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Hand soldering rework fluxes

Dave Jurena

#12952

Hand soldering rework fluxes | 14 January, 1999

Hi all,

I thought I'd use this forum to ask a couple general questions on fluxes for manual operations: First - Is it OK to use a wave soldering type flux (specifically OA)? Thinking about activation temperatures and the ramp rate of the wave solder versus a soldering iron. We really haven't seen any problems, but is there such a thing as a flux specifically made for manual operations? Second - Using no-clean flux for the same processes; we had been using Kester's 951 but found problems cleaning off excess flux with alcohol. Talked to Kester's tech support and they acknowledged the product is not very soluble with the solvent. They also mentioned they are removing the statement that "hot DI water" can be used for residue removal from their tech sheets. Apparently, lab tests looked good, but "the real world" is seeing a white film. Since I want to keep a limited alcohol cleaning process, I'm leaning towards an RMA no-clean (like Kester's 1515). Comments??

Thanks, Dave

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Jeff Sanchez

#12953

Re: Hand soldering rework fluxes | 15 January, 1999

| Hi all, | | I thought I'd use this forum to ask a couple general questions on fluxes for manual operations: | First - Is it OK to use a wave soldering type flux (specifically OA)? Thinking about activation temperatures and the ramp rate of the wave solder versus a soldering iron. We really haven't seen any problems, but is there such a thing as a flux specifically made for manual operations? | Second - Using no-clean flux for the same processes; we had been using Kester's 951 but found problems cleaning off excess flux with alcohol. Talked to Kester's tech support and they acknowledged the product is not very soluble with the solvent. They also mentioned they are removing the statement that "hot DI water" can be used for residue removal from their tech sheets. Apparently, lab tests looked good, but "the real world" is seeing a white film. Since I want to keep a limited alcohol cleaning process, I'm leaning towards an RMA no-clean (like Kester's 1515). | Comments?? | | Thanks, | Dave | DAVE, I do a ton of hand soldering and I find the best flux to be that which you use in the rest of your operations. If you have a wave and use a spicific flux for it than use that flux for the hand soldering . If you don't have a washer system in your shop or a full line for that matter than you can go with what works best. My opinion is go with good old fashioned liquid rosin flux . It is easy to deal with and very cheap. If I have no special cleaning requirments than I always use rosin cause it washes clean with alcohol. the NC and water solubles are not that friendly when out of there automated evironment. use the no clean after rework is done and you catch something and don't want to wash the whole board over.Stay away from the water types because they will cause dendrites if you do not have the proper cleaning systems. Not only that but they will desolve your beutiful work in the field if any trace amount is lurking under a part. you can look up dendrites on the search engine in this forum. The guys gave a lot of good info. If you need help with choosing a good flux than e-mail me and I will help you get the right match for the job.I have one that I use and it is great after it is thinned properly. BOTTOM LINE! If you"re gonna do it the old fashioned way? Than do it the old fashioned way! have a good one and try not to get sticky fingers....hehe...Jeff

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John

#12954

Re: Hand soldering rework fluxes | 15 January, 1999

| Hi all, | | I thought I'd use this forum to ask a couple general questions on fluxes for manual operations: | First - Is it OK to use a wave soldering type flux (specifically OA)? Thinking about activation temperatures and the ramp rate of the wave solder versus a soldering iron. We really haven't seen any problems, but is there such a thing as a flux specifically made for manual operations? | Second - Using no-clean flux for the same processes; we had been using Kester's 951 but found problems cleaning off excess flux with alcohol. Talked to Kester's tech support and they acknowledged the product is not very soluble with the solvent. They also mentioned they are removing the statement that "hot DI water" can be used for residue removal from their tech sheets. Apparently, lab tests looked good, but "the real world" is seeing a white film. Since I want to keep a limited alcohol cleaning process, I'm leaning towards an RMA no-clean (like Kester's 1515). | Comments?? | | Thanks, | Dave | Dave,

We do a fair amount of customer modifications for our customers. So, we do a fair amount of hand soldering. If you are intent on using Kester products, try the '245' "no clean". It is actually a low solids rosin solder. We have very good results with it and depending on your application, you can leave the residue, or it cleans nicely with alcohol.(Talk to your rep... they are pretty helpful) I would advise you to stay away from any OA products unless you have a VERY GOOD cleaning system. ANY residues left on the board can cause reliability problems, particularly if the product is operated in damp locations.(namely corrosion and dendrite formation.) I find that you can learn quite a bit by talking with your supplier(s) Explain what you are doing, and what results you are trying to achieve. If they cannot help you, talk to another supplier.

Good luck!

John

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