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I am working on a project where I have designed a MEMS sensor on a glass (quartz) wafer. I also made a PCB where the glass sensor chip is to be glued to the surface of the PCB for testing purposes. However, since I have more chips than PCB's I would like to re-use the PCBs by removing the chip and sticking another chip on it. What type of glue and dissolvant would you recommend for this? Any help would be welcome. Thanks in advance!

Tallguy
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  • Do you need to glue it at all? Won't the connections hold it in place? If the answers are yes and no then you need to provide details/diagrams most likely. – Andy aka Jun 28 '21 at 13:29
  • I don't think glue is generally a good idea for this. Double sided tape? – DKNguyen Jun 28 '21 at 13:35
  • Maybe a toughened cyanoacrylate such as Loctite 410. It can be removed with acetone which won't affect the PCB noticeably but might attack plastics on the board components or take the silk screen markings off. – Spehro Pefhany Jun 28 '21 at 14:22
  • @SpehroPefhany Super glue fumes glass (and presumably other stuff). Hard to say if it matters without mechanical details. – DKNguyen Jun 28 '21 at 14:24
  • Have you ruled out the idea of a spring clip, or some other mechanical means to hold the parts together during testing? – evildemonic Jun 28 '21 at 14:26
  • @DKNguyen Yes. It would be a good opportunity to talk directly to the technical people at a supplier such as Loctite for advice. Adhesives are an enormous field and quite complex. – Spehro Pefhany Jun 28 '21 at 14:26
  • You could use copper foil tape at two (or maybe just one) corner and solder it. Like stained glass, – DKNguyen Jun 28 '21 at 14:27
  • I've always had great luck when working with the engineers at Loctite/Henkel about a tricky adhesive situation. They have never let me down! – evildemonic Jun 28 '21 at 14:28
  • Some chips depend on electrical and/or thermal conduction through the substrate. Are you sure that this is not an issue for you? – Elliot Alderson Jun 28 '21 at 14:40
  • Thank you all for your responses. I thought about using double sided tape but the sensor measures acoustic frequencies in a material and earlier test showed that the tape introduces too much unwanted attenuation. That is why I want to use a more firm adhesive. Talking to suppliers for more specific advice is an excellent idea. I will try to contact someone and post their answer in this thread. – Tallguy Jun 28 '21 at 14:42
  • Get more PCB's. They're not that expensive - Not expensive enough to justify monkeying around like this for sure. If they are, then you are going to the wrong PCB supplier. If you can wait a few weeks, they're stupid cheap. But even a few days turn is very affordable e.g. www.sunstone.com – Kyle B Jun 29 '21 at 06:58

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Given the low mass and unknown high fragility for warp, you want a clean low tension process.

I would consider very tiny low-temp hot-glue dots 1 in center or 4 in corners or both. Then use a heat gun slowly raising the temperature and pick off with an exacto knife when soft. These parts do not bend.

Tony Stewart EE75
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