Homebrew PCBs

I just wanted to share my recent success and lessons learned.  I need
to make my first PCB which takes a passive RFID reader IC and
integrates it  with a PIC, MAX232 and several LEDs and required
components.

Using Eagle for my design, I layed out my schematic and then went
about making the PCB.

First lesson learned...Some ICs aren't designed for single sided
boards...like the MAX232 for example...Pins 1 and 3 connect together
with a capacitor and pin 2 needs to go to another cap and then to VCC.
 In a future design, I might switch to another MAX chip that has the
caps built in...the IC might be a little more expensive, but you will
save money in the caps and pain of double sided board.

After finding a decent layout, I realized that needed to go 2 sided as
I had about 4 traces that I couldn't route on one side and 2 of those
I couldn't even jumper easily.  So I routed those traces on the front
side...not a big worry as the clad board I am using is 2 sided anyways.

Sooo...I went out and go the Staples Photo Basic paper as everyone
says that is the best (even though I have some hammermill glossy
sitting here, but it isn't the stuff that everyone says you should
use).  Came home and started printing...well my toner cartridge was
low/old as this printer had been sitting in the closet for about 6
months...so back to staples for some "FRESH" toner.  Printed out my
design and looks great.

The transfer went pretty smooth...except:

Lesson 2...Don't forget to clean the board.  Well I did forget so I
had to clean it all off and start over.  2nd time, I don't think I
even cleaned it enough...next time it is getting the FULL treatment.

Etching was pretty simple, I did use Ferric Chloride as I wanted
something simple for my first try, but will probably switch to the
Muriatic/Peroxid cocktail later.

Drilling was pretty smooth, used a drywall screw and hammer to tap an
indention where the hole was to be drilled and a 1/32 drill bit to
drill it out with my dremel.

Assembly...here's where I learned lesson #3...double sided boards
without through plating are a pain to solder.  I had to apply solder
to the lead between the component and the pad, keep it hot and then
push the component down to seat nicely.  I have now reworked my design
and put an extra VIA and small bottom side trace near the component so
i can just solder a wire (using cut off leads) through the board to
pass the signal.

Anyways...hopefully someone will learn something from this post.  I
have been looking at doing boards like this for years, but this is my
first try.  I couldn't have done it without the information on this
list and a few other places on the Internet.

Regards,
Curtis

--- In Homebrew_PCBs@yahoogroups.com, "Curtis Pope" <popecurtis@...> 
wrote:
>
> I just wanted to share my recent success and lessons learned.  I 
need
> to make my first PCB which takes a passive RFID reader IC and
> integrates it  with a PIC, MAX232 and several LEDs and required
> components.
> 
<snip> 
> 
> Drilling was pretty smooth, used a drywall screw and hammer to tap 
>an
> indention where the hole was to be drilled and a 1/32 drill bit to
> drill it out with my dremel.
>

It's even easier if Eagle has a print option to draw the pads with an 
open center. The exposed PCB material in the middle of the pad gives 
the drill an easy place to start. Many CAD packages have this option 
but I'm not sure if Eagle does.


> Assembly...here's where I learned lesson #3...double sided boards
> without through plating are a pain to solder.  I had to apply solder
> to the lead between the component and the pad, keep it hot and then
> push the component down to seat nicely.  I have now reworked my 
>design
> and put an extra VIA and small bottom side trace near the component 
>so
> i can just solder a wire (using cut off leads) through the board to
> pass the signal.
> 

I've always found it easier to install through-hole components before 
soldering and bend the leads over the pads on the bottom side of the 
board. Depending on the layout, many of the components will only 
require bottom-side soldering. Once the bottom side has been 
soldered, though, the top can be done if you need to.


Vias on non-plated boards can be done pretty easily by threading a 
length of stripped wire-wrap wire through all of the vias from one 
side of the board to the other. Once all of the vias have been 
threaded, they can then be soldered on both the top and bottom sides 
of the board. After soldering, you would trim the wires connecting 
them with an Exacto knife. (You may want to use a larger diameter 
wire or cut-off component leads for any tracks carrying significant 
current.)


Regards, Bob

Curtis- Did you encounter any issues with the paper expanding/shrinking during transfer? I have never successfully completed a dbl-sided board due to this issue- The printout always looks great, but after ironing, the image shrinks/expands. I use the staples paper as well.
 
Thanks for sharing with us.
-k 

-----Original Message-----
From: popecurtis@...
To: Homebrew_PCBs@yahoogroups.com
Sent: Thu, 17 May 2007 7:49 AM
Subject: [Homebrew_PCBs] Sharing my success and lessons learned


I just wanted to share my recent success and lessons learned. I need
to make my first PCB which takes a passive RFID reader IC and
integrates it with a PIC, MAX232 and several LEDs and required
components.

Using Eagle for my design, I layed out my schematic and then went
about making the PCB.

First lesson learned...Some ICs aren't designed for single sided
boards...like the MAX232 for example...Pins 1 and 3 connect together
with a capacitor and pin 2 needs to go to another cap and then to VCC.
In a future design, I might switch to another MAX chip that has the
caps built in...the IC might be a little more expensive, but you will
save money in the caps and pain of double sided board.

After finding a decent layout, I realized that needed to go 2 sided as
I had about 4 traces that I couldn't route on one side and 2 of those
I couldn't even jumper easily. So I routed those traces on the front
side...not a big worry as the clad board I am using is 2 sided anyways.

Sooo...I went out and go the Staples Photo Basic paper as everyone
says that is the best (even though I have some hammermill glossy
sitting here, but it isn't the stuff that everyone says you should
use). Came home and started printing...well my toner cartridge was
low/old as this printer had been sitting in the closet for about 6
months...so back to staples for some "FRESH" toner. Printed out my
design and looks great.

The transfer went pretty smooth...except:

Lesson 2...Don't forget to clean the board. Well I did forget so I
had to clean it all off and start over. 2nd time, I don't think I
even cleaned it enough...next time it is getting the FULL treatment.

Etching was pretty simple, I did use Ferric Chloride as I wanted
something simple for my first try, but will probably switch to the
Muriatic/Peroxid cocktail later.

Drilling was pretty smooth, used a drywall screw and hammer to tap an
indention where the hole was to be drilled and a 1/32 drill bit to
drill it out with my dremel.

Assembly...here's where I learned lesson #3...double sided boards
without through plating are a pain to solder. I had to apply solder
to the lead between the component and the pad, keep it hot and then
push the component down to seat nicely. I have now reworked my design
and put an extra VIA and small bottom side trace near the component so
i can just solder a wire (using cut off leads) through the board to
pass the signal.

Anyways...hopefully someone will learn something from this post. I
have been looking at doing boards like this for years, but this is my
first try. I couldn't have done it without the information on this
list and a few other places on the Internet.

Regards,
Curtis


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

I have used Staples Basic Photo paper and I did not encounter any 
problems of shrinkage/expanding. I did get some wavy lines, so now I 
only use straight down pressure. The only real problem with Staples 
paper is removing it from PCB, needs to soak and peeling off those 
layers is tricky. I would take me 30-45 minutes. The Hammermill 
Office One Business Gloss is much easier to remove( 1 -2 minutes).
Izzo

--- In Homebrew_PCBs@yahoogroups.com, kevinmwolf@... wrote:
>
> Curtis- Did you encounter any issues with the paper 
expanding/shrinking during transfer? I have never successfully 
completed a dbl-sided board due to this issue- The printout always 
looks great, but after ironing, the image shrinks/expands. I use the 
staples paper as well.

>  
> Thanks for sharing with us.
> -k 
>  
> -----Original Message-----
> From: popecurtis@...
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Thu, 17 May 2007 7:49 AM
> Subject: [Homebrew_PCBs] Sharing my success and lessons learned
> 
> 
> SNIP <<<<<

Did you drill by hand or CNC? If you are drilling by hand the distortion 
isn't enough to notice. On, say a 40 pin DIL the error is small enough 
to be mistaken for drilling errors. If you are drilling with CNC the 
distortion becomes a problem. If the holes line up perfectly one end of 
the board they may miss the pads entirely the other end of the board.

Les

Ben wrote:

> I have used Staples Basic Photo paper and I did not encounter any 
> problems of shrinkage/expanding. I did get some wavy lines, so now I 
> only use straight down pressure. The only real problem with Staples 
> paper is removing it from PCB, needs to soak and peeling off those 
> layers is tricky. I would take me 30-45 minutes. The Hammermill 
> Office One Business Gloss is much easier to remove( 1 -2 minutes).
> Izzo
>

Manual / Dremel drill press. I do small boards 5x6 is the largest so 
far, and no more then 9 IC's. And with these old eyes that will be it.
Thanks for the info.
Izzo

--- In Homebrew_PCBs@yahoogroups.com, Leslie Newell <lesnewell@...> 
wrote:
>
> Did you drill by hand or CNC? If you are drilling by hand the 
distortion 
> isn't enough to notice. On, say a 40 pin DIL the error is small 
enough 
> to be mistaken for drilling errors. If you are drilling with CNC 
the 
> distortion becomes a problem. If the holes line up perfectly one 
end of 
> the board they may miss the pads entirely the other end of the 
board.
> 
> Les
> 
> Ben wrote:
> > I have used Staples Basic Photo paper and I did not encounter any 
> > problems of shrinkage/expanding. I did get some wavy lines, so 
now I 
> > only use straight down pressure. The only real problem with 
Staples 
> > paper is removing it from PCB, needs to soak and peeling off 
those 

> > layers is tricky. I would take me 30-45 minutes. The Hammermill 
> > Office One Business Gloss is much easier to remove( 1 -2 minutes).
> > Izzo
> >
>