Time to repeat the experiment. Here goes.
Time to repeat the experiment. Here goes.16 days later. Hi-res photos are attached.
...
...But you left off my favorite flux, TF5000, so I'm going to have to ask you to do that over... hah!
...But you left off my favorite flux, TF5000, so I'm going to have to ask you to do that over... hah!
Epic experiment! Thanks for doing that.
If you post csv file, or contents here it's trivial to paste that back into any spreadsheet.
About the flux attacking bare copper... how big of an issue is that really? I'm only ever using flux over board area that is either soldered or has soldermask.
More is coming: I ordered two more Relife fluxes, they'll be here in a week or two.
Geuine rosin, Kester 44
We use only 63/37 Eutectic solder with those flux cores.
Avoid commie china junk solder or wire
Of course, both 44 paste and 1544 would fail shapirus’s requirement to be non-conductive before heating. I don’t think he understands that flux specs refer to the conductivity of the post-soldering residues.
...but I might try something, just for a quick test: for example, set the hot air gun to what, say, 280 °C, heat the PCB with the flux on top from below (to avoid direct blowing on the flux so that more of it stays in place) for, say, 30 seconds, then let it cool and measure what remains. Just to see if the "it must be heated to stop conducting" claims are substantiated, and to what extent, if they are.
I realize I'm late to the party here but....
Indium TACFlux 020B-RC is pretty much the only flux I use for hand soldering/rework anymore, for the reasons everyone mentions in this thread.
Of course, both 44 paste and 1544 would fail shapirus’s requirement to be non-conductive before heating. I don’t think he understands that flux specs refer to the conductivity of the post-soldering residues.Not that I don't understand, but I don't care. I test the fluxes I get my hands on for my specific requirements, which is hand soldering of both THT and SMD parts. And I believe this specific use case is of interest to many electronics hobbyists that can read this, too. Another way of looking at it is worst case scenario testing.
Of course, both 44 paste and 1544 would fail shapirus’s requirement to be non-conductive before heating. I don’t think he understands that flux specs refer to the conductivity of the post-soldering residues.Not that I don't understand, but I don't care. I test the fluxes I get my hands on for my specific requirements, which is hand soldering of both THT and SMD parts. And I believe this specific use case is of interest to many electronics hobbyists that can read this, too. Another way of looking at it is worst case scenario testing.
Besides, the two fluxes from my last post are specifically advertised for BGA rework and general repair, which does not guarantee full heating, either (I believe even when using a hot air gun). And hey, they are 500-1000 times (!) more conductive than the other fluxes I tested.
It would also be interesting to test conductivity after full heating, but that would require having a reflow oven, which I don't have, and the motivation to do it, which I also don't have, since I don't do that kind of soldering.
...but I might try something, just for a quick test: for example, set the hot air gun to what, say, 280 °C, heat the PCB with the flux on top from below (to avoid direct blowing on the flux so that more of it stays in place) for, say, 30 seconds, then let it cool and measure what remains. Just to see if the "it must be heated to stop conducting" claims are substantiated, and to what extent, if they are.
My main concern was you trying to get a refund for flux because of it not meeting the claimed conductivity specs, even though you hadn’t reflowed it. That’s not fair unless they specifically said it was nonconductive in a non-reflowed state.
It’s only whatever flux has flowed far away that is of concern.
You should reconsider. Reflow in an oven is exceedingly efficient. (And practically mandatory for many modern packages.) A simple $50 toaster oven is enough for basic use.
You make it sound as though that’s some crackpot theory… No, it’s how no-clean fluxes are designed to work.
However, I would be leery of your proposed methodology, because it’s quite possible that it wouldn’t heat it evenly enough to draw any conclusions.
Remember: there are TWO temperature thresholds to reach. The first (lower) one activates the flux, the second (higher) one neutralizes it again. If you heat to a temperature that reaches the activation temperature, but not the neutralization temperature, it may be left in a more conductive, more corrosive condition than the unheated state! So the only fair test of this “claim” is to actually get it hot enough to melt solder, since that’s what it was designed for.
It’s only whatever flux has flowed far away that is of concern.That's the point. Unless you heat entire board, you can't guarantee that the still conducting residues do not get trapped in some high impedance circuitry where it can cause trouble. I agree that it's not very likely, especially with almost exclusively digital circuits like laptop or smartphone boards, but it may be an issue with sensitive analog devices.
As I said there: that’s why I always tell people to always clean no-clean flux (except from flux-core solder) when using it for rework.
As I said there: that’s why I always tell people to always clean no-clean flux (except from flux-core solder) when using it for rework.Correct. But cleaning also does not guarantee that all of the residue will be removed. I'm not sure just how much of an issue will the trapped flux be, but even when washing entire boards in ultrasonic bath, some flux easily remains under SMT parts and generally in hard to reach spots.
Well, by “cleaning” I mean “actually cause to be clean”, not just “perform a cleaning procedure regardless of outcome.”
I do recognize that this can be hard to do with some components. I’m very glad I have compressed air at work, since that’s super useful for getting stuff out from under SMD parts.
As I said above, which you didn’t respond to then, either:Well, by “cleaning” I mean “actually cause to be clean”, not just “perform a cleaning procedure regardless of outcome.”
I do recognize that this can be hard to do with some components. I’m very glad I have compressed air at work, since that’s super useful for getting stuff out from under SMD parts.The emphasis is “cause to be clean”. That is, perform cleaning until it is actually clean. Not just “do” a cleaning once, regardless of outcome, and consider it good.
A friend said a -- drat, now I forget which brand exactly, but probably any will do? -- window cleaner is effective on flux residues.
Seems like it would be slow, to me, but maybe a solvent-rich variety, or boosted with a little alcohol or ethyl acetate, would cover that.
16 days later. Hi-res photos are attached.
(I like the MG4381 except for one feature that has me looking for an alternative: it's lumpy. I can squeeze a few dabs from a syringe and then it's blocked and useless.)
Got some of the Relife 422 stuff with which I did a board last week.
The MG8341 is easy to clean because it dissolves quickly in IPA.
I will put a couple of drops (or cotton bud load) of IPA on the area to clean, then get some paper kitchen towel and dab it up using tweezers to move it around. The MG8341-loaded IPA is quickly sucked up and nothing seems to be left behind.
I think that process successfully gets unused flux from under components too.
So, what I would be interested in seeing is a repeat of your bare copper test but this time with the flux cleaned off. Not cleaned off as in bath washed in an ultrasonic cleaner, but using an appropriate cleaner in the way a repair might be done (because that's the worst case). Dribble or spray the cleaner, wipe with rag/towel/whatever then let's see which corrodes. I think the MG4381 might pass the test after doing that, and some others might not (if they just get spread around rather than actually cleaned off).
(I like the MG4381 except for one feature that has me looking for an alternative: it's lumpy. I can squeeze a few dabs from a syringe and then it's blocked and useless.)
(I like the MG4381 except for one feature that has me looking for an alternative: it's lumpy. I can squeeze a few dabs from a syringe and then it's blocked and useless.)How old is yours? I have definitely noticed lumpiness in my syringe of it, which is near its end, but I don’t remember it being lumpy when it was new (which was probably 2015 or so).
BTW, the sticker on the jar says "made in China". Doesn't look counterfeit though, everything looks as it should. Was yours made in Canada?