Ploted Circuit Board tips
Posted by
bfp@e...
on 2000-02-10 01:38:41 UTC
"Harrison, Doug" wrote:
snip
for getting this method to work
the pens I used for resist were (as mentioned)just regular
Sanford "Sharpie" permanent markers the "fine" size works well for thick
power traces and there are extra & ultra fine pens that will do ok on logic
traces(down to about .5mm width)
to make these long pens fit in the plotter carousel I had to remove
the clear top cover from the carousel and cut out the strip of plotter
case between the carousel and the work tray
I then took some dry disposable plotter pens,cut off the ends and reamed
them out to fit snugly arround the marker body
the plotter can handle the extra weight of the board with no complaints
its the extra thickness of the material that causes problems and you will
have to adjust the pens in there new sleaves to keep from blunting the tips
the plotter I was using was an HP colorpro 7440,a lot like the 7475,and it
didnt seem to like making round pads so I had to make all pads & vias
square or octogon
to be sure that you get a good thick resist layer you should set the
pen speed to 1cm/sec with the command "VS 1;"near the start of your program
there is(or was)a list of hpgl commands at
http://www.mhri.edu.au/~pdb/dataformats/hpgl/
the plotter drivers for windows realy dont give you enough control of things
to do this job so I plot to file,edit the file,transfer it to floppy and
plot from an old toshiba T1000 laptop with a dos batch file like this one
=====================================
rem filename plot.bat
rem setup com port to talk to plotter
MODE COM1:9600,N,8,1,P
rem redirect file to plotter on com1
type h_bridge.txt > COM1
rem end
=====================================
to hold the boards in the paper rollers I used a piece of heavy paper
trimed to fit the width of the paper tray,taped 2 strips of card to it 90deg
to locate a corner and baseline for the board then held the board in place
with double stick tape
I should also mention that I only used this method to do single sided boards
but with care you should be able to do 2 sided boards,these old plotters
are fairly accurate
from search of http://www.hp.com
HP 7475A
Resolution
Addressable 0.025 mm (0.001 inches)
Mechanical 0.025 mm (0.001 inches)
Repeatability
With a given pen: 0.1 (.004 inches)
Pen to pen 0.2 mm (0.008 inches)
BFP
snip
>Still another possibility is using my old HP7475 plotter with etch resistI have used a plotter to make some boards before & have found some tricks
>ink. The HP7475 moves the paper and I'm not sure it would handle the extra
>inertia of clad board. Comments?
>Doug
for getting this method to work
the pens I used for resist were (as mentioned)just regular
Sanford "Sharpie" permanent markers the "fine" size works well for thick
power traces and there are extra & ultra fine pens that will do ok on logic
traces(down to about .5mm width)
to make these long pens fit in the plotter carousel I had to remove
the clear top cover from the carousel and cut out the strip of plotter
case between the carousel and the work tray
I then took some dry disposable plotter pens,cut off the ends and reamed
them out to fit snugly arround the marker body
the plotter can handle the extra weight of the board with no complaints
its the extra thickness of the material that causes problems and you will
have to adjust the pens in there new sleaves to keep from blunting the tips
the plotter I was using was an HP colorpro 7440,a lot like the 7475,and it
didnt seem to like making round pads so I had to make all pads & vias
square or octogon
to be sure that you get a good thick resist layer you should set the
pen speed to 1cm/sec with the command "VS 1;"near the start of your program
there is(or was)a list of hpgl commands at
http://www.mhri.edu.au/~pdb/dataformats/hpgl/
the plotter drivers for windows realy dont give you enough control of things
to do this job so I plot to file,edit the file,transfer it to floppy and
plot from an old toshiba T1000 laptop with a dos batch file like this one
=====================================
rem filename plot.bat
rem setup com port to talk to plotter
MODE COM1:9600,N,8,1,P
rem redirect file to plotter on com1
type h_bridge.txt > COM1
rem end
=====================================
to hold the boards in the paper rollers I used a piece of heavy paper
trimed to fit the width of the paper tray,taped 2 strips of card to it 90deg
to locate a corner and baseline for the board then held the board in place
with double stick tape
I should also mention that I only used this method to do single sided boards
but with care you should be able to do 2 sided boards,these old plotters
are fairly accurate
from search of http://www.hp.com
HP 7475A
Resolution
Addressable 0.025 mm (0.001 inches)
Mechanical 0.025 mm (0.001 inches)
Repeatability
With a given pen: 0.1 (.004 inches)
Pen to pen 0.2 mm (0.008 inches)
BFP