Test leads on a TQFP package ?

[gjh]

Whats the proper way to hook up test lead just to a few outputs on a TQFP package (atmega 2560).    Found something like this which might do ?  https://alitools.io/en/showcase/micro-ic-clamp-10pcs-set-sop-soic-tssop-tsop-ssop-msop-plcc-qfp-tqfp-lqfp-smd-ic-test-chip-pin-mini-chips-adapter-socket-32589469448

Just want to hook up 3 ADC outputs to a scope to see if they are still alive.

Have some enamel 0.25mm wire which I might be able to careful temporary solder on to but seems like a pain.

[tepalia02]

You need TQFP burn-in sockets. The Micro IC clamp that you've shared will also work.

[janoc]

You need TQFP burn-in sockets.

The OP has the chip soldered in. How exactly is a test socket going to help them with the problem? Those sockets are meant for programming/testing the chips before they are soldered into boards, not after.


Those micro clamps work (I have also a set, in case I will need to do this) but they can be a pain to set up and it is easy to short two adjacent pins with them.

The easiest way is to find a nearest via or a passive component pad on the track in question and solder your wire there - those are usually a lot larger and easier to access than individual pins of the TQFP. In the worst case you can (very carefully!) scrape off a bit of soldermask on the track and solder directly to it too.

Of course, there are also specialized probing solutions like this:
https://sensepeek.com/

(There was also a nice open source kit made out of aluminium extrusions with various types of holders and attachments but can't find it now).

However, if this is for a one off thing and you probe like this once in a blue moon, then you likely don't have the probe holder and buying/making one would be an overkill.

[Ian.M]

As Janoc has already pointed out, its a PITA to set up micro-probes so they are stably located and safe to use, IMHO more so than the few tens of seconds per pin it takes to prepare and solder on 30 AWG Kynar wirewrap wire or fine magnet wire if you need to go thinner.  The probes only come into their own if its imperative that you don't solder to the board.

Do yourself a favor and mount a female 0.1" pitch header on its side, on 3M VHB tape, somewhere convenient (e.g. at a nearby unpopulated area of board edge) to give you an easily accessible place to terminate the other end of your breakout wires and connect to them.  You can then disconnect the test jig leaving the breakout wires in place, crucial if you ever need to clear your bench and do something else while waiting for parts.   If your hacked in breakout wires are for an ICSP or debug port, consider tacking them down with a suitable adhesive or tape and leaving them permanently if its likely to cross your bench again.