Post by thread:[EE] Soldering nichrome wire

>Doesn't work so well, does it? > >Particularly the little teeny tiny stuff? >Say, 75 micron diameter? > >The alternative is silver paint. Not a >bad alternative, but solder would make >me feel better. Crimp it. Use something like a D series pin as a crimp lug on it - has the advantage that you can then solder to the other end of the pin if need be, or "just" put the pin into a shell to use as the connector.

> >Doesn't work so well, does it? > > > >Particularly the little teeny tiny stuff? > >Say, 75 micron diameter? > > > >The alternative is silver paint. Not a > >bad alternative, but solder would make > >me feel better. > > Crimp it. Use something like a D series pin as a crimp lug on it - has the > advantage that you can then solder to the other end of the pin if need be, > or "just" put the pin into a shell to use as the connector. Crimp causes a weak spot- the wire tends to bend at the crimp and break off. The reason for adding the extra length of wire is to offset the force from the nichrome. I may try it, though, just to see how it goes, but the crimp method has already proved...troublesome...with with steel wire of four times the diameter. Mike H.

>Crimp causes a weak spot- the wire tends to bend at >the crimp and break off. The reason for adding the >extra length of wire is to offset the force >from the nichrome. OK, The only time I have seen nichrome soldered was after some soldering points had been brazed on, effectively tinning the nichrome with some brazing, and then one could solder to the brazing.

On 12/8/05, Alan B. Pearce <spam_OUTA.B.PearceTakeThisOuTrl.ac.uk> wrote: > >Crimp causes a weak spot- the wire tends to bend at > >the crimp and break off. The reason for adding the > >extra length of wire is to offset the force > >from the nichrome. > > OK, The only time I have seen nichrome soldered was after some soldering > points had been brazed on, effectively tinning the nichrome with some > brazing, and then one could solder to the brazing. Maybe now is a good time for me to learn to use our microforge... Although in the grand scheme of this little project, I think the solder/ braze/paint/crimp question may be the easiest to answer. Mike H.

At 06:59 AM 12/8/2005, Mike Hord wrote: >Doesn't work so well, does it? > >Particularly the little teeny tiny stuff? >Say, 75 micron diameter? Believe it or not, I've had good results with standard (relatively) tin-lead solder with Kester 282 or 285 flux (don't remember which). I've got several rolls of the stuff for exactly that purpose. Hit the Kester website and look up both of those flux numbers - one of them will be what you are looking for. I can send you a few feet of solder for you to try if you want, along with the exact Kester part number. dwayne -- Dwayne Reid <.....dwaynerKILLspam@spam@planet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 21 years of Engineering Innovation (1984 - 2005) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.

On Dec 8, 2005, at 5:59 AM, Mike Hord wrote: > Doesn't work so well, does it? > > Particularly the little teeny tiny stuff? > Say, 75 micron diameter? Yeah; a common problem in the amateur rocketry crowd. there are apparently some nasty special fluxes than can help (zinc chloride?), but a lot of effort gets expended on other solutions... BillW

> Hit the Kester website and look up both of those flux numbers - one > of them will be what you are looking for. I can send you a few feet > of solder for you to try if you want, along with the exact Kester part number. Thanks, but no. I have a fairly pressing need for this. I just went with the silver paint option. We'll see how well it works- I'll be passing mere microamps through this, so it should be okay. Mike H.

On Thu, 8 Dec 2005, Mike Hord wrote: {Quote hidden}> On 12/8/05, Alan B. Pearce <A.B.PearceKILLspamrl.ac.uk> wrote: >>> Crimp causes a weak spot- the wire tends to bend at >>> the crimp and break off. The reason for adding the >>> extra length of wire is to offset the force >>> from the nichrome. >> >> OK, The only time I have seen nichrome soldered was after some soldering >> points had been brazed on, effectively tinning the nichrome with some >> brazing, and then one could solder to the brazing. > > Maybe now is a good time for me to learn to use our microforge... > > Although in the grand scheme of this little project, I think the solder/ > braze/paint/crimp question may be the easiest to answer. Can't you electrochemically deposit something on the wire ends that can be soldered ? Like Copper or Silver ? Peter

> Can't you electrochemically deposit something on the wire ends that can > be soldered ? Like Copper or Silver ? Maybe. I do have a tin-plating electrolysis kit here, somewhere. Gets tough, though. For a sense of scale, before I strip the insulation off this wire, it is 3/4 as thick as a hair from your head. After the insulation is gone... Mike H.

On Thu, 8 Dec 2005 12:19:37 -0600, you wrote: >> Hit the Kester website and look up both of those flux numbers - one >> of them will be what you are looking for. I can send you a few feet >> of solder for you to try if you want, along with the exact Kester part number. > >Thanks, but no. I have a fairly pressing need for this. I just went >with the silver paint option. We'll see how well it works- I'll be >passing mere microamps through this, so it should be okay. > >Mike H. Paint doesn't have much strength - conductive epoxy is a lot better

50 odd years ago when fixing range elements we used "Easyflow" a silver solder, wires twisted together and hard solder applied only on the twisted wire. Be sure to remove all the flux. Ian ----- Original Message ----- From: "William Chops Westfield" <.....westfwKILLspam.....mac.com> To: "Microcontroller discussion list - Public." <EraseMEpiclistspam_OUTTakeThisOuTmit.edu> Sent: Friday, December 09, 2005 5:57 AM Subject: Re: [EE] Soldering nichrome wire > On Dec 8, 2005, at 5:59 AM, Mike Hord wrote: > >> Doesn't work so well, does it? >> >> Particularly the little teeny tiny stuff? >> Say, 75 micron diameter?

> What kind of insulation is this & how do you strip it? > > Joe Some sort of epoxy or enamel, and I strip it by very carefully scraping the wire with a scalpel under a microscope. Then, it gets fed through a 100 micron ID, 150 micron OD silica tube, which gets fed through a slightly larger piece of hypodermic tubing. Did I mention that it needs to be EXACTLY 50mm long, no more no less?* Additionally, the wire that I'm affixing to it is not much thicker (~.005"), and stranded with 30 strands. Stripping that is not too much easier- the only way I've found to do so is to take a really sharp scissor close partway, and draw the wire back into the crotch such that the sharp edges dig into the insulation and tear it off. Some days I really wish I could just, say, have a TSSOP package to solder... Mike H. *Hmmm...a hornet's nest...and a stick! ;-) Actual tolerance is +/- .2mm.

you might try thermal strippers. For the enameled stuff there is also a chemical stripper I used to use. Dip the wire end then wipe. Worked very well but may be one of those wonderful things that is so dangerous it was taken off the market. It has been years since I needed it but it would not hurt to check into it. Larry {Quote hidden}> > From: Mike Hord <mike.hordspam_OUTgmail.com> > Date: 2005/12/09 Fri AM 09:54:01 EST > To: "Microcontroller discussion list - Public." <@spam@piclistKILLspammit.edu> > Subject: Re: [EE] Soldering nichrome wire > > > What kind of insulation is this & how do you strip it? > > > > Joe > > Some sort of epoxy or enamel, and I strip it by very > carefully scraping the wire with a scalpel under a > microscope. Then, it gets fed through a 100 micron > ID, 150 micron OD silica tube, which gets fed through > a slightly larger piece of hypodermic tubing. Did I > mention that it needs to be EXACTLY 50mm long, > no more no less?* > > Additionally, the wire that I'm affixing to it is not much > thicker (~.005"), and stranded with 30 strands. > Stripping that is not too much easier- the only way I've > found to do so is to take a really sharp scissor close > partway, and draw the wire back into the crotch such > that the sharp edges dig into the insulation and tear it > off. > > Some days I really wish I could just, say, have a TSSOP > package to solder... > > Mike H. > > *Hmmm...a hornet's nest...and a stick! ;-) Actual tolerance > is +/- .2mm. > > --

>> Can't you electrochemically deposit something on the wire ends that can >> be soldered ? Like Copper or Silver ? > > Maybe. I do have a tin-plating electrolysis kit here, somewhere. Gets > tough, though. For a sense of scale, before I strip the insulation off this > wire, it is 3/4 as thick as a hair from your head. After the insulation is > gone... Spot weld with emphasis on controlled pressure with 'mushroom' electrode ? Peter

On Dec 9, 2005, at 6:54 AM, Mike Hord wrote: > Did I mention that it needs to be EXACTLY 50mm long [+/- 0.2mm] Is that 50mm between the near ends or the far ends of the connection? I don't think I'd trust anything other than a crimp to not affect the resistance of a piece of nichrome to the equivalent of .2mm; don't you have to worry about solder and/or conductive paint wicking along the surface and changing the effective length? BillW

On 12/8/05, Mike Hord <KILLspammike.hordKILLspamgmail.com> wrote: > Doesn't work so well, does it? > > Particularly the little teeny tiny stuff? > Say, 75 micron diameter? > > The alternative is silver paint. Not a > bad alternative, but solder would make > me feel better. Not much better than a room temperature polimerizable silver paste. cheers, Vasile

> > Did I mention that it needs to be EXACTLY 50mm long [+/- 0.2mm] > > Is that 50mm between the near ends or the far ends of the connection? > I don't think I'd trust anything other than a crimp to not affect > the resistance of a piece of nichrome to the equivalent of .2mm; don't > you have to worry about solder and/or conductive paint wicking along > the surface and changing the effective length? Okay, I'll give up a little more info. The fact that it's nichrome is incidental, and not a necessary component in the design. It just happens that the only wire we have which is suitably biocompatible and small enough is nichrome, and the time constraints of the project preclude ordering something else. It's a neuro electrode, meant for tickling a very specific part of a neural circuit. Hence the need for precision in length: without the ability to see where the tip of the electrode is, we can only judge based on past experience and precision in surgical guide implantation. The wire is glued into a silica tube, inserted into a piece of hypodermic tubing. The distance from the tip of the electrode to the end of the hypo tubing is what needs to be so precise. The problem is that a weak point forms at the end of the silica tube, and the electrode tends to bend and break there. I've finally given over on joining a wire to it, and I'm just crimping on an Amphenol pin, pulling a little heatshrink over it for strength, and praying. Mike H.

At 03:31 PM 12/10/2005, Mike wrote: ><snip> >Okay, I'll give up a little more info. The fact that it's nichrome is >incidental, and not a necessary component in the design. It just >happens that the only wire we have which is suitably biocompatible >and small enough is nichrome, and the time constraints of the >project preclude ordering something else. > >It's a neuro electrode, meant for tickling a very specific part of a >neural circuit. Hence the need for precision in length: without ><snip> Have you considered (copper) acupunture wires? ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: RemoveMEralTakeThisOuTlcfltd.com Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causas scire" ================================================================

> Have you considered (copper) acupunture wires? No, and they would probably work quite well. Part of the current problem is flexibility (too much) and the fact that the wire comes off the spool with a bit of a curve to it, which leaves the electrode curved, too. I'll look into for future use. Thanks for the suggestion! Mike H.