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CONTROL OF FLUX DEPOSITION

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#50794

CONTROL OF FLUX DEPOSITION | 22 June, 2007

Good Morning!

I was curious if anybody would be able to help point me in a direction where I can research process control on spray fluxing. Our spray fluxers tend to be neglected. We currently are applying flux and running. My goal is to setup profiles for the fluxers, but I don't know what kind of control limits are needed, tools, etc... I do know that ECD makes a "fluxometer," But that is probably as far as it goes.

Any help would be great,

Thanks.

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#50798

CONTROL OF FLUX DEPOSITION | 22 June, 2007

Sup G!

Normally when spray fluxers get neglected, the spray pattern is the first thing affected. To actually 'see' this, we cut out a piece of cardboard the same size and length of the board. Run it over the fluxer and then turn itover and look at the pattern. You can verify you have proper off set and over lap of the sprayer. To check penitration thru the board, you could buy the ECD Flowometer or just look for op side wetting on your board. 90% of the time if the spray is hitting 100% of your board, you can adjust the pressure to get top side wetting.

Sorry I don't have a cool, high tech answer for ya.

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#50804

CONTROL OF FLUX DEPOSITION | 22 June, 2007

I agree with the down to earth, low tech but very effective peace of card board and is far better then trying to measure Mg/Inch sq with a volatile media. The only addition I would like to make to �Real Chunk�s� advice is: Dry spots on the cardboard = not enough flux Large drops on the cardboard = too much flux The goal is an even distributed flux layer (no flux drops or dry spots)

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#50851

CONTROL OF FLUX DEPOSITION | 26 June, 2007

Patrick, Back in my rich OEM days, i actually DID measure mg/in^2. I bought a scale, which measured in mg, specifically for this. Basically, took a blank PCB, took a "before" weight, sprayed it, and then took an "after" weight. I measured at different pressures to fully characterize what settings on your fluxer will get you.

Yeah, and I bought a Flux-o-Meter too for about a grand. :-) Good tool to gauge if your fluxer is "atomizing" correctly penetrating the through-holes).

What a coink-ki-dink. I was just talking to another shlep about this yesterday.

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#50860

CONTROL OF FLUX DEPOSITION | 26 June, 2007

4.4 Determine the amount of flux on the board. 4.4.1 Get a piece of corrugated cardboard and a weighing scale accurate to 0.01 grams. NOTE: Use cardboard with alcohol fluxes to slow their evaporation and get good data. 4.4.2 Weigh the cardboard. 4.4.3 Run the cardboard across the fluxer. 4.4.4 Weigh the cardboard again. 4.4.5 Calculate change in weight / area of the cardboard 4.4.6 Ask the flux manufacturer to calculate the flux deposition as: (Change in weight / area) X % solids by weight. 4.4.7 Convert the flux deposition to micro-grams/square inch and compare it to the manufacturer's recommendation.

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