Vapor degreasing cleaning

Hi all, (I posted on eevblog also, figured I'd try hear as well since this seems like a semi "niche" question)

I need some advice on PCB cleaning. Up to this point, our assembly line has strictly run NC paste, with all SMT parts. We never washed any boards, as no client has requested it this far. We recently bought a selective soldering machine to do more THT. There's no way that I feel comfortable shipping boards after a selective without cleaning them, the amount of flux on the board is significantly more than from SMT.

We are high mix - low volume, so doing 500 boards a week would be a really busy week for us, normally we are < 100 boards per week, so throughput shouldn't be a huge issue.

Our main issue is water supply and sewer. Our space is basically a converted warehouse/garage, that is separate from our office space upfront. This means we do not have a water supply or drainage in our space. Walking to the offices require us to go outside, so doing anything up there is also not a possibility. We also can't spend a ton of money (<$20k or so), so the zero-discharge triton aqueous systems are out. I also don't feel comfortable using ultrasonic cleaners due to the risk of damage. Same goes for full water-soluble fluxes since we do a lot of QFN's with thermal pads, I won't risk leaving residue under them and rusting. So I assume we will use an NC/R/RMA flux.

It seems to me like the only real option we have is to use a vapor-degreaser since they are zero-discharge as they reuse the solvents. I just don't like how they don't seem to be super commonly used nowadays; it seems like it is an "outdated" technology as compared to aqueous cleaning. I found some nice solvents from techspray (ME-1500) that are low-VOC and plastic safe. There's also an AIM article: "New Vapor Degreasing Chemistries to Remove Difficult Lead-Free and No-Clean Fluxes from Modern PCBs" that showcases some of the new solvents that are used. I found some nice machines (not specifically for PCBs, I can't find any that are) that are new for <$10K.

So am I missing something here? Is there a reason to shy away from vapor degreasing for our application? Any other thoughts/suggestions are much appreciated!

Side note: Has anyone used any of Superior Flux's products? They seem like a nice company, all pastes are built to order, and I was actually able to talk to a chemist for an hour picking his brain. I've never been able to talk to a real person at Kester/Loctite before, so that was a nice change!

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