5 ms·
I have done this a bunch of different times, mostly to resolve sourcing disputes. Dissolving in boiling sulphuric acid/nitric acid will make quick work of most
by Hasz 1y ago
I have done this a bunch of different times, mostly to resolve sourcing disputes. Dissolving in boiling sulphuric acid/nitric acid will make quick work of most epoxy packaging
IMO, I have mostly seen mislabeling, rebinning, and passing off obvious QC rejects.
example from many years ago: https://www.youtube.com/watch?v=e6DfBuPwAAA https://www.youtube.com/watch?v=e6DfBuPwAAA
- q3k 1y ago> Dissolving in boiling sulphuric acid/nitric acid will make quick work of most epoxy packaging That's the better method of course (results wise), but it's not nearly as accessible, hence my recent evangelism of the virtues of 2000 grit sandpaper.
- jacquesm 1y agoI like it. I've used sandpaper to solve some interesting problems in the past as well with great success. I suspect we are only seeing the beginnings here in a trend of high-tech applications of fine grit paper.
- Terr_ 1y agoI expect it's much easier to acquire fine sandpaper, yet my inner child yearns for laser decapping. (Or I suppose more than "decapping", depending on the depth.)
- jacquesm 1y agoHigh power lasers are becoming more and more affordable. Laser ablation is definitely an option but you really want to have some proper fume extraction around that.
- BertoldVdb 1y agoLaser decapping will destroy the die, except if you have a rare package that does not mix glass in the epoxy. You could still compare the internal structure of the package and bonding, but the die itself is mostly destroyed.
- supportengineer 1y agoI'm off to build an MCP so AI can control the sandpaper
- jacquesm 1y agoYou may as well start off with one of these then: https://phillipscorp.com/india/phillipsgrinding/phillips-surface-grinder/ https://phillipscorp.com/india/phillipsgrinding/phillips-sur... All you need is a serial port and some G-codes.
- doubleg72 1y agoSurface grinders generally don’t use CNC, they are a simple machine.
- Dries007 1y agoThis is a fun playlist of a conversion of a manual machine to CNC: https://www.youtube.com/playlist?list=PLDlWKv7KIIr9rlCwZ9K43KoI_UZj36gOa https://www.youtube.com/playlist?list=PLDlWKv7KIIr9rlCwZ9K43...
- jacquesm 1y agoIn the 1950's, yes. But these days they definitely are CNC based. https://www.rooy.nl/en/areas-of-expertise/surface-grinding/ https://www.rooy.nl/en/areas-of-expertise/surface-grinding/
- throwup238 1y agoI prefer Japanese sharpening stones or those DMT diamond whetstones. It’s relative easy to 3d print a jig that converts a woodworking honing guide into an IC holder and you get a feel for how many passes to do very quickly before slowing down and checking each pass.
- q3k 1y agoThat's a super interesting idea! I'll also have to try that.
- Tade0 1y agoThere was a sandpaper expert in that company associated with sour-tasting fruit which shall not be named. I believe you guys have met, though I think by that time he already pivoted to making the perfect cheesecake.
- kragen 1y agoI've heard that boiling epoxy in molten colophony for a few hours, like a long-cooked version of rosin potatoes, will also dissolve it. I haven't tried it myself. Colophony is much more expensive than sulfuric or nitric acid, but safer to handle (when not molten) and often easier to get.
- alwa 1y agoI did not know that. Pine rosin is such lovely and versatile stuff. And sure enough: https://m.youtube.com/watch?v=pIpxawdUb4I&t=30m18s https://m.youtube.com/watch?v=pIpxawdUb4I&t=30m18s …plus it smells much better; and, as you mention, it’s useful for potatoes too! https://bittersoutherner.com/feature/2022/the-elusive-roots-of-rosin-potatoes https://bittersoutherner.com/feature/2022/the-elusive-roots-...
- kragen 1y agoThese slides from the talk say it only takes 5–20 minutes. I'm not sure it will smell better when you heat epoxy to the specified 320–360°. I'm interested in hearing whether anyone else has tried this.
- piyh 1y agoI appreciate the effort, but the bar is already very high when you recommend a SEM in the same breath.
- q3k 1y agoThe SEM was cheaper than an optical microscope or a fume hood though :). (also I don't recommend a SEM in the first post, a cheapo USB 'microscope' will do, I just happen to have had SEM images on hand)
- hinkley 1y ago<NileRed voice> …I wanted to look at this chip… so first I put it in a jar of hot nitric acid.