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The way people treat cold solder joints these days is wild | Electronics Repairers - Thought Shares

The way people treat cold solder joints these days is wild

Ive been fixing electronics for about 15 years now and something that keeps bugging me is how younger guys call any joint that looks a little dull a cold joint. I had a kid in here last month saying my solder joints were cold because they werent shiny enough. I told him look at the flow its fine. I use good flux and a proper iron. Shiny doesnt always mean good and matte doesnt always mean bad. I learned that in 2009 when I was fixing an old amplifier. The original factory joints were all matte and they worked for 30 years. Now everyone thinks you need to reflow everything that isnt mirror bright. Has anyone else noticed this trend taking over the forums and youtube comments?

4 comments

4 Comments

mark_carr75mo ago

A dull joint means incomplete wetting, period. Ive seen too many intermittent failures traced back to matte joints that looked "acceptable" under a scope. That shiny finish isnt just cosmetic, its a sign the solder actually flowed and bonded to the pad and lead. Lead free solder can be shiny if you use enough flux and the right temperature. Most people just rush it or use cheap flux that burns off too fast. If a factory joint lasted 30 years matte, good for them but modern boards have thinner traces and tighter tolerances so you cant rely on old standards. A cold joint is a cold joint, and if you cant make it shine you probably didnt get full penetration.

linda_dixon495mo ago

Oh man, for real though. People see a matt finish and freak out, but good lead-free solder is naturally duller than the old stuff, doesn't mean it's bad.

ellioth375mo ago

Yeah, cranking the iron temp up a bit helped me get smoother joints.

-1

lewis.terry5mo ago

Wait, isn't that kind of backwards though? Cranking the temp can actually burn off your flux faster, which is what makes those matte joints worse in the first place. I've had way better luck bumping the iron to like 350C but keeping the tip clean and using a decent flux like Kester 186 - that stuff hangs around long enough to let the solder flow right. @linda_dixon49 is totally spot on about lead free being naturally duller, but the trick is getting it to flow without scorching everything around it.