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Today's home-fab thoughts

2009-12-01 by DJ Delorie

http://www.delorie.com/electronics/rx/rx-adapters-blank.html

Did a few things differently, got good results, so it's share time...

This is an 8/8 DS project, 13 mil vias, 38 mil header holes. UV film,
CuCl etch.

What I did differently:

I wet laminated the film - I did dry last time, but that's really only
efficient for larger boards where the extra film you need (to hold
onto it as it's laminated) is worth wasting. This project used up
some 2"x3" scraps. I used the old technique - film on some
transparency sheets, wet sand the copper, rinse everything and stick
together. Squeezed out the water with my thumb, did both sides that
way. Used hot water so the film sticks OK. I'm thinking that film is
better on small boards because it's easier to get the bubbles out.

New trick: run the result through the laminator at 200F (94C) - BELOW
the boiling point of water. No new bubbles! I wonder if remaining
water was forming steam bubbles. The temperature control hack for my
laminator is really coming in handy!

New etch technique: This was a small board, so I unplugged the air
pump in the etch tank and just swirled the board around by hand,
mostly moving perpendicular to the board's surface. I think this
simulates the flow of a spray tank. I did seem to get a faster and
more consistent etch - it took about 4 minutes or so.

Observation: my post-processing scripts increase the copper size a mil
or so to compensate for my process, but this time the copper ended up
a little bigger than planned and I had two tiny shorts - I could have
etched for another minute or so.

Also, this is my first board since updating my scanner. The new
scanner does 4800 DPI. Here's a 2400 DPI scan of one of the boards:
http://www.delorie.com/electronics/rx/scanned-closeup.html (this is
the one with the two shorts, which you can easily find in this photo)

I also discovered that Liquid Tin won't last forever in the tray (even
covered) but does seem to last forever in the original bottles. I
wonder if just adding more water will re-constitute it?

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-01 by Erik Knise

Those boards look very nice. Great job. What are the advantages and
disadvantages of uv film verses toner transfer? Is it more about the
process one does each or is one much better for certain kinds of boards?

I bought a laminator, a laser printer, and hp presentation paper a few
months ago. I'm still working on my design and I still need to purchase
toner, pcb's, and etching stuff. I'm holding off buying the rest of the
stuff until I have a board that I really need to make. For now I've been
able to do all of my stuff on a solderless breadboard.

The girls I work with at my office like the presentation paper and the
laminator for making signs. At least it's getting used.

--
Erik L. Knise
Pacific Shipping Company
Seattle, WA

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

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-01 by DJ Delorie

Erik Knise <elknise@...> writes:

> What are the advantages and disadvantages of uv film verses toner
> transfer?

I've found that I can do much smaller traces with UV (5 mil vs 8 for
TT) and the results are more reliable, but the process is more
involved (at least, the first time - there's more "stuff" to buy to
get started). Plus, you have to have a place to buy the film in small
quantities that isn't hugely expensive.

For TT: You need a good enough laser printer, and paper that will (1)
print cleanly and (2) release cleanly. You have to be meticulous
about cleaning the board or the toner won't stick. Small details are
hard to get, and the toner lets pinhole leaks get through. You need a
solvent to remove the toner after etching. Lamination requires a hot
(350F) temperature to get good adhesion.

For UV: You need a source for the film, a UV exposure setup, developer
and stripper chemicals (neither is nasty and they're reusable). You
need an inkjet that can print a solid black reliably, and coated
transparent "paper" on which the ink dries super fast (else the ink
smears before it can dry). Cleaning the pcb isn't as critical, but
laminating the film is - no dust, no air bubbles. Lamination requires
a cool (200-240F) temperature to avoid melting the film.

Etching is pretty much the same for either technique.

I haven't tried press-n-peel TT paper yet. If it performs as
advertised, it would be a much faster way to do thick-trace boards:
laser print on PnP, laminate, peel, etch, strip. For UV, it's print
(takes a while), laminate film, expose, wait, develop, etch, strip.

UV is easier with two-sided boards, because you can see through the
film to align it with pre-drilled holes. I have special registration
footprints I add to my boards that print as black crosshairs on a
transparent square, just for alignment.

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-01 by Dylan Smith

I'm neither particularly meticulous, nor do I use solvents :-)

I've found fine grit wet and dry paper and normal detergent (for
dishes) cleans the copper perfectly, and leaves a surface to which the
toner adheres very well.

For taking off the toner after etching, exactly the same process - I
just scrub the toner off with the same bit of wet and dry and soapy
water that I used to clean the board.

Pinholes can still be a problem, I've found it depends a lot on the
paper (some paper seems terrible for it, with others there's hardly a
problem), and 8/8 is as low as I tend to want to go (10/10 is an order
of magnitude easier to do than 8/8, I find. But then again, I do use a
clothes iron to transfer the toner).

El 01-dic-09, a las 21:34, DJ Delorie escribió:

Show quoted textHide quoted text

> For TT: You need a good enough laser printer, and paper that will (1)
> print cleanly and (2) release cleanly. You have to be meticulous
> about cleaning the board or the toner won't stick. Small details are
> hard to get, and the toner lets pinhole leaks get through. You need a
> solvent to remove the toner after etching. Lamination requires a hot
> (350F) temperature to get good adhesion.

Re: Today's home-fab thoughts

2009-12-01 by Dave

Hi All

I use TT. My paper is semi-gloss photo paper which has proved much easier to remove than the gloss I used when I first tried it =D I hacked a texet laminator by fitting a cloths iron thermostat as a replacement for it's original unit.

I get my prints done at a local printers and I clean my copper with a kitchen sponge and detergent. Then fine wire wool then a final clean.

I have made a bubble etch tank up as well which works quite well but needs a little work to maximise it's efficiency.

results are excellent the majority of my traces are sharp and crisp and I even have parts as close as 0.5mm. I have made around 40 PCB's this year with it and only had very few minor problems that needed an etch resist pen.

For quick prototyping or a one off it's great.

regards

Fenris

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, Dylan Smith <dyls@...> wrote:
>
> I'm neither particularly meticulous, nor do I use solvents :-)
>
> I've found fine grit wet and dry paper and normal detergent (for
> dishes) cleans the copper perfectly, and leaves a surface to which the
> toner adheres very well.
>
> For taking off the toner after etching, exactly the same process - I
> just scrub the toner off with the same bit of wet and dry and soapy
> water that I used to clean the board.
>
> Pinholes can still be a problem, I've found it depends a lot on the
> paper (some paper seems terrible for it, with others there's hardly a
> problem), and 8/8 is as low as I tend to want to go (10/10 is an order
> of magnitude easier to do than 8/8, I find. But then again, I do use a
> clothes iron to transfer the toner).
>
> El 01-dic-09, a las 21:34, DJ Delorie escribiï¿½:
> > For TT: You need a good enough laser printer, and paper that will (1)
> > print cleanly and (2) release cleanly. You have to be meticulous
> > about cleaning the board or the toner won't stick. Small details are
> > hard to get, and the toner lets pinhole leaks get through. You need a
> > solvent to remove the toner after etching. Lamination requires a hot
> > (350F) temperature to get good adhesion.
>

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-01 by Simao Cardoso

DJ Delorie wrote:

>
> New trick: run the result through the laminator at 200F (94C) - BELOW
> the boiling point of water. No new bubbles! I wonder if remaining
> water was forming steam bubbles. The temperature control hack for my
> laminator is really coming in handy!

I thought running the dry film through the laminator after hot water
lamination will over cure it, but your are the second person here that
says to do it. If it works that's fantastic because spread hot water not
always make all board surface at enough temperature.

> I also discovered that Liquid Tin won't last forever in the tray (even
> covered) but does seem to last forever in the original bottles. I
> wonder if just adding more water will re-constitute it?
>
>
>

Not that I am an expert or know much about chemistry. But immersion tin
is a mix like one of the tin electro plating chemistries with thioreia
added. In your case is the fluoroburate mix. Most tin plating
chemistries have the tin(iv) deposition problem in contact with air or
light, which should be your white deposit problem too. So tin
concentration is much lower than required to work. I think sulfonate mix
last even longer than yours but only used sulfuric based which last less
than one month. Is better keep in dark closed bottle full, no air
inside. If you wish to add something to keep it working is tin salt. In
your case stannous fluoroburate. Or try pure tin bars on it with
electric current, but i don't know how thioreia in there will end after
the electrolysis ( but thioreia is also an addictive for at least the
electroplating of copper so...).

>
> I haven't tried press-n-peel TT paper yet. If it performs as
> advertised, it would be a much faster way to do thick-trace boards:
> laser print on PnP, laminate, peel, etch, strip. For UV, it's print
> (takes a while), laminate film, expose, wait, develop, etch, strip.
>
>

You have so much projects shared openly in your webpage, and are a so
valuable open source contributor to electronics tools. Check this:
http://www.techniks.com/free_pnp.htm
Almost 10 years ago, i got (don't really know how or why), 20 sheets
with oversea shipping (i am Portuguese) for free! And later bought
100sheets, some still last today.
Press n peel should make good results as those green sheets used after
toner transfer. But still is much about copper cleaning and printer.

RE: [Homebrew_PCBs] Re: Today's home-fab thoughts

2009-12-02 by piers@u-h-p.com

I would agree (based on a way too small sample size to actually be scientific) that it seems to be more important to slightly roughen the copper with an abrasive than to have it actually hospital clean.

My last board had 10 mil traces running under 0603 LEDs. I just gave it a sand and rinse and ironed. (and them proceeded to nick a trace with the drill for the mounting holes)

PG

---- Sent using a frigtarded app on a dumb phone. Please make allowances

-original message-
Subject: [Homebrew_PCBs] Re: Today's home-fab thoughts
From: "Dave" <thenephilim10@...>
Date: 02/12/2009 08:58

Hi All

I use TT. My paper is semi-gloss photo paper which has proved much easier to remove than the gloss I used when I first tried it =D I hacked a texet laminator by fitting a cloths iron thermostat as a replacement for it's original unit.

I get my prints done at a local printers and I clean my copper with a kitchen sponge and detergent. Then fine wire wool then a final clean.

I have made a bubble etch tank up as well which works quite well but needs a little work to maximise it's efficiency.

results are excellent the majority of my traces are sharp and crisp and I even have parts as close as 0.5mm. I have made around 40 PCB's this year with it and only had very few minor problems that needed an etch resist pen.

For quick prototyping or a one off it's great.

regards

Fenris

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, Dylan Smith <dyls@...> wrote:
>
> I'm neither particularly meticulous, nor do I use solvents :-)
>
> I've found fine grit wet and dry paper and normal detergent (for
> dishes) cleans the copper perfectly, and leaves a surface to which the
> toner adheres very well.
>
> For taking off the toner after etching, exactly the same process - I
> just scrub the toner off with the same bit of wet and dry and soapy
> water that I used to clean the board.
>
> Pinholes can still be a problem, I've found it depends a lot on the
> paper (some paper seems terrible for it, with others there's hardly a
> problem), and 8/8 is as low as I tend to want to go (10/10 is an order
> of magnitude easier to do than 8/8, I find. But then again, I do use a
> clothes iron to transfer the toner).
>
> El 01-dic-09, a las 21:34, DJ Delorie escribiï¿½:
> > For TT: You need a good enough laser printer, and paper that will (1)
> > print cleanly and (2) release cleanly. You have to be meticulous
> > about cleaning the board or the toner won't stick. Small details are
> > hard to get, and the toner lets pinhole leaks get through. You need a
> > solvent to remove the toner after etching. Lamination requires a hot
> > (350F) temperature to get good adhesion.
>

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-02 by DJ Delorie

Simao Cardoso <simaocardoso@...> writes:

> You have so much projects shared openly in your webpage, and are a so
> valuable open source contributor to electronics tools. Check this:
> http://www.techniks.com/free_pnp.htm

Sweet. My son is in the high school robotics club, maybe I'll make
him something and use that. However, the t-recs site appears to be
owned by someone else now :-(

Show quoted textHide quoted text

> Almost 10 years ago, i got (don't really know how or why), 20 sheets
> with oversea shipping (i am Portuguese) for free! And later bought
> 100sheets, some still last today. Press n peel should make good
> results as those green sheets used after toner transfer. But still
> is much about copper cleaning and printer.

Do you have to soak it at all? I mean, if it's just print, laminate,
peel, that would be a leap ahead of the regular TT process - no
soaking, no waiting, no green TRF step.

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-02 by Steve Woodford

On Wednesday 02 December 2009 04:35:24 DJ Delorie wrote:

[press-n-peel]

> Do you have to soak it at all? I mean, if it's just print, laminate,
> peel, that would be a leap ahead of the regular TT process - no
> soaking, no waiting, no green TRF step.

I've been using press-n-peel exclusively for the last couple of years
(tried magazine paper, inkjet paper, etc, without much luck).

It pretty much just falls off the copper once cooled, though a gentle
wipe with a sponge or soft toothbrush may be required to catch any
remaining bits of the backing layer. The instructions suggest using
sticky tape to remove the excess but I've not yet had to resort to
that.

Steve

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-02 by Simao Cardoso

DJ Delorie wrote:

>
> Sweet. My son is in the high school robotics club, maybe I'll make
> him something and use that. However, the t-recs site appears to be
> owned by someone else now :-(
>

Nothing sweet at all. Sorry your time loss, i just remember they had the
offer, search the address and posted it. I never done the process, and
for years that i didn't check their page.

Show quoted textHide quoted text

> Do you have to soak it at all? I mean, if it's just print, laminate,
> peel, that would be a leap ahead of the regular TT process - no
> soaking, no waiting, no green TRF step.

I soak it because i want to cool it fast, there is other type that only
peels under water, mines are dry type, but i use water to not wait so
much. The peel step is really really easy, fantastical easy. But i use
more inkjet photo paper because, preesnpeel sheet aren't that cheap, and
i prefer to use them when i have enough boards to fill all sheet to
justify the spending. Oversea shipment and customs get expensive and
this is only sold in Europe for 3eur each sheet plus shipment so i not
intend to buy pressnpeel ever again.
I never used those green sheets but i don't believe they do a better job
than pressnpeel, and seem hard work. I also never tried to make at home
tracks under 0.4mm (16mils), but letters are thin and end right. My
laziness never liked doing dryfilm at home but I am not too proud to
post pictures either. I just want to finish the machines to build boards
for me and only worry with the developing part.

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-02 by DJ Delorie

Simao Cardoso <simaocardoso@...> writes:

Show quoted textHide quoted text

> more inkjet photo paper because, preesnpeel sheet aren't that cheap,
> and i prefer to use them when i have enough boards to fill all sheet
> to justify the spending.

Tip from the Pulsar docs: Print the design on regular paper, cut out a
bit of the transfer paper just big enough, tape it OVER the printed
design, print again! The first (plain) sheet acts as a carrier, works
fine, doesn't waste expensive paper.

Remember to only tape the leading edge, of course.

Re: [Homebrew_PCBs] Today's home-fab thoughts

2009-12-02 by DJ Delorie

Simao Cardoso <simaocardoso@...> writes:

Show quoted textHide quoted text

> I soak it because i want to cool it fast,

What I do with Pulsar is this:

Laminate as usual. I set up for this on my cast iron table saw -
i.e. a big flat heat sink.

As soon as the board comes out, I put it paper-side-up on the cast
iron, and press on the top with a "push block" - this is a plastic
block with rubber on the bottom. The rubber presses the TT paper
tight against the pcb while the cast iron sucks the heat out the back.

That seems to have reduced the chances of getting lifted-off traces.

Re: Today's home-fab thoughts

2009-12-02 by teknochaman

Hi Delorie and everyone,

Just doubting why is mentioned an 'inkjet printer and paper' in the UV printing method which of my knowledge (I'm finishing the table and lamp) gets a negative film thru 'photographic process' as it's mentioned below.

Conceptually thought that inkjet and paper was something intended to work aside of transparency paper, not UV process and chemicals so here my question about the UV film. Why after being developed, can't be directly used to 'burn' the PCB layer without using toner ?

Hope to be clarified about that.

Appreciate your hints.

Sam

>dj@delorie wrote:

>For UV: You need a source for the film, a UV exposure setup, developer
>and stripper chemicals (neither is nasty and they're reusable). You
>need an inkjet that can print a solid black reliably, and coated
>transparent "paper" on which the ink dries super fast (else the ink
>smears before it can dry). Cleaning the pcb isn't as critical, but
>laminating the film is - no dust, no air bubbles

Re: Today's home-fab thoughts

>Posted by: "DJ Delorie" dj@... djdelorie
>Tue Dec 1, 2009 1:34 pm (PST)

>>Erik Knise <elknise@gmail. com> writes:

>> What are the advantages and disadvantages of uv film verses toner
>> transfer?

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Re: [Homebrew_PCBs] Re: Today's home-fab thoughts

2009-12-03 by DJ Delorie

The inkjet/UV process is as follows:

You print the artwork on a transparent sheet of plastic (I called it
"paper" because it's that size and shape). Usually, this plastic has
a coating on it that makes the ink dry very fast so you can put a lot
down without it smearing. The result is a "mask" (also called "the
artwork" or "the print") which passes UV in some spots, and blocks it
in others. Whether you want to block where copper should remain
("positive") or where copper is removed ("negative") depends on the
PCB's coating - some harden with UV (negative) and some soften with UV
(positive).

Anyway, the next step is to put this mask on top of the coated PCB and
expose it to UV light. The light passes through the transparent parts
of the mask and reacts with the PCB's coating. The PCB is then put in
a chemical bath that removes some of the coating and leaves behind
your etch resist. This chemical bath is the "developer".

We use the word "film" inconsistently. The plastic sheet we print on
is often called "film" although it's just a transparent page. The
coating on the PCB is often called a "film", although often "UV film"
or "photofilm" (for liquid coatings, it's only a film after it's
applied, for laminated coatings, it's a roll of film you laminate on).

None of this has to do with regular photographic film, or regular bond
paper.

The Toner transfer process is different - you use a laser printer
instead of an inkjet, and it's the toner itself that becomes the etch
resist. You can't use an inkjet's print as etch resist because
there's no way to transfer it to the PCB (toner is plastic, it can be
melted and made sticky), but you can use plain paper as long as you
can get it off the toner later.

You *can* use a modified inkjet printer to print directly to a PCB,
but you have to remove the regular ink and replace it with liquid etch
resist.