Discussion : SMD Test Fixture (Two terminals, Kelvin connections type) - Page 1
Forum section: electronics / testgear

author: BravoV
author_rank: Super Contributor
timestamp: March 16, 2016, 07:51:14 am
content: Always drooling on those pro 2 terminals Kelvin connections SMD test fixture, like the one used for benchtop LCR meter or resistance measurement, they are always pricey, even used.Btw, I mean here is not SMD Kelvin tweezers or clips, but the fixture such like the attached photo below as example. (Randomly grabbed from Google) and I'm aware there are so many types of them.Whats your favorite ones or mostly used ? Or any DIY or even ghetto made one ?Please share your thought/experience or discuss about it here.Also, really appreciate if any you that have access/own this precious tool, please, if its not too troublesome, post few close up shots where its in action, like before/after the DUT is installed.Really want to build one for my bench top LCR meter, hopefully can gather thoughts, ideas or designs from you all.TIA

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 08:21:59 am
content: Cheaper one, it's not 4-wires, but I guess that it can be modified:http://www.tequipment.net/ExtechLCR205.aspA DIY Idea using two male micro USB connectors (see below).Maybe not the best solutions, but I hope that this helps in some way.

author: BravoV
author_rank: Super Contributor
timestamp: March 16, 2016, 03:30:33 pm
content: Carrington, thanks for the reply.Yes, I'm aware of those tweezers or clips, but those are merely for quick measurement for handheld application.What I'm looking for is a firm test fixture for holding the DUT long enough and have reliable contacts during measurement, this is needed when doing profiling or like scanning the DUT which sometimes will take a while.

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 01:55:50 am
content: Quote from: BravoV on March 16, 2016, 03:30:33 pmYou are welcome.Quote from: BravoV on March 16, 2016, 03:30:33 pmLook this beast:Link:https://www.skgautomation.com/model-570-precision-test-fixture.htmlAbout its price, probably a lot money.But look here:http://www.wilcocontrol.comThey probably have something more economical, I have seen a kit for less than $100.They can easily make something like this:

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 02:15:03 am
content: Perhaps someone dares to do something using parts from a old DVD/CD, PCBs, and some plastic parts.But, I don't!

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 17, 2016, 02:44:14 am
content: I've got one of these:http://www.ebay.com/itm/NEW-LCR-RCL-METER-TEST-FIXTURE-FOR-SMD-COMPONENT-/351672522740?hash=item51e150d7f4:g:lGYAAOSw7I5TsiWfI'll post a picture of the insides. It isn't suitable for very high frequency measurements, as will be apparent!

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 02:52:50 am
content: Quote from: The Electrician on March 17, 2016, 02:44:14 amProbably not, because of its internal construction. Internally it's a bit dodgy, I've seen it, but I don't have any image.

author: BravoV
author_rank: Super Contributor
timestamp: March 17, 2016, 07:39:44 am
content: Carrington, yeah, I'm aware of those commercial fixtures, especially the metal beast, simply way beyond my league I'm afraid.About salvaging the old optical drive parts, or printers for making the fixture, hey, thats actually a good idea.Quote from: The Electrician on March 17, 2016, 02:44:14 amAlso curious about the materials used, like the white plastic, I guess its PTFE isn't it ? And of course the internal constructions too if its possible. Many thanks in advance.About frequency, my LCR capable of sweeping up to 1 MHz, is it too high for that ?

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 18, 2016, 08:21:15 am
content: Here are pictures of the fixture I got from China. I did just a bit of testing, and it looks like the maximum upper useful frequency is about 1 MHz, maybe.

author: iampoor
author_rank: Frequent Contributor
timestamp: March 18, 2016, 08:24:17 am
content: Is anyone aware of an 0805 socket? I know Peak made a sot-23 adapter for there analyzers. Looked pretty nice an not too pricey!

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 09:15:39 am
content: Quote from: BravoV on March 17, 2016, 07:39:44 amFrequency: DC to 40MHzDC Bias:+/- 40V peak max (AC+DC)Operating Temperature: 0 to 55 degrees CTerminal Connection: BNC, 4 terminal-pairDimensions(approx.): 128(W) x 60(H) x 71(D)mmSMD Test Fixture Selection TableSource:http://www.keysight.com/en/pd-1000000045%3Aepsg%3Apro-pn-16034E/test-fixture-smd-components

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 09:17:39 am
content: Quote from: The Electrician on March 18, 2016, 08:21:15 amGood pictures, not bad!The one I saw was not the same.

author: BravoV
author_rank: Super Contributor
timestamp: March 19, 2016, 10:08:21 am
content: The Electrician, thank you so much !Interesting construction, noted, especially the middle plate of the internal construction between the two terminals, is the plate's purpose for reducing the parasitic capacitance of the fixture it self ?

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 19, 2016, 10:47:08 am
content: I would assume so. I haven't seen the inside of a real Agilent version, but those long unshielded wires from the BNC connectors to the contacts are limiting high frequency performance.

author: BravoV
author_rank: Super Contributor
timestamp: March 19, 2016, 11:44:14 am
content: Quote from: The Electrician on March 19, 2016, 10:47:08 amAbout the limiting factors, is that because of not using PTFE wires ? Or anything else ?Btw, about the 4 coax outer shields, they're all connected internally like that, is that a good enough ? Or there are even better method ?The reason I ask this is because I saw the cablings inside the genuine Fluke PM6306 RCL external measurement box, it has separated ground wire, the black wire that is screwed to the box's chasis.Image of Fluke/Philips 9542A adapter box.Courtesy of forum member : HighVoltage

author: hexamer
author_rank: Newbie
timestamp: November 23, 2019, 06:57:16 pm
content: Quote from: Carrington on March 16, 2016, 08:21:59 amSorry for resurrecting this zombie thread, but I wanted to report back on something.I found this thread because I was thinking about DIY'ing something for my BK-880. The Extech LCR205 mentioned here looked exactly like what I wanted to do, but it was reported that it's not Kelvin connected. That makes sense since the EX-200 LCR meter it was built for isn't Kelvin either AFAICT. I found it very reasonably priced on Amazon so I bought it and some 1.2mm 2 sided PCBs in the hopes that I could modify it to be Kelvin connected. When it arrived I was surprised to see that it did have both sides of the PCB plated, so I put it in my BK-880 and it works great. Took it apart just to see how it's constructed - apologies for all the dog hair in the pics!EDIT: Well ... it was reasonably priced. For some reason the one I bought was $31.58 USD with Prime. Now it's $79 from the same sellerHope this one holds up!