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I've recently brought the px4fmu and px4ui boards. The px4io requires me to solder a power socket and headers onto it.

However there are surface mount components very close to the holes/pads. Also the pads are not silver (see below, points marked in red are of primary concern).

enter image description here

So my question is, how do I go about soldering these without affecting the nearby components. Do I need to tin the pads first? Is 370 Celsius okay for the iron? Do I use the rather thickish chisel tip or go to a fine point?

I'm not the most experienced at soldering but I've done a bit of reading and experimenting on soldering, so I understand the basics (solder applied op the tip of the soldering iron, heat up the wire/pad first, etc). I just cannot find any info on how to handle the situation I find myself in. The closeness of the pins on the header also seem like trouble to me :(

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  • \$\begingroup\$ I would use a 0.8mm chisel tip (my default tip). \$\endgroup\$
    – starblue
    Apr 6, 2013 at 10:00
  • \$\begingroup\$ For this kind of job, some kapton tape around the unsoldered pins would help. \$\endgroup\$
    – MV.
    Dec 15, 2015 at 7:43

2 Answers 2

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There is a variety of different coating/finishes used for solder points. Silver, Tin, Gold, hybrids are all common. All depends on need/cost from the manufacturer.

Just solder as normal. Flux, Tin, Solder.

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  • \$\begingroup\$ The one at the bottom is really close to the other components, less than 1mm between some of them. I'm worried I'll melt the solder on the surface mount components by accident and they will move. ---- So I do tin the pads first? \$\endgroup\$
    – Metalskin
    Apr 6, 2013 at 0:51
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    \$\begingroup\$ @Metalskin 1mm is more than enough. Just don't dawdle around. You really shouldn't have any issues unless you actually touch the smd parts with your iron. \$\endgroup\$
    – Passerby
    Apr 6, 2013 at 0:55
  • \$\begingroup\$ If you could melt solder 1mm from your iron, some soldering jobs would be a breeze that otherwise aren't! :) \$\endgroup\$
    – Kaz
    Apr 6, 2013 at 1:20
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    \$\begingroup\$ Even if a nearby solder joint were to liquify, that part has at least one more soldered terminal keeping it on the board. \$\endgroup\$
    – Kaz
    Apr 6, 2013 at 1:23
  • \$\begingroup\$ Makes me wonder what soldering iron you use. \$\endgroup\$
    – jippie
    Apr 6, 2013 at 9:21
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I wouldn't worry too much about the SMT components. If you do end up with a solder bridge to one it's easy enough to clean up and the components are unlikely to move unless you get both ends hot at the same time and normal SMT components are pretty heat-tolerant.

The bigger worry as far as i'm concerned is that white connector. In my experience connectors like that (even the ones designed to survive reflow) are easily damaged by a stray soldering iron.

Do get some decent-quality fluxed solder wick (I use Servisol Soldermop personally). In my experience solder wick is the best way to cleanly remove unwanted solder from a complex board.

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