Our article provides simple step-by-step instructions for soldering ESC power contacts and other components to ensure your FPV drones are reliable and durable.
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Soldering an FPV drone is a process that requires precision. In this article, you will learn about the most common mistakes when soldering contact pads, as well as get practical advice on how to correct them.
Incomplete contact areas;
Too much insulation removed / exposed wire outside the solder drop;
Badly soldered wires;
Cold soldering;
Insufficient contact area / bare wire not immersed in solder drop;
Not enough flux / “Stalagmites”;
Too much solder;
Not enough solder;
Solder drops on the board / soldered neighboring sites;
Non-conformity of soldering to defoamers.
If the contact areas are not fully soldered and copper is visible, the contact area will be smaller than calculated by the manufacturer, and the connection will be less fine.
Add flux, heat with a soldering iron (for power t=420-450°C, for other connections t=320-350°C) and unsolder the wire. If necessary, add more flux. Take the solder, bring it to the contact area together with the tip of the soldering iron and completely solder the surface of the contact area so that no copper is visible.
The wire insulation must fit the solder drop. To do this, it is worth removing the insulation for a length that is approximately equal to two-thirds of the length of the contact area. If the bare wire is outside the drop, the contact must be resoldered.
It is necessary to unsolder the wire, shorten it, tin it if necessary and solder it again. Do not forget to add flux and clean the tip of the soldering iron.
This error usually becomes obvious together with the previous one. If the veins of the bare part of the wire are visible, or if individual veins stick out to the side, it means that the wires were not properly soldered. A wire that is not protected by insulation is more fragile, which over time can lead to its breakage or the formation of protruding individual strands, which, when in contact with neighboring sites, will cause a short circuit.
It is necessary to unsolder the wire, if necessary, shorten it and solder it completely, then solder it again.
Cold soldering occurs due to insufficiently high temperature of the soldering iron, use of an unsuitable tip, low-quality or unsuitable solder. The solder does not melt and form a drop, but lies in layers that are barely glued to each other and can tear off under stress.
Check that the solder meets the recommendations, the soldering iron holds the right temperature, and the tip is large enough. Add flux and heat the place with a soldering iron at a slightly higher temperature until the solder melts.
If the wire does not have a sufficient area of contact with the site, it will have poorer conductivity and may eventually break off under loads.
Add flux, heat the contact, move the wire closer to the contact pad and add solder to form a solid drop. However, it is often more difficult to correct such a mistake than to redo it. Therefore, a more optimal solution may be to unsolder the wire, add flux, if necessary, solder the platform and wire again and solder again.
If the flux evaporates during soldering, the solder begins to stick to the tip and drag behind it, forming sharp growths. The wires of peripheral devices can be damaged by such “stalagmites” on the solder, so they must be removed so that the drop is rounded.
Add flux and heat the soldering point with the tip of the soldering iron so that the solder spreads and forms a neat drop.
Too much solder can cause poor electrical conductivity and prevent the joint from working properly. Too large a drop of solder on the power contacts can also touch the frame from below or the connector on the FC from above, which will lead to a short circuit or interfere with the operation of the flight controller.
Add flux, heat the contacts, unsolder the wire, clean the excess solder from the platform and the wire, solder again and solder.
If the wire is barely “glued” to the surface of the pad, instead of being submerged in a solid round drop, not enough solder was added when soldering.
Add flux to the place of soldering, clean the tip of the soldering iron, put solder on the tip and apply it to the place of soldering, holding the wire. It is often more difficult to correct a mistake than to redo it. A more optimal solution may be to unsolder the wire, add flux, solder the pad and wire again, and solder again.
When soldering, micro-droplets of solder can fall from the tip of the soldering iron onto the board and or get stuck in the legs of SMD components. Also, when soldering, jumpers sometimes appear between neighboring sites. All this leads to a short circuit.
If there are solder drops on the board that are not soldered to the components on the board, they can be cleaned with a toothbrush and isopropyl alcohol. If the elements on the board are soldered with these drops, or there is a jumper between adjacent pads, you need to clean the tip of the soldering iron and quickly remove the excess solder. In some cases, a special tape for removing solder can be useful.
One of the common mistakes in soldering is the mismatch of the pinout, due to which incorrectly soldered devices will not work.
the polarity of the capacitor is reversed (this will lead to a short circuit)
confused RX and TX from the receiver
tangled video cables and video transmitter data cable
It is necessary to unsolder the erroneously soldered wire and solder it to the correct place.
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