO with your amazing reference devices, instruments, skills and techniques!! 

Here's our latest measurement capability

Best

[mawyatt]

Now the results of measuring the inductance of these pieces of wire. FNIRSI ST2 tweezers.

So FNIRSI (which is a highly respected and exceptional OEM TE supplier) has specified the ST2 to have a 5% +-3 digit accuracy at 100kHz with a minimum inductance DUT range of 1uH-10uH, which equates to slightly worse than +-50nH for a 1uH inductor.

Now because FNIRSI is such a highly regarded OEM TE supplier, we all know they are much better than their specs indicate, just like Keysight, Fluke, Hioki and Keithley. So in the hands of an exceptional individual they can achieve remarkable results, even with crude DUT components, well beyond what the spec limits indicate!!

With this in mind could you please get a FNIRSI DMM (DST-210) and make some temperature drift and long term stability measurements to compare with some voltage references like the LM399, ADR1399, LTZ1000, ADR1000 and Ref80. Selecting a 1N754 or 1N4736 zener diode as a replacement could save lots of $ on reference devices, and with your remarkable measurement skills the FNIRSI could replace/supplement the expensive DMMs to measure such!! Think about it, you'll become and instant world-wide Metrology hero

BTW could you measure the ST2 tweezer test current magnitude with a low Z DUT component (like a short or 0.1Ω resistor)?

Best

[mtwieg]

Now the results of measuring the inductance of these pieces of wire. FNIRSI ST2 tweezers.

What you're actually measuring is the inductance of the loop formed by the tweezer arms and the wire, not just the wire.

Even if you do a zero cal, the zero cal will have the tweezer arms touching each other, therefore the loop area they form will be different compared to when they measure the wire segment. So the displayed inductance still wouldn't reflect the inductance of the wire segment itself.

Measuring very small inductances accurately is a pain, especially when the terminals if the DUT are far apart.

BTW could you measure the ST2 tweezer test current magnitude with a low Z DUT component (like a short or 0.1Ω resistor)?

I would also be curious about this as well.

[mawyatt]

Getting low inductance requires getting things very close together, while getting low capacitance requires getting things further apart, but doubt the OP will accept any of this. Certainly hasn't accepted anything from anyone so far, started from measuring milli/uΩ out to 3 (or more) places some time ago. Awhile back recall a measurement of 1.000 milliΩ (maybe 1.0000 milliΩ) with tweezers and claiming this level of repeatability over and over, then on to femto farads, and now to nano/pico henrys all measured with these magical tweezers (even some were DIY tweezers)!

Best

[2N3055]

It is very simple.
Science requires double blind studies.

If you know how much instrument SHOULD show (according to your expectations), you tweak , rotate and press less and more, until it shows what you expect.
I guess this is in effect here.

I have LCR Pro 1 Plus, for a few years now. I love it. It is very handy. Very useful and I think they were worth the high price.

But they are instrument I use to check if this is 1 or 2,2 kΩ resistor. Is this 10µH or 47µH coil? 1% error is not important at all.
It can show DF and ESR, which can catch bad capacitors almost 100% of the time.
It can light up LED and show me polarity.

If it dies on me I will try to repair it or would buy new one.

Measuring 10 µΩ or 50 nH with it and trust results ? Not with the current physics.
When you are measuring, every time you short the tweezers, it shows different numbers. Measurement noise is several mΩ from uneven handheld contact resistance alone. Convert that to complex impedance at frequencies in question and you cannot be better than that.
But with steady hand and having a firm and unwavering intention what number you want to see, you can train yourself to show what you want.
As we can witness.

[iet]

What you're actually measuring is the inductance of the loop formed by the tweezer arms and the wire, not just the wire.

Do you also have ST2 tweezers?

[iet]

But they are instrument I use to check if this is 1 or 2,2 kΩ resistor. Is this 10µH or 47µH coil? 1% error is not important at all.
It can show DF and ESR, which can catch bad capacitors almost 100% of the time.

There's no need to buy expensive tweezers for this. A regular, inexpensive multimeter will do. The same applies to µH. The inexpensive ST1 can easily handle this.
DF and ESR: The ST1 will also show where the faulty capacitor is.
Also, many people make their own ESR meters. You can even do without LCR tweezers.

[mawyatt]

A couple of us would like to know this:

BTW could you measure the ST2 tweezer test current magnitude with a low Z DUT component (like a short or 0.1Ω resistor)?

Best

[iet]

Inductors-3 test boards.
1 nH and 5 nH inductors are on separate boards.

[mawyatt]

A couple of us would like to know this:

BTW could you measure the ST2 tweezer test current magnitude with a low Z DUT component (like a short or 0.1Ω resistor)?

Best

Hey iet!!

How about providing your Tweezer measurement test current magnitude, a couple of us (maybe more) would like to know

Anyone else with these FNIRST ST2 tweezers be kind enough to measure the tweezer short/low Z test current, a few of us are curious about the level used? Anyone please

Best

[mawyatt]

Our Zoyi MD-1 tweezers measure about 5ma rms test current @ 1kHz and 10kHz, which seems reasonable as they are tweezers and not powered by an 18650 cell!! Some bench LCR meters use over 100ma rms to get enough voltage across low Z DUTs for reliable/repeatable measurements.

Anyway, interested in other tweezers test current levels and specifically the FNIRSI ST2 

Best

[jonpaul]

chi tweezer will not work.


See HP , Waybe Kerr app notes on inductange measurement.

Test freq needs to be in MHz range.

j

[mtwieg]

Do you also have ST2 tweezers?

Respectfully, one does not need to own the tweezers to know their principle of operation. All the other LCR meters (tweezers or whatever form factor) have the same issue.

[mawyatt]

As we all know, you need high current to reliably measure low Z components. Nano henry inductors require higher frequencies and higher currents to produce a reasonable Z*I product vector voltage which the instrument/tweezer actually measure. High frequencies and currents are something tweezers can't deliver. We paid $5K for the Hioki IM3536 (8MHz) to have that capability in-house (literally), along with our Tonghui TH2830. At even higher frequencies VNAs are the appropriate instrument of use.

Tweezers are great for identify and getting a ball park component value, and not intended for precision use. What we've seen so far is micro-Ω, femto-Farad and now nano/pico Henry precise/repeatable tweezer measurements at 10/100kHz, which isn't realistic.

Somehow any of us can't seem to get the message across as these posts of amazing tweezer measurements, with ultra-precise reference components, on highly stable fixture/platforms keep coming.

Anyway, it's all good for morning entertainment and still brings a 

Best   

[iet]

See HP , Waybe Kerr app notes on inductange measurement.

A beautiful device.
I'd be interested, and I think many others would be too, to see how the WK3255B inductance analyzer works. It's even more interesting to see how it works with tweezers.
The datasheet clearly shows how it's made. Two 1-1.5 mm fiberglass plates. I'd like to see how they grip the 0402 inductor.
The ST2 tips aren't very thin at the tips either, making them uncomfortable. Therefore, for measuring very small inductors, I made other tips more suited to these dimensions.
I would recommend FNIRSI make an optional pair of tips, similar to the LCR Pro1. Then, you can customize the ones you need when purchasing.
In other words, make three pairs of different tips.
https://www.waynekerrtest.com/products_detail.php?indexs=10&brand=Wayne%20Kerr
https://www.waynekerrtest.com/datasheet/accessories/40120%20SMD%20Tweezers%20issue%20A.pdf

[iet]

HIOKI has some good tweezers. They work with components as small as 0.3 mm.
https://shop.hioki.eu/HIOKI-IM9902-CONTACT-TIPS

[radiolistener]

With this in mind could you please get a FNIRSI DMM (DST-210) and make some temperature drift and long term stability measurements to compare with some voltage references like the LM399, ADR1399, LTZ1000, ADR1000 and Ref80. Selecting a 1N754 or 1N4736 zener diode as a replacement could save lots of $ on reference devices

Indeed, the issue is not the FNIRSI accuracy — it is clearly the excessive drift of LTZ1000/LM399-class references. They are simply not stable enough to match the resolution of a properly calibrated DST-210.

This is why the industry urgently needs a new class of ultra-stable reference: the FNIRSI Quantum Reference (FQR-1), factory-trimmed against the internal 100 kHz inductance standard of the ST2.

Early simulations suggest that using a 1N4736 zener as a transfer standard actually improves long-term stability, because its thermal drift is naturally "averaged out" by the DST-210 measurement algorithm. 

It also indicate excellent agreement between different FNIRSI units, confirming full traceability to the FNIRSI internal reference framework, as consistently observed on the instrument display, aided by proprietary measurement visualization and interpolation algorithms.

Once this reference is adopted, IC like the LTZ1000 can finally serve their true purpose — as portable temperature sensors for calibrating the FNIRSI ecosystem.