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How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line?

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#77337

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 31 March, 2017

We are trying to build two different PCBs - one with no wash flux solder paste and the other with a washable flux solder paste. How difficult is it to use the same SMT line and switch between the two pastes? I assume there will be some cleaning involved and want to understand the risks we are planning to assume here and how much effort goes into this. Does it make viable sense to request that of a manufacturer or should we consider another strategy for solder paste options?

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#77338

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 31 March, 2017

Need more information.

BUT if your strictly considering just the paste change. I would imagine your changeover would be little to no different than changing to the second board if you were using the same paste. Maybe take extra care cleaning your squeegees, other than that, if the pastes require different reflow profiles, it might make sense to run the boards requiring the cooler profile first. As most ovens will heat up at a faster rate, than they are able to cool.

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#77339

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 31 March, 2017

Thank you for your response.

We build boards on an SMT line that is shared with other companies too and are currently using water soluble flux based solder paste on both boards. We realized an issue with washing on one of the boards so requested to move to the no wash paste.

The manufacturer is pushing back on the concept since there would be excessive cleaning and 'other' risks involved. We do not have more information from that source and are wondering what those risks would be. Thanks!!

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#77340

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 31 March, 2017

Clean everything to do with the print process during the switch adequately and you shouldn't have an issue.

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#77341

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 31 March, 2017

Thanks Phil! I appreciate the response!

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#77364

How difficult is it to switch from a no-clean solder paste to a water soluble solder paste between builds on SMT line? | 7 April, 2017

jng123,

Process-wise using one solder paste type is preferred regardless of paste type.

If you want clean both paste types in one cleaning machine your manufacturer might have, this potentially could lead to white residue issue due to chemical reaction in rinsing bath.

In order to clean both products in one machine your manufacturer will have to completely drain and refill rinsing tanks.

Could you please tell me more about your product? Is it special purpose one? Is it consumer electronics? Why did you select WS paste as primary material?

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