Best way to securely attach probe to a passive SMD component? - Page 1
Forum section: electronics / testgear

author: LaurentR
author_rank: Frequent Contributor
timestamp: September 26, 2017, 02:39:40 pm
content: Seeing the multiple threads on the topic, IC pin probing can be done using micro grabbers of the right size or some of the more exotic ways like the Keysight wedges or the comb probe tips.How about attaching a probe to one side of a passive SMD component (resistor/cap or other component without a real "pin" to grab on)? I have use the big grabbers, but they have a tendency to jump away at the slightest provocation as they are under a lot of tension when doing this. One could also use one of the probe holders (like the 2-legged or articuated Keysight).Are there grabbers that pinch the component hard and securely enough to stay in place? Any other solution?

author: alm
author_rank: Super Contributor
timestamp: September 26, 2017, 06:05:07 pm
content: Use a solder down probe or solder a short length of wire to the component.

author: simone.pignatti
author_rank: Frequent Contributor
timestamp: September 26, 2017, 06:26:57 pm
content: have you seen this ?

author: LaurentR
author_rank: Frequent Contributor
timestamp: September 26, 2017, 06:39:45 pm
content: Quote from: simone.pignatti on September 26, 2017, 06:26:57 pmWhich of these would you use? I have a number of different types of probe accessories and grabbers, but nothing that really stay on well on passives.alm's option is obviously the most secure (and generally easy to execute).

author: cdev
author_rank: Super Contributor
timestamp: September 26, 2017, 07:01:21 pm
content: Pogo pins are made for doing that.I've had the best luck so far making very unprofessional looking holders out of things Ive had around the house.Toys..Also, masking tape and rubber bands have proved themselves very useful in that context.. also, soldering wires temporarily.. especially for the ground.IMHO micro grabbers cant grab SMD components like they would need to be grabbed..to stay connected. They are great for through hole stuff though.Quote from: LaurentR on September 26, 2017, 02:39:40 pm

author: MarkL
author_rank: Unknown
timestamp: September 26, 2017, 07:54:48 pm
content: Keysight has an "SMD Micro grabber" which is made for clipping onto resistors and capacitors. Because it has two contacts, you can also use two of them for micro Kelvin measurements.A bit pricey at US$58.55, but it gets the job done. It can be ordered at the Keysight parts page, part #1400-3652. Or if you really want to spend some money, it's also included in the N2877A, N2879A, and other specialty probe accessory kits.http://www.keysight.com/my/faces/partDetail.jspx?partNumber=1400-3652Below are a couple of photos of it attached to a twin-lead probe adapter.EDIT: I should also note that's an 0805 component it's clipped to.

author: tautech
author_rank: Super Contributor
timestamp: September 26, 2017, 08:05:53 pm
content: For what need ?Prototyping or repair/fault finding ?If you're working with your own design, add SMD test points. 0603 are about the smallest that can be grabbed with a probe hook. Just a few are needed, a gnd and along signal path or at critical points like a PLL.When the prototype is proved unsolder the test points for reuse and/or compact the layout to final size.Working with somebody else's creation with zero thought given to fault finding or rework, get out the iron and add connection points needed.

author: Howardlong
author_rank: Super Contributor
timestamp: September 26, 2017, 09:21:21 pm
content: I use plastic spring clamps to make a tripod, but for anything that is likely to need a more strurdy or permanent connection, I get the hot pointy thing out and add a short through-hole component lead I can clip on to.For high speed probing I make up a coaxial spring setup for ground and testpoint out of wound through-hole component leads so that the probe can be slipped in.For differential high speed probing such as USB HS speeds and above, it’s typically a jury rig with elastic bands and/or kapton tape to hold the bulk of the probe and judicious tip browser adjustment. If the signal is designed to run over a cable, I make up a very short M/F breakout to intercept the signal where I can probe.

author: LaurentR
author_rank: Frequent Contributor
timestamp: September 26, 2017, 09:49:13 pm
content: Quote from: MarkL on September 26, 2017, 07:54:48 pmGreat find, I didn't know this clip existed. It looks another Hirschmann product:http://www.newark.com/hirschmann-testmeasurement/972416100/clip-test-micro-smd-black-mln/dp/67C8450

author: David Hess
author_rank: Super Contributor
timestamp: September 26, 2017, 10:03:12 pm
content: I agree with alm; solder in a test point which may be as simple as a tiny loop of thin bus bar wire.

author: nctnico
author_rank: Super Contributor
timestamp: September 26, 2017, 10:17:09 pm
content: Quote from: David Hess on September 26, 2017, 10:03:12 pmIn my experience a wire often gets loose easely and you have to power down the circuit while soldering it to the component. I like the Hirschmann clip and I'm going to order one to see if it works.

author: MarkL
author_rank: Unknown
timestamp: September 26, 2017, 10:42:05 pm
content: Quote from: LaurentR on September 26, 2017, 09:49:13 pmThat's an even better find since it's less than half the cost. The one I bought from Keysight actually has a very tiny Hirschmann logo on the handle. I didn't even notice it.Not surprising since a lot of Keysight probes are third party now-a-days.

author: cdev
author_rank: Super Contributor
timestamp: September 27, 2017, 02:38:42 am
content: Let me take this opportunity tobitchandmoanabout the practice of taking generic hardware items, attaching the world "probe" or "probe holder" or "micro manipulator" or "probe positioner" especially to them and charging around 20 times more.No way are they getting my money for clothespins.Note: I am not directing my ranting at the mechano.co.jp people whose products look both cute and useful.

author: tautech
author_rank: Super Contributor
timestamp: September 27, 2017, 04:39:43 am
content: Quote from: cdev on September 27, 2017, 02:38:42 amWhich is why I wonder if one of these can be repurposed and modded for SMD.http://www.newark.com/adaptive-interconnect-electronics/501791-b/mitten-style-telecom-clip/dp/82R5267?MER=bn_level5_4NP_LastViewed_1

author: Someone
author_rank: Super Contributor
timestamp: September 27, 2017, 08:12:15 am
content: Quote from: tautech on September 27, 2017, 04:39:43 amNo chance, those clips are very heavy and while excellent for clipping to typical wire sizes they are near useless for electronics.

author: Shock
author_rank: Super Contributor
timestamp: September 28, 2017, 04:46:37 am
content: Solder a short length of kynar wire across end of the component and clip to that, when the probe is laying in position, as you don't want to rip it away suddenly.

author: alm
author_rank: Super Contributor
timestamp: September 28, 2017, 05:37:58 am
content: Supporting the probe and having as little force pulling it is certainly key. Banana plugs are obviously out, and it helps to support the lead and possibly even the clip separately. Something like blue tack might be helpful there.

author: Berni
author_rank: Super Contributor
timestamp: September 28, 2017, 05:40:56 am
content: Quote from: MarkL on September 26, 2017, 07:54:48 pmThose clips actually look really useful.I might get one of the cheaper "clones"The way i tend to do it is just solder a tiny enamel coated wire to the part and clip my probe to the wire instead. I never found micrograbbers useful for SMD stuff. Maybe to grab a pin of a SOIC, but anything smaller is not going to work (SOICs are going extinct these days).

author: Howardlong
author_rank: Super Contributor
timestamp: September 29, 2017, 12:14:18 am
content: Quote from: Berni on September 28, 2017, 05:40:56 amI did find some clips that work on QFP 0.5mm pitch on one of my trips to Japan a couple of years ago. They are even more fragile then the normal micrograbbers. But just like SOICs, QFP are so yesterday as we all head to a leadless paradise, and soldering a wire on isn’t really that hard!

author: nanofrog
author_rank: Super Contributor
timestamp: September 29, 2017, 01:18:59 am
content: Check out what you can DIY for 3rd hands with segmented CNC hose (Loc-Line or similar), and use those to hold individual pogo pins or ready-made probes.Searching for "loc-line" will show you some posts of these sorts of things here in the forum (or "DIY helping hands" on Google if you prefer).