I've noticed that when soldering small PCBs can get very hot. Since I haven't yet been able to find a good vise in which to hold PCBs, I mostly hold them in my hand and after several minutes of soldering, they tend to get uncomfortably hot.
I haven't seen many information on Internet about this, so I'm asking for tips here.
Shouldn't need to cool them while hand soldering. In fact, cooling them whilst soldering would induce a lot of thermal stress with cool areas of the PCB and really hot areas in other bits of the PCB.
You may be overheating the PCB with incorrect soldering technique or maybe your PCB has big ground polygons/planes and you're soldering on joints connecting to these ground polygons/planes without a thermal relief.
Having a vise is critical, especially for small chips, but since you are holding out of the right one, here are some suggestions:
Having the right size soldering iron and power will reduce the amount that your PCB heats up. Ideally you want a soldering iron that can quickly transfer heat to your pad so that you can get your solder on and take the heat off fast. To do this you will want to use the largest tip that you can find that still gives you the precision needed for what you are soldering. Adjustable temperature soldering irons are nice, but you need to also make sure that your iron is able to output enough power to keep your iron at the temperature you want it at.
If you have a large ground plane, you will most likely have to heat it up in order to get good soldering. You can added extra space at the edge of your PCB with no copper for you to be able to hold on to. If you aren't holding it where there is metal then you are more then likely over heating your board and should look at my prior suggestion.
But, with that said, you should really consider getting yourself a nice vise that lets you put your board at any angle that you want, this will really help with getting a great soldering job. The next investment you should consider getting is either a better soldering iron and/or nice lighting.
Like others have said: use a clamping vice. I use a Bernstein Spannfix:
It won't help to keep the PCB cool, but at least you won't burn your fingers.
The seemingly hot PCB is not really a problem. A PCB which is at 60°C may be too hot to touch, but during reflow soldering the whole PCB is exposed to temperatures close to and above 200°C for minutes. This way much more thermal energy is applied than you can with a hand soldering iron.
Try holding your PCB in a vise. Special PCB vises are available.
This is one of the places where proper equipment helps loads. If its a particularly small PCB a third hand type device is invaluble, in more ways than one (it also serves to hold leads in place), though i suppose you can use a small clamp as a temporary improvised holder.
A vise is an essential tool for soldering. If you're still looking, I'd recommend the Panavise tools. The pads for the 203 and 303 heads often have (or can be made to have) grooves which hold PCBs well, or you can use a vise specifically designed for holding PCBs, like the 315.
However, if you're burning your hands because you don't want to spend the money on a vise, or you're just looking for a more economical alternative, a set of 'helping hands' is a perfectly fine for holding small PCBs. These can often be found for less than $10, and usually include a magnifier and heavy base.
If you need it right now, you can probably save your fingertips from being burned with just a heavy piece of wire affixed to your workstation and a pair of alligator clips screwed to each end of the wire.
