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Old 6th September 2003, 02:19 PM   #11
hifi is offline hifi  Sweden
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Really nice pcb but althose vias...without solderd through holes... (especially underneath capacitors...its gonna be a pest to solder that board (IMHO) but still really nice looking!

/ micke
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Old 6th September 2003, 03:22 PM   #12
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Default My Via Technic

I got my own technic to do via. I'm doing the connection between both sides using a very small piece of wire-wrap wire (AWG 30) that I solder first on the traces close to the pad. Then I solder the part.

This is not my own pcb desing. When I do a pcb that need via, I always put a second pad outside the part to do the interside connection. This way, I can use a normal piece of wire to connect the two pads. Thanks for your comment.
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Old 6th September 2003, 04:41 PM   #13
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Default Nice work

Very nice boards. You'll have to share materials and methods.

Vias (in the orginal) were fairly easily done using copper flange pins.
These were soldered in before the components, and not placed under capacitors for the obvious reasons.

Your method sounds even simpler.
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Old 7th September 2003, 04:43 AM   #14
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Default PCB Method, The stuff you need

I'm very please with the process that I used to create the PCB. I was planning to share my experience. Some few tricks are needed or, like me, you will scrap a few PCB before getting the things right...

I used products from MG Chemicals:

1)Copper Clad Board, 6X9", 1/16", double sided presensitized, 1oz, positive process, about 15$ CAN each. see: http://www.mgchemicals.com/products/500.html
The quality of this product is incredible. Tought container bag, strip out covering on the board that protect a perfecly applied presensitised dark blue finish.

2) Positive developper concentrated, Oups! more on that later...
http://www.mgchemicals.com/products/418.html

3) Etchant Feric Chloride: http://www.mgchemicals.com/products/415.html

Material needed:
1) UV lamp or the sun (at noon, clear sky)
2) Exposition frame (that I made myself)
3) plastic bath for the etchant and glass bath for the developper
4) Time watch
5) A Dremel drill, various pcb drill bits and the Dremel pressdrill accessory.
6) Good laser printer (with new cartridge if possible). I used an HP4050 at work...
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Old 7th September 2003, 05:04 AM   #15
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Default PCB Method, the exposition

1) Print the Artwork on a transparency using a good laser printer. Here you need a dark very dark. I used a new cartridge, then I printed 2 TIMES ) the same image over istself. That gave me a very deep dark. The process that I used need the POSITIVE image. Cut the transparency to about 1/2 inch bigger than the PCB dimensions. Using a soft tip marker, indicate what side is the TOP to expose.

IMPORTANT:
Do all these steps with a small section of pcb to practice the correct exposition time with your light source and to find the correct developper concentration. Then once all set proceed with the real pcb.

For a two sides PCB, the top is printed normal, the bottom need to be the mirror image. Your also need alignment cross on the pcb to align both sides images, see next step.

2) Put the top image on the cooper clad board with its protective sheet still in place. Using something sharp mark the PCB dimensions and the alignment cross centers.

3) Using a Dremel drill and a very small drill bit, drill the alignment cross center.

Do the next steps inside at medium to low light condition.

4) Using a knive and a ruler, cut the protective sheet and remove it.

5) Installed on the exposition table, put the top image on the board. Use the alignment holes to position the image perfectly. BE SURE TO ORIENTATE the image correctly. Close the window of the exposition table and clamp it firmly. See my own table here...

6) Using the lamp that I had, I exposed for 8 minutes. Time using a stop watch.

For a 2 sides PCB you need to expose the other side...

7) Open the exposition table. Remove the top image from the copper clad. Flip the PCB. Put the mirror bottom image on the board. RESPECT the orientation of the image. Repeat steps 2 to 6.

Now you have a cooper clad exposed on both sides.

Total time with a little pratice, around 1/2 hour.
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File Type: jpg pcb exposition_small.jpg (91.9 KB, 4066 views)
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Old 7th September 2003, 05:11 AM   #16
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Default PCB Method, Development

Put the exposed cooper clad in the correctly diluted developper bath for 30 to 60 sec. The developper remove the coating where exposed and you see nice cooper. Rinse with tap water. Let it dry for 2 hours. This step is very important. Take a beer in the mean time... or exposed the next PCB

TEST THE CORRECT CONCENTRATION with a small piece of pratice pcb before developping the real pcb.
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Old 7th September 2003, 05:22 AM   #17
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Default PCB Method, Etching

WARNING: Wear protective gear, glasses, glove, etc... Etchant is not that bad but can burn sensitive skin, eyes, etc...

Etching works much better with warm and mouving etchant fluid. You can buy the real kit, see:
http://www.mgchemicals.com/products/416e.html with heater and buble pump but you need a minimum of 4 liters of Ferric Chloride

Or you can do as I do. I put the etchant fluid in a plastic bath, that I warm it for about 30-60 sec in the microwave.

Then I put my board in and wearing gloves, I move it gently inside the bath.

Check the board visually from time to time. Total time, around 10 to 20 minutes depending on fluid condition (new or used), surface of copper to etch away, fluid temp, etc...

I did it in about 12 minutes.

Clean the board with tap water. Dry it.

Cut it to dimension, then using a brush (like SOS house cleaner), remove the sensitive coating.

You now have a gorgeous 2 sides pcb.
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Old 7th September 2003, 05:26 AM   #18
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Default PCB Method. The last steps

Drill the holes using the correct drill bits. PROTECT your eyes and maybe fingers

Protect the copper. I use liquid flux that I put everywhere, then I put solder on every traces and pad. I don't recommend using liquid tin. It is harder to solder after using this solution.

Install the via if using a two sides PCB.

You're done. I did my two ONO pcb's (without the drilling and the tinning) in an evening while listening to a movie with the familly.

Good luck.
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Old 19th September 2003, 01:13 AM   #19
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Default One of the two Main PCB

Here the completed ONO preamp PCB. I will start testing next week...
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File Type: jpg preamp_with parts_small.jpg (85.2 KB, 3924 views)
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Old 19th September 2003, 01:14 AM   #20
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Default ONO Muting PCB

And the quick and dirty little muting PCB.
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File Type: jpg muting pcb_small.jpg (34.6 KB, 3417 views)
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