| First we print
two overheads on a laserprinter, place them on top of each other, and
secure them with self-adhesive tape. Make sure the printpattern is on
the right side of the overhead, it shall turn towards the pcb, and any
text must be mirrored. |
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This is the saw we use to cut the pcb. The sawblade is reinforced with
diamonds to make it last longer. |
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Here is the sawed pcb. We use Bungard positive photopcb because we have
very good experience with it. Notice that we have also cut three small
trial pcbs to test the strenght of the developer. |
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The overheads are now placed in our UV lightbox with a extra overhead
for the trial pcbs. |
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The blue protective film is removed from the pcb and it is placed on the
overheads in the lightbox towards the neon tubes. |
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The UV lightbox is now lit. The box is made with 2 x 20Watt (TL 20W/05)
Philips neon tubes, an ordinary glass plate and aluminium foil to
reflect the UV light. Don't look into the light it can ruin you eyesight.
We exposure our pcbs 7 minute. |
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This is the two chemicals we use to develop the pcbs: soda lye (sodium hydroxide)
and waterglass (sodium silicate). |
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We mix a very little bit of sodium hydroxide in some tap water.
Warning! Be very careful and use safety goggles and gloves during the entire development
process, sodium hydroxide is very dangerous and will ruin your
eyesight in seconds if you get it in your eyes! When the sodium hydroxide
is dissolved, we add 10-20ml sodium silicate which will act as a buffer and
make the develop process much less time critical and reduce the risk of overdeveloping. |
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We start with the trial pcb and make sure the developer is not to strong. |
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We then develop the real pcb. |
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Here is the finished developed pcb. Rinse carefylly with water to stop
the developing process. |
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We then etch the pcb in a solution made of 100 gram tap water and 100
gram ferric chlorid. We heat the solution with hot water in a kitchen
sink. Again be careful ferric chlorid makes stainless steel corrode and
will ruin your clothes if you spill on it. |
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Here is the etched pcb, again rinse good with water. |
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We then drill the pcb with our small Proxxon drilling machine. We use
0,8 1,0 1,2mm tungsten carbide drills. |
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After drilling it is time to strip the remaining photolacquer off the
pcb. We use acetone, with good ventilation. It is then time to apply
solderlacquer, we use SK10 from Kontakt Chemie, let the pcb dry
afterwards. To much solderlacquer can be removed with ethanol. |
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And finally we have the finished pcb, ready to solder. |
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| My brother has
made a very educating drawing showing the whole DIY photo pcb
manufacturing process, remember to check out this pdf. |
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Here is our recipe for making doublesided pcb. We print the two bottom
overheads as described above and join them with self-adhesive
tape with the ink side up (towards you). |
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We then print two top overheads mirrored and and join them with
self-adhesive tape with the ink side
down (away from you). |
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Finally we join all four overheads together with self-adhesive
tape. We cut the raw
doublesided pcb a little bit to big and put doublesided self-adhesive
tape on both sides of the pcb and place the pcb with two overheads on
each side of the pcb. During the 2 x 7 minute exposure, we cover the pcb
side turning up with black cardboard, and voila you have a doublesided
pcb. |
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