I need a hot air tool to make some details.

  • I was working on a small project over the weekend using an Atmel ATMega 324P microcontroller (TQFP44 package, if that matters). Unfortunately, I am stupid and messed up the clock source fuses when programming the chip. To fix the problem, I removed the microcontroller and put on a different one that I had on another board. The other controller was working fine on the old board before I removed it. To remove the microcontrollers, I used a heat gun UR-3000 to melt the solder on all the pads, and a pair of tweezers to pick up the chip after the solder had melted.

    After putting on the new chip, I was able to talk to the chip with the program and send over the code, but it doesn't seem to work right. I am using most of the GPIO lines to blink various LEDs. I tested the LEDs manually to ensure they are all connected to the board, and that seems okay, but the controller does not seem able to blink some of the LEDs. Is it possible that I messed up the microcontroller with the heat gun? I don't think I had the heat gun on the chip for much longer than necessary, but I don't know how sensitive they are to heat.

  • Hardware Contributor

    @laran said in I need a hot air tool to make some details.:

    Is it possible that I messed up the microcontroller with the heat gun?

    Yes it is possible, the problem of those heat guns is they are way too powerful and too hot for electronic components, and heating an IC too much can damage/destroy the tiny connections between the die and the pads.
    Get a 858d or similar heatgun, it more expansive and less powerful but you can control temperature and air flow. Also you can use low temperature solder paste (for example maker paste) to limit the heat needed to solder the components.

    [edit] sorry I didn't realize the heat gun you used had temperature control, so if you set it at a reasonable temperature and not the default 500°C the basic models have it should be ok for an atmega.

  • At which temperature have you desoldered and soldered the IC?

    I have stressed for quite long time an ATMega2560 with hot air gun at 300°C and it is still working.

  • your can use JEDEC solderprofile as guidance, as Pb-free (Leadfree) is standard nowadays and the max temperature is 260°C, which can be seen in below solder profile. and don't heat it too long...