| Scott, | I am not really in a position to answer this as fully as I would like because most military work with which I am familiar is subject to some degree of secrecy most especially on the internet. At least we have signed up to such restrictions. | However, I do know that many missile projects and avionics systems are manufactured using a fully "OA" (Organic Acid) water SOLUBLE process. | I differentiate water SOLUBLE from water WASHABLE. Why? Because washable processes involve the use of saponifiers in the wash section as the flux includes rosin elements. Soluble involves pure water alone, there is no need for saponifier. | A question to the DOD would perhaps gain you more info? | I wish I could answer you more comrehensively but hope that this helps you further. | I have one other observation: it seems that most of the high volume industry, including the high reliability automotive applications, are moving increasingly to the OA process and that polarisation is occuring between "No-clean" for class 1 and 2 and OA for class 3 products. | However, the military, with low volume high rel class 3, seems to persist with rosin based fluxes that are low solids and/or no-clean yet wish to clean them and this is where we seem to have so many problems with cleaning. | For example, many seem to embrace batch "dip n'dunk" cleaners, 3 or 4 stage with evaporative drying. These either "create" white powder reactions at the surface or at least, lead to serious drying problems - processing around 2000 assemblies per week, I know these problems! However, in-line processing with the latest OA formulations do not have such problems. | Bearing in mind that an essential purpose of fluxing is to remove surface oxides, is it any wonder that military applications "turn up the wick" on the fluxer, to get the necessary level of activity from such weakly activated fluxes, and then wonder why they have so many cleaning and reliability issues? The excess flux gets absorbed into the laminate and that is why SIR is becoming such an essential tool for reliability testing. Non-ionic additives in the flux are not detectable via ROSE testing. | However, if you use an aggressive OA flux based upon Malic or Acetic acid, you can be pretty sure you could solder black leaded components! Better be equally sure that you clean the stuff off - that is where the latest technology cleaners will help you. | Sorry for waffling on, but let me kow if you want more. | Regards Graham Naisbitt Thanks for your input, Graham. I, in fact, totally agree with you. As a former mfg. engineer, well seasoned in volume contract manufacturing (in both defense and commercial applications), I've been into no-cleans (even back when they were called "leave-on" , OA, RA, RMA, and synthetic chemistries. It's my opinion that the no-cleans have come a long way in rheology and stability. But they still have a long way to go. Lots of folks aren't willing to invest in the capital and process changes required to implement a successful no-clean program. Of the choices in today's "green" facilities, for the widest process windows I'd pick OA over all others. The synthetic I used in the late 80's and early 90's in one of the top three CEM's in the country (revenue wise) was formerly Kenco; then bought---became Alpha/Kenco 9185D. It was active at room temp! Wonderful stuff when you could clean with TMS or 1:1:1 azeotropic blends. Back in the days when Mfg. Eng.'s didn't control much in the incoming supply chain, it overcame lots of solderability issues for me--from boards to transformers, and everything in between. Today.......I wouldn't recommend it--it's more active than any OA out there. Unfortunately, even as an ISO9001, Mil-2000, 2000A, 9858A, and AS9000 certified facility (going for QS9000 next month), many of our customers SPECIFY RMA chemistry!!!!! As Graham mentioned above, I can't reveal some of their names.....suffice it to say I delve in defense, commercial, aerospace, and satcomm stuff. Very high reliability, high quality...... We are a contract manufacturer with a core competency in RF and wireless........so SIR and dendritic growth is of ULTIMATE concern. 0 field failures are allowed. It just cannot happen. OA just flat scares these guys...... So, rather than use the newer aqueous technologies (whose chemistries in paste are much more mature and stable than in the past), I'm stuck with RMA and semi-aqueous cleaning. I've got the USS Corpane out on my production floor--a nice, effective cleaner with Axarel, but it's huge! takes up lots of floor space. The answer in my mind is OA; WS609 washes with just water--you don't need any saponification.....and the same vendor has off the shelf wavesolder OA's that do the same..... Scott
reply »
Does anyone know what the military uses for water
soluab...
- Apr 02, 1998
by
