Electronics > Manufacturing & Assembly

PCB etching by hand techniques?

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kalel:
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.

cdev:
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.

CharlieWorton:
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

cdev:
More than $200. Easily twice that to get a minimal setup.

Corporate666:
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.

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