I need to anneal mm-scale samples made on Si substrates up to 600°C.
To temporarily mount them, I've seen things like high temperature epoxies, tapes, and pastes as well as mechanical mounting methods. An adhesive would need to be thermally conductive, able to withstand temperatures up to 600°C, non-magnetic, and easily removed from the sample without residue or damage. A mechanical method may be the easiest (slots, clips, screwing down gently under a washer, etc.).
To heat them, I'm looking into different heaters and designs. One possibility is a cartridge heater that I can insert into a piece of metal (like Cu) that can have samples mounted on top (either with adhesive, sitting in a slot, or something else. I've also seen flat heaters: maybe the samples could sit on one of these directly and somehow be mounted.
I'm not sure how to best do this. Any tips or information about how you mount or heat your samples are very appreciated!
Hello Juliana Lisik
Have you tried water glass , a.k.a., waterglass, an aqueous solution of sodium silicate? You can buy sodium silicate dissolved in water as a highly viscous liquid, hence the name water glass, which you can use as an adhesive. Just apply it and let it dry. Once you heat it, it will eventually turn into a glassy solid. To remove it just use hot water and a little scraping. It is heat resistant, non-toxic, works as an adhesive, and is easy to remove.
As far as the metai surface on which to mount your samples, I would suggest nickel instead of copper; copper tends to easily oxidize in air, even at room temperature, and much more so at elevated temperatures. Nickel has a very low oxidation reaction rate even at high temperatures.
Regards,
Thomas Cuff
Thank you very much for the response, Thomas Cuff!
I haven't heard of water glass. It seems like a good idea, but there are two things I'm pondering. (1) Would it react or mix with my silicon substrate or metals that are sputter-deposited onto the silicon? (2) Would it come off in hot water without scraping? I'd prefer not to make any defects on my samples from scraping.
The nickel suggestion is good!
Hi Juliana Lisik ,
To my knowledge, water glass, because it is an aqueous solution, should not etch, corrode, or react with silicon. Sodium silicate dissolved in water is a fairly benign solution. As far as removing dried sodium silicate, if you are willing to wait, hot water and a dunk in an ultrasonic bath should work.
I mean compare water glass with epoxy. Even aerospace types of epoxy, to my knowledge, cannot take 600°C, see the following URL: https://www.hisco.com/henkel-aerospace-adhesives?utm_term=aerospace%20adhesives&utm_campaign=Lead+Gen+%7C+Henkel+%7C+PP&utm_source=adwords&utm_medium=ppc&hsa_acc=8827094775&hsa_cam=19310059336&hsa_grp=143200195623&hsa_ad=642010110713&hsa_src=g&hsa_tgt=aud-936910285664:kwd-337348563058&hsa_kw=aerospace%20adhesives&hsa_mt=p&hsa_net=adwords&hsa_ver=3&gad_source=1&gclid=EAIaIQobChMI9_zqh9HIggMVj0hHAR3TpQusEAAYAyAAEgJyFPD_BwE And even if they could take 600°C, how would you remove them? I once had to reverse engineer a circuit board potted (encapsulated) in epoxy. I had to soak it in lacquer thinner for several days to soften the epoxy, and then use dental picks to scrape away the softened epoxy residue.
As far as using nickel, you don't need a solid block of nickel, you could simply electroplate the nickel onto a machined copper block. You coud also used chromium, platinum, palladium, or iridium. Commercial electroplaters can provide the electroplating service to you, but don't forget to tell them that the plated object will be subjected to 600°C. They might know some organic brighteners, they can add to the electrolytic bath, to reduce the grain size of the electroplated layer.
Good luck.
Regards,
Thomas Cuff
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