How Printed Circuit Boards Are Made 88
An anonymous reader writes "Ever wanted to see how printed circuit boards are made en masse at a professional production house? Well, here you go. The folks over at Base2 Electronics recently got to tour Advanced Circuits, a PCB production house. They took some rather incredible pictures and explained the process along the way."
Been to a few smaller PCB fabs (Score:5, Interesting)
I've been to a few smaller PCB fabs a few years ago, before the days of 4PCB and PCBExpress and the like - mail order, nearly overnight, you fit it into their process flow shops. Anyway, this is back when a 4 layer board run was a $2k/2 week kind of deal rather than the $500 or so you can get now (or cheaper if you can wait). Those places were FILTHY and smelled like all kinds of hell. Nasty business. It's amazing how far these guys have come.
The value is so much better now too. Ten years ago, to get an overnight board we used to mill out two layer boards using a piece of prepreg with copper on either side. A guy would machine off all the copper we didn't want, then drill holes where we needed vias to connect from one side or the other. Then I had to fill the vias with little pieces of wire and solder each side, then stuff the board, then test and debug it; over repeated rework cycles the board would start to peel apart. On top of that, if you get the board hot enough, the vias (wires) would fall out and that was pretty hard to figure out. It was gravity assisted current limit.
Now, you finish your board design and ship it off to one of these guys. During the time you used to spend getting to square 1 with the milled board, you could order parts and then the board shows up from one of these guys like 4PCB here. A 2 day turn on a 4 layer board is no problem and just a few hundred bucks. The time I spent soldering vias into the milled board cost more than the real PCB I can get now. It's amazing. The way they get the price down is a combination of two things - first, you fit into their process flow, as I mentioned earlier. That means that they don't look at your board, they don't think about your board, they just cram it on a panel with some other guys' boards. If you want slots made in the board, you don't get 'em; if you want internal routs cut out of your board you don't get 'em. You get what their process says it does, and so does everyone else. This leads to the second way they get price down - volume. Lots of guys now order from a couple big shops, rather than these little (pretty dirty, as I mentioned) little mom-n-pop PCB houses. And we all order the same process.
It's amazing to see how some of these basic market principals have worked in the past ten years, and it has made a huge change in the R&D industry. It's much easier to do a pilot run of a board, it's much easier and cheaper to make a limited run, and since you are risking less you can order more and try things out. Truly awesome for an electrical guy.
Re:How It's Made (Score:4, Interesting)
In electronics class in high school (13 years ago, so there was still such a thing), we had a PCB maker.
The teacher had found a kit in a mail-order catalog to convert a plastic file box into an acid bath. We drew our circuits, printed them on a laser printer (very expensive at the time), ironed(!) the toner on to the copper surface of the board (which required copper-coated boards, so... not cheap), then let them sit in the acid bath overnight (actually only about 3 hours, but the class was only 90 minutes every other day).
The file box/PCB maker had a pump, reservoir, and stand that kept the board partially submerged during the bath, with acid flowing over it. The timer would kick off and the pump would reverse the acid into the reservoir and turn on a fan to air dry the board. Everything with exposed copper would have the copper eaten away. The laser printer's toner (ironed on, remember?) would prevent the copper underneath from being dissolved.
Once you removed the board from the bath, you had to scrub the toner off of the remaining traces with a toothbrush (gently, so as not to damage the traces), and drill your pad holes (no surface mount in those days). Voila! Instant (+/- 1 day) custom PCB.
You kids with your cheap Chinese labor... GET OFF MY LAWN!
Re:Been to a few smaller PCB fabs (Score:5, Interesting)
I design PCB's for a living, these days. Most board shops I work with have yearly tours/open houses: if you want to see an up-to-date shop see if they're throwing one. It's pretty cool to see. I'm mostly impressed by the electrical test machines: they look like a dozen mechatronic herons madly going after fish.
When I can wait a bit, I use myropcb [myropcb.com] because if I'm ordering 200 boards the size of postage stamps they're less than a dollar a piece including soldermask and silkscreen on both sides, if I can wait 10 days. (It'd be a lot faster but they tend to go slowly through US customs.) If I'm willing to pay a bit more, I use Circuits West [circuitswest.com], who will crank out up to 60 square inch boards for $31, and have had great quality.
However, the really great thing about milled boards is the turn time -- if you have a mill. I regularly go from hastily drawn schematic to finished, working board in under two hours, if it's a simple design. We can do three revisions of a board in a day, and *then* send it out to get a green board, once we're sure we have something working, and have a tested design ready for large-scale production in three days. We *love* having a PCB plotter in-house. It takes some thinking and experience to lay out good boards for it, but it sure helps productivity.
While I'm shilling companies that have saved me in crises, Vector Fabrication [vectorfab.com] is not the cheapest place to get PCB's, but they'll produce a 30x30 cm 14 layer board with 3 ounce copper in two days.
Re:We've been an Advanced Circuit customer for yea (Score:3, Interesting)