STM32F103CB, which is TQFP 48-pin

For the first experimental version of FST-01, I use STM32F103CB, 48-pin TQFP chip.

PCB Design constraint

For FST-01 size (26mm x 13mm, approximately), I needed to have smaller pad pattern of 48-pin TQFP than recommended footprint.

This is not good. For hand soldering, pad pattern is better to be longer.

Articles for hand soldering (in Japanese)

I read following two articles.

• ＱＦＰのハンダ付けは手作業でできる0.5mmピッチのＱＦＰをピッチ変換基板に手作業でハンダ付けする方法: http://verilogician.net/elecDIY/QFPsold/TQFPsold.html
  • old version: http://www.ice.gunma-ct.ac.jp/~kimsyn/elcDIY/QFPsold/TQFPsold.html
• 0.5mm ピッチ QFP のハンダ付け: http://www002.upp.so-net.ne.jp/uratan/ArmUZK/solder.html

Technical points

• Positioning of IC is most important. It would be good to use good glue.
• Loupe is needed (for me). I use head loupe of 2x.
• Touch the head of soldering iron to pad pattern of PCB, not to lead of IC.
• Solder wick is our friend.
• We don't need solder paste, but it would be good to use it.

My conclusion

• QFN soldering is easier for me.