Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

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Print-Glue-Wave process



Print-Glue-Wave process | 11 March, 2003

We ran doublesided SMT thru Glue and Wave process before and but faced a lot of skip solder. Then the customer told us that they have similar problem when they ran the board so what they did was they print the paste-dispense the glue- place the comp than etc.

At post wave, the board finished was bad cosmetically. It was like a splash of fluxes surrounding the components' termination ( watery look ). Customer was with me and told me that the problem was due to the heavy flux applications/spraying, which I think it was not the case. I tried to explain to them that the problem may came from the cured flux from solder paste after the reflow process then react with the wave soldering fluxes plus some preheat effects, them get into contacts with the solder bath. This is the real lay man explaination which never convinced my customer. Have anybody experience this before ? Pls share you do you guys think actually happened.

Thank you and looking forward for an input

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Print-Glue-Wave process | 11 March, 2003

Is a water-soluble flux based paste an option for the bottom side? Then you could wash the residues from the board before wave. That's the only way we've tried that process.

The difficulty we had was with some disturbed joints, apparently from shrinkage of the adhesive when cooling from reflow temperatures. We ended up scrapping the idea and got a chip wave to eliminate the skips.

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Print-Glue-Wave process | 13 March, 2003

That's a good idea...and to add on to it, you could wash after the wave, too--it really doesn't matter.

A question about this though--unless your Customer specifically requires "clean", no-clean flux whether it's ugly or not, is permitted by IPC, and as such we don't worry about it. Alternatively, we have a 'saponified' washer (basically an industrial size dishwasher) that is quite effective at removing the no-clean fluxes from reflow, if the picky Customers require it. We use Armakleen as the detergent. A 45-minute wash makes them clean, dry, and cosmetically appealing to the discriminating eye.

fyi, our Electrovert is equipped with a chipwave, but we paste+glue+component all our 2x-sided assemblies with no problems.


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