Automotive HID Projector Lamp Exposing a PCB?

I expose pcbs with a cheapo 500W halogen work lamp. Exposure time ~30 minutes..

Could I reduce the exp time with an auto HID projector lamp? (Scrap yard. BMWs I think. Who hasn't been blinded by those suckers.)

I see blue light from those HID lamps. If there's more blue end, than perhaps there's more UV too? It's probably not a big spectral span from blue to the UV band.

A point light source is supposed to be best for exposing circuit boards.. A projector makes a nice spot. UV tubes radiate radially. I have no idea how this difference in directionally has on the exposure quality.

Anybody seen a spectral graph for those automotive HID lamps? I tried to Google up a spectrum.. Nothing yet.

Note: UV tubes are not easily found around here but I'm surrounded by scrap yards.. :)

D from BC

Reply to
D from BC
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As far as I know, the HID stands for High Intensity Discharge - in other words they are compact arc lamps.

The envelope is probably doped to block the hard ultra-violet component.

Note that arc lamps are something of swine to drive - the slope resistance tends to be slightly negative, so you need a releatively high impedance source. On eof my old colleagues developed the drive circuit that BMW used when they first introduced the lamps - if you get the lamp from a junked top-end BMW, don't forget to get the drive circuit at the same time.

-- Bill Sloman, Nijmegen

Reply to
bill.sloman

Philatelic supply houses sell UV lamps with a shade that sends most light down. Some of them are even dual wavelength.

Tam

Reply to
Tam/WB2TT

I've used warehouse-type mercury vapor lamps to expose pcb's. A 175 watt lamp, about 3 feet above the board, is close to a point source and exposes a KPR-coated board in 3-5 minutes. I removed the reflector from the fixture, mounted it so that the tube is horizontal, and silvered the top of the tube with a piece of aluminum foil, all of which directs the light down and keeps the source size small. It casts nice sharp shadows.

I don't understand why so many people want to make light boxes, which have terrible optics. I guess they enjoy carpentry.

John

Reply to
John Larkin

Hopefully the drive circuit is easy to pull out and is not buried somewhere in the BMW.

D from BC

Reply to
D from BC

Speaking of light boxes... I had the crazy idea of turning a school overhead projector into a sort of light box. I think that would make a nice spot with low angle light (coherent I think is the word). The light source would be replaced with something with sufficient UV such as halogen, mercury vapor or perhaps UV tubes..

D from BC

Reply to
D from BC

Collimated.

Dude, if you're from BC, you must have TONS of "botanical supply stores" that sell UV gro-lamps.

Reply to
a7yvm109gf5d1

They only sell gigantic pot lighting systems.. No small scale.. Just kidding... :P I might check it out.. There's a shop just down the street.

I did a 10 second search to check my vocabulary on coherent light.

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"Coherent light comes from very small light sources."

The school projector optics would do the collimating to make near coherent light..

D from BC

Reply to
D from BC

That web page is nonsense.

No, a thermal or conventional gaseous source, or an led, is incoherent. Lasers make coherent light, but don't have to be very small. NIF uses coherent lasers that are about the size of sewer pipes.

John

Reply to
John Larkin

Ahh... Often I see the word 'coherent' used to describe laser light but not for anything else. So..what's a good word to describe the directivity of light?

1/2 intensity view angle? I'm probably misusing the word coherent. More or less coherent is probably like saying more or less black. Or more or less true.

D from BC

Reply to
D from BC

I never understand why people etch boards rather than have them made. I guess they like the chemicals :)

Reply to
Brian

I agree. You can get maybe 4 pieces of plated-through boards for about $60.

Once you get FeCl under your fingernails, it pretty much has to grow out.

John

Reply to
John Larkin

I fk up a lot so I make my own boards. :) And.. I get my boards made on weekends, holidays and late at night. And.. I have my boards ready in about 1 hour. Other DIY pcb makers are even faster. 10 minutes should be possible.

10 mil tracks..no problem. Also..some homebrew etchants use cheap off the shelf chemicals without using ammonium persulfate nor ferric chloride. But, for quality, vias, multilayer,I'd go to a pcb fab house after I've worked out the bugs with my own boards.

D from BC

Reply to
D from BC

Get a wife.

--
Thanks,
Fred.
Reply to
Fred Bartoli

Yabbut, to you, $60.00 is pocket change. And I only need one prototype, which is probably going to get hacked anyway.

Idiot! You're not supposed to soak your hands in the stuff! ;-)

Cheers! Rich

Reply to
Rich Grise

Some years ago people had success using sunlight. Claimed it worked better than cheap lights. I have used EPROM erasers.

Tam

Reply to
Tam/WB2TT

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John

Reply to
John Larkin

In those links I also picked up 'angular spread' to add to my collection of technical jargon.. :)

Oops..coherence is an addition/subtraction/interference due to phase difference. Something I see in electronics. (Analog summing circuits.)

Ohhh...collimated or beam divergence are the proper terms.. " To produce usefully collimated light, the light source must approximate a point; that is, it must be small relative to the optical system, like the image of the star formed by a mirror."

D from BC

Reply to
D from BC

It rains here for about 4 to 6 months during the winter season.

D from BC

Reply to
D from BC

I've used sunlight in sunny southern California. :-)

Just look for a "germicidal" fluorescent tube (and probably fixture) at your local household goods shop.

I also have an EPROM eraser for sale. ;-)

Good Luck! Rich

Reply to
Rich Grise

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