First GD32 tests


Sjaak has published a new build, the STM32/GD32F103 QFN32 breakout board:

Uptill now I used 0603 sized resistors and capacitors but for this project I switched to 0402 to save a few mm on the board. I have soldered many challenging chip packages so I felt confident. The technique is the same as for bigger sized devices: flux the area generous, hold the device with tweezers, solder one pad with fresh soldered iron and move the device into the molten solder puddle, retract the soldering iron and watch the solder joint cool down. If the solder joint is solid solder the other side too. I suggest using a fine (curved) tweezer and lots of lighting on your workarea. If you are a bit older as I am using a loupe or magnifying glass. Still use flux as much as possible. Never expected but the micro USB connector gave me (several) headaches to get it soldered properly.

Project info at


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  1. I’ve had great luck getting the microUSB connectors and microprocessor soldered down using a cheap Chinese hot air wand and a microscope. I flux the pads on the board, tin them all, flux and tin the pads on the part, then tack one pin down to keep it in place. Then use the hot air on the bottom to warm up the FR4 and then put the hot air on the top. When it reaches the melting temperature the part drops into position and aligns perfectly to the pads. I’d practice on a dead board a few times but it works great! Soldering microUSB connectors without getting the body to the board eventually rips off my boards.

    1. The footprint is also important. most landingpatterns in datasheet are geared towards machinal assembly and are too tiny for handsoldering. In particular with USB connectors and their shielding they obstruct the pins :)

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