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No-Clean flux residue and RF application

Views: 1891


ING

#36400

No-Clean flux residue and RF application | 30 August, 2005

Hi,

I curently have an interesting challenge. But I don't have all the knowledge to solve it.

One of our boards is used in RF applications. We noticed that the No-Clean flux residue makes interferences in the RF signal. Removing the flux residue solve the problem. But washing the board in an ultrsonic cleaner gives us other problems. Sometimes some RF device aren't operational after washing.

Does anyone know a solution for this kind of application? What the cell phones company does for that? Does exist a solder paste with no residue?

Thanks to all for your collaboration.

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#36405

No-Clean flux residue and RF application | 30 August, 2005

The answer for us at my previous employer was water soluble flux. Wash the board, no residue. If you're not set up to wash (needing a washer, DI water source, waste treatment, ventilation, etc.) it can be expensive and space consuming.

Do some research RE: ultrasonic cleaning of assemblies before you proceed with that step. High power and standing waves means damaged components. Low power, good chemistry, DI rinsing, and variable frequency is alledged to be an option that nets clean boards, although I've never had the guts or resources to try.

Search the SMTnet archives for "ultrasonic cleaning" and look for threads about cleaning assemblies to get started.

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#36406

No-Clean flux residue and RF application | 30 August, 2005

Yes a No-Residue solder paste exist. email me for more info

Pat

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#36410

No-Clean flux residue and RF application | 30 August, 2005

Dear Ing,

Have you analyzed why some RF device aren't operational after washing? An assumption is that failures are related to the ultrasonic energy applied. Other possibilities are for poor rinsing, poor drying, inadequate washing on those failed devices, etc. The use of an ultrasonic cleaner limits the type of chemistry used in your process, perhaps the chemistry is not able to consistently remove the residues. No-clean residues are the most difficult to remove.

Steve suggested going to a water soluble, and, using spray type cleaner. You can also, use a spray type cleaner on RMA, No-clean and Water Soluble chemistries. Spray type cleaners allow for greater flexibility in chemistry selection and typically offer integrated rinse and dry processes. The statistical quality of the cleaning process can be checked using integrated rinse to a specified exiting rinse water resistivity value.

Have a Great Week!

Shean R. Dalton Austin American Technology www.aat-corp.com (+1) 512-335-6400

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Slaine

#36422

No-Clean flux residue and RF application | 31 August, 2005

im running some tests at the moment for hand soldering using a no residue water based flux from MBO, called WBF-01. leaves a good clean finish.

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Reflow Oven

Essemtec Spider SMT Fluid Dispenser