Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


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Cleaning | 16 December, 2015

Hi All,

One of our customer has suggested not to use Aqueous cleaning process as well as IPA for cleaning the PCBA. The reason behind this is they leave moisture contend on pcba.

Can any one suggest any cleaning agent suitable for this condition.

Already searched the forum for answers but none found.

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Cleaning | 18 December, 2015

Using a vapor degreaser with a solvent such as Vertrel, Novec, Techspray 1655, Solstice, etc. may work for you but solvents can attack certain plastics. Should be fine for SMT though. This is assuming you are using a no-clean (RMA) type flux, not water soluble, as the solvents above won't clean water soluble fluxes.

Probably the simplest solution would be to use the aqueous cleaner and then bake the assemblies in a vented oven for a specific time/temperature. Again make sure the bake temperature does not affect electrolytic capacitors or other sensitive parts.

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Cleaning | 19 December, 2015

bake the pcba, continue with the aqueous cleaning but after the cleaning bake them in a circulated oven. we do that with some of our pcbs here we use a water base flux, we clean it and then we bake them for 10 minutes at 190F

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Cleaning | 22 December, 2015

The overwhelming technology used in post-reflow cleaning of electronic assemblies is aqueous. Prior to the 1990's, solvents and vapor degreasers dominated the cleaning industry. After the popular solvents were banned via a United Nations treaty, alternative solvents attempted to take their place. Unfortunately, no alternative solvent worked as well as the banned solvents. The industry en-masse switched to aqueous-based cleaning technologies. Today, aqueous-based cleaning technologies has become the conventional wisdom. While there are specific circumstances where aqueous-based technology can not be used (primarily due to non-sealed components), they are relatively rare and there are "work-arounds".

Concern about assembly moisture is valid. Moisture can cause many reliability issues. Switching to a solvent-based cleaning method does not, on its own, prevent moisture. Moisture pick-up can occur as soon as the laminants are bonded together. Moisture pick-up can begin during board fabrication and continue through storage, assembly, and in-use. Regardless of the cleaning method, assemblies would benefit from an extended drying or bake-out process after assembly and cleaning. Most solvent-based cleaning systems lack a vigorous drying process (and, in many cases lack any drying process). This is because they rely on the rapid evaporation characteristics of solvents.

Aqueous-based cleaning technologies can feature a powerful drying system what will not only remove cleaning related moisture but also moisture gathered over time prior to cleaning. An aqueous-based cleaning process, backed up by real-time cleanliness verification, ending in a vigorous drying process represents best practice in cleaning.

Feel free to download a free book "The Reasons for Cleaning". It covers in more details many of this topics in this response. The book may be dowloaded here:

I hope this information is helpful.

Mike Konrad

Aqueous Technologies

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Cleaning | 13 January, 2016

Baking it's key for success on this task. Water evaporates @ 100 deg. C. Use that temperature, or higher, for that process and your problems or concerns can be taken care of. Be wise on your cleaning process, otherwise this could lead to failures too.

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