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I spent most of the day hacking this:

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The function isn't important, except that it's for some RF guys who own spectrum analyzers and stuff so I wanted to keep it tight and low noise.

This isn't too awful a way to prototype, given that surface-mount parts are what's available. I sheared the little junction squares out of 30 mil FR4, and stuck them down with super double-stick tape; almost nothing else will stick to copper.

It looks great today, but the copper will get grungy eventually. I should send out a lot of copperclad FR4 and get it gold plated.

I sort of recall somebody mentioning that someone may sell pre-punched square or maybe circular FR4 buttons like this. It would be great if you could buy them with the sticky on the back already.

It would be better to slice the top copper into sections, instead of adding these little stick-on bits. That's hard to do with an x-acto or with a dremel, and those PCB milling machines are too much hassle for occasional use.

I deserve a beer now.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin
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Unless it's silicone adhesive, it probably won't last very well, especially with the heat from above. Also rather heavy on capacitance, not that it matters on a power supply.

There is this remarkable thing which sticks to copper, even polished. It's also conductive.

Not much to show for a day's work; I spent about a work day on each board or section here, which includes modifications back and forth.

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There are better tools than X-acto.

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Gold standard of course is etching, but who has time for that?

A complete one of these (I've made two already) takes about three days of on-and-off work.

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Tim

-- Deep Friar: a very philosophical monk. Website:

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Reply to
Tim Williams

Come on.

actually, I found the technique to be novel. I have always used an exacto knife and carved my squares out of the board material. I use a board material that peels real nice -- I forget the exact name, but it is a rogers material which has good rf properties and can fabricate to FR-4. I think my way (standard way) is still faster, but I found the approach to be something interesting which I have never thought of.

Reply to
brent

Solder? Tricky under a puck like this.

It's a freebie for a potential new customer. The possible upside would make it a very good days' work; this could drag along a lot of standard product sales. Besides, it's nice to do some real manual labor and soldering and stuff now and then.

I spent about a work day on each board

How did you cut those slits?

I just got some ebay dental burrs, and they work pretty well in a Dremel. With a little practice, this could get pretty good.

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--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

Some of the teflon RF materials carve and peel beautifully. It's inherent that those same laminates have poor copper adhesion. It's nice stuff to hack up. All the RF stuff I have around now has better adhesion so isn't much better than FR4 for hacking.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

I've been using it ever since I realized what Jim Williams was up to in all those hacked prototypes in the LT appnotes. His Bench (has it been preserved for historical value, or are pictures all that remain?) was covered in 'em. :)

Tim

-- Deep Friar: a very philosophical monk. Website:

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Come on.

actually, I found the technique to be novel. I have always used an exacto knife and carved my squares out of the board material. I use a board material that peels real nice -- I forget the exact name, but it is a rogers material which has good rf properties and can fabricate to FR-4. I think my way (standard way) is still faster, but I found the approach to be something interesting which I have never thought of.

Reply to
Tim Williams

Neat, wasn't there an RF article in one of J. William's books where someone used little RF stripline 'lego's' like that.. probably made by the Germans.

George H.

Reply to
George Herold

I have some Rogers Duroid (5880???) 0.032" Teflon board, I use a paper punch to make round lands for this type of build. You can also cut squares and rectangles with an Exacto. Mikek

Reply to
amdx

Th really interesting property about that rogers rf material is that the copper can be peeled easily, yet you can put a soldering iron on the pad and it does not come off. FR-4 , the pad just falls off after a short while with a soldering iron.

Reply to
brent

a
e

I think it is 5880... It is good stuff... a real breakthrough when it came out in around 1995

Reply to
brent

You could do matched-impedance stuff this way, and microstrip bandpass filters and such, just push the strips around to tune it. I don't do RF myself, never cared much for sine waves.

I did get to use my spiffy new vacuum tweezers to assemble this, worked great.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators
Reply to
John Larkin

Looks fantabulous. No problem with those big effective shunt capacitors to GND on the squares?

Reply to
bloggs.fredbloggs.fred

Cute! Pieces of (what looks like 22mil) PCB material for "top layer" over the workplane / groundplane; each appropriately bypassed and biased as needed. Use nickel plate; gold will alloy with solder and can create all kinds of bad connections, not to mention something that looks like "purple plague" which is an indication of excessive corrosion and likely an open circuit. Seen this before in various places. Gold is BAD with solder this way. Even silver is better,especially when using tin-silver solder (NOT crappy SAC).

Reply to
Robert Baer

Using an Xacto for KNOWN onesies is OK, but there is a better way. Photoresist on the PCB, use a "paper negative" (those islands drawn with black ink) for exposure,develop,etch etc.

Reply to
Robert Baer

Hi,

You could put a drop of solder paste (or a piece of solder wire), and then heat the board on the hot plate, like a reflow soldering.

As for hand cutting slits, somebody recently make me discover the cutters used for denting plexiglass, like these:

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or these (that cut off finger tips too easily):
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Instead of displacing the copper, these tend to rip off it.

Ciao!

--
Muvideo altrove 
Fabio Eboli nella vita reale... 
fabioebChiocciolAquipo.it
Reply to
Fabio_78

Olfa is one of the best, but your links do not work. The site redirects to force a country of origin selection and loses track of the original page request.

Reply to
DecadentLinuxUserNumeroUno

The page loads OK when you click the link twice before the cookie times out.

Reply to
JW

Oh, thank you, I linked to Olfa only because was the first links I found, hope the following links work better. Acrylic scoring tool:

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Hook blades, fit in trapezoidal blade cutters:
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Ciao!

--
Muvideo altrove 
Fabio Eboli nella vita reale... 
fabioebChiocciolAquipo.it
Reply to
Fabio_78

Close enough: it's 30 mils. That one looks good, but it was labor intensive compared to hacking the top copper somehow. I want a pantographic copper cutter.

We now buy all of our PCBs with "immersion gold" plate. That's actually nickel plate with roughly 10 microinches of gold. The gold keeps the boards shiny and makes the solder stick to the nickel, but there's so little gold that it dissolves away into the solder. That plating allows us to build boards ROHS for the people who want it, or tin/lead for sensible people, like aerospace customers.

The immersion gold looks beautiful, solders great, and it's planar, which is good for BGAs and such.

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--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators
Reply to
John Larkin

With proto boards so cheap from china, I would have thought it would be worthwhile making your own 'set' , and getting them gold flashed... Save a fortune in time... and a bit in money too....

Reply to
TTman

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