ironpcbpcb-fabrication
Soon, I'll try to create my own PCB with the iron chloride method. I watched a video on that and it seems quite "easy". The only thing that I don't understand is the need to put the PCB on the iron chloride solution. I read on Internet that it will "burn" the PCB but I don't really understand why it needs to be done as after, we remove all the iron particles from the PCB.
Can someone give me some information about that ?
For one-offs or prototypes I use:
This gives good results down to 10 mil trace widths; could probably go finer but haven't needed to yet.
For double-sided boards I tape the two layers of Press-n-Peel film to two scraps of PCB at the edges so that I can get the two layers well aligned, then put the PCB blank in and feed it through the laminator. Here are some pictures to illustrate:
The bottom (left) and top (right) of a simple double-sided board (the top one is printed out mirrored so they overlay when its turned over). Normally I would print onto the blue Press-n-Peel film, just using paper here for illustration.
With one side taped to the scrap PCB (left side) and the printed sides facing each other, hold them up to the light and align the other one so that all the holes and the board outline line up.
Here they are both stuck to the PCB scrap. You can now put the clean blank PCB between the two (probably best to tape it to both sides to avoid any movement) and run it through the laminator (or iron it) to transfer the toner onto the PCB.
You can tape the two pieces of film or paper together without using the scrap of PCB, but when you put the blank PCB between them you can get some relative movement as they flex around the thick PCB. With the scrap piece the same thickness as the blank PCB they stay in the right place.
A bench drill is good for any drilling. I use drills down to 0.5 mm diameter but with 3 mm shanks so they are easily held in the drill chuck.
For through holes I solder thin copper wire to the pads on either side. The wire comes from a multi-core flexible cable; individual strands are or about 0.2 mm or 8 mil diameter. This takes some time!
And to solder I place solder paste with a fine-tipped syringe, place parts with fine tweezers then reflow in an electric frying pan. A few more pictures:
Syringing solder paste onto SMD pads.
Placing component with tweezers
A finshed board - the PCB was professionally made but I assembled components and soldered as described here. These are 0402-size resistors and capacitors (quite small, amazingly easy to lose), an accelerometer in a QFN-16 package (4x4 mm) and a memory chip in an 8 pin leadless package, similar size to a SOIC-8. (This is part of a small accelerometer data logger, see vastmotion.com.au).
Good luck!
I've had the same problem in the past, here's what I did to fix it:
Best Answer
Before being placed into the solution, the board is lined with a solid layer of copper. Unwanted copper must be removed, so that only the circuit artwork remains.
Although prior to the immersion in ferric chloride, it looks like the board already has a finished circuit on it, the artwork which you see is still only a mask printed on top of a single piece of copper foil which lines the entire surface of the board, allowing electricity to be conducted between any two points on the board.
When we place the board in the solution, the chemical reaction between the exposed copper and the ferric chloride causes the exposed copper to be leached away. Given enough time, it is completely leached away, revealing the bare epoxy board underneath. What remains on the board is the copper that is protected by the mask corresponding to the artwork.
At that point, we have the connections for a circuit: the PCB artwork which we designed on the computer screen (or perhaps in some other way) is now manufactured out of conductive copper, adhering to a rigid, non-conductive epoxy or phenolic board which gives it durability. The board is now thoroughly rinsed so that no traces of the chemical solution remain, and the mask can finally be removed, revealing shiny copper.
Although PCB's are called printed circuit boards, they are actually "printed and etched circuit boards". Another way to make a board is by means of a CNC (computer numeric control) milling machine. This is not really printing at all; rather a tool holding a rotating cutting bit is precisely guided by a computer to remove unwanted copper, leaving behind the shape of the circuit artwork.