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UV exposure machine for PCB manufacturing

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Spidyelectronics

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Hi Everyone ,
I want to make UV exposure machine for PCB manufacturing. I want to know the important things to be consider while making such a machine.
This machine will be for prototyping PCBs only.
Please contribute your thoughts.
Thanks in advance..
:idea:
 

Rob B

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Uniform illumination of the board.

The glass used must be transparent to UV! (Some glass will block UV)

A timer for repeatable results.

The board must be held flat against the glass.

You could include something to help with the registration of the board and artwork.
 

Spidyelectronics

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Thanks Rob for your help.
I saw some UV exposure machines. It includes exhaust Fans for heat transfer, generated by UV lamps.
I also want to know the pricing for UV lamps.
 

rajudp

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i am using 4 x 18w uv tubes costs about Rs250 per tube.
 

FvM

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i am using 4 x 18w uv tubes costs about Rs250 per tube
That's a typical DIY solution. Professional exposure machines are rather using high pressure discharge lamps because
of better edge reproduction, also vacuum pressing fixture.
 

Spidyelectronics

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Thanks everyone for the contribution.
Electronicus, I read the artical and it is very useful. I am going to implement these things.
Rajudp, are you from India? I am from India. I want to know, from where I can get all these parts for exposure machines. Right now I am searching these in my local market.
If anyone is having anymore information, please contribute your knowladge.
Thanks again everyone.
 

rajudp

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I am from India and i brought the tube from polymer stamp making dealer, you can get it in electrical shops, I tried first with 40w choke but I was not able to find the starter for that (not working) so now I am using it with 4 20w choke, what type of copper clad you are using ie photo resist or pre-coated one
 

Spidyelectronics

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I am using Normal copper clad pcb, as I am going to use screen printing method. I have to use itchent resistant ink for that.

Rjudp and electronicus, can you please tell me that how much should the distance between UV lamps and the glass over which we are placing PCB?
 

pranam77

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To expose the cromalin film, You'll have to confirm that the UV light is uniformly spead all over the exposing glass where the film will be placed. Nearer the distance, faster will be the exposing time. But also take precautions not to over expose the same. A distance of 1 to 2 feet will optimally work fine for tube lughts. In case of LED, it all depends on its angle of the beam.
Cheers
 

Spidyelectronics

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Thanks pranam77,
Right now I am using UV black light for it. For this I am thinking to keep the distance about 4 inches. So can you tell me will it be ok or it will over expose the film.
 

pranam77

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Spidyelectronics said:
Thanks pranam77,
Right now I am using UV black light for it. For this I am thinking to keep the distance about 4 inches. So can you tell me will it be ok or it will over expose the film.
Keep a distance of 1 foot to be safer for the films.
Cheers
 

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The exposure time can be basically adapted to any light source distance and intensity. Because low pressure lamps have a
low intensity, you may want to reduce the distance to get acceptable exposure time. But the requirement of uniform intensity
contradicts a too small distance.

As mentioned previously, large area sources have the disadvantage of giving less resolution compared to a "point" source, e.g.
a high-pressure arc discharge lamp.
 
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