Kester flux

[TorqueRanger]

I am going to pick up a kester flux pen on ebay but wanted to known if they are god to buy from ebay and can they good bad and is there any questions i should ask before i buy ?  Also I noticed  that a couple people are selling homemade of kester flux in a jar and are these any good and would you trust them?

[Neganur]

I'd prefer the Kester 951 (non-rosin) over the Kester 186 (rosin) for hot air SMD type work, since it leaves very little residue behind. The 186 can be quite sticky.

Main difference is the percentage content of solids in the flux, the 951 has 2%-3% while the 186 has >30%. The 186 also contains more activator than the 951, which makes the wetting happen a little faster (it removes oxides a little better).

They're fairly cheap though, get one of each?

[marshallh]

I have several Kester water soluble flux pens, they were legit... DO NOT mess with water soluble fluxes unless you know what you are getting into.

I use MG Chemicals rosin flux pen for my SMD/BGA work. Yes, you have to clean up afterwards, no big deal with 99% IPA or flux cleaner, and more importantly no corroded tracks and electrical shorts...

Been buying them off Mouser, best stick to reputable distributors unless you want fakes.

[justanothercanuck]

I recently bought a Kester 952-D6 flux pen off Mouser.  Seems to do the job just fine. 

[nanofrog]

+1 for:

1. Buy from known vendors such as DigiKey, Mouser, Newark, ... to be sure you've a low chance of getting a fake.
2. Avoid water clean flux formulations. Too big a hassle for a hobbyist IMHO (must be cleaned off fairly quickly, and thoroughly, or it will cause corrosion).

As per Rosin or No Clean, that's up to you. As mentioned, though Rosin based (R, RMA, RA) may have more solids, it can be cleaned off fairly easily with IPA or good quality flux cleaner. Another member uses xylene (BTW, it mixes with IPA, though I've never tried it).

If you're not sure, try both and see what happens (IIRC, you already have a no-clean based roll of Kester solder). ***But if you only intend to get one type right now, you'd do better to match the flux pen formulation with the solder you currently have (prevents chemical incompatibilities).***

[Fsck]

I like 951 personally. I would never trust ebay for highly counterfeited items.