Low-thermal EMF Solder

[texaspyro]

You don't want to make CdSn solder in a metal pot, particularly one that has been used with lead.   The metal residue gets into the solder.  Even small amouts of contaimination kills the low thermal magic.    I made mine in a ceramic crucible stirred with a quartz rod.  I cast the solder into a semi-circular wire cross section using a machined ceramic mold.

[MisterDiodes]

I've made my own cadmium solder. I used it to solder copper wire into audio copper banana plugs. You can get the materials off of eBay. Then, a good scale and a cheap solder pot will give you a lifetime supply (obviously, you could self-limit the lifetime...). The solder pot tins the copper, and you can leave enough on there to complete a joint. Not as convenient as flux in, of course, but I don't plan on making many joints wth it.

At first glance I thought you were going to tell us abut the improved "sonic clarity" of the cad-solder, and how much "brighter and more defined" the sound was.... 

Yes a little Cd solder is handy, but not needed most of the time if you have an excellent mechanical copper to copper connection first (at that point the solder isn't even in the circuit) or if you have balanced connections at the same temp where the thermal EMF's tend to cancel anyway.  Otherwise if you have LESS than an ideal mechanical / balanced thermal situation, it does help - a little, at uV levels.  Sometimes you need that.

[martinr33]

I have some banana plugs from the audiophile world - they look like hollow tubes, and are gold on silver on copper. I use a drop of the CdSn solder to secure the inner conductor of the coax to the inside of the plug.

[ap]

I have some banana plugs from the audiophile world - they look like hollow tubes, and are gold on silver on copper. I use a drop of the CdSn solder to secure the inner conductor of the coax to the inside of the plug.

The hollow tubes (spring type copper alloy) are based on CuBe. CuBe has a worse EMF than CuTe. If you want low EMF (which I have doubts you do measure, tbh), you better start with CuTe, no need for SnCd. Or in other words, any potential effect of the SnCd will be covered by the CuBe EMF (which, again, you probably will not see anyhow, unless, it at all, you are working in the 100nV and below range/resolution; i.e. a 34420 or the like). And secondly, a EMF voltage in the small solder spot you mention will only be generated if there is a temperature delta accross it. In such a small spot obviously pretty impossible. The CuBe will equalize all temperature delta over the spot's lenght/cross section of a few millimeters only.
One can do many things every day, some of which make more, some of which make less sense. The use of SnCd is pretty much on the bottom of that scale.

[stijena1973]

Why 60/40 Cd/Sn?  The standard lowest thermal EMF solder is 70/30.

A few years ago, I had to make my own Cd/Sn solder, but I had a proper lab to do it in.  I'd love to get some real Cd/Sn solder.  I know what it is, what it does, when and where to use it, and how to work with it.  It's a very special purpose stuff, and not some use-it-everywhere-everyday material.  For certain applications, there is no substitute that works as well.   Companies that made precision metrology test equipment used to stash a small spool of the stuff inside the equipment that they sold... and not without good reason.

According to (Fig1) :

https://iopscience.iop.org/article/10.1088/0950-7671/36/11/413/pdf

and noted also in table "Values of constants"

If Your ABSOLUTE temperature is 27C, then 75Cd/25Sn is appropriate.
If Your ABSOLUTE temperature is 38C, then 70Cd/30Sn is appropriate.
If Your ABSOLUTE temperature is 53C, then 65Cd/35Sn is appropriate.

Assuming that temperature inside Your device is around 40C then 70/30 is composition to go.

If You are using it inside heated oven then 65/35 or even 60/40  is better,

because zero coefficient is limited to that narrow range of temps (Neutral pt. in table "Values of constants" )

[stijena1973]

Okay,Simon, I don't want to argue,respect your decision, you have the right to ban any person you think irregularities.

I am not a businessman, I am a serious semiconductor engineer. Just wanna try this solder in several experiment to get test data.
This solder wire is not recommended for general applications? I just want to help people who really need it. (Anyway, you never have to use. It's so rare,especially the wire shape. Most people who need it are in this section)
This material is not environmentally friendly, but it is not illegal.  This thread is just a order aggregation thread~~(but NOW OVER)

I saw disdain for the Chinese in your lines and I am not happy about it.  so disappointed~

I hope it is a misunderstanding,thank you!

BG5TOX(XuDa)

hello,

i second that.

if the "Global Moderator"'s rules required to ban this user, it could have been done in a (much more) civilized manner.

regards.

-zia

They are not the global Moderator's rules they are the admins rules i.e. Dave. I'm not quite sure what was uncivilised about the banning. If I deem a poster to be breaking the rules or otherwise disrupting the forum I simply click ban on their profile there is no civilised or uncivilised way of doing it. I click ban on their profile. I could have locked the topic and that would be the end of that but because I didn't want to be uncivilised I left it open for discussion and I have not banned the returned original poster and in allowing the discussion to continue. How more civil due want me to be? I don't know what the rules in China are about such substances but in the EU you can't just sell this stuff over-the-counter which is what made the original post look even more dodgy.

I think the member wanted to initiate "Group Buy", not to sell anything.  As I understood the text, he wanted to order a batch from the factory which imposes 20kg minimum order.

Then he offered to resell the surplus in chunks of 500g. What is wrong with that?

I saw a lot of similar initiatives during years, for anything from ltz1000 chips to PCBs.  How this is different?

[BradC]

I saw a lot of similar initiatives during years, for anything from ltz1000 chips to PCBs.  How this is different?

You are replying to a thread that is nearly 2 years old now. It's done, dusted and all the arguments had and settled long ago.