Slightly off topic ( PCB min spacings)
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Posts: 46,084
All,
I am in the process of laying out my first PCB (I am using the
Eagle light tool) for a Stamp based controller for a Halloween
display. This board will be done in the "garage" utilizing the press-
n-peel method and Ferric Chloride. I have seen claims of line widths
as small as 5mm but these MAY have been accomplished by someone with
a great deal more experience than I.
What would you recommend as the minimum line widths and spacing?
Any rules of thumb that I should be aware of for this technique?
Thanks for any and all suggestions or recommendations.
Phil
I am in the process of laying out my first PCB (I am using the
Eagle light tool) for a Stamp based controller for a Halloween
display. This board will be done in the "garage" utilizing the press-
n-peel method and Ferric Chloride. I have seen claims of line widths
as small as 5mm but these MAY have been accomplished by someone with
a great deal more experience than I.
What would you recommend as the minimum line widths and spacing?
Any rules of thumb that I should be aware of for this technique?
Thanks for any and all suggestions or recommendations.
Phil
Comments
> Eagle light tool) for a Stamp based controller for a Halloween
> display. This board will be done in the "garage" utilizing the press-
> n-peel method and Ferric Chloride. I have seen claims of line widths
> as small as 5mm but these MAY have been accomplished by someone with
> a great deal more experience than I.
Well, I am betting you mean 5 mils (5/1000 of an inch [noparse]:)[/noparse] ... 5mm is about
1/4 inch [noparse]:)[/noparse] ....
> What would you recommend as the minimum line widths and spacing?
If you were going with say APC circuits (which are cheaper than dirt almost
and we love them), they call out 8 mil tracks with a minimum spacing of 8
mils.
If your doing it in the garage, I would say if you can afford 20 mil tracks
and 20 mil spacing, I would do that ... it'll be MUCH more forgiving. I
don't know the minimums, but someone else can help with that .... it all
matters on how much time you etch.
Give APC (http://www.apcircuits.com/) a shot though, they have great prices
and they have an online calculator. If you add up the costs of etch, PCB,
and the amortized costs of the tank, heater, etc... it might just add up to
worth it.
Take care!
John
Minimum spacing between lands should be .012. Land widths of less than .015
are not recommended unless you have a high-speed etcher. Do-it-yourself
etching systems are usually slower and tend to undercut the lands, reducing
the effective width. It is also recommended that you avoid right angle turns
since the etchant will eat away at the corner and again reduce the effective
land width. A land width of .015 solder over copper will carry about 300mils.
Sid
is on the outside corner, not the inside. Thus "T" connections are
not discouraged. Is that correct?
Yes I did mean mils not mm. The problems of fingers not connected
to the brain sometimes. [noparse]:)[/noparse]
That brings up another questions....
What is the rule of thumb for selecting line width?
How do I determine the width of the Power and Ground traces.
What is the resistance (ohms per square) of 1oz/sqft copper?
Thanks again,
Phil
--- In basicstamps@y..., Newzed@a... wrote:
> Good morning, Phil
>
> Minimum spacing between lands should be .012. Land widths of less
than .015
> are not recommended unless you have a high-speed etcher. Do-it-
yourself
> etching systems are usually slower and tend to undercut the lands,
reducing
> the effective width. It is also recommended that you avoid right
angle turns
> since the etchant will eat away at the corner and again reduce the
effective
> land width. A land width of .015 solder over copper will carry
about 300mils.
>
> Sid
http://epcircuits.uniserve.com/ for a second opinion (or quote). They also
provide solder masks for a nominal charge on protos.
Dennis
Original Message
From: John Ledford [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qY6iexYdguYVIxza9zDIIfW4tw2dH5tZ51euQd2o86mpe2L8BPvbFOKO61tIQHVzeJnFDGDX5_kikKZpqfj4]john@k...[/url
Sent: Thursday, July 19, 2001 8:12 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Slightly off topic ( PCB min spacings)
> I am in the process of laying out my first PCB (I am using the
> Eagle light tool) for a Stamp based controller for a Halloween
> display. This board will be done in the "garage" utilizing the press-
> n-peel method and Ferric Chloride. I have seen claims of line widths
> as small as 5mm but these MAY have been accomplished by someone with
> a great deal more experience than I.
Well, I am betting you mean 5 mils (5/1000 of an inch [noparse]:)[/noparse] ... 5mm is about
1/4 inch [noparse]:)[/noparse] ....
> What would you recommend as the minimum line widths and spacing?
If you were going with say APC circuits (which are cheaper than dirt almost
and we love them), they call out 8 mil tracks with a minimum spacing of 8
mils.
If your doing it in the garage, I would say if you can afford 20 mil tracks
and 20 mil spacing, I would do that ... it'll be MUCH more forgiving. I
don't know the minimums, but someone else can help with that .... it all
matters on how much time you etch.
Give APC (http://www.apcircuits.com/) a shot though, they have great prices
and they have an online calculator. If you add up the costs of etch, PCB,
and the amortized costs of the tank, heater, etc... it might just add up to
worth it.
Take care!
John
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that it's OK for coarse work, and I'll only use it to prove out a very
speculative design. Even 20 mils is difficult: you must be sure that no part
of your set-up moves at all, and that you have a really good means of
registering one side to the other. Also, realize that there will be no
plated through holes for vias and other connections - you must make the
connection through the holes with a fine wire or similar.
Also try http://4pcb.com they are running a special - 2 board min, $33 per
w/ silk & mask.
Chris
>
Original Message
> From: Phil Keller [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=hB_cXQnHUAay_z3UMqiAZBZX4NxguD1Bt_t-w9mixyRgxGej9bfqN-asfy9duPFMvTbWUmgrEYk]philk@h...[/url
> Sent: Thursday, July 19, 2001 10:36 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Slightly off topic ( PCB min spacings)
>
>
> All,
>
> I am in the process of laying out my first PCB (I am using the
> Eagle light tool) for a Stamp based controller for a Halloween
> display. This board will be done in the "garage" utilizing the press-
> n-peel method and Ferric Chloride. I have seen claims of line widths
> as small as 5mm but these MAY have been accomplished by someone with
> a great deal more experience than I.
>
> What would you recommend as the minimum line widths and spacing?
>
> Any rules of thumb that I should be aware of for this technique?
>
> Thanks for any and all suggestions or recommendations.
>
> Phil
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
that once it is stuck to the copper if it looks ok it will generallly etch
ok. Also try useing the backing paper off a bunch of laser labels instead of
the dedicated film that can be purchased. ( its a lot cheaper ).
Also if the design doesnt look right just clean it off and reapply it.
Regards
Peter Rogers
Original Message
From: "Chris Loiacono (E-mail)" <chris01@t...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, July 20, 2001 5:26 AM
Subject: RE: [noparse][[/noparse]basicstamps] Slightly off topic ( PCB min spacings)
> I also tried press-n-peel, and was not thrilled with it. My conclusion is
> that it's OK for coarse work, and I'll only use it to prove out a very
> speculative design. Even 20 mils is difficult: you must be sure that no
part
> of your set-up moves at all, and that you have a really good means of
> registering one side to the other. Also, realize that there will be no
> plated through holes for vias and other connections - you must make the
> connection through the holes with a fine wire or similar.
>
> Also try http://4pcb.com they are running a special - 2 board min, $33 per
> w/ silk & mask.
>
> Chris
>
> >
Original Message
> > From: Phil Keller [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=evjILwIO0OCjgsVjS8sh0Mc9flPnsJiOH4F7yiivwZBo0wPdpwRaTa37C2qXFa4OTFzEdg]philk@h...[/url
> > Sent: Thursday, July 19, 2001 10:36 AM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Slightly off topic ( PCB min spacings)
> >
> >
> > All,
> >
> > I am in the process of laying out my first PCB (I am using the
> > Eagle light tool) for a Stamp based controller for a Halloween
> > display. This board will be done in the "garage" utilizing the press-
> > n-peel method and Ferric Chloride. I have seen claims of line widths
> > as small as 5mm but these MAY have been accomplished by someone with
> > a great deal more experience than I.
> >
> > What would you recommend as the minimum line widths and spacing?
> >
> > Any rules of thumb that I should be aware of for this technique?
> >
> > Thanks for any and all suggestions or recommendations.
> >
> > Phil
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
size traces to use for various applications.
http://www.expresspcb.com/ExpressPCBHtm/Tips.htm
Kerry
At 05:32 PM 7/19/2001 -0000, you wrote:
> Thanks for the suggestions. I assume that the right angle problem
>is on the outside corner, not the inside. Thus "T" connections are
>not discouraged. Is that correct?
>
> Yes I did mean mils not mm. The problems of fingers not connected
>to the brain sometimes. [noparse]:)[/noparse]
>
> That brings up another questions....
>
>What is the rule of thumb for selecting line width?
>How do I determine the width of the Power and Ground traces.
>What is the resistance (ohms per square) of 1oz/sqft copper?
>
> Thanks again,
>Phil
>
>--- In basicstamps@y..., Newzed@a... wrote:
>> Good morning, Phil
>>
>> Minimum spacing between lands should be .012. Land widths of less
>than .015
>> are not recommended unless you have a high-speed etcher. Do-it-
>yourself
>> etching systems are usually slower and tend to undercut the lands,
>reducing
>> the effective width. It is also recommended that you avoid right
>angle turns
>> since the etchant will eat away at the corner and again reduce the
>effective
>> land width. A land width of .015 solder over copper will carry
>about 300mils.
>>
>> Sid
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
Sincerely
Kerry
Admin@M...
WWW server hosting [url=Http://mntnweb.com]Http://mntnweb.com[/url]
Kerry Barlow
p.o. box 21
kirkwood ny
13795
> that it's OK for coarse work, and I'll only use it to prove out a very
I've used the copier toner transfer thing before. We ended up using copy
machines and found something very interesting ... that some machines do not
make a perfect 1 to 1 copy. While not really visible to the naked eye, we
found that if you held up the front and back pages to the light, that some
machines distorted the copy and in the scale of the boards, it was
disastarous. I rememeber running around all over town at 3am trying to find
copiers that were not messed up [noparse]:)[/noparse] .... it was an ...... interesting ...
night [noparse]:)[/noparse] ....
[noparse]:)[/noparse]
Take care!
John
>machines and found something very interesting ... that some machines do not
>make a perfect 1 to 1 copy. While not really visible to the naked eye, we
>found that if you held up the front and back pages to the light, that some
>machines distorted the copy and in the scale of the boards, it was
>disastarous. I rememeber running around all over town at 3am trying to find
>copiers that were not messed up [noparse]:)[/noparse] .... it was an ...... interesting ...
>night [noparse]:)[/noparse] ....
John,
Some PCB CAD programs let you independently set X and Y output scale. The
original Tango PCB (written by Protel) and later versions from Protel
(AutoTrax) and MicroCode Engineering (TraxMaker) probably all have this
feature. At least one of the DOS versions (EasyTrax?) is free...
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
> original Tango PCB (written by Protel) and later versions from Protel
> (AutoTrax) and MicroCode Engineering (TraxMaker) probably all have this
> feature. At least one of the DOS versions (EasyTrax?) is free...
Well, what I was referring to was some copiers would be doing fine and then
scrunch up part of the page ... i.e. a non linear copy [noparse]:)[/noparse] ... it wasn't a
scaling issue ...
Now I just use Ivex and AP circuits [noparse];)[/noparse] .... MUCH easier [noparse]:)[/noparse]
John