OT: PC Board Etching - technique
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Posts: 46,084
Couple of comments of technique.
since if you are drilling holes in pcb's you use a lot of drills.
using the drill instead of a different thing, like a resistor is
going to allow more error than something close to the hole size.
My T-tech pcb etcher uses 2 pins and the holes use fitted pins.
Based on that concept, one could take a spare drill bit, nail it into
a board. align and drill one hole in both transparancies, put them
over that nailed in drill bit. verify alignment and drill them again
and into the board.
use the 2 holes and 2 pins for alignment.
The rest is pretty simple.
Dave
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 9/29/2003 9:12:37 PM Pacific Daylight Time,
> ghidera2000@y... writes:
> I've been doing both double sided and surface mount (only brave
> enough to try the SOIC 1.27 stuff). I use photoresist method
instead
> of transfer paper. Lining up the holes on both sides is actually
> pretty easy.
>
> A tip from the homebrew PCB board: Poke some holes in your
> transparancies - choose Three pads, one in each bottom corner and
> one in a top corner. The top corner is a visual aid so you don't
> accidently get the PCB flipped side to side during exposure.
>
> Take a long thin piece of scrap PCB and scotch tape one edge of the
> transparency to it. Slip your PCB underneath and mark the three
hole
> positions. Remove the PCB and drill the holes. Note: This is with
> the protective plastic still in place! You don't want to expose the
> photoresist!
>
> Flip your scrap PCB&Transparency over so the transparancy is on the
> bottom, the poke some resistor leads up through the two bottom
> corner holes. Lay your good PCB over it (taking note of the third
> hole position so you get the proper side) and slip the resistor
> leads through the PCB holes. I usually hang the holes just over a
> table edge with a piece of paper underneath to keep the resistors
in
> place.
>
> Take the second transparency and lay it on top. Slip the resistor
> leads through the matching holes so the two sheets are (almost)
> perfectly aligned.
>
> Now carefully wiggle the top tranparency around until the leads
> stand straight - tape the top sheet to the scrap PCB. Now you have
> something that looks sort of like a book, the covers being
> transparencies and the single page being the PCB. When you want to
> expose, slip the PCB between the sheets and poke resistor leads
> through to the PCB. When the leads are vertical, you have
everything
> lined up. Remove the leads, lay your glass over it, and expose
away.
> Repeat for the opposite side.
>
> The only problem I've run into doing this is transparencies that
> slip a bit during printing so they don't line up even when held
flat
> against one another. IBM laser transparacies slip in my el-cheapo
> Samsung ML-1210 laser. 3M Laser transparancies seem to do ok.
>
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++
>
> Ahhhhhh,
>
> So that is how it's done. I have made several single sided boards.
Recently
> however, I have found to save time (at much greater expense) is to
go the
> www.expresspcb.com route and have been very pleased with the
results.
>
> Must be damn sure that your artwork is correct though.
>
> I just might try the double sided method you just mentioned.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
since if you are drilling holes in pcb's you use a lot of drills.
using the drill instead of a different thing, like a resistor is
going to allow more error than something close to the hole size.
My T-tech pcb etcher uses 2 pins and the holes use fitted pins.
Based on that concept, one could take a spare drill bit, nail it into
a board. align and drill one hole in both transparancies, put them
over that nailed in drill bit. verify alignment and drill them again
and into the board.
use the 2 holes and 2 pins for alignment.
The rest is pretty simple.
Dave
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 9/29/2003 9:12:37 PM Pacific Daylight Time,
> ghidera2000@y... writes:
> I've been doing both double sided and surface mount (only brave
> enough to try the SOIC 1.27 stuff). I use photoresist method
instead
> of transfer paper. Lining up the holes on both sides is actually
> pretty easy.
>
> A tip from the homebrew PCB board: Poke some holes in your
> transparancies - choose Three pads, one in each bottom corner and
> one in a top corner. The top corner is a visual aid so you don't
> accidently get the PCB flipped side to side during exposure.
>
> Take a long thin piece of scrap PCB and scotch tape one edge of the
> transparency to it. Slip your PCB underneath and mark the three
hole
> positions. Remove the PCB and drill the holes. Note: This is with
> the protective plastic still in place! You don't want to expose the
> photoresist!
>
> Flip your scrap PCB&Transparency over so the transparancy is on the
> bottom, the poke some resistor leads up through the two bottom
> corner holes. Lay your good PCB over it (taking note of the third
> hole position so you get the proper side) and slip the resistor
> leads through the PCB holes. I usually hang the holes just over a
> table edge with a piece of paper underneath to keep the resistors
in
> place.
>
> Take the second transparency and lay it on top. Slip the resistor
> leads through the matching holes so the two sheets are (almost)
> perfectly aligned.
>
> Now carefully wiggle the top tranparency around until the leads
> stand straight - tape the top sheet to the scrap PCB. Now you have
> something that looks sort of like a book, the covers being
> transparencies and the single page being the PCB. When you want to
> expose, slip the PCB between the sheets and poke resistor leads
> through to the PCB. When the leads are vertical, you have
everything
> lined up. Remove the leads, lay your glass over it, and expose
away.
> Repeat for the opposite side.
>
> The only problem I've run into doing this is transparencies that
> slip a bit during printing so they don't line up even when held
flat
> against one another. IBM laser transparacies slip in my el-cheapo
> Samsung ML-1210 laser. 3M Laser transparancies seem to do ok.
>
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++
>
> Ahhhhhh,
>
> So that is how it's done. I have made several single sided boards.
Recently
> however, I have found to save time (at much greater expense) is to
go the
> www.expresspcb.com route and have been very pleased with the
results.
>
> Must be damn sure that your artwork is correct though.
>
> I just might try the double sided method you just mentioned.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]