>>if at all possible pre-tin the pad
>
>I plan to order the board from Olimex. I think the board
>is tinned so I can skip this step, isn't it?

Even when the PCB is tinned, you get a layer of oxidation on the tin, which
is what makes component leads look dull instead of shiny. Doing a pre-tin of
the pad and component allows you to get rid of the oxidation, and this is
all the more important with the tiny pads that SMD components use, as you
are likely to try and apply too much heat to get the solder to run nicely
otherwise. Note that for space electronics where the utmost in reliability
is required, this pre-tin of both the pad and component is a required part
of the operation. It also shows up faulty plating of the PCB and component
before trying to do the joint.

Do some experiments and you will find that if you pre tin the pads, you will
get much nicer looking joints. The solder will flow much nicer, and makes a
nice neat fillet with much less chance of a dry joint. I think it helps by
warming the pad and component slightly before you solder them together, so
they are less of a heatsink when doing the joint, so the iron is on for a
shorter time, saving both the pad and component as well.

One item I left out of the previous post. Get some fine solder wick. Use it
on the pads every time you remove a component. A small amount of solder left
behind leaves a "large" amount of solder and can quite easily create solder
bridges and shorts where you don't want them. Allow yourself some practice
on some old PC motherboards or similar items with SMD components, and you
will soon see what I mean.

For solder, the gauge we use is 26SWG (0.46mm, don't know what AWG) and have
some slightly larger 0.7mm for larger components.

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