[xmokshax]

i've been using 60/40 solder and decided i'd like to try some 63/37. i've found some that i think is a good deal on eBay (~$13 for 1 lb, 0.031", if i buy 2 rolls), but it's a core size of 58 rather than 50, which seems to be more standard. this translates into twice the flux content (2.2% vs 1.1%).

is there a big functional difference between these two core sizes? is there an advantage/disadvantage to the extra flux?

 

[xmokshax]

bump... anyone have an answer to this?

 

[el_matt0]

seems like a pretty good question...cant offer my help thouhg lol

 

[threepointone]

personally I've never compared what more or less flux in the core would do, though I'm sure I have a couple of different types I could test out if I have time (I went on a solder-buying spree a while ago). I would imagine that having more flux in the core would mean that you don't need to add extra flux more often / easier to clean up oxidation but also that you'd have a nastier-looking board to clean up. I'd probably go for more flux, since I don't mind cleaning things up but do mind if a joint refuses to accept solder because of oxidation.

 

[mono]

If you don't use extra, separate flux, definitely use at least 2% flux cored solder. The addt'l flux makes soldering easier, allows the best joint possible without applying excess solder to a joint. If you had an ISO compliant manufacturing related workflow where every tiny aspect had great control, no touching part leads and controlled humidity, short time from unpacking recently manufactured or sealed parts to soldering, etc, in these very optimized conditions you might want 1% flux core.

Otherwise, for our purposes 2% is a very good idea for best joints with least effort. It might seem like you'd use up your solder faster this way, but in practice I doubt it, generally you end up applying no more solder, maybe even less because what you do apply already flowed so well with higher flux % in it.

What you have linked is Kester 245, it is not rosin core solder like the ebay listing claims. It is a no-clean formula meaning the flux hardens to an almost clear hard coating. This cannot easily be cleaned off like rosin core can with alcohol. I don't recall what solvent does best to remove it, maybe the Kester product that removes it lists that in it's MSDS.

Kester Website, 245 Product Page

The solder *most* of us would use (the equivalent product from Kester) would be 285 which is a mildly activated rosin core. The part number for this in equivalent product is 24-6337-9713. Another popular solder also suitable for electrical work is Kester 44 Activated Rosin. It's like the mild but not as mild. It'll wear tip tips a slight bit faster and isn't needed for clean parts, but old parts have a bit of oxide buildup it will clean off better. If you were stuck on a deserted island you'd want 44, but 285 is more appropriate for headamps. It's splitting hairs though, either will generally do fine.

Any of these three flux types will work fine for headamps/etc, but if you dislike having a clear residue remaining on the joint then don't get no-clean solder. It's not very unattractive and does not get gummy over time (and at higher humidity levels) like some rosin flux does, but some people are more picky about these things than others - to each his own.

 

[mono]

On a related note, what the heck happened to solder prices recently? I bought a pound of Kester 285 from Digikey back in March this year for $13.40 (in one unit quantity).

Today Digikey is wanting $29.13 for it!

Seems like right before I bought it at Digikey I had emailed MCM (Or maybe it was Newark) to tell them they must have made a mistake in their catalog because their price for solder was similarly high. Their reply was the price was correct, that it had gone up recently. Gone up is one thing but by 217% is another.

There's ONE HERE for $15 delivered in case anyONE person is interested.

 

[xmokshax]

Quote:

Originally Posted by mono /img/forum/go_quote.gif On a related note, what the heck happened to solder prices recently? I bought a pound of Kester 285 from Digikey back in March this year for $13.40 (in one unit quantity). Today Digikey is wanting $29.13 for it! Seems like right before I bought it at Digikey I had emailed MCM (Or maybe it was Newark) to tell them they must have made a mistake in their catalog because their price for solder was similarly high. Their reply was the price was correct, that it had gone up recently. Gone up is one thing but by 217% is another. There's ONE HERE for $15 delivered in case anyONE person is interested.

ooooh, don't mind if i do...

thanks for pointing out the difference between the no-clean flux and standard rosin. i was under the impression that the no-clean stuff was still rosin, just a different formulation that's less conductive/corrosive and therefore doesn't need to be cleaned. i'm glad you straightened out that misconception. based on your description, the 285 sounds ideal for me. SOLD!

i've also been balking at the price of solder... i only just recently started soldering, but i bought a 1lb roll of 60/40 from Jameco for 9 bucks and was stunned to see that 63/37 isn't really available for less than around $20/lb. i'm not sure if this is because i bought generic, non-RoHS-certified 60/40, or if it's because 63/37 is actually that much more difficult to make. either way, i was rather taken aback.

for what it's worth, jameco is selling 1lb rolls of 0.020" Kester 285 for $19.99, which is at least a better deal than Digi-Key is offering.

 

[mono]

63/37 is not difficult to make, it's just that the price of solder is crazy recently. Upon until 4 months ago, there were (most) places you could get a pound of 63/37 for about $10 for generic or $$12-15 for name brands.

I suspect Kester reduced production of lead-bearing solders and this accounts for it, but that should also mean lead-free gets cheaper and I don't see any from Kester for $13 a pound yet.

I didn't necessarily mean to discourage use of no-clean solder, I used up a lb. roll of it (kester 245) recently and have no complaints but my opinion is that for general purpose new(er) electronics parts soldering the 285 is the best choice. Well, it was the best choice but there's no way I'd pay $29 for a pound of 63/37

 

[cling]

Extra flux will not do you harm, but too much will. Get what I am saying? 58 is not too big...not sure what makes you think this.

 

[mono]

Quote:

Originally Posted by xmokshax /img/forum/go_quote.gif ooooh, don't mind if i do... thanks for pointing out the difference between the no-clean flux and standard rosin. i was under the impression that the no-clean stuff was still rosin, just a different formulation that's less conductive/corrosive and therefore doesn't need to be cleaned. i'm glad you straightened out that misconception. based on your description, the 285 sounds ideal for me. SOLD!

No clean is not hygroscopic, doesn't absorb moisture from the air. Therefore, (and due to being hard and clear) it doesn't need to be cleaned off in almost any situation unless you dislike the looks of having a clear residue around joints. It is also not rosin based so alcohol is not a solvent, it's meant to stay on the board.

Rosin Activated or Rosin Mildy Activated (RMA) is hygroscopic, it will absorb moisture from the air and the more active it is (generally speaking), the gummier it can become. When it get gummier, it becomes more liquid and thus more active, wearing away at the metal surfaces over time. This is usually a very slow process, many of the electronic parts you have bought over the years may have never had the rosin core solder cleaned off and it didn't make a difference. However, it "can" potentially dissolve enough metal into the rosin/moisture made solution to become moderately conductive which could have an undesirable effect on low signal level, close pitched parts, or those with very high voltage.

IOW, there is no rush to clean off rosin flux based solder within a few hours or even days later like there would be with an acid flux based solder as you'd find used for plumbing or stained glasswork, but ideally rosin flux is eventually cleaned off in a hi-fi project because it looks nastier over time than no-clean does. IMO, often we make too much of a fuss over what our projects look like, it's mainly a matter of vanity, but so it is with the evolution of most hobbies and since there is still a small chance that humidity could cause a problem a small % of the time, the default position is to clean off rosin flux residue when the whole board is finished (or righ before adding parts to the board that would be less tolerable of the (generally alcohol) solvent used to remove the rosin flux.

Frankly if a project doesn't require it look good, will be cased up and never awed over, it is easier to use no-clean flux because it removes an extra cleaning step. Good for field work where you just want to solder and be done already. I guess it comes back to the same situation as with many other areas of tools and supplies, if one product did everything without some kind of compromise, there'd only be one product to choose from.