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Can I substitute kapton with aluminium foil when de/soldering a component onto a PCB?

I want to desolder a tiny surface mount button from the motherboard of a phone... There are a lot of similarly tiny components surrounding it that I do not want to damage with heat from the soldering iron. Can I use aluminium foil in lieu of kapton tape to protect these components?

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    \$\begingroup\$ Aluminum is a far too good as a heat conductor. I'd worry some. But I'm not sure. Haven't tried the idea. \$\endgroup\$ – jonk May 28 '18 at 21:23
  • \$\begingroup\$ I would look at aluminum tape and use a heat gun (hot air pencil) with a narrow nozzle. \$\endgroup\$ – mkeith May 28 '18 at 23:56
  • \$\begingroup\$ In theory Al foil should reflect heat with an air gap as well as adhesive kapton tape is thermal insulation like any other plastic or cellulose but Kapton withstands a higher temp. I use a propane torch \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 29 '18 at 4:25
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If you're doing hand soldering with an iron, you should only be making contact (and potentially warming the surrounding components) for about 3 seconds. Only the point of contact with the tip of your iron should be reaching temperatures of any concern. Assuming the components you're worried about are also soldered in, there should be no issue or need for further precaution. They can clearly take full solder temp for a few seconds so a brief rise in ambient temperature will be nothing.

Aluminum foil is a marginally useful trick for creating a heat shield when doing hot air rework. You still want to keep it off the components you're trying to protect as much as possible. It should only serve to divert the hot air since it still conducts heat.

Kapton tape's virtue is that it doesn't break down under high temp, and it's available in anti-static formulations. It's great for holding things in place as you solder them, or maybe for holding down the aluminum foil as you do your hot air rework. Borderline useless for heat protection by itself though.

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    \$\begingroup\$ Oh, I didn't know this about Kapton and aluminium! I assumed they were interchangeably used for heat protection...learned something new today. \$\endgroup\$ – Jet Blue May 29 '18 at 1:40
  • \$\begingroup\$ @JetBlue I've used Kapton just to make sure some SMD parts don't blow away if they get a little warmer than expected. A quick reflow never hurt anything anyway. I only very rarely use aluminum when I've got a larger IC with smaller components tightly packed around it. Proper temp and tool selection to keep the heat focused on where it needs to be for as brief a window as possible is 90% of the battle really. \$\endgroup\$ – Phil C May 29 '18 at 1:59
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If you are using a iron, then just apply it where needed. Other nearby components won't that that hot unless you do something really wierd.

Also, Kapton tape doesn't protect against heat. It keeps things from getting soldered by being a physical barrier to molten solder. The reason Kapton is used instead of other tape is that Kapton can stand high temperatures. It's also useful that solder doesn't wet Kapton.

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  • \$\begingroup\$ If the button in question is defective and to be discarded then maybe "where needed" is the button itself, not its pins. It will be destroyed but with heat transferred to pins indirectly through button body the danger to surrounding parts could be minimized... I hope. \$\endgroup\$ – Maple May 28 '18 at 22:56
  • \$\begingroup\$ @Maple huh, will try that \$\endgroup\$ – Jet Blue May 29 '18 at 1:41
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    \$\begingroup\$ Yeah, but if your fry something, please blame @Olin :) \$\endgroup\$ – Maple May 29 '18 at 1:43
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Aluminium is a good conducter for heat So it is not better for use pcb when we use smd rework station

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  • \$\begingroup\$ It is difficult to understand what you want to say. I think you should add some more words to make clear what's your reasoning. \$\endgroup\$ – Ariser Sep 29 '19 at 12:37

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