I am having an issue due to my own stupidity: I designed a PCB with the good old Atmega328P in TQFP-32 package. I broke out the pins for UART in order to be able to Arduino-flash it (beginners/students will have to work with this board, which is why we thought Arduino IDE is the best option). However, I somehow forgot to break-out the ICSP / SPI-pins that I'd need for flashing the bootloader.

Unfortunately, they are currently all connected only to 0603-components, which makes soldering jumper wires to them tricky (I did it, one ripped off quickly including the pad). I could probably get it to work this way, but I have 7 of these boards and asked myself, if no-one else was ever that stupid and came up with a nice in-circuit IC adaptor or another good solution - I was thinking, something with pogo-pins and a fixture...

Any comments, has this happened to you before, and how did you deal with it?

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    \$\begingroup\$ See electronics.stackexchange.com/questions/145468/… \$\endgroup\$ Sep 4 '17 at 9:38
  • \$\begingroup\$ Details of your PCB layout would help you may be able to use sprung loaded test pins as suggested by the comment from @BrianDrummond depends what is accessible. \$\endgroup\$ Sep 4 '17 at 11:21
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    \$\begingroup\$ ATmegas are wide pitch TQFP's and 0603 are really not that small, so this is quite do-able. This can be done unassisted, but will be far more enjoyable under magnification - get your lab a decent soldering iron and a $300 stereo zoom dissecting microscope (typically 3.5x-22.5x when configured with 10x eyepieces and half power distance extender) - or as it sounds like you're in an academic setting, maybe you can walk down the hall to the biology department and use one of theirs. For 7 pieces this is maybe 2-3 hours of detail work; next board spin give yourself a connector. \$\endgroup\$ Sep 4 '17 at 14:37
  • \$\begingroup\$ Get yourself access to a decent soldering setup and this will be trivial: with a good iron and some practice, soldering 0603/TQFP without magnification is straightforward, and with a stereo microscope you should have no problem with 0402 and whatever other teeny tiny packages you wish (perhaps excepting 01005). \$\endgroup\$
    – uint128_t
    Sep 4 '17 at 15:44
  • \$\begingroup\$ Much thanks for the replies! In the end, soldering to 0604 wasn't the problem, but people touching the soldered jumper-cables and thus ripping the cable+pad off. \$\endgroup\$
    – Stef
    Sep 5 '17 at 12:28

It seems to me that you already have a good solution. All you have to do now is make it mechanically sound. Drill a small hole, insert a terminal pin and crimp or glue it in place. Solder the jumper from the 0604 to the pin. Use the pin to connect the ICSP wire.


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