What is this style of PCB called? It's single-sided, with lots of orthogonal jumpers and strange "horns"

Question

A hobby of mine is to take apart discarded electronics -- to see what I can learn. Sometimes, I'm just puzzled.

I've seen this style in name-brand stuff, meaning high quantity, like radios and vcr's. This PCB was I believe removed from an old tv having mini fluorescent tube backlighting, I sure would like to know what to call this style of pcb-design, and is this something only the big guys do (is this totally custom) or is there a pcb mfg house that does this, because I've never seen it (though I admit, I didn't look too hard). I assume this style is to make design and manufacture as cheap as possible. And there's probably software that allows to design this way, though I don't know what it is.

PCB, component side, without flash:

PCB, component side, with flash:

PCB, underside, no flash

It also has this interesting style for MOSFET that I'm curious about (I call these horns -- what are they called?):

SMT TPC8214 MOSFET

And here's another (A unicorn?), with teardrop-shaped solder on the middle pin:

EDIT:

Here is an asymmetrical one:

Answer 1

It's a single-sided punched paper-based phenolic PCB. Extremely cheap per square meter in high quantity compared to FR4, but some tooling costs for the dies.

The features you show are to get high yield without a lot of touch-up after wave soldering. The parts on the bottom are immersed in molten solder as the board moves through one more more "wave(s)" caused by a stirrer in a solder reservoir, subsequent to preheating and fluxing.

Those triangle patterns take up some of the solder on the trailing edge of the wave that would otherwise tend to cause shorts that would have to be manually touched up later.

Answer 2

The comments about solder thieves (the unicorn horns) are spot on. In some cases you'll find two different boards of the same basic design with different orientation of the thieves because of the way multiple boards were panelized.

This is from the era when it was cheaper to cut and place jumpers in the board than have a double sided plated through hole design. The boards were also often punched with a huge die rather than drilled. A lot of non-recurring cost traded for lower unit cost in a high volume product.

The main thing that killed this approach was the transition to surface mounted parts. As long as you were going to wave solder a board anyway, the only cost of the jumpers was inserting them and they were incredibly cheap. The transition to SMD made the boards smaller and used cheaper parts. The jumpers would have been much more expensive that double sided or even multilayer boards in the new environment.

Answer 3

That board could have been laid out in any PCB CAD program. The layout person just has to put most tracks on the bottom side, and ensure that any top side tracks are short and straight.