what is surface mounting soldering ?
Wikipedia / Google broken again? ;-)
Through-hole - "the old way", drill holes, stick wires through, solder onto bottom side (usually) of the board.
Surface mount - the new way, don't drill holes, just solder parts directly onto the board. Easier / faster / cheaper, works especially well with small and lightweight parts.
Both methods can be mixed & matched as needed (and depending on what parts are used).
Optimal is a
temperature controlled soldering station of say, 30W at least. But if you go for a simple / cheap fixed-wattage iron, then for
i work with lcd display ,pic , connectors, stepper and dc motors (12v),IR sensors LDR
a 15 or 20W iron will do nicely. 30W is already on the high side for this work. For a fixed-wattage iron, higher wattage translates into higher temperature, and (as they also often come with a thicker tip) a higher heat flow from tip to work area.
Very sometimes that's what you need, but most times that just serves to kill components & damage circuit boards quicker (and makes the tip corrode faster, too).
I do virtually all my soldering (SMD and through hole) with a simple but
good quality 15W / 230V iron (Weller). The only situation were I run into trouble is metal layers that are both wide and thick. Like thick ground planes, the shielding around a HF circuit, etc. Which is rarely a problem since I rarely need to solder there. :grin: Sometimes I get out a cigarette lighter to pre-heat such an area a little, and presto, also done with my 15W iron.
The point is to get a few different tips for different jobs: a fine tip for fine-pitch SMD IC's, a thicker tip for soldering onto ground planes, thick wires etc.
Additional flux like from a pen or liquid dispenser is only needed in special cases: very corroded board surface / component leads, soldering flat pack IC's using the drag soldering method, etc. The common rosin core solder wire is enough for regular work (I use 0.7mm solder wire, could use 0.4 or 0.5mm since I find myself soldering small SMD parts more often lately).