solder to brass connection?
solder to brass connection?
(OP)
First off, I'll confess that I know little about electrical. I'm a mechanical engineer that has the following situation:
A PCB which has a gold trace on it. This gold trace is flat and doesn't always protrude high enough above the PCB. The gold trace is intended to make contact with a brass housing for which the PCB sits inside. We press these parts in an assembly, and this is how the connection is finalized.
We have found a simple fix where we solder around the gold trace, giving us the same exact shape, except now it is proud in the shape of a dome (no longer a flat profile) running about .001" to .003" above the PCB. We are still pressing these together (the solder is cool and hard by the time they are pressed together).
And we get great results!
However, I'm concerned with the longevity of a connection using solder and brass. How will this fair against corrosion?
The solder is lead-free (if this helps).
My official question is... has anyone ever heard of this, or know of an example I can research? Are there any considerations when using solder to brass connection?
May many blessing and good luck fall upon you for helping me :)
evolD
A PCB which has a gold trace on it. This gold trace is flat and doesn't always protrude high enough above the PCB. The gold trace is intended to make contact with a brass housing for which the PCB sits inside. We press these parts in an assembly, and this is how the connection is finalized.
We have found a simple fix where we solder around the gold trace, giving us the same exact shape, except now it is proud in the shape of a dome (no longer a flat profile) running about .001" to .003" above the PCB. We are still pressing these together (the solder is cool and hard by the time they are pressed together).
And we get great results!
However, I'm concerned with the longevity of a connection using solder and brass. How will this fair against corrosion?
The solder is lead-free (if this helps).
My official question is... has anyone ever heard of this, or know of an example I can research? Are there any considerations when using solder to brass connection?
May many blessing and good luck fall upon you for helping me :)
evolD





RE: solder to brass connection?
I think you may have some serious longevity issues using your fix.
Gold does not oxidize. This why crows like it!
Solder material most definitely oxidize. The oxides that form are almost all insulators. If the voltage is high enough it will 'punch thru' the oxides and you won't notice the problem. If you have low voltages then those voltages cannot punch thru and you can get opens circuits.
If your connection somehow is 'gas tite' then this can prevent the oxidation from occurring due to a lack of oxygen getting to the joint.
Keith Cress
kcress - http://www.flaminsystems.com
RE: solder to brass connection?
You can submerge this assembly in a gas or a fluid and it is at least very resistant due to the press fit and potting after the press fit.
However, our products operate in the worst conditions, such as the oregon coastal range in the middle of winter. Also, our customers don't feel an overwhelming need to care or properly stow the products due to an exceptional reputation only preceeded by a lifetime warranty.
The voltage is low. We use a 1/3N battery. So we're talking 3 Volts.
RE: solder to brass connection?
You say you pot this thing?
If so can you just solder the joint? Press fit then solder.
Keith Cress
kcress - http://www.flaminsystems.com
RE: solder to brass connection?
RE: solder to brass connection?
Keith Cress
kcress - http://www.flaminsystems.com
RE: solder to brass connection?
Dan - Owner

http://www.Hi-TecDesigns.com
RE: solder to brass connection?
Picture is worth a thousand words. This isn't 1000 words lol. Sorry.
RE: solder to brass connection?
Dan - Owner

http://www.Hi-TecDesigns.com
RE: solder to brass connection?
RE: solder to brass connection?
Roy
RE: solder to brass connection?
I'd love to toss up some solidworks models/drawings. But, I'm sure I can't do that.
I appreciate all the input, but for now, I'm just trying to figure out what it means to have a soldered PROUD trace contacting a flat brass surface... for the long run?
We've also talked about boiling the assembly to try and accelerate oxidation.
I'm only concered with oxidation at this point. A redesign (at my company) would take months (not weeks) to implement. And we're trying [desperately] to bring this design to market as it's already a year (or more) late.
You know how it is ;)
RE: solder to brass connection?
Dan - Owner

http://www.Hi-TecDesigns.com
RE: solder to brass connection?
That said, the usual user's approach when the flashlight starts to dim is to give it a shake, presumably this abrades any oxide layer that has formed at the junction, and allows proper current flow to be re-established. At the very least, the rotation of the joint when the batteries are replaced will help to scrub the joint clean.
But your joint won't have any motion after it's made up, so corrosion will likely cause trouble if allowed to progress. There are chemical oxygen absorbers (corrosion inhibitors) available on the market, google Cor-Tech, among others. A small amount of a dessicant material, or at least a controlled low-humidity environment in the assembly area could help too. Finally, is there any way to purge the ass'y with nitrogen or argon prior to assembly.
RE: solder to brass connection?
Like tin plated with nickel under-plating. Then during assembly just place the brass housing on the gold contact and then solder the 2 together.
RE: solder to brass connection?
Steve Wagner
RE: solder to brass connection?
A.
RE: solder to brass connection?
Is it that the PCB isn't thick enough for the shells to squeeze it properly?
If the trace is close to the edge, can a brass shim sheet be placed there to ensure a proper contact?
RE: solder to brass connection?
RE: solder to brass connection?
Dan - Owner

http://www.Hi-TecDesigns.com