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I would like to open a TO-18 can to look at die-bonding/heatsinking and do some electrical experiments with increased airflow. Is there a non-destructive way to do this?

My only thought is to drill a hole into the side of the can and then use my smallest shears to cut around the perimeter of the can, but I worry that the vibration and debris caused by this will degrade the NPN transistor inside the can. I would like the electrical characteristics of the transistor to still be in-spec after this decapping.

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  • \$\begingroup\$ If you have some spares, I'd test clamping around the can for support and as a heat sink, e.g., with a small hose clamp, and carefully using a fine diamond file or fine-grit grinding wheel in a high-speed rotary tool, pausing to allow cooling, to grind off the top. BTW, consider an old EPROM for investigation, since you can see through the cover: en.wikipedia.org/wiki/EPROM . The older, the better, as it would have larger components. \$\endgroup\$
    – DrMoishe Pippik
    Commented Sep 27, 2023 at 1:43

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I've used a Dremel tool with a cut-off blade to cut open metal cased transistors like I've done in the photo below. This was probably to see the BE junction glow when reverse biased as shown in this post. I've also used hacksaws with fine teeth to cut open larger transistors.

enter image description here
Photo credits: own work

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  • \$\begingroup\$ Ok, I think you're right, that I just need to saw it open, but I'm still hoping someone who knows how these parts get sealed in the first place (some hermetic glue or molten glass?) might know a trick to just dissolve the sealant... \$\endgroup\$
    – bobuhito
    Commented Sep 27, 2023 at 2:17
  • \$\begingroup\$ @bobuhito That's not going to happen, not with solvents that won't completely destroy the part inside as well. I believe they're mostly brazed closed. \$\endgroup\$
    – Hearth
    Commented Sep 27, 2023 at 3:08
  • \$\begingroup\$ @bobuhito There's a picture of a cross sectioned TO-18 in Wikipedia. Perhaps you can decap it by heating the cap and pulling it apart. \$\endgroup\$
    – qrk
    Commented Sep 27, 2023 at 4:00
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Over the years many different closures have been used including epoxy, glass frit, indium and resistance welding. You might find the data you need on the datasheet for your specific part.

I know in some cases you can open by just grinding off the "lip", and then sliding off the cap, because I've done that in the distant past.

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