Metcal STTC soldering cartridge/tip teardown

[wkb]

To satisfy my curiosity about its construction details I just Dremel-ed one of my broken Metcal STTC soldering cartridges/tips.

It is constructed of a stainless steel tube with low heat-conductivity, a brass coaxial connector for connecting to the handpiece/13.5MHz HF generator/powersupply, and a iron-clad(?) copper soldering tip along with a inductive heating coil.

Picture 1: complete assembly cut in 3 parts.  Note the discolouring of the stainless steel tube due to the heat.  The wires to the coil and the coil itself are also  discolored.  I suspect the degradation of the isolation shorted out the coil, and led to the failure of this soldering cartridge.

Picture 2: this is the actual soldering tip with the induction coil.  The exposed copper is due to to my Dremel cutting work.  The tip is
hermetically welded to the stainless steel tube.  The actual copper tip is clad in some steel(?) alloy to protect it from the adverse conditions of the soldering process as well as welding it to the tube(?).  The induction coil is wound on a part of the tip that is clad with an alloy with a very specific Curie temperature.  Different compositions of this alloy allow for different temperature tips to be produced.

Picture 3: the 'back' side of the coaxial connector.  The 2 wires are twisted, this is part of an impedance matching design.

Picture 4: the handle side of the coaxial connector.  The brass part is, like the soldering tip, hermetically connected to the stainless steel tube to avoid 'leaking' the 13.5 MHz HF power feed.

All in all an interesting teardown I think.

For more background information lookup the Metcal patents filed with the US patent office.

[saturation]

Thanks for sharing.  Just getting to a backlog of older posts.  Appreciate the work you had to do get into the Metcal tips.

[mobbarley]

Looks just like the pictures



The mass of the tip seems more than I expected. From it's fast thermal response I expected there to be almost no metal in there!

[wkb]

Looks just like the pictures



The mass of the tip seems more than I expected. From it's fast thermal response I expected there to be almost no metal in there!

Well, there is hardly any copper in it, you are right.  The photograph tends to exaggerate the size

[sonicj]

any chance the tip was brazed rather than welded? if so, i wonder if heating the tip with acetylene or mapp would allow the tip to be removed?
-sj

[wkb]

any chance the tip was brazed rather than welded? if so, i wonder if heating the tip with acetylene or mapp would allow the tip to be removed?
-sj

No idea to be honest. I do not have access to that equipment. My guess it is a laser weld.

[thm_w]

Bumping this to add a photo of the internal tip construction.

Tip is 3mm across in the mid section of the photo. Plating on the sides of the tip is 0.3mm, quite thick. It appears to slightly taper thinner toward the tip.
Visually the heating pellet looks the same copper material as core of the tip.

Appears pressed/crimped in place, which also holds the pellet.

Relevant PDF: https://www.newark.com/pdfs/techarticles/oki-metcal/extendingTipLife.pdf