PCB etching by hand techniques? - Page 1
Forum section: electronics / general

author: kalel
author_rank: Frequent Contributor
timestamp: June 12, 2017, 04:21:36 am
content: I'm wondering if there are any usable techniques for etching a PCB (a copper board) without sinking a board into chemicals, by any potential manual/hand techniques.If there are, I'd like to know about some of them, as well as how costly (if very specialized tools are required), cluttery, and accurate they can be (accuracy in this case should definitely depend on your hand and practice as well), either by your opinion, or if you know a source that already describes all of them, that should be sufficient.

author: cdev
author_rank: Super Contributor
timestamp: June 12, 2017, 04:45:24 am
content: You can etch using toner transfer, hydrogen peroxide, vinegar and salt, with nail polish remover to get the black layer off at the end.Everything else is the same as other toner transfer etching methods. Note that the used etchant is still toxic..You can let the liquid evaporate off but copper is still toxic. So wear rubber gloves. But it doesnt stain things. It takes a bit longer. Its still pretty fast.

author: CharlieWorton
author_rank: Regular Contributor
timestamp: June 13, 2017, 05:04:33 am
content: Yes, I second the CNC milling machine suggestion. There's a video floating around on YouTube that shows a board being manufactured in this fashion, and the results are fully equal to anything you would buy from a commercial supplier. (OK, I went and found it. Here's the link:) There are lots of other CNC PCB videos, but this one is a quick overview.First, the board is milled. This process removes copper from around the circuit tracks. It typically does not remove most of the copper from the board, although it could if the operator so specified. When the initial milling process has been completed, it is removed from the machine and UVA curing photoresist ink is applied over the entire copper side, and the board is then cured under a UV lamp - it cures to completion, so timing is not critical. Then the board goes back into the milling machine to remove the hardened photoresist ink in order to expose the copper solder points. Through holes and mounting holes are also cut at this stage. The milling machine also routs out the board edges, giving the board a spectacular finish. Finally, the board goes into a solution - probably MG Chemicals Liquid Tin - which tin plates the exposed copper. At this point, the finished board is ready for component population.A milling machine suitable for this type of work sells for vaguely in the $200 Canadian price range on Aliexpress. Do a search for CNC machine. They will typically create boards measuring about 150mm X 200mm max, although larger boards are possible.Typically a program on your computer is used to create the CNC file, and then the file is transferred to the milling machine. Transfer can be done using a micro SD card, or over a USB cable. Micro SD cards allow for faster machining times, and do not tie the computer to the milling machine. The process is extremely similar to a 3D printer, with the exception that a dremel tool has been substituted for the 3D printer head.The primary disadvantage to the method is the time it takes to create a board; typically several hours for a 3" X 4" board. And, like every other process, consumables - in this case bits - have to be replaced.The advantages are that the production quality is superior to any other mechanism available to the hobbyist, no chemicals are required, and additional copies of the board will be identical in every respect. For small production levels, multiple machines could be used to generate more boards per day. However, the process is of primary interest to the home electronics enthusiast, or - possibly - to someone selling a few items a week through a home based business.The machine can also be used to do etching, and carvings. Typically, the vertical travel of a CNC machine of this type is only an inch or two.Hope that helps - Charlie

author: cdev
author_rank: Super Contributor
timestamp: June 13, 2017, 05:42:59 am
content: More than $200. Easily twice that to get a minimal setup.

author: Corporate666
author_rank: Unknown
timestamp: June 14, 2017, 02:25:42 am
content: The results in that video are fantastic - however, that is far from the norm for a CNC milled PCB. A $200 machine is not going to produce those results without tons and tons of tweaking and fiddling to get it just right, and with brand new tools and a PCB suited to the method of manufacture.

author: CharlieWorton
author_rank: Regular Contributor
timestamp: June 14, 2017, 02:56:13 am
content: Yes, you're quite correct re price. I thought I was looking at Canadian pricing, but was in fact looking at American. For about $300 Canadian, you can get an entry level machine that can do small boards, sourced through AliExpress. The machine used in the video I linked costs around $900 euros, so roughly $1,000 USD.Now, having said all that, I should also hasten to mention that I have no personal, first hand experience with CNC PCB manufacture. I have a lot of experience with 3D printers, which is similar. The difference would be the need to move a relatively heavy tool - a Dremel or similar - very precisely. 3D printers also must be precise, but the weight on the Z axis is far less. It's sorta like the difference between a ballerina and a sumo wrestler. They both capture your attention, but for different reasons.At this moment, I have etchant on order, 365 nanometer UV LEDs on order, a power supply on order, UV resist film on order... and I have to build the UV lightbox exposure unit, and that isn't free, either. And there's the various trays, and bottles, and chemical storage, and the inevitable aging and replacement of chemistry. I've also invested in several different printing surfaces - photo paper, backing paper, transparencies - in order to conduct experiments. I sorta wish that I'd put all that energy and investment into a cheap CNC machine instead.Once all my goods arrive, I'll be well supplied with enough stuff to run various experiments on thermal transfer, as well as photoresist film. But I now think that the simplest and best approach is CNC. Sigh. There's no question that you can get bad results with CNC. There are videos on YouTube. But I think the very best results that can be achieved through CNC, are superior to the very best results from any other method. And the ongoing costs are probably less, as well.Sigh again. >Charlie

author: P90
author_rank: Frequent Contributor
timestamp: June 14, 2017, 03:15:38 am
content: the other nice thing about the CNC as opposed to etching method is it drills the holes. Imagine all the holes you would have to drill by hand for through hole pcb's.

author: KL27x
author_rank: Super Contributor
timestamp: June 14, 2017, 01:49:09 pm
content: QuoteI don't consider CNC a manual/hand technique.Ironically, in the title, OP specifically requests a manual method to avoid the etching, specifically. In the past, there were little rub on decals shaped like DIP IC footprints and traces and such, for manually creating an etch resist. But the etching required an acid.There is no practical way to manually etch a board. You can manually cut copper tracks, but it is so time consuming that it is best left for very small adaptor boards and low pin count SMD IC's, just big enough for you to bodge them onto a veroboard. Soldering jumpers or wire wrapping is going to be faster than cutting tracks with any hand tool I know of.

author: cdev
author_rank: Super Contributor
timestamp: June 16, 2017, 03:44:45 am
content: Depending on the circuit, there are numerous breadboarding techniques that might work better for you in terms of speed, convenience, and good balance between effort and results.Look up Manhattan or "dead bug" style prototyping.

author: Corporate666
author_rank: Unknown
timestamp: June 16, 2017, 08:36:52 am
content: Quote from: CharlieWorton on June 14, 2017, 02:56:13 am3D printers are inherently imprecise so they are usually built with shit hardware like stepper motors and leadscrews instead of servos and ballscrews. When you're squirting blobs of plastic, a few thousandths here and there isn't even noticeable. But when you're trying to mill 6/6 tracks, that becomes a really big issue, especially on sharp corners where all the error leads to crappy looking results.I don't agree on results... I think it is virtually impossible to approach the quality you can get from a good photographic process with any sort of CNC machine. Disagree on the ongoing costs too - you need PCB substrate for each, but chemicals are cheap. Endmills (good ones) are expensive!