Don’t be afraid of SMD

A lot of people are hesitant to use 0805 and SOT-23 sized parts because they fear they will not be able to solder them, or will get frustrated with the size. Fair enough too, if you have shaky hands. I have recently transitioned from using through hole components to using SMD almost exclusively where possible and immediately I’ve noticed it’s become much easier to shrink my designs, producing boards that cost less than $1.50 each with silkscreens on both sides.

Once you’ve got enough practise, you might even find soldering SMD resistors and capacitors to be easier than their through hole counter parts. LEDs can be a little tricky because you’ve got to keep an eye out for the anode marking, as desoldering it and flipping it around could be quite an ordeal with a dense layout. The hardest part is still just the TQFP parts, such as microcontrollers. By far the easiest method is to simply place it as best you can and use a flux pen to apply flux to every side. After applying solder directly to the tip, wipe some off on opposite corner pins, this just helps hold the chip in place for the next steps. Now, with the thinnest solder you have, tin the tip and drag the soldering iron along the pins towards the surface of the board, holding the iron at a 45 degree angle. Remember that solder will flow from cold to hot spots, so this keeps it from bridging between pins. To remove any remaining bridges, clean the tip, tin it lightly and then position it nearly horizontal, pressing down on the pins and dragging away.

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