Wave Soldering - Icicling/Bridges

While not familiar with the flux, I'd increase the conveyor angle in a New York Minute.

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How are these connectors and dips oriented? If the leads are parallel as opposed to perpendicular to to the wave this can promote bridging depending on spacing and length. The long leads showing icicling are most likely either inadequate heat OR the flow of the laminar wave is not set correctly. Do you have back flow over the wave former that is the same speed as the board moving over it? This can be a pretty tricky adjustment sometimes but is worth it. I am not familiar with the flux either but if you are getting top flow, all other joints look good, etc... I would prbably look at the orientation and wave setup. Increasing the angle to 7 deg. will reduce bridging as Dave F pointed out.

Russ

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I sent you a couple of charts to assist with your troubleshooting. One is the Electrovert Wave Solder Troubleshooting chart and the other is Sandia Labs/Electrovert Optimum Solder Contact Time. Electrovert has a 6 deg. conveyor angle standard on the Econopak and Vectra machines. Correction: The Ultrapak (UPK) 600 and Electra models allow for adjustablity from 4 to 7 deg. The model Ultra 2000 wave machine can adjust from 4 - 6 deg.

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I am not familiar with your flux but with no-cleans (which I use) the primary cause of icicling is the amount of flux solids left on the board prior to wave and how long the board is in the wave (2.5 to 3.5 seconds should be OK). The amount of flux solids left on the board prior to the wave can vary depending on the amount of flux that was applied during fluxing or how much if any was burnt off prior to the wave due to excess board temperature. With a foam fluxer, you should be applying a good amount of flux (usually too much) but check out the fluxer in any case. Also check out your fluxer air knife settings if you�re using one. You could also try hand spraying a board and turn off the fluxer to see what difference that makes. Your top side board temperature just prior to wave should be around 100 - 110 degrees centigrade but that can very depending on board finish and flux type. Have you tried a different flux to check to see if your flux is the problem? If not, get a sample and try a different flux. Lead length can be a factor but usually it just causes bridging not icicling. Let us know what you come up with. Randy

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Hi,

Distance Engineering is always difficult.

I am guessing that the old machine and process ran wonderfully / acceptable.

If you still have the old machine, how about running an empty board through it and then the new machine. Without flux observe the temp with temp tabs prior to the pot to see that you are getting up to exactly the same temp.

With flux observe how you would have to adjust to get the same level of flux. If you do not have the old machine have the most familiar person help adjust the flux quantity prior to preheat to be similar, and use dryer, and wetter as test runs or alter the SG of the Flux to get the same effect.

The airknife and any brush make sure is working well.

I would look closely on the top side to make sure that all the solder fillets including those on components are just like they were on the old machine. Any solder balls? Any more rosin than normal between brickwalled R or C paks?

Please let us know when you figure it out.

YiE, DDave

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RMA needs to be dry prior to the wave to work. If coverage is good and part orientation is good, then you should be okay. Pad size can be adding to the amount of material left as well. Granted it soldered before fine with .2 long leads, I would ditto the preheat settings to be correct and make sure they are dry via the knife and temps prior to wave. I would opt for a topside temp of at least 100 - 110C.

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I agree with most of the other suggestions here, but 90 C for a topside preheat temp seems low to me. I remember aiming for 98 to 104 C for topside temp just before hitting the solder. Boards that had large ground/power planes or a lot of layers I would aim for the 104 end as I would have less problems with the solder solidifying before it got to the top side.

You might try raising the temp of the solder pot to 505 F for this board. That extra few degrees may give the solder a chance to drip off the leads before it cools and becomes an icicle. The downside of a higher temp solder pot is you will generate more dross, but it may save you rework time.

Let us know which change(s) work.

Mike F

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