Soldering to strange metal contacts.

[daedalux]

To soft solder that surface easily, scratch the surface lightly in a criss cross pattern, add resin based flux, and then tin the surface well. Then tin the cable, flux again, and press the soldering iron on the tinned cable over the solder blob that you tinned in the surface. Once melt remove the soldering iron while keeping the wire in place a couple of seconds for the joint to solidify.

[Ian.M]

I had a similar experience with these pretty terrible grabbers.  Got a pack of 10, two wouldn't take any solder at all, the rest did, but took some roughing up with fine sandpaper and some flux.  I have no idea what the metal is, or if it is copper underneath, but most of them soldered reasonably well.  I have no idea about the two odd ones.

Mine are definitely spring steel, however their attraction to a magnet is a bit lower than I would expect from ordinary carbon steel, and they show no tendency to rust where I've handled the contacts, so I would suspect they are a low grade stainless steel.

Trying to directly soft-solder stainless steel with ordinary flux is an exercise in frustration.  You *may* get somewhere with acid zinc chloride flux, (aka: 'killed spirits of salt'), but that stuff is very corrosive and removing the residue after tinning the surface is a PITA, and any remaining trace will rot away your wire or rust out the spring contacts.  Copper flash plating it as I described above takes a few seconds and makes it readily solderable with ordinary RMA flux core soft solder .

[Fraser]

You have to wonder who manufactures an electronics grabber that cannot be easily soldered to a test cable..... someone who does not give a damn about quality or the end user, that is who  No wonder these grabbers are the cheapest of the cheap. Maybe the manufacturer just buys the cheapest sheet metal material available at a particular time and that dictates whether the grabbers are soft or harder ‘spring’ metal and whether or not they can be easily soldered to a cable 

[jchw4]

Electroplating worked really well. Thank you!

The project: https://www.eevblog.com/forum/testgear/the-ultimate-kelvin-grabbers/

[Ian.M]

You don't need to electroplate as copper plates onto iron or steel chemically by substitution on contact with a copper salt solution (immersion plating), with no external electrical circuit or power supply required.  Electroplating is only required if you need a thicker copper layer, but that's not a particularly good idea, as without the correct additives in the bath, and good control of current density, the resulting copper deposit can be fluffy or otherwise poorly adhering.   This may result in failure if the solder joint to the copper layer is stressed.  The thinner copper layer from immersion plating will almost totally dissolve in the solder leaving a good solder to steel bond

[Buriedcode]

You don't need to electroplate as copper plates onto iron or steel chemically by substitution on contact with a copper salt solution (immersion plating), with no external electrical circuit or power supply required.  Electroplating is only required if you need a thicker copper layer, but that's not a particularly good idea, as without the correct additives in the bath, and good control of current density, the resulting copper deposit can be fluffy or otherwise poorly adhering.   This may result in failure if the solder joint to the copper layer is stressed.  The thinner copper layer from immersion plating will almost totally dissolve in the solder leaving a good solder to steel bond

I was gonna say, self-plating generally produces poor adherence (sometimes with a void between base metal and the reduced plating metal) but it seems in this instance it just needs enough to help the solder take.

Gonna try this on the last two I have, I'm sure I've got some CuSo4 somewhere.

[Ian.M]

Yes.  Its similar to what happens when you solder ENIG plated pads.   As you no doubt know, the gold flash plating on top of the nickel dissolves almost instantly in the solder, leaving a solder to nickel joint.

[jchw4]

Yes.  Its similar to what happens when you solder ENIG plated pads.   As you no doubt know, the gold flash plating on top of the nickel dissolves almost instantly in the solder, leaving a solder to nickel joint.

This is interesting point, I'll try it next time.
I am worried though that the plating did not initially appear uniform mostly attracted by the sandpaper scratches.
I wonder whether slower chemical plating will make it more even, but I'll try. Thank you!

[cdev]

I had a similar experience with these pretty terrible grabbers.  Got a pack of 10, two wouldn't take any solder at all, the rest did, but took some roughing up with fine sandpaper and some flux.  I have no idea what the metal is, or if it is copper underneath, but most of them soldered reasonably well.  I have no idea about the two odd ones.

Mine are definitely spring steel, however their attraction to a magnet is a bit lower than I would expect from ordinary carbon steel, and they show no tendency to rust where I've handled the contacts, so I would suspect they are a low grade stainless steel.

Trying to directly soft-solder stainless steel with ordinary flux is an exercise in frustration.  You *may* get somewhere with acid zinc chloride flux, (aka: 'killed spirits of salt'), but that stuff is very corrosive and removing the residue after tinning the surface is a PITA, and any remaining trace will rot away your wire or rust out the spring contacts.  Copper flash plating it as I described above takes a few seconds and makes it readily solderable with ordinary RMA flux core soft solder .

This is good to know.

Very low current/voltage right?

-----

Also, since we're on the subject of grabbing metal to metal. I am looking for the smallest alligator clips (solderable) that I can find. They are for RF. They don't have to be fancy, just good quality, identical in size and small. Often I have to move the point of contact to get a good match mark it so I can solder a wire there. So I just want a good solid pair of clips, so I can buy 20 or so of them for my text fixtures that connect to baluns, etc, and be done with it. Most of the alligator clips I've got are too big. This isnt for GHz range its for HF, VHF and UHF use in concert with my vna.

[Doctorandus_P]

I agree with most of the above, but have not bothered to try to solder to these cheap garbage pins.
They are quite bad and there is not much they can grab.

For breadboard use I prever to connect my logic analyser with the simple "dupont" wires.
For other uses I've bought a box with 10 or so separate grabbers.
Also relatively cheap chinesium, but when you pay arond EUR10 for a bag of 10 you get much better quality grabbers, and they're well worth the extra money.

But these grabbers also do not work properly on for example a 0.5mm QFP, and on QFN you have no luck at all no matter how good your grabbers are.

I do however always have a hot iron ready when I'm working with electronics.
My solution is to add a male IDC connector with a dab of hot glue to the PCB and then use enameled 0.2mm copper wire to temporarily solder between pins and the IDC connector.
Because the IDC' connector is glued to the PCB, the stress on the wires is negligible and once the tips of the 0.2mm enameled wire is tinned, they solder easily.
And then, from that IDC connector I can easily use a short flatcable to my logic analyser.

[cdev]

I have two identical inch long clips that I use for balanced RF when I need a connection to that. It works reasonably well but I know this clip is not going to last a long time.. And its a bit too big. This is why I would like to find a manufacturer of small robust identical clips..  There really isnt any. There are all kind of the same cheap metal alligator clips being sold. The ones that I am using are made I think in the US. "EZ-MINI HOOKS" The mini grabbers from China don't grab tightly enough to make a good reliable connection. They are likely fine for logic analysis but not so good for use as an RF interconnect, unbalanced to balanced interface. Which is what I am trying to use the clips for. I am also looking for a better kind of wire to use for the hookup. I'm currently using clear speaker wire. It works out to around 100 ohms impedance. This is my demarkation point, to be used as the "measurement plane" at HF frequencies for HF stuff...

[cdev]

I use IDC connectors to add test points to anything that I need to connect to what I am using for my MSO, which currently is an old bitscope...

It came with a 24 pin IDC header (pod connector) which it uses as its logic probe input, so I am just using that.

It works okay for now. Although I am not sure how long I will use it. I already had some IDC connectors that I had gotten to use for Raspberry Pi GPIOs.. (old style) But they don't always make a positive connection to the first pin.. I must be doing something wrong.

I agree with most of the above, but have not bothered to try to solder to these cheap garbage pins.
They are quite bad and there is not much they can grab.

For breadboard use I prevfr to connect my logic analyser with the simple "dupont" wires.
For other uses I've bought a box with 10 or so separate grabbers.
Also relatively cheap chinesium, but when you pay arond EUR10 for a bag of 10 you get much better quality grabbers, and they're well worth the extra money.

But these grabbers also do not work properly on for example a 0.5mm QFP, and on QFN you have no luck at all no matter how good your grabbers are.

For logic probes you can use the chinesium grabbers which in my lab, vary a lot from one to another. Thats okay.

But for RF I need two completely identical clips. So I am always struggling to get clips for mesurement that I feel are identical, and robust in their grabbing ability. I think I have tried all of them by now. Solder is the best way to connect a wire, temporarily..


Connecting to the differential input, which is really sensitive, is difficult and easy to mess up.  This is really hard.. Even if you immediately attempt to glue the wires down..

Like the connection for HF RF on an RTL2832 is just to pins 4+5 on the RTL chip. I can solder this but it never lasts long, as even the slightest movement will detach it.

>I do however always have a hot iron ready when I'm working with electronics.
My solution is to add a male IDC connector with a dab of hot glue to the PCB and then use enameled 0.2mm copper wire to temporarily solder between pins and the IDC connector.
Because the IDC' connector is glued to the PCB, the stress on the wires is negligible and once the tips of the 0.2mm enameled wire is tinned, they solder easily.
And then, from that IDC connector I can easily use a short flatcable to my logic analyser.

You are better at this than I. For RF I think what may work better is dual RG-174 with a third clip for ground in the middle. Its certainly better than speaker wire.

[m3vuv]

I have brought cheap grabbers in the past,total garbage,hooks bend easly,does anyone know where i can get better ones?,i brought some bnc to grabber test leads,they were about £5 each but had nice grabbers,i need to buy just the grabbers not the bnc leads included.tia.

[cdev]

No I don't. I had a weird interaction with the Chinese supplier of these hooks.. which were individually - several bucks apiece, but thats what they charged.. each one precious.. I could tell the guys I was dealing with understood where I was coming from but they had no source of better. These EZ-hooks are as good as it gets. For RF its even worse..

The ones I have used (semi-successfully) are the ball shaped X-100 SKU.. The force they grab with is enough to keep the wire connected and the clip still..    They make other hooks, that may not be as good for this specific use.. (RF measurement)  I went looking for a photo of the ones I use, and wasnt able to find the exact same kind.. the photo is of some similar hooks, but slightly different. These have a little J hook.. That works better than the dual sided grabber hooks for me..

[antenna]

If you can remove the metal from the plastic, braze the surface first.

[Ian.M]

If you can remove the metal from the plastic, braze the surface first.

<LOL>
That would destroy any chance of them having any spring temper or even work-hardening, turning the contact fingers back into Chineese soft steel noodles

[antenna]

quench it again. not hard when its already hot.  Besides, you could put it in a vise stopping the heat from reaching the finger.
edit: <lol>

[Ian.M]

What's wrong with my suggestion in reply #20 of flash plating them with immersion copper, and photo as evidence of success?


Why do *YOU* feel the need to mess around heating small bits of very thin spring steel held together by a brass rivet to brazing temperatures?

Also, fully extracting the contacts of the style I have shown from their plastic shell, then reinserting them without damaging them, while possible, is a PITA.

[antenna]

Nothing at all. I was just offering a suggestion that didn't involve toxic chemicals.  I do like your suggestion (and thought I hit the like button on it - looking back, i guess i didn't, sorry).  I didn't think an alternative option would offend you, didn't know this was a competition for best idea...

The only reason I do not particularly like the method you suggest is that it contaminates the etchant with other metals and proper disposal of copper salts at home requires tossing in aluminum foil and waiting DAYS for it to displace the copper to be environmentally safe to flush.  I use copper chloride all the time, but only to etch copper because I can add HCl and bubble air through it to reactivate it.  Adding contaminant metals interferes with the recycling process and I do not particularly like starting over with a bottle of etchant that has served me well for over a decade.  And before my statement about aluminum turns into a pissing match with how fast other metals displace copper, I use it because the end product is not a water soluble chloride salt (like iron, zinc, nickel etc), it forms an insoluble oxide.

It's a great idea, you win.

[Ian.M]

You raise some very good points re: disposal of contaminated etchant, but in the quantities needed to wet a Q-tip or a couple of ml in a bottle cap, as I used to dip the above grabber top, it isn't an issue for hobby use - wipe the few drops remaining up with kitchen paper, bag it and trash it.  OTOH if you are at any sort of business that produces hazardous waste, *ALL* hazardous waste must be disposed of properly and most importantly LEGALLY.  Also I forgot to emphasize that you need to avoid contaminating your 'stock' bottle of whichever copper salt solution - I thought that would be obvious to anyone who remembers their college chem, but maybe I'm too optimistic?

On the contaminated copper etchant disposal side of things, as a hobby user, why are you trying to recover copper metal using aluminum? Unless you have a use for very fine copper powder, surely it would make more sense to precipitate it out as basic copper carbonate using sodium bicarbonate or as copper hydroxide using lime, then mix the sediment with cement and powdered limestone and cast it in disposable containers to lock up the copper salts as a solid lump in an alkaline environment that will keep them insoluble.

[antenna]

I agree that the small amounts a hobbyist would require are negligible, but that's not what hobbyists do. They grab the most convenient kitchen pyrex bowl and fill it to a sufficient depth without considering what happens to the solution when finished.  You make good points about the carbonate and hydroxide, as both are also mostly insoluble, but I live on a lake with water on 3 sides in an area with a particularly low soil pH, so I like bringing it back to the metallic state just to do my part.  Sure, acid rain will turn any copper metal into nitrates eventually and still get into ground water, but I like to think that takes far longer than reacting with carbonates and hydroxides.  Nonetheless, I agree with you in that there are safe alternatives to aluminum, circumstances allowing. That is just what I choose because it seems to be my best option - and I have the time to do it.  My concern is that 99% of the people on this forum that use copper salts as etchants or plating solutions don't even consider the issue.  I agree that your solution is probably the best and the easiest for a hobbyist and it wasn't my intent to go off on an environmental rant, I was just defending my alternative suggestion.  I support and recommend your suggestion.

[Ian.M]

Yes, I see where you are coming from, and hobbyists who mix up a bucketful of *whatever* when they only need a thimbleful are certainly part of the problem.   

Given your local ecological concerns, you should probably look into smelting your copper powder, maybe with whatever solder dross you accumulate to lower its melting point and make low-grade bronze, as that would lock it up for far longer by vastly reducing the surface area to volume ratio.

[antenna]

I do have a pill bottle full of various solder blobs that wiped off the tip of my iron onto my sponge (yep, I save 'em).  Well, one thing is for sure... I'll be forever labeled a fish-loving tree-hugger here, lol.