Professional looking PCBs

J

JJ

Guest
Hi!

You know those professional PCBs that look greenish,
rather than the paler, semi-transparent light green
usual color of a glass fiber epoxy laminate?

Once I made my own PCBs, how do I make them look "pro"?

Do I have to use a spray? What kind of spray? Will it
be easy to spread it in a even way?

Don't get me wrong, I want this primarily because I
think the PCBs will resist better to age and oxidation.

Thanks!
John
 
The (usually) green stuff on professional boards is actually a solder resist
coating that is screen printed onto the boards. It stops the wave soldering
machine shorting out tracks.

This site

http://enc.ic.polyu.edu.hk/Training/PCB%20fabrication/single-sided_pcb.htm

says...

"After soldering, conformal coating like Plasticote 70 from CRC Industries
can be used. This conformal coating provides a thin layer of electrical
isolation but also allows repair soldering without first stripping off the
coating"

There are several companies that do small PCB on the cheap and some will do
solder resist for not much more.

http://www.expresspcb.com/ExpressPCBHtm/Download.htm
http://www.pcb-pool.com/ppuk/info.html
http://www.pcbtrain.com/



"JJ" <johnospam@invalid.com> wrote in message
news:born5k$1hqlch$1@ID-50260.news.uni-berlin.de...
Hi!

You know those professional PCBs that look greenish,
rather than the paler, semi-transparent light green
usual color of a glass fiber epoxy laminate?

Once I made my own PCBs, how do I make them look "pro"?

Do I have to use a spray? What kind of spray? Will it
be easy to spread it in a even way?

Don't get me wrong, I want this primarily because I
think the PCBs will resist better to age and oxidation.

Thanks!
John
Click to expand...
 
"JJ" <johnospam@invalid.com> wrote in message
news:born5k$1hqlch$1@ID-50260.news.uni-berlin.de...
Hi!

You know those professional PCBs that look greenish,
rather than the paler, semi-transparent light green
usual color of a glass fiber epoxy laminate?

Once I made my own PCBs, how do I make them look "pro"?

Do I have to use a spray? What kind of spray? Will it
be easy to spread it in a even way?

Don't get me wrong, I want this primarily because I
think the PCBs will resist better to age and oxidation.

Thanks!
John

That is called solder mask and it can be silkscreened on or applied
Click to expand...
photographically...that process is called LPI (Liquid Photoimagable
Soldermask). Your decision will be based on the thickness of mask you can
tolerate. With surface mount there are some issues if the mask is too
thick....Like the previous post suggested, just call a local prototype
circuit board shop and get a quote. Their engineering department should be
able to suggest a product that will work for you. Look under printed and
etched circuits in the yellow pages or just do a google search.....good
luck, Ross
 
On Wed, 12 Nov 2003 15:26:45 GMT, "CWatters"
<colin.watters@pandora.be> Gave us:

The (usually) green stuff on professional boards is actually a solder resist
coating that is screen printed onto the boards. It stops the wave soldering
machine shorting out tracks.
Click to expand...

No. The solder mask layer is just that. Another physical layer on
the board.

It is a photo etched film that basically, but not always and
everywhere., follows the pad layout of the board.

There are different colors available, and different materials as
well. It is film stock, however. Laminated onto the board, just like
the circuit layers are.

It is NOT silk screened onto the board.

FR4 PC board layers are yellowish in raw form.
 
On 11 Nov 2003 22:17:24 GMT, johnospam@invalid.com (JJ) Gave us:

Hi!

You know those professional PCBs that look greenish,
rather than the paler, semi-transparent light green
usual color of a glass fiber epoxy laminate?
Click to expand...
Raw laminate is usually a yellowish color. It also actually depends
on the media involved, such as FR4 or G10.

Once I made my own PCBs, how do I make them look "pro"?
Click to expand...
You can't. Not with the circuit fabrication process you seem to be
referring to. What you need to think about is post assembly conformal
coating of the board, or full potting (which hinders servicing).

Conformal coating still allows direct access for servicing, whereas
fully potted assemblies are harder to service, and require reliable
circuits for trouble free operation.

Do I have to use a spray?
Click to expand...
Yes. Do a search for "Dolph's AC-43"

What kind of spray?
Click to expand...
See above
Will it be easy to spread it in a even way?
Click to expand...
It is a spray. You apply it drippingly heavy. Let it dry, and
apply it again. Let that dry in air for an hour, then bake it at 175F
for a couple hours.

Oh yeah... You have to solvent clean the PCB after assembly, but
BEFORE any electrolytic caps, OR transformers or chokes go on the
board. Then add those mentioned parts, being careful to spot clean
the solder flux on the solder joints after each part gets added,
before the flux solidifies, as it is easier at this time. Use water
soluble solder and flux, not RMA. Use hot 90% IPA ($12 gal) for the
solvent step, if you do not have a Pro solvent ("EnSolve" they are
like $35 plus a gallon).

After that clean step, you must bake the board out for an hour or so
at 175F. As PCB material is hygroscopic (draws water in), you will
want to dry it out real good.

Don't get me wrong, I want this primarily because I
think the PCBs will resist better to age and oxidation.
Click to expand...
The conformal coating will make your assemblies reliable for years.
 
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:eek:ae8rv0a3gri4rrocs2h6fd77k0nq5ljl5@4ax.com...
On Wed, 12 Nov 2003 15:26:45 GMT, "CWatters"
colin.watters@pandora.be> Gave us:

The (usually) green stuff on professional boards is actually a solder
resist
coating that is screen printed onto the boards. It stops the wave
soldering
machine shorting out tracks.


No. The solder mask layer is just that. Another physical layer on
the board.

It is a photo etched film that basically, but not always and
everywhere., follows the pad layout of the board.

There are different colors available, and different materials as
well. It is film stock, however. Laminated onto the board, just like
the circuit layers are.

It is NOT silk screened onto the board.

FR4 PC board layers are yellowish in raw form.
Click to expand...
That's interesting...then why do most PCB companies still have a silk
screening area for applying soldermask and legends. I have a good friend
that manages the area. It is not the norm anymore since LPI, but they do it
on short runs if the customer allows.
 
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:eek:ae8rv0a3gri4rrocs2h6fd77k0nq5ljl5@4ax.com...
On Wed, 12 Nov 2003 15:26:45 GMT, "CWatters"
colin.watters@pandora.be> Gave us:

The (usually) green stuff on professional boards is actually a solder
resist
coating that is screen printed onto the boards. It stops the wave
soldering
machine shorting out tracks.


No. The solder mask layer is just that. Another physical layer on
the board.

It is a photo etched film that basically, but not always and
everywhere., follows the pad layout of the board.

There are different colors available, and different materials as
well. It is film stock, however. Laminated onto the board, just like
the circuit layers are.

It is NOT silk screened onto the board.

FR4 PC board layers are yellowish in raw form.
Hey, have you ever seen how the PCB shops remove soldermask from an area
Click to expand...
that it should not be? They used to just scrap out the whole order, but now
they use a laser drill and just ablate down to the surface. The customers
seem satisfied with buying the boards.....Just an interesting factoid
there.....Ross
 
On Fri, 14 Nov 2003 21:47:19 GMT, "Ross Mac"
<macroeng@example.invalid> Gave us:

That's interesting...then why do most PCB companies still have a silk
screening area for applying soldermask and legends.
Click to expand...
The only thing silk screened on a PCB IS the legend/reference
designator/logo. The printed info.

The solder mask itself is a laminated film.

that manages the area. It is not the norm anymore since LPI, but they do it
on short runs if the customer allows.
Click to expand...
Whatever. Read the topic again. I still contend that if it was not
a pro board to begin with, there is no real way to make it "look
professional".
 
On Sat, 15 Nov 2003 22:04:54 GMT, "Ross Mac"
<macroeng@example.invalid> Gave us:

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:eek:ae8rv0a3gri4rrocs2h6fd77k0nq5ljl5@4ax.com...
On Wed, 12 Nov 2003 15:26:45 GMT, "CWatters"
colin.watters@pandora.be> Gave us:

The (usually) green stuff on professional boards is actually a solder
resist
coating that is screen printed onto the boards. It stops the wave
soldering
machine shorting out tracks.


No. The solder mask layer is just that. Another physical layer on
the board.

It is a photo etched film that basically, but not always and
everywhere., follows the pad layout of the board.

There are different colors available, and different materials as
well. It is film stock, however. Laminated onto the board, just like
the circuit layers are.

It is NOT silk screened onto the board.

FR4 PC board layers are yellowish in raw form.
Hey, have you ever seen how the PCB shops remove soldermask from an area
that it should not be? They used to just scrap out the whole order, but now
they use a laser drill and just ablate down to the surface. The customers
seem satisfied with buying the boards.....Just an interesting factoid
there.....Ross
Click to expand...
Film masks are ONLY applied to those areas where they are specified
to be applied. Areas that are without mask never had it to begin
with.
 
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:v4rdrvcopd13ugvq47ariu329dele7suok@4ax.com...
On Sat, 15 Nov 2003 22:04:54 GMT, "Ross Mac"
macroeng@example.invalid> Gave us:


"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in
message
news:eek:ae8rv0a3gri4rrocs2h6fd77k0nq5ljl5@4ax.com...
On Wed, 12 Nov 2003 15:26:45 GMT, "CWatters"
colin.watters@pandora.be> Gave us:

The (usually) green stuff on professional boards is actually a solder
resist
coating that is screen printed onto the boards. It stops the wave
soldering
machine shorting out tracks.


No. The solder mask layer is just that. Another physical layer on
the board.

It is a photo etched film that basically, but not always and
everywhere., follows the pad layout of the board.

There are different colors available, and different materials as
well. It is film stock, however. Laminated onto the board, just like
the circuit layers are.

It is NOT silk screened onto the board.

FR4 PC board layers are yellowish in raw form.
Hey, have you ever seen how the PCB shops remove soldermask from an area
that it should not be? They used to just scrap out the whole order, but
now
they use a laser drill and just ablate down to the surface. The customers
seem satisfied with buying the boards.....Just an interesting factoid
there.....Ross


Film masks are ONLY applied to those areas where they are specified
to be applied. Areas that are without mask never had it to begin
with.b
That's true, but mistakes are made and fixed with the laser drills...that
Click to expand...
was my only comment there!
 
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:hvqdrvg4b57o5fokmgisjim1baue6e6nn1@4ax.com...
On Fri, 14 Nov 2003 21:47:19 GMT, "Ross Mac"
macroeng@example.invalid> Gave us:


That's interesting...then why do most PCB companies still have a silk
screening area for applying soldermask and legends.

The only thing silk screened on a PCB IS the legend/reference
designator/logo. The printed info.

The solder mask itself is a laminated film.

that manages the area. It is not the norm anymore since LPI, but they do
it
on short runs if the customer allows.

Whatever. Read the topic again. I still contend that if it was not
a pro board to begin with, there is no real way to make it "look
professional".
I'm sorry, that is incorrect too. Legend is also applied with film,
Click to expand...
nowadays. On an occassion, soldermask and legend are applied the old way,
via screen printing....trust me, I spent close to 30 years around that
business!
 
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