Naughty cables

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I think I'm using the wrong type of cable for my veroboard. The covering melts and does bad stuff. Does this happen to you also? What to do to prevent it? Solder at a lower temperature? :-D

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There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Most plain PVC insulation has a melting point of 90deg C. The melting point should be specified on your cable spool. I've read about intermediate-cost irradiated PVC insulated cables which have a higher melting point, but I don't know the actual melting point.

For the (expensive) teflon-insulated cables I buy, they've all been labeled as 200deg C melting point. They certainly melt much less for me than plain PVC-insulated cables.

As for the "bad stuff", yeah, the smell isn't great. But, the retraction of the insulation and associated exposure of the wire can be a serious problem.

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That's why some of use prefer to wire-wrap these types of connections.

Actually soldering at high temperature, and being quick about it would work best. You might look into wire insulation with a higher melting point.

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There is some wire out there that seems to melt when you look at it. Here in the U.S., telephone wire is this sort. It looks nice but when a soldering iron gets anywhere close, it gets soft. The telephone companies us "insulation displacement" technology with single-strand (solid) wire. What you show looks very much like this ugly stuff.

Cheap, easy to get, worth what you pay for it.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Since I only use cable from time to time, (I mount nearby everything on hand made PCB), I use mainly the kind of wire used to hand-made coils/transformers. It's a little tricky to remove the insulation with the solder tip, but they work perfectly.

Only one color available thought (copper), but many different sections.

Guillem.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Guillem, are you referring to enamel-coated wire? I did read that certain coatings can be removed by soldering tip for 30 seconds or so.

Here's one link to using enamel-coated wire for veroboarding, but I haven't tried it.

http://elm-chan.org/docs/wire/wi...

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I use enameled copper wire ("magnet wire") extensively for prototypes, even occasionally for high voltage (200V) circuits like nixie tubes - it can stand the voltage. I got the idea when somebody gave me one of these. I guess the person at Kevin's link came up the same route. I didn't much like the wire supplied with it, as the enamel evaporated ok when heat was applied but immediately condensed on the nearest pad, making it unsolderable. I use 36 gauge Belden wire now. The iron needs setting a little hotter than normal (400 C) for quick stripping. I've built some extremely dense circuits this way, using SMT parts and ending up with a proto the same size as I could do it with a proper PCB (see pic).

The solution Dagg is looking for, though, is 30 gauge Kynar insulated wire, sometimes called wire-wrapping wire. It strips easily and the insulation doesn't melt and pull back like PVC. The yellow wire in the top picture is 30 gauge Kynar, which I used for the power rails.

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Nice board, peret. Do you have a high-resolution version of the photo that I can view?

Thanks very much for the info. You helped me find exactly what I was looking for. Beldsol ( http://bwccat.belden.com/ecat/pd... ) having specified solderability is perfect. I had been asking electronic retailers about the solderability of their in-stock magnet wire, but no sales rep knew anything about soldering magnet wire.

I'm off to search for a Beldsol source. Seems like Digikey, Mouser, and McMaster don't carry it.

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I'm also a big fan of the Roadrunner prototyping system having developed many tens of microprocessor boards that way in the early eighties. I'd like to get hold of some of the 'combs' that can be used to help route the wires - they're a little expensive from Farnell here in the UK.

Maybe I'll add a picture of my recent board later :D

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But, some of the joints look reasonable. Just need more practice to improve consistency :)

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Uuuuh! Perfect! Now just to find out if they ship to slovakia and for how much. It's quite expensive, but I guess it's worth it.

How is the cable scratch proof? I mean, will it the coating survive scratches?

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Hey Kevin, that's exactly what I do, but instead of wiring pencil, I'm still using 'presoldered' (this removes the insulation before the soldering process, thus avoiding the condensing problem that Peret commented before) and cutted-to-fit cable. That allowed me to solder some QFN and DFN chips to test them.

Anyway, I still found self made PCB much more reliable and easy. Specially for 0.5 mm pitch connectors (FCP) and ARM processors.

Guillem.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Hi Guillem,

I just ordered some Beldsol from Newark. I was planning on presoldering it as well, mostly because of the high temperatures involved. But, your point about the condensation issue not being a problem with presolding is well taken.

Thanks for your thoughts.

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Quote:
I just ordered some Beldsol from Newark.

I was going to tell you Newark - that's where I get mine from - but you found it before I got round to it. I'll take a hi-res photo for you. I split the square pads to put two IC pins on each, and bring two wires up through the hole, left and right to the IC pins.

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Peret, thanks for the confirmation on the source and the wiring description. I'll look forward to seeing the hi-res photo. I look forward to moving away from the teflon-insulated cables for low-current work.

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Here are some hi-res pictures. The solder joints look messy close-up. These pics are front and back of the same end of the board, so they're vertically mirrored. When I came to lay out the PCB for this, it took six layers, and it was a hell of a job finding a place to put vias that didn't come up in the middle of a component pad.

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Thanks for the hi-res photos, Peret, I appreciate you taking the time to capture and post them. Nice, tight prototype. I gives me some ideas for my when Beldson arrives. Newark states a 20day lead time.

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Thanks for sharing your wisdom, you got a lot of it! In the end I've chosen the best method for me:
I dissaemble any coil/transformer/motor/any induction that I won't need in this life and use the wire
for the assembly of the board. I really would like to obtain the wire itself, but it seems that in slovakia
it is a bit unobtanium. And besided, old diskette mechanics are plentiful :-D

Thanks!

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.