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How Printed Circuit Boards Are Made
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."
let's have a story about how circuit boards are manufactured! sure this crowd either already knows the subject
PCB manufacturing was "news" in the 40s for proximity artillery shells.
I made my own PCBs by hand in the 80s, I made a nice capacitance meter that essentially used an 80s 8-bit micro as a very complicated stopwatch to determine the RC time constant, then it ran the calculations to convert the measured time into uF or pF as appropriate. It actually worked.
The modern-ish way to build non-PCB stuff at home now seems to be Manhattan-style construction, cutting little squares of PCB and soldering them into a substrate as terminal blocks. The modern way to make PCBs at home now a days seems to be download a windows only wanna-be cad program, upload the PCB to somewhere in China, magically a PCB arrives in the mail in a couple days.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Any suggestions for circuit design companies? low cost, one off devices primarily for development / prototyping?
(nothing complex; primarily sensing circuits be it pH, ion selective probes, etc)
Not specifically looking for something to be made right now, but in the future it is a possibility.
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.
Just my $0.55 (US inflation, 1774-2008, for $0.02)
You used the word "sheeple." Your rant has instantaneously become invalid, and you are now officially the stupidest person in the thread.
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!
We used the UV-sensitive boards. Print the design onto an overhead sheet, put on board, expose board, etch, rinse, remove the photosensitive layer that's still on the tracers with some acetone, rinse again, done. Works much better than toner transfer; but also more expensive. Even did some 2-sided boards that way.
Then again, rarely do people etch their own boards these days. Either use one of the island pads/strips boards that are cheap and do some wiring for cross-traces, or have the board fabbed. By the dorkbotpdx guy - Laen, perhaps.. bit more expensive than the far east options, but quality is great, shipping is faster, boards are U.S.-made (for those who care), and hey.. the mask is purple.
Whatever happened to the good old days when we would construct mnemonic circuits out of "bear skins and stone axes"? Seems logical to me!
Welp, speaking of the devil, advance circuits has great rates for all of their capabilities. For 2 layers without soldermask you can get a run for under $50. If that's still too much but you can wait a month or so, Sparkfun runs something called batchpcb.com. If you only want one board, they will collect other user's boards into one big file and do a run for dirt cheap.
Inner layers are processed as you would expect. Etch resist is applied to the areas you want to keep, then copper is etched away. The outerlayers are different. The resist image applied to the board exposes the what you want to keep. It can be considered a "plating resist". The exposed image is then plated with copper (this is where the hole walls get plating) then tin. The resist is then removed. The tin then acts as the etch resist. It's a pain to etch through copper. That is why copper plating is only applied to where it is needed.
On the other hand, you can buy your boards for the expensive American price, and it still won't be the most expensive component in your project.
The determined Real Programmer can write Fortran programs in any language.
Fabrication, or the actual design? For fab, and if you have the time, Batch PCB does boards for $2.50 per square inch plus a $10 set-up fee. I did a couple of small simple boards through them earlier this year. Once I passed the automated design rule checks (easy for simple boards), 17-21 days from submission to finished boards in my hands. Production is in China, but the quality was more than good enough for my needs. In both cases, I ordered two copies and received four. Apparently there is some duplication as things are panelized and produced, and they send along the extra copies rather than discarding them. No testing, but all of the boards I received worked.
They use Gold Phoenix for the actual production. If you need enough copies to fill, or even mostly fill, 100 or 150 square inches, it's cheaper to deal with Gold Phoenix directly. Other people have suggested DorkbotPDX; their prices may end up cheaper, but it appears to take Dorkbot a long time to fill up a panel; BatchPCB seems to fill a panel every couple of days.
No, the modern way to build PCBs at home is to home etch. The modern way to build PCBs not at home is to send CAD files to China.
Occasionally I make 2-layer boards at home. The usual technique is to use laser printer toner transfer (use a CAD program, not a "Windows only wannabe CAD program", but gEDA (GPL EDA) which was designed for Unix, and is a set of tools such as gschem (schematic capture) gnetlist, PCB, etc. Shiny inkjet paper is used to print the PCB layout and then a clothes iron (or a laminator) is used to transfer the toner onto the bare copper clad board, it's then etched in your favorite etchant (I use ferric), tinned and drilled. You can also get fancy laser printer toner "paper" (I've never used it) which is a bit easier to use for toner transfer, but it's expensive.
Some people have modified inkjet printers to directly print etch resist onto copper board. I don't make enough boards at home to justify doing that. There are also reasonably low cost CNC machines for milling PCBs if you're making them regularly. Some brave souls have made 4 layer boards at home, but that's just too much effort, I'd rather just pay the likes of Advanced Circuits or PCB-CART for something like that...
When I send PCBs away to be made in a factory I use the same toolchain since gEDA PCB emits an industry standard Gerber file.
Oolite: Elite-like game. For Mac, Linux and Windows
In electronics class in high school (13 years ago, so there was still such a thing), ..... (no surface mount in those days).
I think it depends who you hang with and what you do. In the microwave RF world, surface mount was already old, 13 years ago. I was building ham radio microwave transverters using SMD, oh probably 15 or 20 years ago. For a variety of reasons such as ground-lead inductance and impedance mismatches, I don't think anyone's ever used MMIC-technology ICs in old fashioned thru-hole construction, and those started coming out in the late 70s or maybe early 80s, so its gotta be older than that.
Surface mount is much easier than thru-hole, if you own the right gear (Hakko Inc and their competitors)
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger