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Ionic testing and No-Clean flux

#7596

Ionic testing and No-Clean flux | 4 February, 2000

If No-Clean flux does not need to be cleaned, then why do I get readings of up to 27(ug NaCl/sq in) on boards that are not washed, up to 23.4(ug NaCl/sq in) on boards washed with DI water only and from 1.2 to 10.1(ug NaCl/sq in) on boards washed with a cleaning agent, the boards were tested at Kester using an Omega Meter 600 SMD, if the flux residue is not harmfull why do I get such readings.

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Graham Naisbitt

#7597

Re: Ionic testing and No-Clean flux | 4 February, 2000

Casimir

This is not an easy subject. How did you process the test pieces? Was the flux used correctly at the required and recommended level? Did it see the wave properly?

I am not an advocate of no-clean but we do have customers who coat over no-clean without problems.

Be sure that it isn't some other form of chemical reaction between the flux and something else on the board.

Of course, it may well be that this stuff isn't as good as is caimed.....

regards, Graham

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#7598

Re: Ionic testing and No-Clean flux | 5 February, 2000

Casimir: Let me expand on something that I said in my response to your thread on ionic testing. Generally, no-clean people don�t use ROSE testing as part of their process control, because the ROSE test is essentially washing your board in DI/IPA � a sure fire approach to turning your solder connections white on each board you test. And the assumption when using no-clean is the flux residues are non-ionic.

The issue you are struggling with is one I�d expect should be the struggle of every no-clean shop (actually every assembly shop for that matter, but non-no-clean people accept the issue, to a greater degree). If they�re not (and they aren�t because their soldering process is so far out of control that they�re limited to whining about solder balls), had better get in touch with this issue, because it surely will affect the long term reliability of their product. Can you spell electromigration and corrosion?

There, I got that out of my system.

Ooooh them�s some ugly "no-clean" boards. OK, let�s think about these corrosive, ionic salts on your board. They come from three sources. 1 What is the level of ionic contamination of the boards you receive from your fabricator? For instance: � Many fabricated boards are hot air solder leveled. Is that no-clean or some other type of solder? What level of ionics are left from this process, when you receive them? � The "F" in FR-4 stand for fire retardant. Bromine is used as a fire retardant. Br- is not far from Cl- on the periodic table. Both combine with things to make corrosive salts. � Solder masks are potential source of ionics. � Fabs wet process their product. What is the level of ionics in their rinse water? 2 What is the level of ionic contamination of the components you receive from your suppliers? Look at "Circuits Assembly" magazine, November 1999 for "Component Residues" by D. Pauls and T. Munson. The article discusses ionic residues on various in-bound components. 3 Your processes. As Gramham said, things like the amount of flux you put on the board contributes. But fluxing is not the only in-house process that can add ionics to your board.

Look at: "How to qualify the solder flux of a new vendor? - Gyver 00:59:33 11/17/1999" in the SMTnet archives.

Good luck

Dave F

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#7599

Re: Ionic testing and No-Clean flux | 5 February, 2000

Graham: Maybe a twist on your comments, I don't believe that people understand the true cost of using no-clean. Dave

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Graham Naisbitt

#7600

Re: Ionic testing and No-Clean flux | 7 February, 2000

Dave

You are so right about that point.

I still use some cost models we ran up some 5 years ago. I took one to a customer and showed them that they could make $400K more PROFIT PER YEAR running OA v No-Clean.

Their response? Well, we don't believe you and anyhow, we just decided to go no-clean so we'll let you know.

After losing a ton of business to their major competitors who run OA, they are now re-assessing OA......watch this space.

BTW, the ops cost at the OA customer is << $12 per hour all in. The No-clean guy is running around $90 per hour!

regards, Graham

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Brian E. Steelglove

#7601

Re: Ionic testing and No-Clean flux | 7 February, 2000

Graham,

Please describe the term OA? I have never heard of that acronym.

Thanks,

Brian E. Steelglove

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#7602

Re: Ionic testing and No-Clean flux | 7 February, 2000

Graham STOP!!! You can not be totally serious. A five year old cost model counts bean, and beans are beans. I have to know more about the calculation. If this bores some of your gear-heads, click on "return."

� Help me with the terms: - "Ops cost" - "All in" � Where do direct (touch) labor, in-direct (non-touch) labor, product material, production material, rent, utilities (gas, water, and electric), equipment costs, etc. fit in with these quoted costs? � How are the processes similar, dissimilar? � How are the products similar, dissimilar? � Did the $90 people have a lot handy-capped workers? Or was it just the bosses? Bad teeth? � What are these "$?" US dollars? � Was the $78 cost delta strictly clean versus no-clean? Or was there some other cost drivers?

Thanks

Dave F

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#7603

Re: Ionic testing and No-Clean flux | 7 February, 2000

Brian: SMTnet has a "Terms & Definitions" section in the "Library."

OA Flux. Flux, Organic Acid. A water soluble flux.

Good luck

Dave F

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Reflow Ovens thermal process improvement