I have a STM32L432KS circuit with this 0.5mm pitch UFQFPN32 package:
I have to take a look at some pads but with which kind of oscilloscope probe could I use?
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**I misread the initial question, my below recommendations are for an IC with exposed leads/legs. An interposer is our best guess at this point: https://www.arieselec.com/products/data/24007-high-frequency-interposer-socket.htm **
Dean already mentioned it, but I spoke with our probes expert and he mentioned 3 options:
Use a wedge adapter with an N287xA passive probe and dual lead adapter or an N2795A/96A active probe with a dual lead adapter. The adapters we have are the E2613A (0.5mm, 3 signal), the E2614B (0.5mm, 8 signal) or the E2643A (0.5mm, 16 signal) (replace the "x" in N287xA with a 0,1,2,3,4 for different bandwidths).
Use an IC clip like the 10467-68701 0.5mm IC clip
Every one of our N287xA passive probes comes with 5 different IC caps for IC lead pitches.
Hope that helps!
Single ended active probes here: http://www.keysight.com/en/pc-1659295/oscilloscope-single-ended-active-probes?nid=-32556.0.00&cc=US&lc=eng
For this I solder a very fine wire (like wrapping wire) to the pin and then use the scope's grip tip on the other end. It works quite well.
You can get probes with a plastic shield at the end that helps align the probe pin with the IC pin without shorting to adjacent pins. You can also get wedge probes that probe two adjacent pins by wedging in between them.
Keysight's offerings: http://literature.cdn.keysight.com/litweb/pdf/5989-6162EN.pdf?cmpid=zzfindkeysightprobes
I assume you already have a board so it is too late to add test pads, but either test pads you can probe, or full-on debug connectors you can connect to a logic analyzer or oscilloscope make life much easier.
When I had to probe a 0.5mm QFN28 the other day, I just put the oscilloscope behind the SMT microscope - I looked through the microscope to position an ordinary cheap scope probe by hand, then looked past it at the scope's screen to see what was there.
Even if the IC doesn't have metalization on the sides, usually there's some exposed solder on the PCB trace, though yes, it's possible to design a board where there's not much gap between the soldermask and the package.
The microscope isn't even strictly necessary, though it helps get the right pin without mistakes (and if you are designing with QFNs and similar, you really should get one to diagnose assembly faults). Obviously, if you know the same signal is available elsewhere on a lower density connection, grab it there instead.
Granted, direct manual probing is harder if you need multiple signals. I also spent quite a while preparing fine enamel wires to solder in to break out an entire SPI bus from the adjacent pins on the side same of that QFN28 to a logic analyzer - in the end I got enough signals to see what was being sent, but MISO wasn't actually connected - fortunately I learned enough without that.