Positive-20 Problem. (photo)

[Sobakava]

positiv 20

I make simple PCBs at home for my own use
but I've problems with positive 20. I spray it
from 30cm distance to cleaned (brushed with
teeth brush and powder detergent) copper
at room temperature but I can not get uniform
photoresist layer on the board.
Please see the attached picture. Such circles
and non uniform pattern appears. I changed
my spray and it is still exist.

Does positive20 spray (while in the metal can)
is messes in 2-3 months at room temperature?

What is the reason? Room temperature, cleaning, air-flow,
ambient temperature, spraying technique????

thank you guys!

 

[lollobrigido]

positive 20

Perhaps the problem is the dry method.
After spraying by fotoresist set the board in a vertical position. The lower border will be unusable but the remaining surface would be good.
try this.
Lollo

 

[twinsen]

positive 20 spray

Is it not maybe the detergent you are using that doesnt completely rinse off? I have never had that kind of patterning. I also used to use a powder (Its called VIM here) which is actually scouring powder for cleaning pots...

 

[Sobakava]

positive20

I clean VIM very well... I'll try to dry it in vertical position and let you know about the results.

Any other idea?

 

[Fragrance]

positiv 20 problem

hi

i used positive 20 couple of year back with out any problem try out these
solutions,

1= spray the positive 20 first on the pcb board in horzental position in mild dark room used zero watt bulb in the room so you can see the thing

2= leave it to dry properly at least one hour's

3= now attach your positive image on the pcb board with help of sotch
tape as close as possible with pcb keep in mind room is mild dark

4= now put your work in box which is covered properly better to make
wooden box top open, now cover the top with UV lamp which is used for
eprom erasing the distance betwwen UV lamp and PCB around 15 TO 20
CM not more then this allowed range.

5= expose the pcb for 15 to 20 minutes so tracks become on the pcb
used proper detergent to wash the waiste now atch the pcb in faric acid

hope this will help you to make your pcb in start i aslo unsuccesfull
but finaly i get succes by trying these mathod also read the instruction for proper detergent use

 

[mr_ghz]

positive 20 pcb

I also used positiv 20 for making PCBs a couple of years ago. I also have had problems with regular coating of the resist (OK, perhaps not as bad as in your picture...) until I tried the following system:
I mounted the PCB on a little DC motor, put the positiv 20 resist in the middle of the PCB and turned on the motor. Like in a zentrifuge the resist will build a regular coating on the PCB.
For drying I left the PCB one hour at room temperature and an additional 15 minutes at 50°. So my results were not too bad.
After some years I bought coated PCB's directly from a PCB manufacturer. You have to pay attention, because they often use a negative resist!

ye

 

[pool_77]

positive20 spray

this surface is named "orange peel" and can be me from:
-bad cleaning before (oily surface)
-high temperature during spraying (more than 30)
-the film is too thick (probably!)
-production mistake in positive spary
-residual water on PCB

positive has "autoleveling" efect and is not needed to be centrifuged.

 

[neuralc]

postitive20

I have a very bad experience with Positiv20, to get an uniform distribution in all board.

My solution is: PH4. I can get an uniform distribution even without clean the board....

HE

NeuralC

 

[sokrat]

positiv-20

I have a very bad experience with Positiv20, to get an uniform distribution in all board.

My solution is: PH4. I can get an uniform distribution even without clean the board....

HE

NeuralC

what is ph4?

i was use Positiv20 since 4 years ago but now i don't found it if any one can tell me where i can found it !


S 8O KRAT

 

[Analyzer]

проблем с positiv20

Hi!

The one reason (I'm pretty sure about it) is humidity of ambiance
Try it in cool room.

Analyzer.

 

[neuralc]

positiv 20 drying

PH4 is a similar product to Positiv20, but much more easyer to get good results.

I can check the manufacturer and tell you if needed.=> jelt-cm france

NeuralC

 

[sokrat]

positiv 20 photoresist

PH4 is a similar product to Positiv20, but much more easyer to get good results.

I can check the manufacturer and tell you if needed.=> jelt-cm france

NeuralC

If you have any link i want to buy it or positive20


S 8O KRAT

 

[pool_77]

pozitive 20

manuf:
http://www.kontaktchemie.dk/Produktoversigt/positiv_20.htm

 

[ben123]

positive 20

i cant see photo not clearly, only guess

your board must be flat. sometimes not. if that, i'm using iron -not much hot- to make it flat.
work always dust-free environments.
and use larger board then cut it. most probably centre is useble.
check and change if required your spraying methot.

 

[Epegic]

pcb positive 20 spray

I can think of two causes
1. Spray nozzle partially blocked.
2. Spray film too thick.

Thin spray layers always better than one thick layer. Spray steady thin stokes horizontal then vertical and then in diagonal direction will produce good result.

 

[leemarrow]

buy positive 20 spray

hi,
there are 2 possibilities:
1 - the positiv20 has expired
2 - the support is dirty

 

[hwswboy]

positiv 20 thinner photoresist

See for Application:

http://www.crceurope.com/wwwcrc/tds/TKC3 POSITIV20/css/TKC3 POSITIV20.htm

 

[sokrat]

using positive 20

Hi all


ANY ONE USE POSITIVE PHOTORESIST "PRP200" :?:


S 8O KRAT

 

[Guest]

uv lamp positive 20

I had the same case when holded positiv20 out of the fridge more than few months.If you put it in the fridge, (not to the icy part , but in the lower part of the doors ) you can extend its life to more than 2 years.The case on the picture is the case of bad cleaning or expired positiv20.

Greetings
Dragan

 

[GrandAlf]

where to buy positive 20

I have tried a few of these spay/wipe on products over the years. Never had a great deal of luck. Always use precoted boards these days, never a problem. Expose, develop and etch in ferric cloride solution made with boiling water, only takes 5 mins to etch at that temp.