I am new to surface mount soldering. On a board with both SMT and through-hole parts (header pins), which parts should I solder on first?

I imagine the technique I use for SMT soldering is important. I have access to an oven and a heat gun - baking the circuit board after soldering on my header pins might cause some trouble, but I was wondering that the standard practice was in general.

I read here that

The surface mount soldering must be done before thru hole soldering because thru hole soldering creates imperfections on the underside of the board that will prevent good thermal conduction between hot plate and board.

but this is specific to SMT soldering using a hot plate.

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    \$\begingroup\$ With thru hole, you should always start with the smallest components and work up, otherwise you can't reach in with the iron. I suppose the same applies to the smd parts, whether hand soldered or reflow. \$\endgroup\$ – tomnexus May 1 '15 at 10:48
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    \$\begingroup\$ In my personal experience, soldering the bigger components first makes the whole board tilt or at least become a bit wobbly because parts aren't distributed evenly across the board and my soldering isn't even. You'd have trouble with the SMT parts after that. \$\endgroup\$ – Dr Coconut May 1 '15 at 15:12

As tomnexus said, it is always best to solder the largest components last. Most of the time this means that the surface mounted devices should be soldered first. Otherwise maneuverability is significantly decreased, trying to navigate around large components to solder the smaller ones.

The other reason I, personally, solder surface mount components first is because I use a reflow oven--I don't want the solder on thru-hole components to melt while reflowing the solder on the SMDs. I put the whole board in the oven with the solder paste and the SMDs, reflow, let cool, then do the thru-hole components with my iron. I wouldn't recommend doing it any other way.


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