Transcript
Phil
Welcome to Board Talk. This is Phil Zarrow and Jim Hall, the Assembly Brothers, also of ITM Consulting, broadcasting to you today from high atop Mount Rialto. Jim, it looks like we have wave soldering question.
Jim
We are wave soldering very close pitch through-hole components and see bridging. What is the finest pitch for through-hole components that can be successfully wave soldered? Is there anything you can recommend so we can reduce bridging on this component?
Phil
Whoa, where to begin? You're talking about a technology that's essentially something like 50, 60 years old.
Jim
And there has never been zero-defects. Even with 100-mil pitch, you still see some bridging. So, what is your acceptable level of bridging? With fine pitch connectors bridging can be 100 percent and can be a real issue. So, what do you do, Phil?
Phil
There's been all sorts of innovations, or duct tape if you will, on the wave soldering process, trying to keep up with this stuff.
Jim
First off, obviously, tuning your wave soldering process, getting your flux down, getting your lead lengths cut, doing everything you can on the front end of the process to optimize it.
Solder pot cleanliness, solder pot temperature. All those can effect bridging in general, so they'll help the situation. But then you have to get onto something else.
Phil
Over the decades, there have been all kinds of things. Hollis Wave Soldering was famous in the 70s. I remember working with peanut oil and one of the supposed advantages was for de-bridging.
Other things that may be more practical; possibly worth a try? One is inerting the solder pot, if you haven't done that already. A number of studies that were done many years ago by both SolTec and Electrovert gave very credible data that shows inerting helps the solder go where it's supposed to go. This is done by reducing the tendency towards oxidation.
Jim
We've talked a little bit about them before, and they're not really popular.
Air knife de-bridging tools may be something you have to look at. They are available from some companies, and this may be the situation where you have to grin and bear the reality of paying for that tool and learning how to use it to achieve a reasonable level of bridging.
Phil
The ultimate answer may to give this old technology a ride and take a look at selective soldering with the various new systems that are out there. As well as exploring whether this product might be feasible for intrusive soldering.
Jim
Pin and paste, reflow of through-hole, intrusive soldering, whatever name you want to call it. Bridging and wave soldering is a way of life. You manage it. You never eliminate bridging 100 percent, regardless of the pitch. Obviously, it gets worse at small pitch, and I agree with Phil. At some point, you're just going to have to say, wave soldering is not the way to handle this component.
Jim
So, thank you. It's a lot to talk about. We could expand on this, but I think we gave a reasonable overview of the general principles involved.
Phil
Beyond that we'll say thank you. And no matter what methodology you're using, don't solder like my brother.
Jim
And don't solder like my brother.
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