Welcome to Board Talk with Jim Hall and Phil Zarrow, the Assembly Brothers pick and place. Coming to you high atop Mount Rialto in New Hampshire at the Board Talk headquarters.
This came from B.B. It's a process question.
We are a contract house using no-clean paste and wire solder. We clean assemblies by hand dipping using Insolve and want to get away from that. A third of our customers' products are R.F. Which would be better for R.F., vapor degreasing or aqueous cleaning?
To be honest with you, regardless of you using R.F. or whatever you are trying to clean, the basics of cleaning apply. There are two key elements you have to have here. You have to have a solvent be it in vapor form or a engineered aqueous in this case or whatever your solvent is, that is suitable for the residue that you are trying to remove and that is matched to the flux residue that of the solder that you are using.
Whether it's solder paste, wire solder, flux, wave or selective soldering, it's got to be matched. So that's the chemical aspect of it.
The mechanical energy aspect is the other important thing and that's going to depend largely on what you have on your board in terms of clearances and board geography.
You have to have ample mechanical energy to spread that chemical solvent, as well as rinse and dry, depending on what you are using. So regardless of whether you are doing R.F. or anything else, it's really more determined upon what you are cleaning. Try to clean, doing it right.
I'm no expert on R.F., but I would be more concerned with the board and solder mass materials' compatibility with whichever cleaning chemistry I'm using in terms of compatibility because you don't want to mess up the surface chemistry at all. So you want to make sure that the solvent, be it aqueous or vapor, is compatible with your board materials and solder mass.
Well one of the other important things with regard to the R.F. situation and I don't know what frequencies you are going, if you are going up to the UHF spectrum, at least you are cleaning your boards.
There is a lot of debate as far as using ultra-high frequencies and above, you start getting up above the 15 GHz - 20 GHz range if no-clean will suffice to stay on the board or whether it should be cleaned.
We don't know if you are getting up anywhere near there, but again, it's good to keep track of what papers are coming out and work is being done with clean versus no-clean, but in your case, you are cleaning it so almost becomes a non-issue now.
But you've got to have proper cleaning and that's the most important thing. As Jim is saying you don't want to do anything detrimental to anything else on the board and we've seen that happen a lot too.
And big is how it is initially a no-clean that you are trying to clean. You have to make absolutely certain that whatever solvent again, aqueous or vapor, is compatible with the specific paste formulation that you are dealing with.
So hopefully that answers your question, and doesn't provide you with further confusion.
Don't solder like my brother --
And please don't solder like my brother.