| Electronics > Projects, Designs, and Technical Stuff |
| (ultra)acoustic in circuit component level crack detector? |
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| Mr. Scram:
--- Quote from: coppercone2 on December 20, 2018, 03:51:58 pm ---thats really hardcore and slow and expensive. I can imagine this being made cheap if it works. and fast and idiot proof. maybe you can even do that transform to bring it into the audio range and listen to it on headphones if you do FFT shifting and scaling. like break it into bins and shift em around or/also if its a in circuit maintenance test you might be able to beam it into smart glasses so you can see the spectrum while you work and inspect wiring and stuff the book 'airframe' comes to mind, maybe it would be a use for smart computers if you talk outloud and it tabulates the data so you say like r17 looks good or even ask to see/ replay what you measured before if you store your maintenance data on a network drive or something. https://en.wikipedia.org/wiki/Airframe_(novel) maybe you can check crimps this way too? would be nice for a multimeter and oscilloscope/scopemeter too. i would actually get smart glasses if you can do that. and take something like siri seriously. you could actually focus on not frying half the board moving the probes around while you work, what we do now is antediluvian. --- End quote --- Sounds good. Develop it! |
| ejeffrey:
What you are describing sounds very similar to scanning acoustic microscopy (SAM) which is a very common technique to look for cracks within materials. We use it to assess wafer bonding to look for voids in the bond. I think the tools to do this are quite complicated and expensive to actually get good results. I doubt you are going to have much luck with the cheap 40 kHz range finding piezo transducers and just shooting random ultrasound in an uncontrolled fashion, at least for something as small as an IC. It would be an interesting thing to try on some larger objects like some metal casting or something to see if you can get useful data out of a much simpler setup. |
| coppercone2:
what does this multi MHz transducer look like, cost, who sells one that can be attached to tweezers? i am guessing you can't vibrate a inductor for this purpose? or electrorestriction using a capacitor as a source and reciever. Are the amplitude levels too low to be measurable if you connect it to a high gain multi stage amplifier? |
| Benta:
--- Quote from: coppercone2 on December 20, 2018, 05:11:10 pm ---what does this multi MHz transducer look like, cost, who sells one that can be attached to tweezers? i am guessing you can't vibrate a inductor for this purpose? --- End quote --- This is something that the companies making this kind of equipment keep very close to their chest as trade secrets. Any dork can build electronics, but transducers are specialty knowledge. Off the shelf parts are unlikely. I know of piezo transducers, but magnetostriction types are also around, and perhaps the best option for your project. |
| Kleinstein:
The transducers in the MHz range would likely be small (e.g. 1x1x0.2 mm³) piezos. Coupling to the sample would likely need something like a small cone or pyramid from a relatively hard metal or similar to protect the actual transducer and get a reasonable point like contact. Attaching this to a pair of tweezers could be tricky. I would consider his remotely similar to a crystal type record pickup, just a little smaller. So something to do under a microscope, maybe using wire bonding. The ones I once used had the transducer at the end of an 3.2 mm rod with a flat thin metal film on top and the actual transducer inside embedded in some plastics. I used those to check small samples (e.g. 2x2x3 mm³), using the sample corners for weak contact. I remember it was not that easy to find those transducers. |
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