how yo apply legend & coating

[chithublissly]

Dear Sir,

I gone through some home made PCB'S. I got the some idea.
But I don't know how to apply legends on the PCB. Then where to get the green-ink and how to use that...?

 

[shaiko]

The "green-ink" isn't an ink actually - It's called a solder mask.
It comes in other colors also: red, black, blue etc...

It's a dielectric protective coating to prevent copper corrosion and short circuits.

Apply a Solder-Resist Mask to PCBs (Printed Circuit Boards) - YouTube
Mouser Electronics - Electronic Component Distributor solder mask

---------- Post added at 10:53 ---------- Previous post was at 10:51 ----------

**broken link removed**

 

[allenf]

Ebay UV SOLDER MASK
one gut from china also does blue red yellow black and white. (some are for legends only but it tells you which)
also is a quick description of how to use it.
Basicly you print out a solder resist mask on a transparency (OHP FILM ) (can be highqual inkjet). then cover pcb in the same film that they wrap flowers in (CELLOPHANE) cover with mask clamp in aphoto frame and expose to uv light for 5(ish) mins then wash off all "unset" ink with acetone petrol or even hot water (although not as good)

For the legends exactly the same principle.
Print a NEGATIVE of the legend (so the text is clear) then the same as before
Try ebay guy goldpart items in Computer Repair GoldPart Store store on eBay! He is on holiday till 12 feb though
This is what he has though
**broken link removed** FOR SILKSCREENS
**broken link removed** For solder resist


Sorry if this breaks any rules about advertising

 

[Mattylad]

For a home made PCB try paper.

Print the silkscreen on paper, spray glue the back, place pcb on a light box and fit to PCB, rub well down.
It helps to have some alignment marks.

Not as nice as a proper silkscreen legend but works well.

 

[allenf]

Or print the silk in MIRROR and use toner transfer method to "iron" it on the laquer it

 

[chithublissly]

For a home made PCB try paper.

Print the silkscreen on paper, spray glue the back, place pcb on a light box and fit to PCB, rub well down.
It helps to have some alignment marks.

Not as nice as a proper silkscreen legend but works well.

Thanks you Sir. I want know how to apply glue on PCB. normal method or any specific method should use...?
Still more can you explain.

 

[Mattylad]

Spray glue, spray it on the reverse of the paper then while still tacky it can be positioned on the PCB.
Not much use for SMT though, only good for PTH boards.

 

[allenf]

Or you could WRITE them on with a GEL pen

 

[chithublissly]

Or you could WRITE them on with a GEL pen

really can be write....? I am sure. can you explain more...

 

[allenf]

Take a look at these
**broken link removed**


You can buy them at stationary shop I think its staedltler that make them (an art shop des more colours)
Why and how it works take a read here
Gel pen - Wikipedia, the free encyclopedia

Admittedly you need small neat writng but that is just practice

Allen

 

[aetosa]

Trying to find informations about the correct application of **broken link removed**, I stumbled upon this thread.
I did what was suggested in post #3:
1. print out a solder resist mask on a transparency
2. cover pcb with the ink, and expand it in all its surface (this step was missing in post#3 :roll
3. cover pcb with cellophane (plastic film that they wrap flowers in)
4. cover with mask clamp in aphoto frame
5. expose to uv light for 5(ish) mins
6. wash off all "unset" ink with acetone

The result was 'poor':
the density of the ink layer on the pcb is not the same in all the surface.
air gets trapped between the film and the ink

Has anyone managed to make a descent solder mask with uv curable ink?
May be in some other way?

 

[allenf]

Ok Re read the instructions . If your getting air trapped then you HAVEN`T "Clamped" it in a photo frame {I know I`ve tried skipping that bit and just covering it with something you CANT. IT MUST BE CLAMPED TIGHT (tighter than you think actually a lot more than for photoresist exposure where you can just "cover it "
The "weight " of the glass and the clamp effect spreads the ink (About five ten splats) over pcb then cover with film. PRESS a piece of (heavy is) glass {MUST BE FLAT} onto film remove glass cover with transparency then Clamp the whole thing as one in one of those cheapo "no frame "frames (all glass with 4metal tag clamps) then expose to UV.
It does take some practice (Maybe a tube) but when you get it then its fine cheaper than a silkscreen printer
If all else still fails try spreading the ink EVENLY with a small foam roller or an old credit card( Harder to do with a credit card) then refollow the above steps



Or if you cant get on with it try the "Enamal glass paint havent tried it dont know mch about it but google it and see what you get.
Basically you "paint" this stuff on with the pads covered (cant remeber what with but easy ) then bake in an oven at 200 degrees for a set period of time "Apparently" very good colours" and a good selection of colours available

 

[aetosa]

Ok, thank you allenf, I'll try to do EXCACTLY as you suggest.
If I don't succeed, I'll try the glass paint, I guess you mean this.