Been looking for some solder paste lately, my old Mechanic jar is dry and contaminated, I wrongly mixed it with :facepalm: ethanol in the past because it ended up very dry and now it is working mixed with turpentine but needs extra flux.
I am resolved to get a syringe of Sn63Pb37; good, beautiful :-) and cheap.
However, I've found maybe a pair different paste mixes worth mentioning:
Is this stuff being used in mass production? I wonder how does it behaves versus Sn63Pb37.
Found its melting point more specifically being listed as 178 - 183 °C @ HC Solder Products, seems like a lower cost version of Sn64Bi35Ag1 (probably eutectic, 178 °C).
Huh? What the… ? Did Apple came out with some secret mumbo-jumbo solder paste for their devices recently? Because I don't see a composition, I see X/XS/XSMAX/11 and whatever instead.
That is correct, some solder paste is sold as more ideal for specific iphone models, i.e. Paste for iPhone X/XS/XSMAX
I believe these types are low temperature paste.
I use Chipquik SMD291AX50T3 and it was well worth the money spent. Works super for me, excellent paste for reflowing.
I understand your looking for alternatives and wish I could help but I haven’t had a reason to look for anything else.
What I do when my paste starts drying out is add several drops of Kester 186 liquid solder flux to the jar and stir it around until it becomes runny again.
The added liquid flux seems to work well mixed with the Chipquik solder paste.
I do have solder with the 2% Ag added, the silver makes a more conductive joint. The added silver is used mostly in connections of high-fidelity sound system.
I also used SMD291AX pastes for production for a couple years here, but recently switched to the SMDLTLFP (Sn42/Bi57.6/Ag0.4 melting point around 140°C) for surface-mount processes because I’ve been working with more thermally sensitive ICs and wanted to reduce heat requirements both for installation and rework, in addition to the obvious benefits of removing lead from mass production processes. It’s behaving quite nicely. We’ve got tubes of 291 flux to add when it gets dry so as not to change any evap or cleaning properties.
Can’t speak for a ~180°C alloy but I’ve become a fan of bismuth solders.
Oof! I think I am sending myself on a wild goose chase. I will mostly use the solder paste for reflowing leds and stuff, but nothing thermally sensitive as a rule. Can some of these solder pastes offer me some perceptible advantage over Sn63Pb37?
Not knowing the solder formula and properties certainly doesn't helps. Lots of unnecessary secrecy.
On the other hand, I'll get some thick flux because applying runny ethanol + rosin over surface mount devices and then applying heat with my hot air gun causes bubbles, bubbles which move :facepalm: the components.
The trick with bubbles is to preheat letting the flux out gas before applying the melting point heat.
I’m like you though though instead of pulling the hotplate out, I just use hot air as it takes less time.
Using the hot air if you’ll heat at a greater distance for a minute or two to let the flux out gas then move in to your melting point distance it should just start reflowing with out the components doing a little dance.
