Battery contact springs soldered to PCB

[Purduephotog]

I have an old amplifier I fixed for a coworker (now 3 years) unfinished because part of the battery compartment was so corroded. And Also I Am A Bad Person.

I'd like to finish so need to etch/create a new PCB for the battery contacts. Previously it used a weird spring, but wasn't so much soldered as it was pushed through the hole to hold it. They corroded off, and so did all of the traces.

I have the image to work from, but what is the best way to solder a spring? I have some 'copper' ones from higher powered flash lights, and I thought about making a disk with a small trace leading from it for the thru-hole insertion of the power wire. Then I could plop a big chunk of solder down onto the copper where the spring rests and allow that to hold it in place.

Trying to do the toner transfer with acetone but I may just end up using a sharpie to draw it. I'm having trouble learning new ideas lately since a stroke.

Thanks for advice on soldering springs.

[Zeyneb]

Good battery springs are usually made from spring steel and that is hard to solder. Maybe you can mount it to the PCB with an small screw and nut, in combination with a spring washer to maintain good electrical connection. Another option is a product like Digikey 36-5201-ND, this has a solder lug. But I don't know if you can properly fit this into that battery compartment.

Apart from the technical aspect I think it is important to keep your motivation up as you mention things aren't going so well for you. Specifically I'd encourage you to strive for a good professional result to put a nice green check mark on this repair task.

Good luck!

[Benta]

A solder joint under continuous mechanical stress will always fail, whether in a year or in five years is impossible to say.
You should look for a way to fix the spring mechanically and not just through the solder joint.
Suitable material is phosphor-bronze. I wouldn't select steel.

[Ian.M]

See my comments on flash plating steel with copper to make it solderable here:
https://www.eevblog.com/forum/beginners/soldering-to-strange-metal-contacts/msg3315024/#msg3315024

However, Benta is right - the solder *MUST* *NOT* be on or directly adjacent to a part of the spring that flexes and must not carry a high mechanical load on its own, otherwise failure is a certainty.