Every FPV drone is held together by a few dozen solder joints. Motors to ESC, receiver to flight controller, battery lead to power pads. Learn to make a good one and you can build, repair and upgrade your own drone, which in this hobby is half the fun and most of the savings.
Soldering is gluing metal with melted metal. Solder is a soft alloy that melts at around 180 °C. The iron runs much hotter than that so the work is quick. Inside the solder wire is flux, a cleaner that helps solder flow and stick.
Safety first
The tip of the iron is hotter than any kitchen oven. Wear glasses, work with a fan or fresh air (the smoke is flux, don't breathe it), put the iron back in its stand every time you let go, and wash your hands afterwards. No food or drinks at the bench. Never solder with a LiPo plugged in.
Heat the joint, not the solder
The biggest beginner mistake is melting solder on the iron and dabbing it onto the joint. It doesn't stick. Solder flows toward heat, so heat the parts and let them melt the solder:
1. Touch the iron to the pad and the wire at the same time. 2. Feed solder into the joint, not onto the iron. 3. When it flows, take the solder away first, then the iron. 4. Don't move anything for a couple of seconds while it sets.
On drones you'll mostly solder wires to flat pads. The trick is to tin both first: put a little solder on the pad, a little on the stripped and twisted wire end, then hold the wire on the pad and touch with the iron. Both melt together into one joint.
Hot and quick
A hot iron for a short time beats a cool iron for a long time. Holding the iron on a joint for ages cooks the board and can lift the copper pad right off. If a joint takes longer than two or three seconds, use a bigger tip and more flux, not more time. Big battery pads and XT60 connectors need much more heat than tiny signal pads.
Good joint, bad joints
A good joint is shiny and smooth, shaped like a little volcano, and the solder has clearly flowed onto both the pad and the wire. A dull, grainy one is "cold": it moved while setting or never got hot enough. A ball sitting on top never stuck. Strands still showing means too little solder. And a bridge of solder between two pads is a short circuit waiting to happen. The fix is almost always the same: add a little flux, reheat, try again.
Before the first battery
Every build and every repair ends with the same five checks: look for blobs and bridges; clean flux off with isopropyl alcohol; beep-test between + and − with a multimeter (it must not beep); check that red goes to +; and power up the first time through a smoke stopper. That's how you never meet the magic smoke.
Heat the joint, not the solder.
Read
- Soldering is Easy: comic book (Mitch Altman, Andie Nordgren, Jeff Keyzer)
the classic, CC BY-SA. Also in Estonian: Jootmine On Imelihtne (PDF). Great to print for the bench. English PDF. - Oscar Liang: A Beginner's Guide to Soldering for FPV Drones
FPV-specific: temperatures, tinning, pads, common mistakes. - Oscar Liang: Soldering Tools 101: buyer's guide for FPV pilots
which iron, tips, solder and flux to get. - Unmanned Tech: How to Solder FPV Drones: a comprehensive guide for beginners
blog.unmanned.tech - Adafruit Guide to Excellent Soldering (PDF)
great photos of good and bad joints. - Stony Brook University: Soldering safety guide
the safety rules, explained.
Watch
Videos are picked from search. We’re still checking them.
- Solder Practice Board: How to solder your 1st FPV Drone
youtube.com - Soldering for FPV Pilots
youtube.com - How to Solder Motors to ESC
youtube.com - Soldering Examples: The Good, Bad, and the Really Bad
youtube.com - How to Spot a Bad Solder Joint
youtube.com
For trainers: the 10-minute plan
| Time | Slide | Talking points |
|---|---|---|
| 0:00 | "Who's afraid of the iron?" | Hands up. Everyone was at first. It's a skill, not a talent: 20 joints and you've got it. |
| 1:00 | What soldering is | Gluing metal with melted metal. Solder melts around 180 °C; the iron runs much hotter so it's quick. Flux cleans the metal so solder can stick. |
| 2:00 | Diagram 5: Safe at the bench | Do this first, every time. Glasses, fresh air, iron in the stand, wash hands, no LiPo plugged in. |
| 3:30 | Diagram 1: Four steps | Heat the joint, not the solder. Solder flows towards heat. Never carry a drop of solder on the iron to the joint. |
| 5:00 | The FPV way | On drones we mostly do wire-to-pad: tin the pad, tin the wire, hold the wire on the pad, touch with the iron, both melt together. Done. |
| 6:00 | Diagram 3: Hot and quick | A hot iron for a short time beats a cool iron for a long time. Long heating cooks the board and can lift pads. Big pad = bigger tip + flux, not more seconds. |
| 7:00 | Diagram 2: Good vs bad | Shiny little volcano = good. Dull, blob, strands showing, bridge = reheat, add flux, try again. |
| 8:30 | Diagram 4: Before the first battery | Look, clean, beep test, red is +, smoke stopper. This is how you never see the magic smoke. |
| 9:30 | Takeaway | "Heat the joint, not the solder." Practice board time. |
Demo: one practice board per pair, side by side. Each pair makes five joints and grades them with diagram 2, then fixes the worst one. A cheap USB microscope or phone macro lens on the projector makes the "volcano vs blob" difference obvious.