Need  "flying wire" probes for small feature PCB probing? - Page 1
Forum section: electronics / testgear

author: Faringdon
author_rank: Super Contributor
timestamp: December 17, 2022, 10:59:15 pm
content: Hi,AYK, when you probe a PCB with small chips and res/caps on it, you have to solder a "flying wire" to the 0603 resistor or whatever , and then clip the scope to that flying wire.We do this with a twisted pair of kynar wire, ..but then find the scope cannot be connected to the stripped ends of the kynar as the kynar is too thin.......but we need it thin so we can solder the other end correctly to the small feature PCB......so therefore we solder 2cm pieces of 0.7mm tinned copper wire to the kynar ends, and then connect the scope probe "hat" and gnd clip to these 0.7mm pieces...However, the 0.7mm tinned copper wire pieces keep falling off.We have thought of wrapping the kynar round the tinned copper wire, (then soldering it to the 0.7mm) and also wrapping some of the kynar insulation too.....then taping that to the tinned copper wire (or heatshrinking it), but that will mean ages spent making such probes.Is there anything offtheshelf like this?We searched but cant find.

author: alm
author_rank: Super Contributor
timestamp: December 17, 2022, 11:27:30 pm
content: The big scope manufacturers like Lecroy, Keysight and Tektronix have been making active probes with solder down tips for a while. I don't know if the B brands like Rigol have caught up with these yet. These tips provide optimal signal integrity, but you probably won't like the prices.As intermediate, good passive probes will have (optional) adapters to5025 mil square pin connectors, which can be connected to small grabbers such as the EZ-Hook XKM series that will grab better to thin wires.

author: tautech
author_rank: Super Contributor
timestamp: December 17, 2022, 11:32:28 pm
content: Quote from: alm on December 17, 2022, 11:27:30 pm25 mil actually is the standard grabber size.

author: alm
author_rank: Super Contributor
timestamp: December 17, 2022, 11:53:04 pm
content: Quote from: tautech on December 17, 2022, 11:32:28 pmYou're right, fixed.Does Siglent have solutions forsolder in probes, orpassive probe to 25 mil square pin adaptersthat have prices not quite as eye-watering as the A brands?

author: Martin72
author_rank: Super Contributor
timestamp: December 17, 2022, 11:58:50 pm
content: Hi,I got these ones :https://warwickts.com/1298/PJP-6800-KIT-Micro-Pincer-SMD-Clip-KitsThey are very, very small...Post pics later on.

author: Martin72
author_rank: Super Contributor
timestamp: December 18, 2022, 12:08:31 am
content: Additional:I remember at our lab one of our engineers got this from sensepeek:https://www.batronix.com/shop/measurement/pcb-holder/sensepeek/4019-PCBite-kit-SP200.htmlDirectly connection to the scope (probes 100 or 200Mhz) and the needle tips are really like a needle...Can make pics from it next week.

author: tautech
author_rank: Super Contributor
timestamp: December 18, 2022, 12:26:56 am
content: Quote from: alm on December 17, 2022, 11:53:04 pmNo but there are some bits and bobs that come with their $ active probes:https://siglentna.com/products/accessories/probes/active-probes/Check the manuals for the lists of accessories.In the past I've cobbled various solutions together at basically zero cost for personal use but now we keep a couple of Pintek's Pro model probe in stock just for the accessories they come with:Won't attach as a pic:http://www.pintek.com.tw/customer/pintek/product/CP-3501R-PRO-b.jpg

author: tautech
author_rank: Super Contributor
timestamp: December 18, 2022, 12:48:08 am
content: If the PCB density is not too high 25 mil square pin can be soldered instead of wires and flying leads with 25 mill crimp on sockets used for connect.Fitting SMD test points are the proper way to design in the first instance for which 0805 can be easily hooked onto with scope probes or if you need higher density go to smaller and use grabbers.Trace clearances are the only restrictions to dropping a SMD test point pad onto the PSC in the layout stage.https://www.keyelco.com/category.cfm/Test-Points-Tips-Probes-Clips/Test-Points-Surface-Mount/id/523

author: Martin72
author_rank: Super Contributor
timestamp: December 18, 2022, 09:51:58 am
content: QuoteReally small...

author: alm
author_rank: Super Contributor
timestamp: December 18, 2022, 01:13:03 pm
content: Sigrok has anice comparison of clips. But the main problem here is how to hook up the clips to a scope probe. Many passive probes either come with or have optional twin-lead adapters that adapt them to square pin connectors, but apparently not Siglent or Rigol probes. Probe tip sizes, and the dimension and location of the grounding sleeve, are not universal, so using adapters from other brands is a gamble.There is nothing complicated about these, but the probe tip connector is uncommon, and you want a minimum of bulk, weight, and length, so something like a probe tip to BNC adapter, then a BNC socket, and then wires is sub-optimal.

author: JehTeh
author_rank: Contributor
timestamp: December 18, 2022, 09:33:22 pm
content: I have a collection of sensepeek probes that I really can't recommend enough. They offer passive scope probes up to 500MHz, as well as just low speed 'DMM' pogo probes, and they all work fantasticI use them often on boards with 0.5mm QFPs and lots of 0402 components with zero issues. I have not had to solder on a test lead in ages.

author: Faranight
author_rank: Unknown
timestamp: December 19, 2022, 06:24:27 am
content: Oh yeah! Sensepeek all the way. Gets a recommendation from me as well. I have zero regrets buying ithttps://easyengineering.eu/wp-content/uploads/2022/09/200126_Sensepeek39125_head-1024x1024.jpg

author: Nusa
author_rank: Super Contributor
timestamp: December 19, 2022, 07:25:50 am
content: I'd just pull out my old wire wrap tool and wrap wires to square header pins. They're close enough to wire wrap pins to work, and that's what kynar wire was used for in the first place, way back when.

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2022, 04:12:19 pm
content: I use 30 gauge kynar insulated wire wrap wire for the same thing. Better oscilloscope probes have no difficulty grabbing it, and there are micro sized oscilloscope probes which are better yet.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 19, 2022, 04:48:34 pm
content: Quote from: Faranight on December 19, 2022, 06:24:27 amof course we seldomly regret buying expensive stuffs... btw i made my own probes (2nd prototype.. those with colored rings) the grabbers can perfectly grab directly to smd components, but i dont feel like damaging them with many clip unclip and wiggles, so flying wires there are...

author: luudee
author_rank: Frequent Contributor
timestamp: December 20, 2022, 04:31:31 am
content: I made my own adopters for the tiny clips.