Best way to make home made PCBs?

[Oliver]

Have you looked for 'direct toner transfer' method?

This way doesn't need any photolithography. Basically, you use either a black and white laser printer, or a photocopier, to make a print of your circuit layout onto colour photo grade paper, which produces something like an iron on transfer.

If you do a Google search for 'direct toner transfer PCB', you will find lots of hits.

You still need to etch the copper from the board, so you have to know a bit about chemical safety, but it's not too bad with the products currently available. You can get purpose built etching tanks, with in-built heaters, and airaters, which should work well, though I've not used them. Try to use ammonium persulphate rather than ferric chloride, for safety reasons.

If you have a friend who's done it before, then try to get some help.

As far as cost goes, the PCB is often the most expensive component in a circuit.

Good luck.

Oliver

[Oliver]

trekiej wrote:
Is making multilayer boards a matter or sandwiching two boards together with an insulator in between?

Commercially produced multilayer boards are done this way. There are copper traces on insulated sheets, which are fused together. Various materials are used. Something like fiber glass can be used for this.

Home made dual layer boards can be done from double sided blank copper boards. It is quite tricky though.

One needs to be able to pass signals between the layers of the boards. Vias are the normal way to do this, but you may be able to get away with running wires around the edge of the board (not a great solution, for various reasons).

Using vias requires one to have the layouts for each side of the board to be very well aligned. Doing this by hand, probably requires quite large pads to be used for vias, with a generous amount of clearance around the pads, to allow for a little error.

A via can be made by drilling a hole through the board, and inserting a solid pin through, which is soldered to pads on each side.

The trick is to have the layout patterns aligned well to start with. I achieved this by ironing on my top layer first, then drilling a few holes, then use these holes to align the transfer for the bottom layer. You need to user a transparent toner transfer, or a transparent photolithographic sheet.

Generally, if you are doing double sided boards, then one would be using mostly surface mount components. Having some through hole components is OK, but if there are too many, then one side of the board will be lost to holes and pads.

Home made boards usually won't have very narrow traces, and quite generous clearance, which makes some surface mount packages unavailable.

Good luck, and have fun.

P.S. All the info you need is available online. Make sure you understand the safety issues, though.

[Oliver]

trekiej wrote:
Thanks, I plan on doing my own electrolysis .  I am not for sure what the thickness of the substrate is.
I want to use about .030 inch for the upper and lower layers.  I would vacuum bag it before I apply copper.

Hi,

Would you be able to explain this process? I'm curious to know what the electrolylitic process is for. Are you talking about nickel plating the copper? When you write "apply copper", is this a method of chemical deposition of copper traces, as opposed to etching out spaces in a copper clad board?

Oliver

[Oliver]

trekiej wrote:
I do not know if .030 thick boards can be found with dual copper already applied...
edit: Nov.30,2007
...Does anyone sell .030 inch double sided boards on the web?...

Why are you concerned about the board thickness? Are you doing particularly high frequency circuits? Do your boards need to be particularly robust, or conform to a particular form factor? The thickness is rarely an issue worth considering.

I had a brief look at the Think & Tinker site. I found it a bit too dissorganised to scan through it quickly, but I think their processes are rather elaborate.

What kind of circuits are you designing? Usually, quite simple processes are sufficient for beginner to intermediate home made PCB's.

If you are doing more complex designs, or releasing a significant number of boards, then home made usually doesn't work out too well.

edit- spelling  :-(

[Oliver]

HenryCase wrote:
Check out this video...

I think the direct toner transfer method is a lot more useful.
1)  Design the circuit in a schematic capture program (I use protel)
2)  Download, import, or draw your own PCB layout library parts (basically just footprints, and pin assignations)
3)  Take a netlist from the schematic into a PCB layout program
3)  Layout the PCB
4)  Print the copper signal layers with a laser printer, onto coated colour pinting paper, or tranparency (this can also be done with a photocopy of a layout, onto the appropriate coated paper/transparency)
5)  Clean the PCB with scotchbright or similar plastic scourer
6)  Iron transfer the toner from the printed layout onto the copper cladding
7)  Dissolve the paper away from the copper, leaving the toner
 Touch up the toner with a sharpie or equivalent pen
9)  Allow to dry
10) Etch (I use heated sodium persulphate)
11) Drill, etc

One can make quite sophisticated layouts in this fashion, with a good success rate. A few minor errors per board can be fixed, but I have rarely had to do this. Of course, the key to success is in a good circuit design, and not too ambitious a layout for the first time.

[Oliver]

@trekiej
I've never tried home made 4 layer boards. I think that would be too much trouble. 2 layers is difficult enough for DIY. How would you fabricate and test blind and buried vias? If doing something that intricate, I would suggest getting a prototype frame manufactured.

Judging the number of layers one will need for a particular circuit is a matter of experience.

If you have a simple signal flow, from one input port to one output port, single layer is likely to be fine. If one has a few ports, each with input and output, the topology is likely to be multi-point to multi-point, and extra layers would be very handy. Many layouts can be done in a neat and simple manner, with suffient forethought. This forethought should start when doing the brainstorming for the schematic.

I have not yet needed to make any four layer boards for my job. They are about double the price of a 2 layer board. The company I work for, mostly just does our main products on 4 layers. All our peripherals are done on 2 layers.

It's often cheaper to make a board a bit bigger, more generously spaced, or if doing home made, one can use jumper wires for the extra layering.

If doing high frequency designs, one may need internal gound/power planes, for which the additional layers are most useful. There are many other reasons as well, but for most people doing DIY PCB's, single layer w/jumpers or 0 Ohm links would be quite sufficient.

Just as a matter of interest, what kind of circuits are you designing?