# hobby double sided pcb's

S

#### samiam

Jan 1, 1970
0
Just throwing this idea out there - I am actually going to try it this
week for a double sided LAYOUT

1. print 4 images on the laser printer
image 1=component side mirror
image 2=solder side
image 3=copper pour of the length of the board
image 4=copper pour of the length of the board

2. clean the double sided blank pcb
3. use image 1 on one side and image 3 on the other side
4. etch the board
***
the result is that the component side is etched but the copper on the
solder side is untouched
5. drill out ALL HOLES
6. use image 2 on the blank side and image 4 on the etched component
side
7. etch the board
***
the result is that the solder side is etched but the copper side (
prviously etched but now covered with etch resist) is untouched

VIOLA
double sided board - at the cost of more toner

Registeration should be near perfect as the suffering through
"eyeballing" the images is dispensed with

A various of the above involves building the two sides on two single
sided .032 or .024 boards and glueing them together ... I might try
that in the future

S

#### samiam

Jan 1, 1970
0
Actually I found a post on the yahoo homebrew_pcb group and on google
that suggested using either of the following to coat the other side

nail polish
lacquer
or
varnish

And the last two come in spray bottles which should make coating much
easier

R

#### RST Engineering $$jw$$

Jan 1, 1970
0
Print two images, red side and blue side (call them component and solder,
top and bottom, whatever you want).

Lay down red side on one side of the pc board substrate using iron-on or
photo process, whichever you prefer.

Spray paint color of your choice on the other side.

Etch.

Remove spray paint with paint thinner.

Drill two holes through red side pads.

Pierce blue side artwork same two holes.

Run small wires through red side pads and blue side artwork holes
(registration).

Lay down blue side art on the pc board substrate.

Spray paint red side traces.

Etch.

Remove paint with paint thinner.

Clean board.

Jim

J

#### JeffM

Jan 1, 1970
0
samiam said:
I am actually going to try it this week for a double sided LAYOUT
[Homebrew 4-layer PCBs]
RST said:
Spray paint color of your choice on the other side.
Etch.
Remove spray paint with paint thinner.
I'm missing something here. Why is paint necessary at all?
Drill two holes through red side pads.
Pierce blue side artwork same two holes.
Run small wires through red side pads and blue side artwork holes
(registration).
If you do this when you iron on the 2nd side of each board,
paint is not necessary and everything can be etched in 1 go.

S

#### samiam

Jan 1, 1970
0
I'm missing something here. Why is paint necessary at all?

Its a pain in the ass trying to align the holes without doing them
one at a time
If you do this when you iron on the 2nd side of each board,
paint is not necessary and everything can be etched in 1 go.

Yes but getting the holes to register is much more difficult with
this method. Its really better to do them one side at a time

J

#### JeffM

Jan 1, 1970
0
RST Engineering (jw) wrote:
::rill two holes
samiam said:
Yes but getting the holes to register is much more difficult with
this method. Its really better to do them one side at a time

After ironing-on the 1st side,
I drilled out 1 hole each near opposite corners of the board
and stuck a straight pin thru each hole.
I never had the slighted problem getting the 2nd layer registered.

....and registration-wise,
I still don't see how putting on and taking off paint changes
anything.
..
..
It would be nice if you left in the attribution in your blockquotes.

D

#### DJ Delorie

Jan 1, 1970
0
JeffM said:
I still don't see how putting on and taking off paint changes
anything.

You put on the paint so you can etch the first side separately from
the second. That way, the drilling and handling doesn't mess up the
first side. Iron and etch ONE side, drill and align, iron and etch
SECOND side.

C

#### [email protected]

Jan 1, 1970
0
If you have a double sided UV source it is a lot easier to do it
photographically. Take your plots of both sides and line them up on
top of each other. Stick them together round three edges to make an
envelope, put pcb in envelope and expose to UV. Others have suggested
sunlight works better than a UV source so this may work for you.

Colin

M

#### Marra

Jan 1, 1970
0
If you have a double sided UV source it is a lot easier to do it
photographically. Take your plots of both sides and line them up on
top of each other. Stick them together round three edges to make an
envelope, put pcb in envelope and expose to UV. Others have suggested
sunlight works better than a UV source so this may work for you.

Colin

By the time you have bought all the chemicals, copper clad board etc.
Then still failed.

It would have been cheaper and less traumatic to get someone to make
it for you.

D

#### DJ Delorie

Jan 1, 1970
0
Marra said:
By the time you have bought all the chemicals, copper clad board
etc. Then still failed.

Why the defeatist attitude?
It would have been cheaper and less traumatic to get someone to make
it for you.

We've had this discussion before. There are many valid reasons,
including cost, for making your own pcbs. It's not *always* the right
thing to do, but sometimes it is.

J

#### JeffM

Jan 1, 1970
0
Marra said:
By the time you have bought all the chemicals, copper clad board etc.
Then still failed.
Even if you DO fail the 1st time, you have a greater appreciation of
ways to get the pros to get your boards back to you more quickly.
(Fewer mistakes/questions == Faster turnaround)
It would have been cheaper and less traumatic
to get someone to make it for you.
Maybe. Depends on what parameters count most to you
and how you weight your time:

DIY PCBs == Protos *NOW* -- Tim Auton

Good technique + cheap materials == Useful PCBs -- slebetman, DJ

If the boards are going to stay in-house, DIY could be just the
ticket.
..
..
...ckp-railways...

M

#### Marra

Jan 1, 1970
0
I have been in electronics for 25-30 years and have never been
impressed with amateur PCB's.

If we show a customer a PCB it has to look the business.

I think it requires quite a bit of skill to produce PCB's at home.
Even the drilling requires a high level of dexterity to ensure the
holes at least line up fairly well.

Over etching/ under etching both cause problems.

One problem I had was uneven etching, where one side of the board was
over etched and the other side under etched !

I have seen the professionals get it seriously wrong so I dont expect
much from an amateur.

I once got a PCB back and it was all copper but it had the holes in
the right place.
Some idiot had input a wrong size into the system at the pcb
manufacturers end.
At least we got it redone free of charge.

D

#### DJ Delorie

Jan 1, 1970
0
Marra said:
I have been in electronics for 25-30 years and have never been
impressed with amateur PCB's.

I don't expect mine to be impressive, just quick and functional.
If we show a customer a PCB it has to look the business.

I hope you put as much effort into your grammar.
One problem I had was uneven etching, where one side of the board was
over etched and the other side under etched !

I use a sponge to etch, so I can control over/under etching fairly
well. At least, well enough for my unimpressive boards.

R

#### RST Engineering $$jw$$

Jan 1, 1970
0
Amateurs built the Ark; professionals built the Titanic.

Jim

J

Jan 1, 1970
0
Marra said:
I have been in electronics for 25-30 years and have never been
impressed with amateur PCB's.

You probably don't get out much then. I've seem homebrew PCBs that
looked as good as what you get off of a $40k LPKF-type machine, for instance. If we show a customer a PCB it has to look the business. For a final PCB, sure, but personally I'd be a little wary of any company that *didn't* have a bunch of cut boards or "ugly construction"-style boards around that they did various tests/development on. It tends to vary with the compleixty of design, of course -- with digital boards there's often no need for a prototype. I think it requires quite a bit of skill to produce PCB's at home. Even the drilling requires a high level of dexterity to ensure the holes at least line up fairly well. Sure, it does, and for those in the U.S. getting PCBs made commercially is cheap enough that it's difficult to argue that it's worthwhile to make your own unless you simply enjoy doing it. For many people outside the U.S., even something like US$39 is still expensive enough that most hobbyists have
no choice but to make their own.

M

#### Matthew Kendall

Jan 1, 1970
0
samiam said:
Just throwing this idea out there - I am actually going to try it
this week for a double sided LAYOUT

1. print 4 images on the laser printer
image 1=component side mirror
image 2=solder side
image 3=copper pour of the length of the board
image 4=copper pour of the length of the board
<snip>

You can eliminate 3 and 4 if you are careful.

Many years ago in my youth I made double sided boards one at home one side
at a time as you describe by floating the board on the surface of the
etchant. Ferric chloride has quite a high surface tension and it if fairly
easy to float the board on top of it. It is even possible to agitate it a
bit if you are careful. If it sinks, no matter so long as you fish it out
again quickly.

M

#### Matthew Kendall

Jan 1, 1970
0
samiam said:
Just throwing this idea out there - I am actually going to try it
this week for a double sided LAYOUT

1. print 4 images on the laser printer
image 1=component side mirror
image 2=solder side
image 3=copper pour of the length of the board
image 4=copper pour of the length of the board
<snip>

You can eliminate 3 and 4 if you are careful.

Many years ago in my youth I made double sided boards one at home one side
at a time as you describe by floating the board on the surface of the
etchant. Ferric chloride has quite a high surface tension and it if fairly
easy to float the board on top of it. It is even possible to agitate it a
bit if you are careful. If it sinks, no matter so long as you fish it out
again quickly.

S

#### samiam

Jan 1, 1970
0
It would have been cheaper and less traumatic to get someone to make
it for you.

And this ladies and gentlemen is the reason our country is in decline
manufacturingwize.

This notion that: SOMEONE ELSE should always do it for you: CHEAPER

I need prototypes so sending them out at $100 a pop for a 4x6 double sided boarded is a waste of money. As for gathering the chemicals and tools - I ALREADY have that from earlier projects and with the exception of FECL and bare copper- its all a one time investment S #### Spehro Pefhany Jan 1, 1970 0 And this ladies and gentlemen is the reason our country is in decline manufacturingwize. More like steady, unless you have an overwhelming interest in employment rather than production. This notion that: SOMEONE ELSE should always do it for you: CHEAPER I need prototypes so sending them out at$100 a pop for a 4x6 double
sided boarded is a waste of money.

Only if your overall time is worth less. Their productivity and
quality is bound to be higher. Hobbyists can count their time at $0/hr (or perhaps they would pay for have such fun) but the rest of us need to use a higher (positive) number. You may lose out on the learning of how to make boards, but you will learn how to create usable Gerber files and drill files. As for gathering the chemicals and tools - I ALREADY have that from earlier projects and with the exception of FECL and bare copper- its all a one time investment And will you dispose of the chemicals responsibly when they are spent? That's typically a significant cost for businesses that produce prototypes. Best regards, Spehro Pefhany S #### samiam Jan 1, 1970 0 And will you dispose of the chemicals responsibly when they are spent? Absolutely. I pour it into a plastic bottle and seal the cap. Then write FeCL and hazardous on the side. I take it to either the waste disposal plant in the next village or to the local repair shop. They know what it is and charge$3 to dispose
of it.

Trust me they know what it is and its not mixed with other liquid waste
they have to dispose of. Its one trip to the waste disposal/threatment
plant for them.

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