How to access signals on BGA?

< What are the options for accessing a half dozen signals on a 26x26 (1.0 mm < pitch) BGA? Some of these signals are not connected to he PCB (ie, some of < the IC's features not utilized) so tapping into traces is not an option. < Thanks.

I think I'm speaking out of my leage here. I don't even know what 26x26

1 mil is (unless thickness), but I just saw the coolest idea from the phone man (I probably shouldn't be saying anything).

First, I do not know what a BGA is. Unconnected signals seems to imply radiation - RF/EMF/? Is it possible to ground them (non-leaded chips).

You might try tapping the traces with an induction type magnet. Speakinh again out of my leage, the self sealing gel phone taps are like totally out of style these days...

I have been using a simple lm272 opamp circuit, from a book, that acts as an electromagentic signal reciever and field strength indicator. It is able to play a tone based on the amount of electromagnetic radiation passing through the induction coil, also it displays magnetic strength via a 10-segment bar graph (276-081). These items are store bought at the radio hut. 10k pot and 100k pot. Circuits was not designed by me.

Some investigating should come you across more sensative instrumental amps. Perhaps piercing the skin of these traces without tap, possibly even activating them? Sounds like a fun project but very tedious and frustrating.