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Intermittent USB VCP Com Port

Question asked by Nor Muzakkir Nor Ayob on May 11, 2017
Latest reply on May 29, 2017 by Nor Muzakkir Nor Ayob



i designed a flight controller board based on STM32F303. i have a weird problem where each time i assembled a complete board, initially there will be no problem and PC will be able to detect and connect with the board via USB VCP. but after a while, the board will be disconnected and USB VCP com port is not detected.

i have to resolder usb pins (PA11 pin32 & PA12 pin33) or reflow the whole board, test it again, no problem but after awhile USB VCP is missing again. if i repeat the whole reflow & retest eventually the USB VCP missing problem goes away.


the board is a two layer PCB with HASL lead surface finish. did i get a faulty STM32F303 batch or should i have used immersion gold surface finish for better solder connection?

Please help me with this weird problem, thank you.