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SMT electronics assembly manufacturing forum.


STENCIL CLEANING WITH SOLVENTS

S L CHANG

#8567

STENCIL CLEANING WITH SOLVENTS | 12 November, 1999

We are currently cleaning solder paste (TAMURA SQ-1030FP) from stencil using an ultrasonic stencil cleaner with solvent (HYSPER-Non CFC). The process cycle time is 30 sec. cleaning in 1st ultrasonic tank and another 30sec. cleaning in 2nd ultrasonic tank and subsequently 360sec. in a blower tank.Cleaning was fantastically clean. However, we have one set back . The tension of the stencil becomes loosen and looses its tension. Reasons being that the solvents are aggressive on the epoxy. The stencil manufacturer uses VERSACHEM EPOXY which is a conbination of polyamine resin and atomized stel powder.

Can someone proposes an alternative solvent that is non-flammable and Non-CFC to complement the epoxy so that the stencil will not losses its tension ? Please help.

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#8568

Re: STENCIL CLEANING WITH SOLVENTS | 12 November, 1999

You may want to consider Zestron's Vigon SC200 (703) 589-1198.

Many of our customers use this chemical with great success.

Another alternative is Hydrex from Petroferm (904) 261-8286.

Good Luck,

Mike Konrad Aqueous Technologies Corporation

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Claude Couture

#8569

Re: STENCIL CLEANING WITH SOLVENTS | 12 November, 1999

I use Aquanox SSA from Kyzen corp. No damage to stencils ever noticed. http://www.kyzen.com/index.htm

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#8570

Re: STENCIL CLEANING WITH SOLVENTS | 12 November, 1999

Just out of curiosity - are you sure it is the solvent? What is your process temperature? John Thorup

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Bill Schreiber

#8571

Re: STENCIL CLEANING WITH SOLVENTS | 16 November, 1999

According to a paper by Richard Clouthier, published in 1996, there are two major factors about normal cleaning chemistries that may affect stencil adhesives. 1) Elevated temperature above 110 degrees F. (45 degrees C). Stencil adhesives are heat cured and hot wash solutions and/or hot drying air can debond the adhesive and cause the metals on the stencil to expand and contract which will distort the etched image and cause screen tension problems. 2) Long exposure to moisture. The adhesive is hygroscopic and will absorb moisture, swell and break the bond. If the solvent is too aggressive, it may also dissolve the adhesive. This paper can be found on the Smart Sonic Web Site: www.smartsonic.com

There is only one chemistry that is certified environmentally safe and user safe by the Environmental Protection Agency. That chemistry is Smart Sonic's 440-R SMT Detergent. Smart Sonic guarantees that it will clean any type of solder paste from any fine-pitch stencil.

Good luck.

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Ricky L. Price

#8572

Re: STENCIL CLEANING WITH SOLVENTS | 30 November, 1999

Bill S. is correct on the positive effects of the Smartsonic 440-R SMT detergent. We have been using this in conjunction with a Smartsonic 4200-2D ultrasonic washer that is equipped with a tank heater set at 100'F. Our suggested process window to prevent delamination of the stencil from the mesh is 90 to 110'F. We are cleaning no clean, aqueous and epoxy based solder pastes from our stencils. Our process cycle time is currently 4 minutes and we have been very pleased with the results.

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