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Topic: Input / INT0 pin shorts on ATTiny85v - No way: It's the FLUX! (Read 229 times) previous topic - next topic


Dear people!

As a newbee, I just wanted to share this with you: I had a quite difficult & intermittent problem on a switch on PB2 on the ATTiny85V. I used the internal Pull-up resistor, but sometimes it just fired, or kept firing. When measuring on the PCB, the PB2 pin read very low voltages, although I used the pull-up (so it should read Vbatt).

Yesterday I found the problem: I used soldering flux to solder the SMD switch on the PCB: The flux itself has a (though high) resistance which is also highly fluctuating. Cleaned the PCB and problem was gone.

This is of course a beginners mistake, but just wanted it to share with you.

Thx - Steven


Moral of the story: Read the flux usage instructions. Some must be cleaned off the board with specific materials and processes. Some are no clean.

If you're buying cheap, no name flux without specs and material data safety sheets on eBay for cheap, well, you only get what you pay for.


Did you use electronics flux, or plumbers flux.
If you have used plumbers flux, then it's time to throw it all away and start with new components.

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