¿ A very different approach for circuit boards ?

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Externet
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¿ A very different approach for circuit boards ?

Post by Externet » Mon Apr 21, 2003 8:33 pm

Hi fellows.<p>The soldering paste used for surface mount components is a mix of solder in microspheres with a binding flux to form a paste.
If such paste could be deposited by some modified printer or plotter on bare fiberglass boards (with no copper clad), and then fed to an infrared or not "pizza oven" type of melting chamber, the traces formed would have no copper, but fairly decent conductive rivers of solder as traces.
The adhesion part between the board and the solder rivers would have to be thought about, but could be a start for simple domestic easy and fast production with no chemicals. Maybe extra porosity or roughness of the board would achieve it.<p>How lunatic am I ? Is there something polishable here ? Does anyone has an horizontal plotter that could handle an ink bottle whose contents be replaced with somewhat diluted soldering paste in order to try? I do not have one to experiment with. I have solder paste and bare fiberglass sheets.
Opinions are very welcome,
Miguel
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Re: ¿ A very different approach for circuit boards ?

Post by rshayes » Mon Apr 21, 2003 11:49 pm

Soldering paste probably would not work this way. Molton solder does not bond or wet glass-epoxy board very well, if at all. I would expect surface tension to convert the printed lines into rows of solder balls.<p>On the other hand, some electroless plating processes require activation of the surface in some way to cause plating to occur. Possibly the activator could be printed with the ink jet printer, followed by a plating step. This wouldn't even require a heating step.<p>If the electrical resistance of the ink was low enough, it might be possible to electroplate copper directly over the ink. This might require a special ink with a high proportion of copper.

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Re: ¿ A very different approach for circuit boards ?

Post by Bernius1 » Tue Apr 22, 2003 5:50 am

What about something like silvered mylar? Deposit copper on a flexible sheet ( like those t-shirt iron-ons),then the printer sprays heat activated adhesive. But the copper might tear. Or those 'white-out' rollers; roll out copper tape,w/heat activated adhesive. But I think the paste would bleed when re-heated to attach the components. I see those printer heads with copper deposited on flexible plastic. It's gotta-B doable.
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Re: ¿ A very different approach for circuit boards ?

Post by Externet » Tue Apr 22, 2003 1:10 pm

Hi.<p>Tried, by handwriting lines of soldering paste on shiny finish fiberglas board, the worse case.
An unconnected "string of pearls" is the result as predicted by Stephen.<p>Well, to something else now.<p>Miguel
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Re: ¿ A very different approach for circuit boards ?

Post by haklesup » Tue Apr 22, 2003 1:22 pm

Conductive Ink printed on a hard paper substrate with ICs bonded directly was supposed to form the basis of really cheap disposable cell phones. Even though I saw a prototype on TV, I have never seen a commercial product for sale anywhere that uses this PWB technology. <p>What ever happened to that? I would expect the [high] resistivity of the ink and the possibility for breaking conductive paths if the substrate is flexed would be the problems with this tech. We may still see this in future products.

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Re: ¿ A very different approach for circuit boards ?

Post by nedtron » Thu Apr 24, 2003 8:26 am

Conductive & Resistive Inks: Conductive and resistive inks are available from Kyocera and other manufacturers that may be applied by silk screen or other masking methods. The inks may be used to create conductive paths, resistors, capacitors and inductors. Frequently, these inks are applied to alumina (aluminum oxide) and then furnace fired to produce surface mount resistors, capacitors and inductors.<p>Ned

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Re: ¿ A very different approach for circuit boards ?

Post by analogee » Thu Apr 24, 2003 9:42 pm

Once when visiting a customer site in Korea I had to make a breadboard, but they didn't have much stuff. They did have a roll of copper foil, though, so I took a piece of paper and stuck the foil down in a pattern on the paper, cutting as needed with an X-Acto knife, making a crude surface-mount single-layer "printed circuit".<p>Don't know if it has any real practical application, though, but perhaps some kind of paper-like substance could be the substrate instead of fiberglass. Now just need a way to deposit the copper...<p>Regards,
Todd
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Re: ¿ A very different approach for circuit boards ?

Post by bodgy » Thu Apr 24, 2003 9:53 pm

Actually back in 1980 something, there was a company who marketed a a thin glue backed copper sheet, to do exactly what you just described.<p>One cut out the tracks, and then peeled the backing paper off and the tracks plus substrate were then plonked onto paxolin, veroboard or even wood to make a circuit.<p>They used to advertise in ETI magazine.<p>Colin
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Re: ¿ A very different approach for circuit boards ?

Post by Bernius1 » Fri Apr 25, 2003 3:39 am

Analogee, I liked your paper idea; But maybe a sheet of adhesive plastic laminate would hold better. Or sandwich the copper between two sheets & poke terminals through. Or stick the copper foil on one sheet, stick the SMT's to the pads, bond with conductive epoxy, & vacuum seal the whole thing in a 'freezer-food-saver' bag. The epoxy ensures pad contact, the inside of the bag adheres to the laminate, & the vacuum helps prevent corrosion of the contacts. Hi-heat is the only limitation.
......regards, y'all .....
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Re: ¿ A very different approach for circuit boards ?

Post by gadgeteer » Sun Apr 27, 2003 12:54 am

Man --- I have just spent MONTHS trying to get my keyboard to work. Rather than buy a new $100 from CTX (this is a laptop), I bought a USED laptop keyboard; which ofd course didn't have the correct matrix, nor the cable in the right place. How do you connect wires to a laminated encapsulated flimsy plastic sheet with internal conductive ink traces? WELL, you pierce pinpoint holes with a sewing needle, and thread tinned wires through (24 wires, each with 4 pinpoint holes), and daub on "Calectro Silver Paint" ($35 per ½ ounce). Solder hair-fine enameled magnet-wire, more silver paint on the actual keyboard. The ACTUAL KEYBOARD itSELF is made from flimsy plastic sheets, conductive silver paint, black carbonous contacts. Lots of Calectro silver paint now, and a half-dozen jumpers made from tinned-end enameled wire and daubs of silver paint). One plain sheet in the middle for insulation and contact separation. Yesterday was the first day in WEEKS that it was 100%; then today it is screwing with me by adding spurious characters, inserting "D" and 24erzty wherever it feels like. Oh now I wanna give an EXAMPLE and it's not gonna DO it! (The FIRST part of this post it was messing with me MERCILESSLY! This thing just doesn't LIKE me...)<p>Maybe I shoulda bought the actual keyboard (but couldn't justify the $100 when the entire laptop only cost $278, and a new laptop is only a few hundred; this has no USB so buying a new one, instead of a PCMCIA-USB converter, soon, is given...)

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Re: ¿ A very different approach for circuit boards ?

Post by wd5gnr » Sun Apr 27, 2003 9:53 am

You can get copper foil tape from anyplace that sells stained glass supplies. <p>See one of my QRP transmitters made with foil:
Here

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Re: ¿ A very different approach for circuit boards ?

Post by BobLynas » Mon Apr 28, 2003 9:02 am

Slightly off-topic i know, but over here in the UK we have a supplier that sells an acetate-like sheet that you laser print your PCB design onto, you then iron-on (yes with an Iron ladies!!) your design onto a copper-clad board and then etch as usual, cuts out all this photo-fixing stuff... If only they could come up with iron-on copper/silver in the same way !
BobMcN

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Re: ¿ A very different approach for circuit boards ?

Post by analogee » Mon Apr 28, 2003 9:00 pm

wd5gnr -- like the transmitter photo, nice! And cheap.<p>I've taken to making almost all my breadboards now doing something similar, but using a piece of copper-clad as a substrate and a ground plane. I put Kapton tape down as an insulator wherever I want to put the copper tape, so that it does not short to the ground. This stuff is the only tape-like substance I know of that can stand the heat of soldering. Unfortunately it costs like $20 a roll, but it lasts a long time. Since there are usually lots of ground connections, this method makes for a pretty quick breadboard, since ground is available over the entire surface.<p>But if you don't need the ground plane, shoebox lids are pretty cheap, and easier to cut holes in to mount your connectors.<p>Regards,
Todd
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Re: ¿ A very different approach for circuit boards ?

Post by erdc » Fri May 02, 2003 9:43 am

I remember in the late 70's Radio Shack would sell a "magic" black pen marker. All one had to do was to just draw out the traces by hand on a copper curcuit board, and then do the acid bath to it. <p>It worked quite well, but if you had poor penmenship or not an artist, the boards came out looking like it was made for a Dr. Seuss type TV curcuit board.

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Re: ¿ A very different approach for circuit boards ?

Post by Dimbulb » Fri May 02, 2003 1:25 pm

The heat transfer has been the easiest.
The pnp blue wet has given good results. <p>In trying glossy photo-paper it was getting the paper off that was time consuming.<p>I tried to find a way to dissolve the paper.
What I found was that during paper mill pulping process they use some of the following:<p>The paper industry uses substances like sulfur dioxide, calcium bisulfite, sodium sulfate, sodium sulfide, and sodium hydroxide (lye) to dissolve lignin. sodium hydroxide, acid bisulphite solution or a combination of sodium hydroxide and sodium sulphide.<p>I thought maybe soaking the paper stuck to the toner in something used to remove hair or unclog a sink would allow an easier way of removal rather than rubbing but leaving those fine lines.

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