I made a PCB without a UV box

[cobra1]

Just made me a PCB without the use of a UV light box.

Instead u used a desk lamp with a reflector bulb in.

Exposed PCB for 8 minutes and then developed and etched.

Results:

**broken link removed**

 

[#12]

This would be ever so much more helpful if you told about the reflector bulb and the type or brand of blank board you used.

 

[cobra1]

Hi #12

The board is cheap paper type, photo sensitive double sided board, i also tried this method with FR4 and it worked just as good.

The bulb is a standard reflector bulb as found here.

**broken link removed**

£0.99 for a bulb or £89 for a UV box i know what ill be using from now on

The traces on that PCB above are 0.4mm

 

[#12]

Thank you.

 

[cobra1]

No probs mate

 

[cobra1]

one thing i noticed that might be worth mentioning is that the developing solution i used had to be rather weak, at normal strength it stripped the resist straight off, not sure if this is the cheap board i was using or the way the light affected it...
Im using 10g per 1/2 litre of developer (sodium metasilicate)

Anyhow i see it as a further saving

 

[RMMM]

It is the way the light effected it.

The stronger the UV, the HARDER the resist cures.

You could remove any UV filter from the bulb and/or increase time under the light.

 

[SABorn]

I have used caustic soda for a developer for as long as i can remember, and the mixing strength is 7 grams per 1 litre of water so i think your mixing ratio might be a little to strong.

It is better to have the developer on the weak side, and if developing is to slow place the developer solution in a bucket of hot water to warm up, as it will develop faster the hotter the solution is.

I have seen a post from another person using the CFL light bulbs with good results to, which make me wonder what levels of UV are we being subjected to with the current trend of low energy light bulbs??????

Pete.

 

[atferrari]

In two years time you could tell us also about the effects of exposition to UV on you. Maybe six months?

 

[bryan]

I have had very good results using a CFL black light from Home Depot. i keep it approx 8 inches from the PCB and expose for around 7-8 min. I do use a old aluminum parabolic reflector I had on hand as well.

**broken link removed**

 

[cobra1]

@SABorn

Caustic soda, is Sodium Hydroxide, the developer i am using is Sodium Metasilicate which is Sodium Hydroxide free, both are different chemicals.

Sodium hydroxide if too strong will strip all the photo sensitive layer off, best result i had using it was decent tracks but with lines through them breaking the tracks up

 

[ericgibbs]

hi,
If you expose your pcb in bright sunshine for a few minutes that will produce a good result..... thats if you ever get sunshine where you are...

BTW: most drain cleaners are caustic soda,handy if you have a local hardware shop... check the label of course.

 

[Boncuk]

In two years time you could tell us also about the effects of exposition to UV on you. Maybe six months?

There is a song "It never rains in California".

Do you expect the same for the island of the UK?

The climate is very similar to that in Northern Germany and I remember an extremely long summer one year.

It lasted from 12:30 to 15:00 on June 28 in the year of 1974.

Boncuk

P.S. I prefer UV-LEDs at a wave length of 340nm. They reduce exposure time drastically to a few seconds. Secondly I never use that cheapo paper stuff to make PCBs. Especially prototyping becomes a nightmare when desoldering a part ripping off the copper pad as well.

 

[#12]

I am constantly learning things here

Sodium Metasilicate, the climate of Northern Germany, bad pc boards are available, 3 kinds of UV source, and American music gets to Thailand!

I do enjoy this site.

 

[Boncuk]

I am constantly learning things here

Sodium Metasilicate, the climate of Northern Germany, bad pc boards are available, 3 kinds of UV source, and American music gets to Thailand!

I do enjoy this site.

Not quite true.

The song never came to Thailand, but to Germany!

I know of four UV sources - one of it is natural and it is commonly known as sunlight.

Boncuk

 

[#12]

Being a cheap farang, I use sunlight. We have plenty of it in Florida.

 

[cobra1]

Im in the UK so sunlight is a rare commodity..

 

[Boncuk]

Im in the UK so sunlight is a rare commodity..

I'm pretty sure the UK has the same amount of sunlight as every country in the world.

It's just a matter of penetrating the cloud ceiling to expose your PCBs to sunlight.

Boncuk