PCB photo-resist exposure times? Mine won't develop!

[HandyMan]

Thank you to everyone who gave suggestions. I've tried them and found Eagle the best for my needs, so thanks again for the invaluable advice.

I'm now ready to start making my PCB, but I'm having trouble with the photo-resist and developing procedure.

I'm trying to get the correct exposure time by sticking a piece of photo-resist board under my UV lamp and then trying to develop it, increasing exposure time by degrees until the PCB develops. However, it just isn't developing in the solution, even when I can see a remarkable colour change to the photo-resist on the board (if I put something across it, the photo-resist is still green beneath, whereas it's very copper pinkish in exposed areas).

I'm using my wife's face tanning UV thing to expose. It has four UV tubes and I'm using it horizontally held about 3 inches above the board.

I've tried exposure times from 90 secondss to 10 minutes with no luck - I stick the PCB in the developer for just over the recommended 30 seconds and nothing happens, the photo-resist is still in place. The developer is newly bought and mixed correctly today.

I've got no idea about usual exposure times, all I know is what I read on a few sites where proper PCB UV exposure boxes were used, and they said 90 seconds was about enough.

Am I doing something very wrong, can anyone please shed some light on this?

Many thanks again,
James

 

[Russlk]

Perhaps the tanning lamp is not strong enuf. I was told that grow-lights were not good altho they look the same as the PCB exposure lamps.

 

[Sebi]

If available, the best thing a quicksilver-lamp with brokened glass. The 250W type give about two-three minutes exposure time - depending from lack thickness and developer.

 

[jbeng]

Here's a link to a thread in which we spoke about this ...
https://www.electro-tech-online.com/threads/pci-card-blank.9965/
When operating, these fluorescent tubes, type F15T8BL, look very similar to tanning bulbs. On my last project, I used these bulbs and these positive-acting, presensitized boards:
**broken link removed**
Seems like they developed in seconds (might have overexposed them a bit). Boards turned out great though.
JB

 

[mbramwel]

I do not know where you are. I am in Canada. I went to Walmart and purchased a Poster Lamp meant for a college kids dorm room. It cost about $10 canadian. Physically it was a tube about a foot or so long in a housing meant to be mounted to a wall. The tube was purple and went lit, gives off a deep purple light. It makes posters light up very nicely and seems to expose my circuit boards in about 4 minutes. I have my boards very close to the lamp, about 3 inches from the light. I find that more than 4 minutes is too much light, less than 3 1/2 minutes is not enough. I am using laser printed clear plastic for my circuit print-out.

When you are not exposing circuit boards, it gives off the perfect atmosphere for a dance party!

PS: Two of my buddies use similar lamps. One uses a fish aquarium bulb.

 

[solidhelix]

If available, the best thing a quicksilver-lamp with brokened glass. The 250W type give about two-three minutes exposure time - depending from lack thickness and developer.

i had a success on using on this kind of lamp...

 

[Sebi]

O.K. but be careful, it's dangerous for Your eyes! 4minutes and half meter distance from face equvivalent as 30min solarium.

 

[svtiss]

Did you use a brush to clean your board ??? thats important ,

 

[csaba911]

Hi

Get this **broken link removed**

or

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You can get it from MRO, Active, if you want qality result every time, then buy the MGC **broken link removed**, **broken link removed**
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Good luck.

STEVE