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Last time I visited my PCB manufacturer to do some modifications on a prototype PCB, they used some very thin wire (probably something like AWG 30-35) where they just burned away the insulation with the soldering iron.

Is there a name for such (thin) wires where you can burn away insulation, or is there a specific thing to look for in the datasheet to know if I can do this for a given wire?

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The general term is solderable magnet wire. Magnet wire comes with many types of insulation. Some insulations are solderable (heat from soldering iron will melt the insulation), some require mechanical stripping/abrading or chemical stripping.

A common solderable magnet wire is PN (Polyurethane-Nylon insulation material), however, there are other solderable types of insulation available like polyurethane and polyester. The insulation is also classed in to thickness of the insulation, single, double (heavy), triple, & quadruple build.

I normally use HPN-155 (H: heavy insulation which is a double coat; PN: polyurethane-nylon insulation, 155: 155°C temperature class) for winding transformers and inductors.

Polyimide (240°C class) and enamel insulation requires mechanical abrading or chemical stripping, so I would avoid those types of insulation.

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Is there a name for such (thin) wires where you can burn away isolation?

It's generally called copper-wire (or magnet-wire) with self-fluxing insulation/enamel thus allowing it to be soldered.

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Over 30 years ago I remember using a verowire pen. This dispensed polyurethane enamelled wire which was wrapped around pins for through hole components on verboards with square pads, and then soldered to make a connection between the component lead and wire.

This is still available from distributors. E.g. the following picture is from the RS components Vero Technologies Manual Wire Wrapping Tool 34AWG page:

enter image description here

At the time I used verowire and leaded solder to make hobby circuits and didn't have any fume extraction setup.

There is the following warning for verowire:

Warning : Polyurethane coatings may produce small quantities of toluene di-isocynanate (T.D.I.) when subjected to normal soldering temperatures. Therefore, fume extraction may be neccessary to ensure the maximum permitted concentration is not exceeded.

After reading Medical Management Guidelines for Toluene Diisocyanate about the toxic affects of TDI, at the time should have payed attention to fume extraction.

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I recall the tools used to apply the wire being called "wiring pencils" and the wire by extension being called "wiring pencil wire".

A well-known brand was/is "road-runner".

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It's called enamel wire or magnet wire. It can be difficult to remove the enamel. If you want a good tool to remove enamel and other insulation, hot tweezers are great for that.

enter image description here
Source: Here
enter image description here Source: https://widaco.net/shop-2/hand-soldering/tools/tools-accessories/hot-tweezer/

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    \$\begingroup\$ OP asked about a specific kind where the enamel burned off, so that's not relevant. \$\endgroup\$ Jan 11 at 8:03
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    \$\begingroup\$ The wire I sourced is enameled wire, it's not red or green, but you can have clear enamel \$\endgroup\$
    – Voltage Spike
    Jan 11 at 17:30
  • \$\begingroup\$ Yes, I've had all of those as "solderable enamel" insulation, sometimes- if memory serves- referred to as "self fluxing". But that's really not a property you'd want in windings which were expected to carry any amount of current. \$\endgroup\$ Jan 11 at 19:07

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