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What's the best way to clean a misprinted PCB?

Trapped solder paste around pads and in vias

During stencil printing, circuit boards are periodically misprinted due to clogged apertures, stencil out of alignment, solder paste rheology shifts and other issues. Stencil misprints are defined as

  1. A-Side Misprint: Initial print out of alignment with no components previously placed
  2. B-Side Misprint: A-Side was successfully printed and components placed and soldered. The subsequent process of printing the B-Side results in the solder paste being out of alignment resulting in a B-Side misprint
Companies commonly address the misprint by either hand wiping the misprinted side of the circuit card and/or cleaning the misprint in a stencil cleaning machine.  The method of hand wiping the misprinted side of the PCB is not recommended as solder paste can be trapped in the solder mask defined channels and through-hole vias - this can be seen in the image above.
The best approach is to clean the misprinted circuit board using an automated cleaning process that provides programmable wash, rinse and dry steps. Production cleaning systems remove both wet solder paste and reflowed flux residues while meeting quality and yield objectives. To capture the wet solder paste, innovative collection and filtration systems safely capture and contain solder spheres from being sprayed onto production assemblies. Additionally, the containment and filtration systems prevent raw solder paste from entering the rinse water streams.

The printed circuit board should be cleaned as soon as possible after the mis-print to achieve the best results.

SMT PCB Stencil Cleaning Machine:

Machine Description
SME-800 is a high quality aqueous detergent stencil cleaning machine which used to clean solder paste stencil, red glue stencil, red glue cooper stencil, mis-print PCB, large size PCBA.
The total process--aqueous detergent clean, water rinse, hot air dry are complete just in one wash chamber. The Unique 4 fixed cleaning spray rods, 4fixed air knives and stencil move back and forth design makes the machine stable, reliable and super cleaning result.
Machine Features
1.Suitable to clean SMT stencil ,cooper mask, resin mask, misprint PCB and large size PCBA
2.The unique 4 spray rods and 4 air knives fixed and stencil moves clean mechanism, more stable. quick and efficient to clean remaining solder paste ,red glue and flux on SMT stencil ,cooper mask, resin mask, misprint PCB and PCBA.
3.The unique real-time aqueous detergent filtering system is right for precise stencil cleaning.
4.State of the process is visible through a large observation window.
5.Real-time measure DI water resistivity and monitoring cleaning effect.
6.The remaining detergent in the pump and pipes are blown off by compressed air and flow back to cleaning tank. This function saves detergent up to 50%.
7.Can used as PCBA cleaning machine to clean PCBA up to 800mmx800mm
8.English color touch Panel operational interface, PLC procedure control, cleaner temperature,  clean time , rinse time and rinse times ,clean temperature, hot air dry time and temperature,  resistivity can be set and monitored as required.

Machine Spec


SME-800 Spec

Max Stencil Size

L800 x W800 x H40(mm)

Liquid tank


Clean time


Wash time


Dry time


Rinse times


Clean detergent

Aqueous detergent

Rinse water

DI waterwateropen-loop or close-loop

Dry method

High pressure hot air dry

Detergent heat temp


Hot air dry temp


Clean heat power


Rinse heat power


Hot air heat power


Clean/rinse filter


Resistivity range




Machine size



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Flason Electronic Co.,ltd provide a full SMT assembly line solutions, including SMT Reflow OvenWave Soldering MachinePick and Place MachineSMT Stencil PrinterSMT AOI SPI MachineSMT Reflow OvenSMT Peripheral EquipmentSMT Assembly lineSMT Spare Parts  etc any kind SMT machines you may need, please contact us for more information: wechat whatsapp:+8613691605420, Skype: flasonsmt, Email: sales@flason-smt.com
1) This is the first time I use this kind of machine, is it easy to operate?
There is English manual or guide video that show you how to use machine.
If you still have any question, please contact us by e-mail / skype/ phone /trademanager online service.
2) If machine have any problem after I receive it, how can I do ?
Free parts send to you in machine warranty period.
If the part is less than 0.5KG, we pay the postage.
If it exceeds 0.5KG, you need to pay the postage.
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1 set machine, mixed order is also welcomed.
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Contact: Mr Tommy

Phone: +86 13691605420

Tel: +86 -755-85225569

Email: sales@flason-smt.com

Add: No.94,Guangtian Road,Songgang Street,Bao an District Shenzhen China