Name of a vintage PCB manufacturing technique.

[truhlik_fredy]

I tried to google for a half day and I can't find it at all  . There is a technique which was applied to miniaturize the PCBs, they were 2 boards and components were sandwiched between them, but all the components (through hole) were vertical and each component was connecting to both boards.

I found few techniques which are bit similar to this, but I can't find this one. I would be so happy  if somebody could give me hints or point me to the right direction.

[Ian.M]

https://hackaday.com/tag/cordwood-construction/
Also,
http://www.jhuapl.edu/techdigest/views/pdfs/V01_N1_1961/V1_N1_1961_Cordwood.pdf

[cvanc]

"Cordwood", if I recall correctly.

[truhlik_fredy]

Yes It's cordwood, thank you very much Ian and Cvanc. I was thinking that i'm going insane, I was looking at the history of PCB and other ways making board and there was lot of other approaches, but this one looks very hard to find, even when you try looking for it

[Ian.M]

Its still occasionally useful e.g: when prototyping a large diode matrix^* on stripboard - but for your sanity, don't build it fully sandwiched in case you make a mistake or damage a diode.  Instead, for the top cross connects use the thickest tinned copper wire you can solder through drilled out holes without breaking the strips, bent to form a leg either side of the matrix, with all the diode top leads formed to hook over the wires.  Stagger the legs in two strips either side of the matrix to allow for track cuts, and fly-wire them back to the rest of the logic.

* One possible application would be as a decoder for a multiplexed starburst display. Drive 1 of N lines of the matrix and directly hook the other side of it to the 14 or 16 segment pins.  I've built a 7 segment HEX decoder in sandwiched cordwood, which is why I do NOT advocate sandwiched cordwod construction any more!