Thanks for all the (varied) opinions! No consensus here. We are a build to print shop, so I'm not responsible to dictate how to put it on - my obligation is to point out the issue and recommend a solution. I'm going to recommend the "attach last by hand using no-clean flux" method, it will work on this application as the module has castellation terminations, accessible by hand. If it was bottom terminations only I'd be facing a bigger problem, in that case I would recommend the "wash and bake". cheers, Graham regards, Graham Collins Senior Process Engineer Sunsel Systems (902) 444-7867 On 12/1/2017 4:37 PM, Richard Kraszewski wrote: Ditto to Bob's thought. Localized clean if need be. Rich Kraszewski Senior Staff Process Engineer Plexus Engineering Solutions -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann Sent: Friday, December 01, 2017 12:28 PM To: [log in to unmask]<mailto:[log in to unmask]> Subject: Re: [TN] board wash / non-washable modules - the dilemma My vote because this is what we have done for small Proto builds is to leave the module off, build and wash w water soluble flux then install the RF module using the no-clean? Bob Wettermann BEST Inc Your BEST source for PCB Rework/Repair, Training and Tools 847-767-5745 On Dec 1, 2017, at 10:15 AM, Tom Brendlinger <[log in to unmask]><mailto:[log in to unmask]> wrote: I have heard many times that in high humidity environments with very small amounts of condensing humidity, no clean flux can become re-activated. This paper discusses some options: https://link.springer.com/article/10.1007/s11664-014-3609-0 In my opinion, reach out to the part manufacturer and see if you can perform cleaning in a particular way to not risk having issues. Tom On Fri, Dec 1, 2017 at 1:05 PM, Robert Kondner <[log in to unmask]><mailto:[log in to unmask]> wrote: I would go for wash and bake but I worry that washing will "Wash Crud Into" the shielded areas and the rinse will not rinse it out. Are your concerns about no clean flux in a marine environment really justified or is it hog wash from somewhere? Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins Sent: Friday, December 01, 2017 10:09 AM To: [log in to unmask]<mailto:[log in to unmask]> Subject: [TN] board wash / non-washable modules - the dilemma Hello Technet! Wondering what other people are doing with this dilemma. We have had several customers design in pre-built RF modules on their boards. I totally get why, it is a pre-built, FCC approved, easy solution - the fastest way to get a good Wi-Fi or bluetooth solution. Where things go off the rails for me are where this is used in a high humidity application (e.g. a marine setting). We strongly prefer to wash boards, we can build no-clean if needed but I'd prefer not to for an on the water use. But the part a customer has designed in specifically says not to wash it (it has an EMI shield, so they are properly concerned with water entrapment). So - would you: - build it no-clean? - leave the part off, build and wash as usual, install RF module later using no-clean? - wash it (and maybe bake it to dry it out)? - ???? -- regards, Graham Collins Senior Process Engineer Sunsel Systems (902) 444-7867