Phil
Welcome to Board Talk. This is Phil Zarrow and Jim Hall of ITM Consulting, in this forum known as the Assembly Brothers. We’re here to answer your process questions regarding SMT and electronic assembly in general. What's today’s question, Jim?

Jim
Today's question has to do with wave soldering. It's very interesting that people are still having the questions about wave soldering. It just reminds us that it is a process that we all would wish would go away.

Anyway, today's questions. How can we prevent components from lifting or tilting during the wave solder process. The board in question is 80 millimeters by 100 millimeters and it is a four up panel array. Each board is populated with 15 tall electrolytic capacitors, all the same height.

We've heard about weighted bean bags, chain mail and glue sprays being used to hold components in place. Can you offer any advice or suggestions?

Phil
Chain mail, yeah we get a lot of chain mail. It usually has something to do with – well, we can’t go there. But getting back on topic. I can tell you, back in the old days when that’s all we had was through hole, one of the things we used to do was the ancient art of lead forming, and there were and still are machines out there that form leads.

Now, that’s assuming you’re doing a low enough volume and hand inserting. You can take components that are taped and run them through different types of forms for radial components or you can, stick one at a time in the tool and it will form the leads.

Jim
Phil is doing a wonderful imitation of the tool and die with a scissors.

Phil
Watch my hands. My hands never leave my wrist. But anyway, these will form the components so they actually stay in place and stand up. Of course, you know, we’re assuming, obviously, you’re not using auto insertion on these, but would do a cut and clench.

Jim
Right, because auto insertion machines, virtually all of them, feature a cut and clench which was done specifically for that.

But if you wanted the components to stand off the board, effectively, you still had to lead form them, even with cut and clench. So you can still cut and clench manually if your volumes are low enough. As you insert the components, you cut them off and actually bend the leads over.

But to get a good stand off – cause it mentions not only lifting, but tilting, the lead form creates little bumps or dimples, whatever you want to call them. The bumps help fixed the components in your board.

You talk about bean bags and chain mail, this is the idea of putting some physical force on top of the components to keep them from being lifted. Obviously, what’s happening here is the dynamic forces that soften the solder are pushing the solder up into the barrel of the hole and actually pushing on the lead and lifting the component or tilting it

Phil
Where do you get chain mail these days? Re-enact the Battle of Hastings?

Jim
It’s probably out there. I’ve certainly seen a number of hold down fixtures which have a plate or a grid with fixed hold down points that you clamp on top of your board. The hold down points can be adjusted in vertical height and so forth. If you’re not using a fixture, that would be another additional expense.

I personally don’t have any experience or knowledge using an adhesive to hold the parts in place.

Phil
Here's a Tale from the Crypt. There was a system offered in the last 70’s that I had some dealings with Hollis. Remember Hollis Wave Soldering. If you remember Hollis, you’re old and should be retired by now.

It was called a stabilizer system. Your board was inserted, it would pass over  a fluxer, and then after the fluxer passed over a wave of paraffin wax, to actually coat the bottom of the board, particularly the leads with this paraffin, and this was called a stabilizer.

Next it went over three high speed blades that would trim the leads. And then it would go over the preheat, which would vaporize the wax and finally over the wave to solder it, something along those lines. It actually did work. Of course, the fun thing was those blades were very expensive, and guess what? When somebody accidentally left a piece of hardware in there, ka-ching. But anyway, that’s ancient history and that system doesn’t exist anymore, nor does Hollis. So I don’t think you could find one of those on eBay.

Anyway, just some other solutions to an age old problem. But there are solutions, and we suggest you take a look at something like lead forming.

Phil
On that note, this is Phil Zarrow and Jim Hall saying don’t solder like my brother. And don’t solder like my brother, whether using wax or not. And keep the kids away from the flux spot.