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Coffee House => Coffee House Boards => CH / General => Topic started by: tonyyeb on October 14, 2007, 11:17:42 AM
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Hi all
I bought an electronics kit from ebay and would like to make another. But as the parts came to a 1/4 of the kit cost I wanted to know how easy/cheap a PCB could be made at home. Plus i can then make other stuff from info on the net.
Cheers
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Not quite what you're asking, but why not convert the PCB layout to stripboard? Then you can just buy a cheap piece of veroboard and use that as the base of your project.
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moto
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I thought about that but i would like to makes cases where needed for these projects. Plus i just want to make my own PCBs.
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I don't think making your own PCB's would be cost effective unless you are making them in large quantities.
I used to work with electronics and all the PCB's were from another company, although we had the facilities to make them ourselves. Time and cost were probably a factor.
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I only want to make the odd one every so often. Ive found a few cheap kits. Thanks for the input guys.
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UV light and acid is basically what's needed, I'd say.
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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
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I hope this is not too far off topic.
Is making multilayer boards a matter or sandwiching two boards together with an insulator in between?
Is it something more involved? Does anyone know of a good book on the subject?
Thanks.
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Is making multilayer boards a matter or sandwiching two boards together with an insulator in between?
Yes
Is it something more involved?
Yes. Through Hole plating for one.
Does anyone know of a good book on the subject?
Do a search for multilayer PCB process. Here is one site with a fairly detailed method:
Multilayer PCB Prototyping (http://www.thinktink.com/stack/volumes/volvi/multilyr.htm#overveiw)
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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.
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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.
Good day.
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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
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I do not know if .030 thick boards can be found with dual copper already applied.
www.thinktink.com talks about the process of making boards,including multilayer. A copper spray is used to make the boards conductive and then it is plated.
I was planning to make my own boards with acid copper electrolysis.
It will be a while before I can give some real experience info.
edit: Nov.30,2007
Sorry, I am still in the experimental stage myself.
Does anyone sell .030 inch double sided boards on the web?
Thanks.
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Best results I have obtained from home made was when I was in school and worked at a hospital. I would draw the circuit in lead pencil and have the X-ray tech shoot it. It results in a super sharp photo mask for your board. I made many boards this way and it was great. I no longer have the X-ray facilities so now I just send them out. I miss those days of experimenting all day long. Don't make any cracks about medical costs going up either, that was like 30 years ago. :-D
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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 :-(
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Check out this video:
http://www.youtube.com/watch?v=sDddSJd617g
The relevant sections start around 31:15 and 43:20.
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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
8) 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.
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@ Oliver
I guess it depends on how thick you want your board to be.
Have you made 4 layer boards before?
I wonder how one would judge the density of the circuits before needing multilayers.
Good day.
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@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?
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@ Tonyyeb
Sorry to have taken over the thread.
@Oliver
I wish I could get two high density FPGA chips on a mATX or standard ATX board for building a new computer.
As far as 4 layer board are concerned, the blind vias, I believe, are electro-plated and have contact pads between boards that dig into each other between each layer( thinktink).
If a board was layered A,B on the first board and C,D on the next board, I could connect A to B and C to D then A to D. Edit: I bet I would have to make sure the two boards were good before I joined them.
What do you think?
I do not know much about signal integrity and noise and other related physics to really be of help.
Good day.