Test clips/grabbers for fine pitch ICs - Page 1
Forum section: electronics / testgear

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2017, 04:40:52 pm
content: Are there good solutions for hooking onto the pins of an 0.65mm or smaller SSOP or QFP? I have a set likethisthat are great for SOIC but almost impossible to grab onto anything smaller--or at least, you can't get them onto adjacent pins of anything smaller without shorting together or having them pop off at inconvenient times.The Pomona 72902 clips claim to work down to 0.2mm, which I find hard to believe, since it seems like even 0.5mm is going to be pushing the limits of material strength vs thickness for the leaves of the grabber and the body tube, so I'm a little hesitant to drop $15+ per clip without knowing if they'll work as advertised. Anyone know if they do the business? Or any other recommendations?

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2017, 06:33:47 pm
content: There is the style of probe that has a sprung contact on each side of an insulator (usually Kapton). When slid between two pins it provides contact to the pin on each side. They are used for high speed differential - HDMI or similar.I can't think what they are called, or whether anyone other than the likes of Tek makes them.

author: georgd
author_rank: Regular Contributor
timestamp: September 24, 2017, 06:40:38 pm
content: The called Wedge Probe Adapters:http://www.keysight.com/en/pc-1455359/wedge-probe-adapters?cc=US&lc=eng

author: Jwalling
author_rank: Unknown
timestamp: September 24, 2017, 07:32:27 pm
content: Perhaps these...Google Tektronix SMK4 or Agilent 10467-68701 or Pomona 6311

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2017, 08:09:10 pm
content: Quote from: georgd on September 24, 2017, 06:40:38 pmThose look neat, but quite spendy! Especially since they're pitch- and pincount-specific, and you'd need one for each side of an IC you want to tap into. I think I'd prefer to stick with individual grabber-style probes, since they'll be more versatile.Quote from: Jwalling on September 24, 2017, 07:32:27 pmThe Pomonoa 6311 have been superseded by the 72902 that I mentioned in the OP. The others appear to be obsolete as well, and not widely available as used/NOS. Anyway, I appreciate the suggestions, but my main question remains--I know there are probes that *claim* to work on 0.65mm ICs and smaller, but do they *actually* work reliably, especially when several are connected to adjacent pins?I suppose worst case I can get a couple of the individual Pomona 72902 clips on my next Mouser order and see how they do before deciding where or not to buy the full $250 set.

author: tautech
author_rank: Super Contributor
timestamp: September 24, 2017, 08:14:04 pm
content: The Mechano range was mentioned in a thread a little while back and I grabbed the link for future reference:http://www.mechano.co.jp/pdle2.html

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2017, 08:25:43 pm
content: Quote from: tautech on September 24, 2017, 08:14:04 pmInteresting, apparently their FP-5L are the Tektronix SMK4, and are or were sold by Chip Quik as well. They at least show photos of a bunch of their clips side-by-side on a QFP, which is encouraging. Now to figure out if they're actually available to buy and at what price...

author: RayRay
author_rank: Frequent Contributor
timestamp: September 24, 2017, 10:03:03 pm
content: You might wanna give these a go:http://www.dx.com/p/plastic-multimeter-flat-test-hook-clip-grabbers-for-pcb-smd-ic-green-20-piece-134204

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2017, 10:44:11 pm
content: Quote from: RayRay on September 24, 2017, 10:03:03 pmThose sometimes work on SOIC, but only if you get the good ones, and even then it's tough to get more than two or three on adjacent pins at the same time. They're completely hopeless for anything finer pitch.

author: alm
author_rank: Super Contributor
timestamp: September 24, 2017, 10:45:19 pm
content: The question is about 0.65mm and smaller pitch, and one of the reviews from the cheap DX hooks is "Plastic tip is too thick for SOIC pins (cannot attach three 1.27mm pitch pins in a row, two are OK)". Does not seem like a suitable product for SSOP/QFP.The Sigrok wiki has a decent overviewincluding some pictures of the probes attached to ICs. In general the good ones will work down to the pitch they specify, but may have trouble if you are trying to probe more than a few adjacent pins at a time. Obviously the small ones are much more fragile than grabbers designed for SOIC or larger.

author: RayRay
author_rank: Frequent Contributor
timestamp: September 24, 2017, 11:00:42 pm
content: Quote from: ajb on September 24, 2017, 10:44:11 pmWell, let me offer you an alternative solution then!How bout you get a 30AWG wire spool, I.E this:http://www.dx.com/p/7005-diy-pcb-copper-core-jumper-cable-wire-single-conductor-coil-blue-250m-183904Cut up a small piece of wire for each pin you wanna test, solder it to it (using 0.3 or 0.5MM solder) and an SMD-compatible soldering tip, and then hook up an alligator clip to the other end of it for measurement. I think it'd work quite well.

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2017, 11:12:33 pm
content: I've gone through enough Belden 8057 to know a thing or two about bodging wires onto ICs, thanks. At the moment I'm looking for test clips so I don't have to do that every time I want to debug a board with a QFP or SSOP.

author: RayRay
author_rank: Frequent Contributor
timestamp: September 24, 2017, 11:22:50 pm
content: Well, I guess you'll have to give those clips you've mentioned (Pomona 72902) a go then.Clips for such fine-pitch IC's are hard to find. Just get a single clip for now and see how it goes.And if it doesn't work as expected, at least you didn't shell out too much money for it!

author: Assafl
author_rank: Frequent Contributor
timestamp: September 25, 2017, 07:59:25 am
content: I was using the Machano clips today (on a SOIC so no big deal - just 4 simultaneous connections to hand hold while the scope was capturing). Not very impressive so I took a picture hooking it up to a random higher density device. Sorry for the poor quality of the pictures - hand held microscope...The models I have in the picture are:FP2S (the 4 green/yellow clips on the quad package)FP7L (the 2 white clips on the motor driver package)FP1B (only the tip is shown on the motor driver)I try not to use the FP2S - they are very finicky. But for sub 0.5mm pitch, I don't have anything better.The yellow rubber hose (called "position keeper") keeps them from slipping, especially at high pitch and "heavy" connecting wires. For really dense connections they come with a bar that keeps them aligned. Pain in the neck to connect though....

author: Gabri74
author_rank: Regular Contributor
timestamp: September 25, 2017, 10:56:04 am
content: Maybe E-Z Hook XKM?http://catalog.e-z-hook.com/item/test-hooks/e-z-micro-hooks-single-hook-style/xkm-1They are about 20€ for ten on DigiKey:https://www.digikey.it/product-detail/it/e-z-hook/XKM-S/461-1012-ND/528233

author: ajb
author_rank: Super Contributor
timestamp: September 25, 2017, 11:43:39 am
content: That's super helpful Assafl, thank you!And for what it's worth, your pictures are better than most of the ones on the Mechano website!Quote from: Gabri74 on September 25, 2017, 10:56:04 amThose are the name-brand version of the clips in the DX link earlier, good for one or two pins on an SOIC, no good for anything finer pitch.

author: LaurentR
author_rank: Frequent Contributor
timestamp: September 25, 2017, 05:23:14 pm
content: If you are probing around with an oscilloscope probe, I like the IC comb tips like this one from Cal Test:http://www.caltestelectronics.com/ctitem/35-35mm-probe-accessories/CT3676(for 0.65mm pitch)Or the Tek equivalent (which seem to be cheap on EBay).Of course, you need the probe. These exist for other types of probes.

author: Dubbie
author_rank: Unknown
timestamp: September 25, 2017, 07:48:35 pm
content: Because I am a bit agricultural sometimes, I just tack on a short stub of wire such as a through hole resistor lead trimming. Then I can use any clipsA touch with the iron and they come right off again. While not fancy, it is a secure method with no risk of shorting adjacent pins.

author: _Wim_
author_rank: Super Contributor
timestamp: September 25, 2017, 07:59:26 pm
content: Quote from: ajb on September 24, 2017, 04:40:52 pmAs a cheaper (but not cheap) alternative to the pomona's, you could buy this set:https://www.rapidonline.com/pjp-6800-8-smd-test-probe-set-17-2576I have used them for a pitch of 0.4mm, but it really takes some fiddling. In my opinion the internal spring is not strong enough, so the grabbers are not always pulled back enough, creating sometimes bad contacts. But if you open and close a couple of times, normally you get them to grab firmly. In theory you should be able to do many pins next to each other, but luckily I never had to, because that will not be easy...

author: RoGeorge
author_rank: Super Contributor
timestamp: September 25, 2017, 08:04:16 pm
content: I'll go for wire-wrap or magnet-wire soldered from the chip pins to some 0.1 inch standard pins header.The pin header is soldered somewhere on a ground plane for mechanical rigidity.Then, can attach almost anything to the 0.1 inch headers, from the lousy Chinese logic probes to oscilloscope probes, ribbon JTAG connectors, or just simply solder wires on the male headers.

author: bson
author_rank: Unknown
timestamp: September 25, 2017, 10:13:45 pm
content: There are also IC cap tips (for SOIC or bigger, obviously not SSOP), like these from LeCroy (to fit LeCroy probes):https://store.teledynelecroy.com/collections/probe-parts-and-kits/products/pk007-008-ic-cap-0-05-pitch. The little plastic horns make sure they only contact a single pin. Obviously you need to hold the probe onto the pin; they won't clip or wedge in place.

author: ajb
author_rank: Super Contributor
timestamp: September 26, 2017, 02:31:41 am
content: Quote from: _Wim_ on September 25, 2017, 07:59:26 pmThose appear to be identical to the Pomona clips--are they both rebranding someone else's clips, or did one of them knock the other off? Looks like I can get those for ~100USD, which is still a lot cheaper than the Pomona ones. Anyway, I just ordered two of the Pomona clips in today's Mouser order, so we'll see how they do.

author: LaurentR
author_rank: Frequent Contributor
timestamp: September 26, 2017, 05:24:53 am
content: Quote from: ajb on September 26, 2017, 02:31:41 amCal Test also has those in bundles of 6, 8 or 12 ($125, $160, $237 - before TEquipment discount).http://www.caltestelectronics.com/ctitem/49-clips-surface-mount-device-smd-tweezers-a-test-clips/CT2848-6These seem to be made by Electro PJP (also mentioned on the Sigrok page mentioned byalmabove):http://www.electro-pjp.com/fr/fichesearch?combine=6800The rapidonline (UK) site has the set of 8 for $100 shipped to the US. The Reichelt (Germany) site is about the same price, but also has the set of 6 which comes down to about $85 shipped to the US - all a lot cheaper than Pomona and Cal Test.

author: Gabri74
author_rank: Regular Contributor
timestamp: September 26, 2017, 10:32:31 am
content: Quote from: ajb on September 25, 2017, 11:43:39 amNope, E-Z Hook are completely different from the cheap DX clips from Chinese vendors and are often suggested as best cheap-but-decent grabbershttp://catalog.e-z-hook.com/item/test-hooks/e-z-micro-hooks-single-hook-style/xkm-1See also:https://sigrok.org/wiki/Probe_comparison

author: ajb
author_rank: Super Contributor
timestamp: September 26, 2017, 02:41:32 pm
content: Quote from: Gabri74 on September 26, 2017, 10:32:31 amMaybe we have different ideas of "completely different". The basic geometry is the same, and it's the basic geometry that's the problem. I have a whole pile of that sort of clip ranging in quality from terrible to very good, and none of them are suitable for smaller than 1.27mm SOIC.I'm not opposed to spending decent money, I just don't want to wind up with even *more* clips for SOIC and still none for SSOP. I should have the Pomona clips from Mouser tomorrow, if they look good then I'll probably order the set from Rapid. If not, it'll be time to look for the Mechano.

author: ajb
author_rank: Super Contributor
timestamp: September 27, 2017, 02:47:08 pm
content: Got the Pomona 742902 clips today. Photos attached showing them hooked to an SOIC and a TSSOP. I made sure to include a bodge wire in the photo just to prove that yes, I am capable of soldering magnet wire onto leads.Unfortunately I'm still not impressed with these clips for 0.65mm pitch. The photo has a bit of glare that makes it look like there's a gap between them, but they are actually touching. It might be possible to finagle two adjacent clips into a position where they wouldn't touch on this IC, but three or more in a row wouldn't work out so well. I'd say this particular part has roughly typical width leads for this package size; there's on SSOP on this board that has particularly thin leads, and on that the clips work substantially better. These would be quite good for SOIC, but I don't see how they can claim that these will work on ICs down to 0.2mm pitch.Guess it's time to look for the Mechano clips.