Making PCB ...

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I have failed once and I then stopped for at least 6 months. I want to do it
again.

Therefore I need some guidance in making pcb again. The actual schematic has
converted to PCB.

I remembered  what I have done last time
My step are wrong because I do not get a nice clean pcb at the end of the
day.

1. I printed it out from internet in a laser printer.
2. made transparency copy of the pcb and cut it a the size of the actual
perimeter said 4 by 5 cm.
3. I have "ever-Muse"  presensitized P.C.B.
4. I  used a glass to cover the transparency that covers the "ever-Muse"
5. I applied  strong "flood" light for about 10 minutes ( I do not know
exact time that I have apply and I need to find out where is the flood light
located since I have not used it for six months.
6.   I remembered I applied some "yellow pebbles and hot water to form a
yellow liquid"  and also the electrolube- photo resist developer".
I bombed the last project.


Now I wish someone would guide me a "newbie".


Thanks.
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Re: Making PCB ...
Read this page for everything you need to know about making good PCBs:
www.electricstuff.co.uk/pcbs.html


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Re: Making PCB ...

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it
has
light
ls

Look at:
http://www.fullnet.com/u/tomg/gooteepc.htm

and even better:
http://www.electricstuff.co.uk/pcbs.html

pieter



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Re: Making PCB ...
I  think I failed once again.

I do not see it developed good shape ( circuit) after the "exposure to a
small UV light ( insect- killer light).

I dipped it into the developing liquid for 3-4 minutes.

it is etching. I do not think it will turn out any good result.





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do
the



Re: Making PCB ...
Perhaps your insect UV source is insufficient. I haven't done PCBs for
years, and I used to live in South Africa, where the sunshine is quite
strong, but I used to expose using sunlight and didn't have to buy special
UV equipment.


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schematic
actual
"ever-Muse"
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know
a



Re: Making PCB ...
You don't even need strong sunlight. In the days when I made my own boards I
found 10 minutes of overcast English sky to be enough. I used an old SLR
camera to measure the overall illumination so I could make some sort of
calibration.

You need to do a test strip like a photographer. Just take a small bit of
board and expose different areas for (say) 5, 10, 15 and 20 minutes to find
the best exposure time with your lamp.


Peter

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to
of
flood
form



Re: Making PCB ...

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An insect-killer light is not the right source for this job.

pieter


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Re: Making PCB ...

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I tried the sun light method at 3:45 pm for 6 minutes, that failed too.





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Re: Making PCB ...

Possibly there is nothing wrong with you. BUT there may be a problem
with your transparency. Most I've seen are not opaque enough for uv
exposure. The tracks and pads are not dark enough.
Try exposing something solid, say a coin or ?  Expose, develop and
look at the differences.
If your film is too light, the traces will come off in the developer.
If the coin shape is present on the board, then you know what the
problem is.  If the coin pattern is not there, maybe the developer is
too strong.

Bill Jenkins




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Re: Making PCB ...
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I'd be surprised if the entire board wasn't washed out at that
exposure.  I started to see overexposure at less than 3 minutes, but I'm
in a lower latitude and it was summertime when I tested.  In all,
sunlight is not a good source - too many environmental factors
influencing its effectiveness and availability.

So, what result are you seeing - does the board appear to change at all
when you develop it? Aside from the overall bad results, you need to
narrow whether it's your exposure or your chemicals.

Among other tricks, warming the chemicals helps them develop much faster
(we're talking on the order of  seconds before results start becoming
visible).  But I think exposure is your first problem.

Also, be sure the developer you're using is chemically matched to the
PCB coating.  I seem to recall there's more than one system, and perhaps
you're not using a compatible developer.

Other tips for quality: ensure the toner side of the transparency is in
contact with the PCB for best results.  And I develop in very low
lighting (e.g. 4W nightlight) to avoid affecting the exposure.  (Of
course, the PCB is also bagged immediately before/after exposure.)


Here are some comments from an old posting of mine with some more
details on my testing...

I happened to have an empty picture frame handy, and it
made an excellent holder / clamp with glass included (the gap for a
photo with a cardboard backer was just right for a PCB with a
transparency).

For the source, I used a fixture in my office; it works well enough that
I haven't tested further.  It's a 21-inch 13-watt under-counter light
fixture from Home Depot, with a replacement bulb (a Philips "Home Light
Cool 4100K").  Exposure was done 6" from the fixture (for a 2"x2" PCB).

With the diffusing panel left installed on the fixture, an exposure of 5
minutes worked fine, though it was very slow to develop.  I've seen the
best results with the diffuser panel removed, and an exposure time of
~10-15 minutes).

FWIW, a UV "grow lamp" flourescent fixture did not yield much better
results.  At least for my purposes, it wasn't worth setting up a special
rig when I could use a lamp at-hand.


FYI, I initially tried using sunlight at a 180-second exposure, but the
results were badly overexposed.  It could be a viable source as well
with some testing, but I abandoned it because I realized the source
would be too inconsistent (e.g., clouds, time of day - particularly
nighttime ;-).  Also, I was concerned that the sun was too intense as a
source (that the toner on the transparency might not block it
effectively at any exposure).  So, I opted for a less intense light
source (i.e., slower), but gained consistency and control.

Your mileage will vary with your setup (e.g., larger PCBs may require
more distance from the bulb for angle and even lighting, and thus a
longer exposure).  I took a PCB and cut it into 2"x2" sections and
exposed under a variety of settings until I got results I was happy
with.  IIRC, it only took 3-4 cycles to get the settings "dialed in".

When I switched to photo etching, I picked up a packaged kit at the
local Fry's Electronics.  The kit's handy, and it was about the same
price as buying separately packaged chemicals, but also included some
PCBs.  Here's the manufacturer's site:
http://www.mgchemicals.com/products/416k.html

I've had great results with the photo process, with one glitch.  An
early batch of boards apparently had scratches in the photosensitive
material, which caused cuts in the trace lines.  I tried boards from
DigiKey (more expensive, naturally) and did not have this problem.  I
can't imagine it's a regular problem with MG' products, but I wasn't
going to keep experimenting to find the good batch. ;-)

Curiously, I just found this on MG's site - it's general instructions
for photo etching.  They suggest any 18" fluorescent lamp will do, at a
distance of 5" for 10 minutes using a glass sheet.  Coulda saved me a
couple rounds of trial and error...
http://www.mgchemicals.com/techsupport/photo_inst.html

Re: Making PCB ...
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No shit. I have that problem with MG. It's not to the point where I'd
change brands though. None of the boards were seriously effected by the
flaw. (Usually just on the ground plane.) I couldn't get the digikey
boards to work... likely because I was running low on chemicals at the time.

Did MG Chemicals admit this?

Brett


Re: Making PCB ...
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No.  I didn't pursue it with MG.  Chalked it up to buying cheap stuff at
Fry's.  It would've been a problem though, because the traces I was
testing were pretty narrow for hobbyist (7-10 mils).

Looking at one of the test boards lying here, there are 1/16" to 1/8"
gaps in some of the traces - pretty bad by any standard.  Since I used
the same transparency for all the tests, it was pretty certainly the
PCB.

Anyhow, I've been paying to have PCBs made lately... a more expensive
(but easier) fix.  The solder mask alone makes it worth the cost when
trying to hand-solder fine-pitch SMDs. ;-)

Incidentally, the MG Chemicals did work fine for me with the DigiKey
PCBs, though as the chemicals depleted I found myself heating them for
best results.

Re: Making PCB ...
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And there are the videos too:
http://mgchemicals.com/techsupport/index.html


Re: Making PCB ...

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there is no "bare copper", the green layer has not comes out in my all
trials.







Re: Making PCB ...
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Pardon the very fundamental questions, but making no assumptions here...

* Are you sure you're buying photo-sensitive PCBs?  They'd come sealed
in a light-proof pouch with a protective film that needs to be removed
before exposing.

* After exposing the PCB, the "developer" solution will cause exposed
areas to fall away from the PCB, leaving only bare copper and coated
traces.  If you never see bare copper, then the photo developer is bad,
the photo-sensitive material on the PCB is bad, or they're chemically
incompatible.

* The etch process uses a separate chemical solution to eat the copper
that's exposed.  Again, a very noticable process.  But from your
comments, you aren't making it this far.

Are you sure the stuff you think is developer really is developer?
Perhaps you've mixed up the developer and the etchant solutions?

Re: Making PCB ...

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yes , it is called Ever_muse presensitized P.C.B.

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ELECTROLUBE ( order code PRD250) PHOT RESIST Developer. I dipped the exposed
PCB down and up at least two dozen times. NO bare copper was found, "no
green things" comes out.

I have done exactly what the film instructed even this is first time I saw
the film.


http://mgchemicals.com/techsupport/index.html

the rest of the etching process is out the question since I do have a
noticable clean clear "BARE" copper PCB.



In the film, he used a day light floursecent lamp , I guess it has 2 lamps
and it may a 18 inches.  can u confirm this lenght of the lamp?

TIA.


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Re: Making PCB ...
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exposed

Or perhaps using positive process boards but using developer for negative
process boards??  Or vice-versa??
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Re: Making PCB ...
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Well, I got a big goose-egg trying to find these products online.
Google and Electrolube's site turned up nothing.  How old are your
materials?


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Sounds like some seriously dead materials.  Considering the only
reference I found isn't even carrying those PCBs anymore, I wonder if
you didn't get some really old stock.


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No.  I use a single-lamp 18" fixture as detailed previously.  MG's looks
very similar, so I'd guess it has one 18" bulb.  See
http://www.mgchemicals.com/products/416x.html


I'd suggest getting some fresh materials (PCB, developer, and etchant),
cut up a board (score/break) into small pieces and try several different
exposure times.  The info I provided before should give a good
jump-start.  It sounds like you're fighting a loosing battle with
depleted / inactive chemicals.

It's really a very easy process once you work out your exposure
technique.

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