pcb board construction

sriegel

Member
2001-11-24 1:24 am
wow, this is an amazing resource!!! as i'm getting deeper and deeper into this pit of DIY, i wonder if anyone out there knows a resource on DIY pcb's. i have the art work and would really like to construct my boards. thanks for any help.
P.S. it's for an aleph5
 
If you're doing only a couple of boards then I find it's better to get a local shop to make the boards for you. There are many ways to etch the boards and for most, UV etching seems to work the best - therefore, you will spend a lot of $$ buying proper equipment. Alternatively if you are on a tight budget you can still draw / etch by hand - but the chemical solutions aren't cheap to buy.

Do the homework and price out what a PCB shop can make them for you. For me, it was a no brainer getting boards done locally and tin plated. You can check out my PCB on my website

http://www.geocities.com/super_bq/BLS3.html
 
Prices

PaulB,

I did 6 boards (4 main + 2 power supply) for a total cost of $140 NZ which is around $23/board - also includes tin plating. Max. board dimension was roughly 14cm x 14cm (didn't matter if the boards were much smaller as it would be the same cost). The local shop charged $40 for filmwork ($20 for each PCB layout) so in the future if I do decide to make my own UV etched boards, I can use these negative film slides.

Now let's talk about savings. Converting those prices to Canuck money ($1nz=0.67cdn). We get a price of around $15 cdn per board. Of course it may be far fetch to compare Canadian labour rates to NZ labour so I expect not many people in Canada can take advantages of these savings.

For a home based UV setup. Locally in NZ you can spend at least $150 for a proper UV box. Then you need to buy special UV lightbulbs. So easily $200 on hardware. I havn't looked around in Canada for prices because places like Radio Shack don't normally stock those items (i know places in Vancouver that do carry those items). Not a necessity but i'd buy a heater for the etching fluid which is another $80nz.

Then you have to look at etching the boards after UV baking the PCB. You can use the powder stuff (just add water) or the liquid ferrous sulphate stuff. The powder stuff is cheaper but doesn't work as good - $20/liter. The key to making clean PCB is to keep the etching solution hot.

Optionally, the boards can be tin plated or simply laquer laminated to protect the copper from oxidizing. $10 fix.

I'm surprised where you live to get boards done is so expensive. I was expecting no more than $50cdn each. I sure hope that includes resist plating or at least, tin plating.

Brendon
 

paulb

Member
2001-06-01 4:53 pm
Calgary
Your prices sound pretty reasonable. It's been a few years, I should check around again. There are sources for bulbs and things, but I want to design & solder stuff, not play with chemicals and etching vats.
I was hoping you'd say you found a great cheap Canadian source for boards...
 
UK Pound vs Kiwi $

"Helix no way :-
UV light setup, £35
chemicals - £20
board - £10
laquour - £5
a little time and care - free

you don't need a heater or any fancy UV box, just make ur own out box of all that MDF lieing around , get a couple of small UV striplamps and fittings, bobs ur unkle "

You're forgetting the UK pound is worth 3.33 times the NZ$. So adjusted for NZ currency:

UV light setup, $116.55
chemicals - $66.6
board - $33.3
laquour - $16.65

To the original poster, here's a Canadian link that will help you: (if you want to do as much by hand as possible and not worry about neatness of the etched PCB:

http://www.capable.on.ca/etching.htm
 
The Fred Flinstone method

I have over the years, after many, many failures, developed a method of making my own pcb boards. It is slightly time consuming, and is tough with many many thin traces, but for amps and preamps,(tube & ss boards), it works for me.
I use Assist pcb layout program. $50.00 from Welborne labs.

1.Design your pcb artwork from your schematic on your computer using Assist.
2. Print 2 COPIES out on your printer and triple check it against your schematic for errors. It prints out the traces as though you were looking through the board from the top,(parts placement side), and seeing the artwork from above. Just keep that visual in mind. Imagine a clear glass board, and you are looking from the parts side through it.
3. Spray 3m adhesive on the copper side of the board.
4. Cut excess paper around artwork and lay the design facing up on the board copper. Press to get a tight glue bond.
5. Using a Dremmel tool, drill pads with appropriate size bit for component holes. ie 1/16, 1/32, whatever needed.
6. Drill the center of each "pad" shown on the Assist pattern.
7. Peel off the paper. Scrub with finger nail polish remover to remove the glue.
8. Steel wool or lightly sand entire copper side until smooth.
9. While viewing the second copy of your pcb artwork,(glued copy will be ruined in removal),copper side facing you, Use a thin camel hair artists brush, and your choice and color of paint. Acrylic enamel works well and is cheap. Dab a dot of paint on each hole drilled for a pad. Connect the traces to the pads as shown on your 2nd Assist copy.
10.Allow to dry a couple hours.
11. Fill a plastic or glass only appropriate sized container ,(I use a 8 by 12 glass pyrex cake baking dish), with enough FERRIC CHLORIDE FROM RADIO SHACK, to cover your board with a couple inches of level.
12. Immerse the board in the FC.
13. Gently swirl the FC over the board for about 1/2 hour.
ie "agitate the fluid" while its etching.
As a better alternative, Mouser sells a plastic tank, heater and agitator for hands free etching for about $100.00.
14. When all excess copper is etched away, leaving only your pads and traces, safely disposes of the spent fluid, and rinse the board thouroghly in water.
15. Use appropriate solvent to remove the paint from the copper traces and pads. ie. water for acrylic paint, or thinner for oil based paint.
16. Clean the board up and start soldering your parts.
It works well if your carefull, but is a little time consuming.
mg16
 
mg16,

Seems like a lot of steps. For the transformer PCB (shown on my website) I:

1) CAD program to layout the PCB and printed it on laser printer transparencies.
2) Get out the scissors and razor blade and cut out the transparency (your template).
3) Place the transparency template on top of the copper board and use a permanent market to draw in the lines.
4) Heat the bottle of ferrous chloride in boiling water and fill in a plastic dish large enough for the PCB to fit in.
5) Add PCB and agitate for at least 30 mins, remove and rinse under water.
6) Use nail polish remover to remove the black ink which will reveal the nice shiny copper traces.
7) Laminate boards with laqueur spray and drill the holes.

I find that if you drill the holes before etching the board, the etchant can sometimes disolve the copper right around the drill holes - thus making soldering more difficult.
 
to super bq

I have never had the problem of losing copper around the holes do to pre-drilling. If you use a good 2oz copper board. The radio shack thin crap will sometimes do that. I use boards of 2oz copper from Digikey.
For a simple transformer pcb that you speak of,(I haven't seen your web site), it should take less than an hour or so.
I don't use transparancies. That is a different method. I use plain old white printer paper and that is my guide for drilling the holes. After the holes are drilled and the paper is removed, connecting the traces to the hole pads is fairly easy using a brush and paint, while viewing a copy of the artwork. Removing the glue with fingernail polish remover takes about 30 seconds.
It works well for my projects.
BOZ, ZEN AMP, Daniel preamp, various active crossovers, power supply boards.
mg16
 
Big components? just eyeball it

as long as there's no ic's in a circuit, i'll usually just draw the stuff freehand on the board with a couple of ordinary permanent felt pens, and a straightedge, if it needs to be precision. You can get a couple different sized pens. I find ordinary Staedtler lumocolour pens work very well. They're intended for writing on transparency film, and come in several diferent sizes. Just make sure to get the permanent ones, any colour seems to work reasonably well, except for yellow, which is just as well, as you can hardly see it on the copper.

Just clean the board well with a scotchbrite pad, or steel wool, Try not to touch it any more than you have to, because the fingerprints are slow to etch, and you'll need to leave it in the bath for longer than what will give you the best results otherwise.

Draw the circuit onto the board with the pens, and try and draw your soldering pads round, leaving an uncoloured hole in the middle of them.

After double checking to make sure you haven't forgotten any traces, put it in the ferric chloride, I found a plastic sandwitch container works very well for this. it's wide enough to fit most boards in flat, and you just need to pour in just enough to cover the board. I also like to drill a small hole in the corner of the board, and put a loop of fishing line through it, so i can easily lift it out to look without making a mess. Check it every few minutes until the traces are the only copper left, Wash the board well. If you're washing it in the sink, make sure to leave the water run for a while, or it'll eat your pipes.
scrub the ink off with steelwool, scotchbright, or use some alcohol.

Then get a TINY drillbit, and throw it in your dremel tool, and drill the holes.
It'll pretty much line itself up, thanks to the low spots where you left a hole in the pads. You drill all the holes in a couple minutes, and you're done.

Don't bother trying to drill the holes with the paper template beforehand.
I used to do it that way.. It's a lot harder to keep everything lined up, and to get a good etch you need to use a much thicker etch resist which will cover the inside edges of the holes. Nail polish, or paint, or whatever. It takes a long time to dry, and is harder to deal with when you screw up. With the ink, if you accidentally connect 2 traces, just score it lightly with a sharp knife, and it'll etch fine.

I think that's pretty much it. Another thing i don't think anyone has mentioned is that you can keep reusing the ferric chloride. It'll get a little slower over time, but you can do dozens of boards in the same fluid. Just pour it into a NON-METALIC container that seals well, and it'll be fine for next time. Or use one of those tupperware sandwitch containers I use, and you can just snap the lid on when you're done.
 
The last PCB's I etched were for my Aleph L. They cost me under 20 bucks to make not counting the cost of the PCB kit. I used direct positive-precoated fibreglas boards. These are the easiest way for onsies or twosies as you expose directly to sunlight using the original artwork, or a line negative generated from your CAD data. A properly exposed board is very apparent as you will clearly see the artwork......developing is a simple one step process then wash off. Then into the ferric chloride for etching. I drilled using a small drill press at work with the appropriate size bits.

CLUE!!!!
When you etch a PCB float it face down on top of a hot ferric chloride solution. This way the heavier copper thats being etched off the board simply falls to the bottom of the tray causing fresh solution to always be in contact with the PCB. Etching boards this way can take less than 10 to 15 mn!! Be sure you are not trapping an air bubble under the PCB when you go to float it......also, if the board is too heavy to float...not likely with the boards we are making here.... then it can still be done face down by supporting it with plastic points of some sort and filling with etching solution to a level just over the top of the board.

Happy Etching!!
Mark