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a new PCB manufacturing method wanted

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digital

New Member
Whats that UV lamp used for, isn't UV light a hazard to your body :?:

How do firms(computer companies like Dell for example) manufacture their PCB's, with such great speed and precision, how do their methods differ from the methods discussed here :?:
 

Nigel Goodwin

Super Moderator
Most Helpful Member
digital said:
Whats that UV lamp used for, isn't UV light a hazard to your body :?:

It's to expose the photographic sensitive resist, which then has to be developed (just like a photograph). Yes, UV is a hazard, particularly the UV used for this process - so it's done in light proof boxes.

How do firms(computer companies like Dell for example) manufacture their PCB's, with such great speed and precision, how do their methods differ from the methods discussed here :?:

The same photographic method as discussed, although I don't know if Dell manufacture their own PCB's or not? (although it seems unlikely?). Multilayer boards (as for PC motherboards) are simply double layer boards glued together, and then through hole plated to join the layers together where required.
 

zachtheterrible

Active Member
I'm thinking about using the photoresist method because its less messy and much easier than the toner transfer. Also, you don't have the suspense of "did it come out right this time??" I don't mind paying a couple extra bucks for the special boards.

Until I get myself a UV light, could I just expose the boards in the sun?

And is there such thing as overexposing the boards?
 

evandude

New Member
zachtheterrible said:
I'm thinking about using the photoresist method because its less messy and much easier than the toner transfer. Also, you don't have the suspense of "did it come out right this time??"

I beg to differ!

yes, when using photo paper, that can all be true.... making a mess with water and dissolved paper goo everywhere, the effort of scrubbing off all the paper, and it almost never comes out right every time.

However, press-n-peel is a whole different world. the ONLY thing you use water for at all is to cool the board down after ironing (just run it under some cold tap water), so there's no mess... printing and ironing are very easy, and it comes out pretty much perfect every time. And, when it comes to removing the backing, it just peels off with no effort... no scrubbing involved!

I know, I know, I brag about it a lot, but it really is incredibly good! believe me, I used photo paper toner transfer for a long time, and when I first tried press-n-peel my jaw hit the floor. it's just amazing, and so much faster and easier than with photo paper.

If you don't believe me, email me your mailing address (evandude AT gmail.com) and I'll send you a piece of press-n-peel :D
 

mstechca

New Member
zachtheterrible said:
glad to see you finally realized that the wax method just isn't practical!
It was practical, but I want to switch methods because I want to speed up the process a bit and I don't want to scrape any more wax off.
 

evandude

New Member
mstechca said:
it was practical, but I want to switch methods because I want to speed up the process a bit and I don't want to scrape any more wax off.

I wouldn't call it "practical" for very complex boards... what about boards like these?

**broken link removed**

it seems like it would take hours to scrape the wax for a board like that! especially to get all the holes lined up properly and everything.
 

digital

New Member
Nigel Goodwin wrote: Multilayer boards (as for PC motherboards) are simply double layer boards glued together, and then through hole plated to join the layers together where required.

Do you mean that they plate the adjacent holes(from the two boards) through the holes to make a conductive path ?

How do they make conductive connections needed between the two glued or multilayer boards :?:
 

zachtheterrible

Active Member
I still think im going to go the photoresist way just because I like it :lol:

I'll check into the photoresist more and if I end up not liking it, ill give u my address.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
digital said:
Nigel Goodwin wrote: Multilayer boards (as for PC motherboards) are simply double layer boards glued together, and then through hole plated to join the layers together where required.

Do you mean that they plate the adjacent holes(from the two boards) through the holes to make a conductive path ?

How do they make conductive connections needed between the two glued or multilayer boards :?:

I'm not a PCB 'expert' (and in fact DON'T make PCB's at all), but as I understand it the boards are glued together, then holes which pass completely through both boards are plated internally, joining all the layers together at that point (assuming you wanted ALL the layers connecting?).
 

mstechca

New Member
evandude said:
I wouldn't call it "practical" for very complex boards... what about boards like these?

***insane picture not shown***

it seems like it would take hours to scrape the wax for a board like that! especially to get all the holes lined up properly and everything.

That's TOO complex for me to do by hand. In fact, what I am doing now is almost TOO complex. I'm even doing a superregen on a PCB, and 1/2 the time, adjacent tracks spill into each other.

I'll try the photoresist method, and hope it works.
Let me see if I get the steps right this time:

1. Print on a transparency
2. Place the transparency ink side down on the green photoresist on the board
3. Place glass on top of the transparency
4. Blast the transparency with UV light for 5 minutes
5. Remove the transparency and the glass and stick the board in developer until the unwanted green is removed
6. Etch the board.

If any of these steps are in the wrong order, please correct me. I HATE spending money on making mistakes. In other words, I don't want to make a single mistake.
 

chemelec

Well-Known Member
I Make Hundreds of boards using a UV Photograpic Process. Not Sure What UV Lamp your using, but 5 Minutes Exposure is quite long for a Good UV Lamp.

I Use a Sunlamp and about 2 minutes at a one foot distance.
I also Coat my own boards with the Shipley's Liquid Photo Resist.
(not the Spray)
 

Screech

New Member
Yeah, It depends on how many uv tubes you use and how far away they are from the board.

As I said earlier, cut small pieces of the pre-sensitised board, and test them at different exposure lenghts.

HINT:
If the boards are not exposed long enought, the boards will not delevope.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Screech said:
As I said earlier, cut small pieces of the pre-sensitised board, and test them at different exposure lenghts.

The usual method for photographic film is to make a test strip. A thin strip of material which you cover most of with a piece of opaque material. You then expose it for a certain time, then slide the cover back a little, expose again, slide back a little further and so on. This gives you a strip of material with specific timed 'stripes' on it - rather than all seperate pieces.
 

Screech

New Member
The usual method for photographic film is to make a test strip. A thin strip of material which you cover most of with a piece of opaque material. You then expose it for a certain time, then slide the cover back a little, expose again, slide back a little further and so on. This gives you a strip of material with specific timed 'stripes' on it - rather than all seperate pieces.

You got it Nigel.
:D
 

spuffock

Member
I,ve tried the spray photoresist, and I think it would work very well if only I could keep dust and cat hairs away from it while drying. A light proof enclosure with a fan and filter, a matt black baffle to keep light out............... I bought some more presensitised board.
 

Random

New Member
I'm looking at building a UV exposure box out of an old broken scanner - do you have to expose the entire board all at once, or can you do it in a sweeping motion for a longer time?

Also, where could I buy the Bungard Original PCB's?
 

mstechca

New Member
How do I know if the board is over-exposed? Is there any indication of it without me detaching the transparency from the board?

and couldn't I juse use clamps to hold the board and the transparency together as opposed to a piece of plexiglass?
 

evandude

New Member
It seems to me that laying the board on the table, setting the pattern on top, and then laying a piece of glass or plexiglass on top would be faster and easier than clamps... Not to mention, it would ensure that the pattern lays totally flat against the entire board, not just in the areas where it was clamped...

and a piece of glass or plexi should only cost you a couple dollars at the most, if you don't have one around already.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
mstechca said:
and couldn't I juse use clamps to hold the board and the transparency together as opposed to a piece of plexiglass?

I don't do PCB's, but it's fairly obvious that the transparency has to be in extremely close contact with the PCB - it's normal to have the printed side of the transparency next to the board so as not to introduce the thickness of the transparency between the board and the design.

Using clamps wouldn't hold the transparency flat or tight, and light would leak underneath, ruining fine tracks.

I would suggest a piece of glass might be better than plexiglass?, as it's flatter - but don't use UV resistant window glass :lol:
 

chemelec

Well-Known Member
Here is my Simple Setup. Not Fancy, But it Works very well.

This is a Hinged wood frame with a Piece of Soft Foam on the Bottom, under the Glass. Putting the lid down compresses the Artwork between the Glass and the Foam.
Distance between the Sunlamp and the glass is One Foot.
Exposure time is Typically 2 Minutes.

Other lights that are on in the room don't really affect the Exposure as Incandesent bulbs are Low in UV.
 

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