The best solder for electronics, for most people, is Kester 44 63/37 in 0.031″.
It melts at one exact temperature, flows fast, and it’s been the standard rosin-core wire for decades.
If you don’t want any residue on your boards, grab MG Chemicals 4860 no-clean instead.
And if you need lead-free, MG Chemicals 4900 SAC305 is the one to get.
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Quick picks
- Best overall: Kester 44 63/37, 0.031″
- Best for tiny parts: Kester 44 63/37, 0.020″
- Best no-clean: MG Chemicals 4860 63/37
- Best budget leaded: MAIYUM 63/37, 0.8 mm
- Best lead-free: MG Chemicals 4900 SAC305
- Budget lead-free: ZSHX Sn99/Ag0.3/Cu0.7
How we chose
We didn’t put these on our own bench.
We read the makers’ technical data sheets, the Amazon listings, and Amazon’s summaries of owner reviews (October 2026).
Then we sorted the picks by the three things that actually change your results: alloy, flux type and wire thickness.
Comparison table
| Solder | Alloy | Diameter | Flux | Amazon rating (Oct 2026) |
|---|---|---|---|---|
| Kester 44 (1 oz tube) | 63/37 tin-lead | 0.031″ | Activated rosin | 4.8/5, 796 ratings |
| Kester 44 (3/4 oz tube) | 63/37 tin-lead | 0.020″ | Activated rosin | 4.8/5, 238 ratings |
| MG Chemicals 4860 | 63/37 tin-lead | 0.032″ | No-clean, 2.2% | 4.7/5, 334 ratings |
| MAIYUM 63/37 | 63/37 tin-lead | 0.8 mm | Rosin core | 4.6/5, 22,600+ ratings |
| MG Chemicals 4900 | SAC305 lead-free | 0.032″ | No-clean | 4.6/5, 156 ratings |
| ZSHX lead-free | Sn99/Ag0.3/Cu0.7 | 0.8 mm | Rosin core, 2% | 4.6/5, 1,500+ ratings |
Quick note: 0.031″, 0.032″ and 0.8 mm are basically the same size.
1. Kester 44 63/37, 0.031″: best overall
This is the safe pick for through-hole parts, wires, headers and most Arduino work.
63/37 is a “eutectic” alloy, which means it goes from liquid to solid at one temperature (183°C / 361°F) with no mushy stage.
That makes it harder to get a grainy, weak joint if your hand moves a bit while it cools.
Pros
- Kester calls 44 an activated rosin flux with fast “instant-action” wetting, so it cleans and spreads well.
- Kester says the residue is non-corrosive and non-conductive and doesn’t need removing for most uses.
- 4.8/5 from 796 Amazon ratings; owners mention good flow and fast melting.
Cons
- The flux leaves a visible residue on the board.
- If you do want it gone, Kester says plain isopropyl alcohol won’t remove it; you’d need a cleaner made for that job.
- Contains lead, so it’s not RoHS compliant (fine for hobby use, not for products you sell in the EU).
Skip it if you hate residue or need lead-free.
2. Kester 44 63/37, 0.020″: best for tiny parts
Same solder as above, just thinner.
Thin wire lets you feed a tiny amount, which is what you want on small SMD pins and fine-pitch chips.
Pros
- Less risk of bridging two pins with a blob.
- Same Kester 44 flux and 63/37 alloy as our top pick.
- 4.8/5 from 238 Amazon ratings.
Cons
- Slow on big joints like power wires or ground planes (you’ll feed it forever…).
- Smaller 3/4 oz tube.
Skip it if you mostly solder through-hole kits.
3. MG Chemicals 4860 63/37: best no-clean
Pick this if you want clean-looking boards without a cleaning step.
MG’s data sheet says residue removal is “not required,” and the flux is halide-free and non-conductive.
Pros
- 2.2% flux core that MG says spreads like an activated rosin flux and barely splatters.
- Same 183°C (361°F) melting point as any 63/37.
- Small 0.6 oz (18 g) pocket pack fits in a toolbox.
- 4.7/5 from 334 Amazon ratings; owners say it flows well for small repairs.
Cons
- 18 g goes fast if you build a lot; MG also sells it on 1/2 lb and 1 lb spools.
- MG rates the flux activity as low, so badly tarnished leads may need extra flux.
4. MAIYUM 63/37, 0.8 mm: best budget leaded
This is the most-rated solder in this list by far, and you get a 50 g roll.
It’s fine for learning and for casual repairs.
Pros
- 4.6/5 from 22,600+ Amazon ratings.
- Owners praise the value and say it’s easy to use.
- More solder per roll than the small tubes above.
Cons
- Amazon’s review summary shows mixed feedback on flow, melting and joint quality.
- No public data sheet like Kester or MG, so you’re trusting the listing.
Skip it if consistent results matter more than saving a few dollars.
5. MG Chemicals 4900 SAC305: best lead-free
Go lead-free if you’d rather not handle lead at all, or if you build things to sell where RoHS rules apply.
SAC305 is 96.3% tin, 3% silver and 0.7% copper, and MG calls it the predominant lead-free alloy.
Pros
- No-clean, halide-free flux with non-corrosive residue, per MG’s data sheet.
- MG says it’s about 14% longer by weight than leaded wire.
- 4.6/5 from 156 Amazon ratings; owners say it flows smoothly.
Cons
- It starts melting at about 217°C (423°F), so you need a hotter tip than with leaded solder.
- Owner feedback on the melting point is mixed.
6. ZSHX Sn99/Ag0.3/Cu0.7: budget lead-free
A cheaper lead-free roll with a lot more ratings than the MG.
The listing gives 99% tin, 0.3% silver, 0.7% copper, 2% flux and a 217°C (422.6°F) melting point.
Pros
- 4.6/5 from 1,500+ Amazon ratings.
- Owners say it melts smoothly and the thin wire fits tight spots.
- 50 g roll.
Cons
- Less silver than SAC305, and the specs come only from the listing, not a data sheet.
- Some reviewers say the product doesn’t clearly state it’s lead-free.
How to pick: alloy first, then flux, then thickness
Choose in this order and you can’t really go wrong.
Leaded or lead-free: leaded is easier
Leaded 63/37 melts lower, so it’s more forgiving.
Lead-free needs more heat: Kester lists 315-343°C (600-650°F) tips for leaded and 371-400°C (700-750°F) for lead-free.
If your iron can’t hold those temperatures, stick with leaded (our soldering iron guide helps there).
With any solder, MG’s advice is simple: avoid breathing the fumes and wash your hands after use.
Rosin or no-clean: depends on your parts
Flux is the stuff inside the wire that cleans the metal so solder sticks.
Activated rosin like Kester 44 is the stronger flux, so it’s the better bet on old or tarnished parts.
No-clean like MG 4860 is a low-activity flux, so it suits new, clean parts and boards people will see.
Wire thickness: 0.031″ for most jobs
- 0.020″ (0.5 mm): small SMD parts and fine-pitch chips.
- 0.031-0.032″ (0.8 mm): through-hole parts, headers, most kits. Start here.
- 0.040″ (1.0 mm): thick wires and big connectors.
Starting out with an Arduino starter kit or one of these DIY electronics projects?
One 0.031″ roll of 63/37 covers all of it.
FAQ
Is 60/40 or 63/37 better for electronics?
63/37 is a little better, because it’s eutectic: it switches from solid to liquid sharply instead of passing through a pasty stage.
60/40 isn’t eutectic, but it still works fine for most hobby joints.
Do I need extra flux?
Usually not with flux-core wire.
Kester even says added liquid flux should be a last resort with 44.
Do I have to clean flux off the board?
Not for most hobby work with the solders above.
Both Kester 44 and MG’s no-clean wires leave non-corrosive, non-conductive residue, according to their data sheets.
What else do I need besides solder?
A temperature-controlled iron, a tip cleaner and good light.
Our list of electronics repair tools covers the rest.
Sources
All checked October 24, 2026.
- Kester 44 Flux-Cored Wire Technical Data Sheet (issue May 2021): kester.com – flux class, residue, IPA note, tip temperatures, extra-flux advice
- MG Chemicals 486x Sn63/Pb37 No Clean Technical Data Sheet: mgchemicals.com – eutectic alloy, flux %, flux activity, melting point, pack sizes, fume advice
- MG Chemicals 4900 SAC305 Technical Data Sheet: mgchemicals.com – alloy, flux, length by weight
- MG Chemicals 4900 data sheet (TEquipment copy): tequipment.net – 217°C solidus
- JLCPCB, How to Choose the Right Solder Wire: jlcpcb.com – 63/37 sharp solid-liquid transition
- Amazon listings and review summaries, ASINs B00AVLM4SO, B00AYJ0B7Y, B004258YDE, B075WB98FJ, B073VR8D7Y, B07QZX9LG2 – ratings, counts, listed specs