Homebrew PCBs

Hi
I tried to make my first PCB. It didnt work out. It was the ugliest PCB ever
made :-(

I used toner transfer method.

What I learnt.
1. Dont print the image too dark or else while using the electric press the
whole thing will spill.

Mistakes I made
1. The wholes I drilled were too big
2. The artwork contains the outlines of the IC and though they are seperated
in the image during toner transfer they overlapped I think because of extra
dark copies.

Questions
1. What is the drill bit size I should use?
2. What is the darkness level I should use?

Thanks
Regards
Gaurav


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

You *should* use the darkest setting your printer supports.  If the
toner spreads, you're probably melting it instead of just softening
it.  Try a lower heat setting.  You want the toner to stick to the
paper *without* melting.

For home-brew, I leave very little clearance around pins and such.
Maybe a few thou.  I use 13 thou drills for vias (unravel some 22
gauge stranded speaker wire), and usually 26 thou for pins (press
fit).  For regular pin/wire holes, 35 thou is the biggest I'll use
unless the pin requires bigger.

Don't include the component outlines.  Do those as a separate pass
after you etch, and just leave the toner on (black outlines).

On Sat, 19 Sep 2009 14:34:07 +0530, you wrote:

>Hi
>I tried to make my first PCB. It didnt work out. It was the ugliest PCB ever
>made :-(

No, that was one that I tried to make with electrical tape for resist,
many years ago.
>
>I used toner transfer method.
>
>What I learnt.
>1. Dont print the image too dark or else while using the electric press the
>whole thing will spill.
>

You want as much toner as possible, that becomes the resist.  But if
you press too hard, the image spreads.  It can also smear if the paper
moves.

>Mistakes I made
>1. The wholes I drilled were too big

I use 0.030 inch for IC pads, a #70 drill for component leads, and
drills as close to the lead size (but a bit larger) as I can get.  I
try to make sure that the pads are at least 0.050 to 0.066 inches for
home built boards, it gives me extra soldering surfaces for the parts.

I use carbide drills, but they must be used in a drill press.
 

>2. The artwork contains the outlines of the IC and though they are seperated
>in the image during toner transfer they overlapped I think because of extra
>dark copies.

I use EAGLE, and in that, you want to print the dimension (board
outline), BOTTOM, PADS and any VIAS.  That's all you need to print.
What you want is only the traces, pads, and an outline to cut the
board.  VIAS are used for double sided boards only.

The outlines, part values, and so on belong on what's called the "silk
screen layer", which is printed on the board after the board is made.

I also use the flood/fill capability of EAGLE.  I generally make a
polygon that's the size of the board, label it GND, and set the
minimum offset to 0.024 inches.  This gives me a ground plane on the
board, enough room that the traces do not short together, and cuts
etching use.  It also makes some of the circuits more stable because
of the ground plane.

If you don't use EAGLE, then that's something you'll have to look at
in your own program.  Some examples are at www.dragonworks.info in the
section on PC board building (electronics).

Harvey

>
>Questions
>1. What is the drill bit size I should use?
>2. What is the darkness level I should use?
>
>Thanks
>Regards
>Gaurav
>
>
>[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_PCBsYahoo! Groups Links
>
>
>

Hi Thanks a ton everyone, I will retry an attempt probably tomorrow or next
week depends if the shops are open on sunday... I am most grateful for all
the help


On Sat, Sep 19, 2009 at 8:36 PM, dave_mucha <dave_mucha@...> wrote:

>
>
> check e-bay for carbide PCB drills.
>
> you absolutly MUST use a drill press with carbide pcb drills. they are
> fragile.
>
> I use 0.02" for resistors and such.
>
> 0.04" for T-220 packages and dip chips.
>
> If you need to do a large DIP chip of 14 or more pins, considder getting a
> machined carrier and drilling out the holes.. you can drill your first two
> holes on the pcb, place your carrier over it and use paper clip wire to
> align it.
>
> I highly recomend you make a custom pad. tiny hole, large ring. when you
> etch, the hole should be small. it will help keep your drill more in the
> center.
>
> dremel makes a nice drill press for your dremel, btw.
>
> Dave
>
> --- In Electronics_101@yahoogroups.com <Electronics_101%40yahoogroups.com>,
> "leon Heller" <leon355@...> wrote:
> >
> > ----- Original Message -----
>  > From: "Gaurav Verma" <gaurav.verma.mca@...>
> > To: <Electronics_101@yahoogroups.com <Electronics_101%40yahoogroups.com>>;
> <Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com>>
> > Sent: Saturday, September 19, 2009 10:04 AM
> > Subject: [Electronics_101] First PCB made, attempt = unsuccesful, some
> > leasons learnt some questions
> >
> >
> > > Hi
> > > I tried to make my first PCB. It didnt work out. It was the ugliest PCB
>
> > > ever
> > > made :-(
> > >
> > > I used toner transfer method.
> > >
> > > What I learnt.
> > > 1. Dont print the image too dark or else while using the electric press
>
> > > the
> > > whole thing will spill.
> > >
> > > Mistakes I made
> > > 1. The wholes I drilled were too big
> > > 2. The artwork contains the outlines of the IC and though they are
> > > seperated
> > > in the image during toner transfer they overlapped I think because of
> > > extra
> > > dark copies.
> > >
> > > Questions
> > > 1. What is the drill bit size I should use?
> > > 2. What is the darkness level I should use?
> >
> > Your PCB program should tell you the correct drill size for the various
> > holes. I use 0.7 mm and 1.0 mm most of the time.
> >
> > Leon
> >
>
>  
>



 --
Gaurav Verma
Email - Gaurav.Verma.MCA@...
Phone - 9910732960



-- 
Gaurav Verma
Email - Gaurav.Verma.MCA@...
Phone - 9910732960


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