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I have noticed a lot of electronics use kapton tape in places where a heat resistant tape isn't necessary. Why is that so? Is it just because it's a good adhesive?

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    \$\begingroup\$ Can you give an example? It's often used to give a surface for a pick and place machine to grab on components such as sockets. \$\endgroup\$
    – Colin
    Apr 21, 2021 at 10:41
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    \$\begingroup\$ I usually use kapton tape because it's what I have at my lab desk. It could be as simple as: "It's what they had" \$\endgroup\$ Apr 21, 2021 at 11:05
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    \$\begingroup\$ One reason may be for optical clarity. E.g. on part reels when splicing or holding ends, can see that there are parts in the compartments. The adhesive isn't that special IMO. Laboratory tape (similar to painter's tape but slightly stronger adhesive) feels similar to me at room temp - low/medium-tack, clean release, long life. \$\endgroup\$
    – Pete W
    Apr 21, 2021 at 12:18
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    \$\begingroup\$ When it goes into the reflow oven it sure needs that heat resistance. Could you provide an example of a component where you feel the heat resistance isn't needed? If it's being placed onto an SMD board intended for reflow soldering it will get hot. \$\endgroup\$
    – J...
    Apr 21, 2021 at 19:03
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    \$\begingroup\$ @HotGlue I have coworkers who've repaired car bumpers with kapton... because we had rolls of it around. Definitely wrapping wires it doesn't need the thermal resistance because those wires are probably not more than 90C rated anyway... probably more like 60C if it's a cheap 3D printer. \$\endgroup\$
    – J...
    Apr 21, 2021 at 23:26

4 Answers 4

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If you go through all the trouble to test and qualify something, like tape: check it doesn't unstick after a few years leaving glue everywhere, doesn't shrink, loosen, harden, or crack even if the product is left in a car baked in direct sunlight for months... then you probably won't feel like re-doing that work for another tape, especially if it saves no money and using a new tape brings new risks of failure for your product.

If you repair old equipment, you'll notice the kapton tapes always look like they're new, but the other types not so much. PVC "electric tape" is one of the worst.

So basically, "if it ain't broke, don't fix it".

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  • \$\begingroup\$ The worse tape ever is autoclave indicating tape - the adhesive goes gummy and the tape goes brittle \$\endgroup\$
    – D Duck
    Apr 23, 2021 at 22:43
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    \$\begingroup\$ It's almost as if that type is optimized for something other than holding things together for long periods of time, @DDuck. \$\endgroup\$
    – Cody Gray
    Apr 24, 2021 at 7:22
  • \$\begingroup\$ Kapton is also safe as far as static electricity goes. Clear tape (what we call scotch tape in the US) generates static when you peel it off and is considered unsafe for electronics. \$\endgroup\$
    – mkeith
    Jul 31, 2021 at 3:36
  • \$\begingroup\$ This answer has been locked at the author's request, to prevent further anonymous edits. Please contact a moderator if there is a genuine need to edit or comment on this answer. \$\endgroup\$
    – SamGibson
    Aug 1, 2021 at 22:04
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On top of being a good adhesive, it's chemically inert, thermally stable, and does not off-gas when it gets hot.

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    \$\begingroup\$ and optically clear, a good insulator, waterproof, low friction on the smooth side, and one of the most wear resistant polymers \$\endgroup\$
    – Pete W
    Apr 21, 2021 at 12:22
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    \$\begingroup\$ I too subscribe to the Kapton Lovers Weekly Newsletter. Great stuff. \$\endgroup\$
    – crasic
    Apr 22, 2021 at 3:29
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    \$\begingroup\$ What are the environmental considerations? \$\endgroup\$ Apr 24, 2021 at 6:05
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    \$\begingroup\$ @AdamBarnes I think that should be its own question somewhere. It's a plastic resistant to most things you can throw at it (even fares fairly well against radiation), so you probably shouldn't litter it and it's hard to recycle (one proposed method discussed here). The health impact of Kapton itself is fairly low, but the production process is not something you'd want in your backyard. \$\endgroup\$
    – Mast
    Apr 24, 2021 at 7:25
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    \$\begingroup\$ My life has been changed by learning about Kapton Tape ! \$\endgroup\$
    – Fattie
    Apr 24, 2021 at 16:31
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It gives vaccuum pickups something to grab in the pick and place process.

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Kapton (generically polyimide) is a good material for tape in situations where it does not need to stretch and needs to withstand relatively high temperatures. It does not melt or soften greatly with temperature. It is resistant to most solvents, more so than most tape materials. As an insulator, it has limitations, which is why it is not used as much in aircraft as wire insulation as it once was. As the Wikipedia article states:

Kapton-insulated electrical wiring has been widely used in civil and military aircraft because it is lighter than other insulators and has good insulating and temperature characteristics. However, Kapton insulation ages poorly: an FAA study shows degradation in hot, humid environments, or in the presence of seawater it was found to have very poor resistance to mechanical wear, mainly abrasion within cable harnesses due to aircraft movement. Many aircraft models have had to undergo extensive rewiring modifications—sometimes completely replacing all the Kapton-insulated wiring—because of short circuits caused by the faulty insulation. Kapton-wire degradation and chafing due to vibration and heat has been implicated in multiple crashes of both fixed wing and rotary wing aircraft, with loss of life.

The adhesive on tape is a matter separate from the tape material itself. Typically polyimide tape is available with either silicone or acrylic adhesive. Silicone adhesive has a a higher temperature rating but cannot be used in situations where surface contamination with silicone is a concern (for example on surfaces that will be painted or wire bonded).

Some of the same physical and chemical properties that make silicones attractive, namely a high degree of chemical inertness, thermal stability and resistance to oxidation, make silicone contamination a ubiquitous problem.

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