Homebrew PCBs

I've been using the laser printer method and ironing the transfers on 
to single sided boards with no problem.

But now I want to do a double sided board.

Does anyone have any suggestions for lining the sides up?

I'm lucky if I can get a single sided board to be square, normally 
things are slightly cocky.

"fredbutz" <fredbutz@...> writes:
> Does anyone have any suggestions for lining the sides up?

I recently did a double sided board.  Since I usually post-process my
cad files to include a border around the board (to hold the TT paper
down), I simply put a via in each corner of the border, with a 13 mil
hole in it.  This is the size of my smallest drill bit.  I pre-drilled
the blank pcb for those holes, and poked holes in the TT for those
also.  I used the drill bits themselves to align the TT with the PCB,
then taped it down.  I was off by less than 10 mil.  Not sure what
I'll try next.  Another option is to do two single sided boards and
glue them back to back after etching.

On 29-Apr-07, at 6:15 AM, fredbutz wrote:
>
> But now I want to do a double sided board.
>
> Does anyone have any suggestions for lining the sides up
>




	I used to make positive art work for both sides, align the two sides  
visually, tape the two together along two edges and go from there.  
Lately, I'm thinking about making each PC side independently on .031  
inch thick single sided and gluing the two cards together.
	The advantage is there is no need for artwork registration just  
before exposure. The artwork registration comes from the CAD program  
(Canvas�) in its layers.
	After assembly, the two PC cards are also held together by small  
rivets that act as plated through holes. There aren't many of these  
as the circuitry is mostly surface mount with some three pin  
regulators and grounds.
Terry M

[Non-text portions of this message have been removed]

Print both sides on a regular sheet of paper and hold them up to light 
to see how they register.  The registration on many lasers is pretty bad.

K Wolf wrote:

> Anyone having trouble with alignment due to expansion of the paper? Whenever
> I transfer the image onto my boards, its always much larger than when it
> comes out of the printer. I  assume that its due to the heat of the iron.
> Anyway, it seems to make dbl sided boards nearly impossible. Any suggestions
> on how to avoid this?
>
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Terry Mickelson
> Sent: Sunday, April 29, 2007 4:03 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Double sided boards
>
>
>

Anyone having trouble with alignment due to expansion of the paper? Whenever
I transfer the image onto my boards, its always much larger than when it
comes out of the printer. I  assume that its due to the heat of the iron.
Anyway, it seems to make dbl sided boards nearly impossible. Any suggestions
on how to avoid this?

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Terry Mickelson
Sent: Sunday, April 29, 2007 4:03 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Double sided boards


On 29-Apr-07, at 6:15 AM, fredbutz wrote:
>
> But now I want to do a double sided board.
>
> Does anyone have any suggestions for lining the sides up
>




    I used to make positive art work for both sides, align the two sides  
visually, tape the two together along two edges and go from there.  
Lately, I'm thinking about making each PC side independently on .031  
inch thick single sided and gluing the two cards together.
    The advantage is there is no need for artwork registration just  
before exposure. The artwork registration comes from the CAD program  
(CanvasT) in its layers.
    After assembly, the two PC cards are also held together by small  
rivets that act as plated through holes. There aren't many of these  
as the circuitry is mostly surface mount with some three pin  
regulators and grounds.
Terry M

[Non-text portions of this message have been removed]



Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

Here is what I do.

Make print on regular printer paper of the drill pattern
glue it to pc brd with fabric adhesive ( sewing shop )
drill the four corners with a small drill ( mounting holes )
I usually drill all my holes ( your choice )
remove paper and clean the brd.
make print of artwork top and bottom
place them back to back ( align carefully by looking thru the paper with a 
good light behind them.
put a pin thu one of the holes.I use a pin to mount a carnation in you 
lapel.It has a plastic ball on the end for easy handling.The corner holes 
should be close to the size of pin used.I place the artwork on rigid 
styrofoam it gives room for the pins to pass.Both top and bottom also the pc 
brd now have registration marks ( holes )
Pass the pin thru paper top side and thru the pcb and foam.After all the 
pins are in I use an iron just to tack toner paper to the brd. If the brd is 
small remove one pin.Flip brd and do the same.I fold a piece of printer 
paper in half ,place the brd in the fold and pass thru a laminator several 
times.Redrill corner holes for mounting to suit your hardware

                                    73 Bob

----- Original Message ----- 

From: "fredbutz" <fredbutz@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, April 29, 2007 9:15 AM
Subject: [Homebrew_PCBs] Double sided boards


> I've been using the laser printer method and ironing the transfers on
> to single sided boards with no problem.
>
> But now I want to do a double sided board.
>
> Does anyone have any suggestions for lining the sides up?
>
> I'm lucky if I can get a single sided board to be square, normally
> things are slightly cocky.
>
>
>
> Be sure to visit the group home and check for new Links, Files, and 
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>

On Sun, 29 Apr 2007 21:08:06 +0200, DJ Delorie <dj@...> wrote:

>
> I recently did a double sided board.  Since I usually post-process my
> cad files to include a border around the board (to hold the TT paper
> down), I simply put a via in each corner of the border, with a 13 mil
> hole in it.  This is the size of my smallest drill bit.  I pre-drilled
> the blank pcb for those holes, and poked holes in the TT for those
> also.  I used the drill bits themselves to align the TT with the PCB,
> then taped it down.  I was off by less than 10 mil.  Not sure what
> I'll try next.  Another option is to do two single sided boards and
> glue them back to back after etching.


leave one side of the paper longer so you can pinch the two sheets  
together while you insert the board between them (after aligning against a  
light). Use a folded carrier sheet (thin cardboard) to put them through  
the fuser.
The registration isn't great, but it's quick and OK for smaller boards.

ST

> fredbutz wrote:
>
> I've been using the laser printer method and
> ironing the transfers on to single sided
> boards with no problem.
> 
> But now I want to do a double sided board.
> 
> Does anyone have any suggestions for lining
> the sides up?
> 
> I'm lucky if I can get a single sided board
> to be square, normally things are slightly
> cocky.
>

Many many moons ago when I did punish myself
with toner transfer I did double sided as
such.

Transfer Toner to one side of board only
spray a good coat of varnish on back side
spray a good coat of varnish on the back side
    of the PCB as well (Sorry could not resist
    that joke)
Etch the first side
Remove varnish and toner
Drill 2 registration holes
Line up 2nd transfer paper with drill holes
apply heat/iron/laminator to transfer toner
Spray varnish on already etched side
Etch second side
Strip again

It's not fast but it got everything lined up
nice.

> On 29-Apr-07, at 6:15 AM, fredbutz wrote:
> >
> > But now I want to do a double sided board.
> >
> > Does anyone have any suggestions for lining the sides up
> >
> >
> Anyone having trouble with alignment due to expansion of the 
> paper? Whenever I transfer the image onto my boards, its 
> always much larger than when it comes out of the printer. I  
> assume that its due to the heat of the iron.
> Anyway, it seems to make dbl sided boards nearly impossible. 
> Any suggestions on how to avoid this?


Run the paper thru the laser a few times before printing the PCB image.  

Since it can be a bit hard to print a blank sheet, make a small text file,
(just a single word will do), and print that to the same page a few times.
Then print the PCB.

Movement is caused by water content.  When printing the paper dries out, so
it shrinks or warps a bit.

You need to use the paper straight away, before it starts absorbing water
from the air.  Don't forget to turn off the steam option on the iron too!
:)

Tony

I just drilled two holes for registration, removed burrs and applied the 
second side, etching both at once.

Andrew wrote:

>> fredbutz wrote:
>>
>> I've been using the laser printer method and
>> ironing the transfers on to single sided
>> boards with no problem.
>>
>> But now I want to do a double sided board.
>>
>> Does anyone have any suggestions for lining
>> the sides up?
>>
>> I'm lucky if I can get a single sided board
>> to be square, normally things are slightly
>> cocky.
>>
>>     
>
> Many many moons ago when I did punish myself
> with toner transfer I did double sided as
> such.
>
> Transfer Toner to one side of board only
> spray a good coat of varnish on back side
> spray a good coat of varnish on the back side
>     of the PCB as well (Sorry could not resist
>     that joke)
> Etch the first side
> Remove varnish and toner
> Drill 2 registration holes
> Line up 2nd transfer paper with drill holes
> apply heat/iron/laminator to transfer toner
> Spray varnish on already etched side
> Etch second side
> Strip again
>
> It's not fast but it got everything lined up
> nice.
>
>
>
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links
>
>
>
>

Thanks for the tip Tony- I'll give that a try next time
-K 

-----Original Message-----
From: ajsmith@...
To: Homebrew_PCBs@yahoogroups.com
Sent: Mon, 30 Apr 2007 5:21 AM
Subject: RE: [Homebrew_PCBs] Double sided boards


> On 29-Apr-07, at 6:15 AM, fredbutz wrote:
> >
> > But now I want to do a double sided board.
> >
> > Does anyone have any suggestions for lining the sides up
> >
> >
> Anyone having trouble with alignment due to expansion of the 
> paper? Whenever I transfer the image onto my boards, its 
> always much larger than when it comes out of the printer. I 
> assume that its due to the heat of the iron.
> Anyway, it seems to make dbl sided boards nearly impossible. 
> Any suggestions on how to avoid this?

Run the paper thru the laser a few times before printing the PCB image. 

Since it can be a bit hard to print a blank sheet, make a small text file,
(just a single word will do), and print that to the same page a few times.
Then print the PCB.

Movement is caused by water content. When printing the paper dries out, so
it shrinks or warps a bit.

You need to use the paper straight away, before it starts absorbing water
from the air. Don't forget to turn off the steam option on the iron too!
:)

Tony


 
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[Non-text portions of this message have been removed]