John P. Anhalt:
Your point is well-taken.
Infrared (IR) is on one side of the visible spectrum, and
Ultraviolet (UV) is on the other side. Big differences in wavelength
between the two.
I think that most, if not all photoresist materials
polymerize when exposed to UV.
The mixup might come from the commercial names given to
various light sources (especially consumer reflector-type lamps)
commonly available.
Most "heat lamps" are Infrared (IR).
Most "sun lamps" are UV.
Physically, the reflector type lamps look alike.
High intensity reflector-type sun lamps (UV) are getting
more difficult to find, what with all the hoopla about
skin cancer, etc.
Sun lamps generally carry caveats regarding overexposure,
eye protection and the like.
The old Kepro system I used many years ago with Kodak KPR
photoresist material used an IR oven (heat) for drying the resist, and
UV for
photographic exposure.
The IR had no effect on the resist insofar as polymerization was
concerned.
Roland F. Harriston
John P. Anhalt wrote:
>
> Thanks for the information, Richard.
>
> That is interesting. In graduate school, we used "sun lamps" for near
> UV. The reactions we were studying were similar to what I understand
> is the basis for most positive-resist boards. I am surprised there is
> enough absorption of "infrared" to make the photochemical reaction go,
> or alternatively, enough near UV from an infrared lamp. Does the lamp
> have a reddish glow, or is it a brighter white? If you have the actual
> lamp number (which should be printed on the face of the lamp), I will
> check it out.
>
> John
>
> ----- Original Message -----
> From: Richard
> To: Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> Sent: Sunday, March 04, 2007 5:52 PM
> Subject: Re: [Homebrew_PCBs] sensitized boards
>
> 250 watt 120 volt GE Infared Heat Lamp.
> Spaced 11" from the pc board with an exposure time of 75 to 90
> seconds. I generally do the 90 seconds.
> I bought it at Walmart about 10 years ago and it's still going strong.
>
> Richard
>
> ----- Original Message -----
> From: John P. Anhalt
> To: Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> Sent: Sunday, March 04, 2007 9:11 AM
> Subject: Re: [Homebrew_PCBs] sensitized boards
>
> Richard,
>
> Can you give a little more detail about the heat lamp that you use,
> such as brand, wattage, and identifier number on it?
>
> Thanks.
>
> John
>
> ----- Original Message -----
> From: Richard
> To: Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> Sent: Sunday, March 04, 2007 9:40 AM
> Subject: Re: [Homebrew_PCBs] sensitized boards
>
> I use Infared Light to expose my positive sensitized boards because I
> can expose them in about 90 seconds using a IR heat lamp.
>
> Richard
>
> ----- Original Message -----
> From: docstein99
> To: Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>
> Sent: Thursday, March 01, 2007 11:28 AM
> Subject: [Homebrew_PCBs] sensitized boards
>
> I was wondering if anyone can give me some advice, looking at the
> threads recently it looks like lots of people here have tried
> sensitized boards.
>
> This material appears to be the same stuff as silkscreen printers use
> on silkscreens, where the exposed areas to intense light are hardened
> and the unexposed areas are washed away with water.
>
> Do any of the sensitized boards or materials react to INFRA-RED light?
> I have an infra-red laser diode on a cnc machine, its not powerful
> enough to cut stuff with but will smolder black foams. I was wondering
> if its possible to use that to rastorize the image, but I dont know
> about all the different types of sensitizer or what types of lights
> they react to. I know in screen printing, they make types which react
> to a 4k watt metal halide bulb, and newbie stuff that works with a 150
> watt lightbulb.
>
> [
>