Preparing cross section samples

In this video, Andrew demonstrates cross-section sample prep for electronics material specimens. The samples are cast into disks of transparent epoxy then sanded and polished to a mirror finish. This video demonstrates hand polishing however the same basic concepts apply when using a rotary polisher.
This video is part of a collaboration with Breaking Taps aka Micrographia. I've prepared a bunch of samples using similar techniques that he'll be showing off on his channel over the coming weeks.
Check him out at / micrographia

[@LongnoseRob]

Nice walkthrough on sample-preparation,

[@tablatronix]

awesome

[@nanda2902]

Hi Andrew, I'm currently preparing sample for cross section viewing in a Scanning Electron Microscope (SEM). I need a really good and clean cut and sand paper isn't clean enough.. Can you please advise a cleaner method of cutting? Thank you in advance

[@AndrewZonenberg]

Hi, Generally whatever you use for the first cut is going to cause a lot of damage. A low speed diamond wire saw or similar will help, but there will still be cracking and possibly some heat effects in the immediate vicinity of the cut. This is why you start by making the initial cut a bit back from the plane of interest, then use increasingly finer abrasives and fairly slow polishing speeds to get closer to your final imaging plane with increasingly higher surface quality. What grades of sandpaper are you using? I usually start around P500 and run out to P10000 before switching to the diamond polishing paste. For low magnification optical microscopy (stereo scope) even around P5000 would likely be enough. For optical microscopy I usually run slightly submicron, say 500 or 250nm diamond. For SEM, depending on magnification, you might want to go all the way to colloidal silica with particle sizes in the tens of nm.