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Vectra Wave

John Sims

#4290

Vectra Wave | 2 May, 2000

My company just purchased a Vecta (E-vert) wave soldering machine. Bridging has become a serious issue, both on SMT components and thru hole. We are currently seeing about 500 ppm. The products that are being run now were run previously on our older Econopak. Skips were a problem then, but bridging didn't become an issue. I have checked the profile, reduced the nitrogen flow to the exit end of the laminar wave, adjusted the conveyor speed, and tried changing the orientation of the panels. Does anyone have other suggestions? Would a hot air knife solve the problem?

Thanks in advance,

John

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C.K.

#4291

Re: Vectra Wave | 3 May, 2000

Which wave solder flux are you using and what types of preheaters did you have on both your old econopak and your new vectra? From my past experience, an alcohol-based flux does NOT work well with Convection style preheaters....the flux burned off too rapidly. Alcohol-based worked okay when we ran it on a wave with IR preheat.

Water-based (VOC-Free flux) works well better with convection preheat. If you can answer these questions, then maybe I can help out...

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SONO-TEK CORPORATION

#4292

Re: Vectra Wave | 3 May, 2000

John - CK can probably help you further once you answer those questions, but for now what's your top side temp and how are you applying flux? Two of the primary causes for bridging are conveyor instability (vibration) and turbulance in the solder wave when the board exits. I have a defect/process sheet that I could fax to you - email me if you want it. cycorda@sono-tek.com. Claudine Corda Sono-Tek Corp.

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John Sims

#4293

Re: Vectra Wave | 5 May, 2000

We are using NR300F from Alpha. Topside board temp is 220 deg. F. We have 3 bottom side convection preheaters, and we use a foaming fluxer. The machine (except for the rotary chip wave) is almost identical to the old econopak. An electrovert applications guy recommended increasing the conveyor speed from 4 fpm to 5. Apparently the contour wave is wider than the one on the econopak causing my dwell time to be too long. This has helped but not eliminated the problem. Any other suggestions would be a great help.

Thanks

John

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C.K.

#4294

Re: Vectra Wave | 5 May, 2000

I'd have to disagree with the Electrovert applications guy. I'd recommend SLOWING down the conveyor between .5 to 1 FPM - effectively, you're REDUCING contact length (because contact length = dwell time * conveyor speed), hence getting better peel-off from your laminar wave. Also, turn DOWN your laminar and chip waves by another 10 - 20 RPM's.

...also, the fact that you're FOAMING a no-clean water-based flux might also be a problem....specific gravity is almost impossible to measure, and you also need the right acid values, so titration also becomes an issue. Foam-fluxing works great for RMA and OA type fluxes, but for low-solids, I'd recommend investing in a spray fluxing system....you're quality levels and process control will improve drastically. Lack of process control in your fluxing process is definitely a contributor to wetting/solder bridging issues.

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C.K.

#4295

Re: Vectra Wave | 5 May, 2000

I read my posting again, and it didn't sound right....what I meant was slow down your conveyor speed BY .5 to 1 FPM. So, if you're running @ 4 FPM, slow it down to 3.0 to 3.5 FPM.

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John Sims

#4296

Re: Vectra Wave | 8 May, 2000

I was running the conveyor at 3.75 when we started the discussion with Electrovert. Unfortunately, foam fluxing is a fact of life for us. Our products have open contact relays that can become contaminated by spray fluxing. Titration is our only method of controling the flux, but we obtain similar results in a relatively wide range. Electovert recommended speeding up the conveyor because they were concerned that the flux was not surviving long enough. Since speeding up the conveyor the results have been somewhat better, but I still see excess solder.

Thanks again,

John

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