Stencil cleaner

Always a joy to see a stencil cleaner thread get opened up....lots of varying opinions as to what's needed, best, environmentally sound, etc.

We use an ultrasonic batch cleaner that uses a detergent (dilute to 1:10 or 1:20, can't remember), then boil off the water in an evaporator and send the dregs to a hazmat handler. Some people use spray washers and swear by them.

Try searching the archives here for your subject line....I'll bet you find more than you can read during your lunch break. Enjoy!

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The specific answer depends on what your specific application includes.

#1: What are you removing? (solder paste, adhesives)

#2: What are you cleaning? (stencils, screens, misprints, pallets)

#3: What type of machine are you using? (Spray-in air, ultrasonic, heated / unheated)

A general answer� There are numerous brands of stencil cleaning chemicals available.

Aqueous Technologies http://www.aqueoustech.com

StencilWash: For the removal of no-clean and water soluble pastes

StencilWash Plus: For the removal of all solder pastes

StencilWash-AD: For the removal of adhesives and all solder pastes

Petroferm http://www.petroferm.com Hydrex AC: For the removal of all solder pastes Hydrex WS: For the removal of adhesives and all solder pastes

SmartSonic http://www.smartsonic.com 440R: For the removal of all solder pastes

Kyzen http://www.kyzen.com 5005: For the removal of all solder pastes A4402: For the removal of adhesives and all solder pastes

Zestron http://www.zestron.com Vigon SC200: For the removal of adhesives and all solder pastes

All of the chemicals listed above work well. When choosing a specific brand, consider the following:

#1 Cost How much per gallon / liter? Is it sold as a concentrate or ready-mix? What is its loading capacity (how long will a batch last)?

#2 Safety Is the solution flammable or non-flammable. What type of machine is it designed for (some chemicals are designed for ultrasonic but not spray-in-air).

#3: Environmental Is the chemical environmentally safe and legal? Is it VOC free or VOC compliant? Can it be discharged?

Mike Konrad www.aqueoustech.com konrad@aqueoustech.com

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Hi

Just below MikeK gave a good answer with lots of links.

I think what I write is already contained by MikeK and the the other poster as of right now. Mike is fast.

As I read your question and you read his input ask yourself 1>What object am I cleaning 2>What chemicals/deposits am I removing (Chemistry?? 3>What is the process my machine uses.

Now if Water Based works than you are OK from a cleaning aspect. The only problem as Mike noted, at least to my reading, is what can you allow, according to local laws and regs, to go down the general drain or sewer.

Back to one part of your questions: What's everyone doing?? If others are doing it wrong do you want to copy them. I think to be best you want to copy best practices. IMNSHO.

YiEng, MA/NY DDave

This message was posted the Electronics Forum @

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Something else I just thought of, and MikeK touched on it briefly, is what you'll be cleaning. If you need to be capable of removing both epoxy and solder paste, for instance, you need to look at chemistry and processes that will clean both, and the temperature that is required. We ran into a problem with our stencils potentially not surviving for long with the temperature required to clean epoxy with our existing chemistry.

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Hello Alwil,

It appears that some of the other respondents are recommending that the waste stream be discharged to drain, if possible. Keep in mind, the chemistry used is not the only factor to determine legal drain disposal. If you are cleaning solder paste, all effluents will be considered hazardous because of the heavy metal content.

My experience tells me that most users prefer not to send anything to drain because of the associated liabilities with drain disposal. If you are discharging to drain and your filtration system is operating properly, you could still be held responsible for cleaning up an illegal discharge if the originator cannot be identified!

You may want to consider if the resulting waste stream is compatible with atmospheric evaporation. Some of the chemistries mentioned are and some are not. By evaporating the wastewater, nothing is discharged to drain and therefore your operation would be removed from the liability selection pool if there were a heavy metal discharge in your area.

Another problem I see with your system is the 350 - 400 liter capacity. It doesn�t matter what chemistry you decide on using, you will always have 350 � 400 liters of liquid waste for disposal (not to mention the liquid generated by a rinse, if necessary). Most modern stencil cleaners use less than half that amount of chemistry and therefore generate less than half the waste. The savings on chemistry and waste treatment alone may justify a new stencil cleaner.

Best regards, Bill Schreiber Smart Sonic Corporation www.smartsonic.com bill@smartsonic.com

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