Homebrew_PCBs

Hi,

Does anybody has access to the sensibility chart related to wavelength
of exposing light source ?
I would like to know if a KES-400AAA PS3 laser module
(http://www.fineartradiography.com/hobbies/lasers/blu-ray/) would be
usable to directly expose the photoresist from a pcb.
This laser diode has a wavelength of 405nm (it's not uv is near uv)
but maybe it would impress the resist from pcb at an acceptable
exposure time.

Any comments are greatly appreciated.

Daniel

It is OK.
Cristian

>Does anybody has access to the sensibility chart related to wavelength
>of exposing light source ?
>I would like to know if a KES-400AAA PS3 laser module
>(<http://www.fineartradiography.com/hobbies/lasers/blu-ray/>http://www.fineartradiography.com/hobbies/lasers/blu-ray/)
>would be
>usable to directly expose the photoresist from a pcb.
>This laser diode has a wavelength of 405nm (it's not uv is near uv)
>but maybe it would impress the resist from pcb at an acceptable
>exposure time.

[Non-text portions of this message have been removed]

IMHO it should work, but you are aware that you would have to expose
every pixel for quite a while with the beam and thus the overal exposing
time would be alot higher. I mean I would love to look at such an
aproach etc.

Just my 2¢

Markus

dandumit schrieb:

The following article may be of interest
http://www.circuitree.com/Articles/Column/18623649067d7010VgnVCM100000f932a8c0____


"dandumit" <dandumit@...> wrote:

warrenbrayshaw - Thanks ! indeed the article is very close to what I
was searching.
It seems that the peak sensitivity is around 370 nm and some resists
are better at 405nm. I have found on a forum about using laser diodes
from BlueRay players that they have achieved 60mW and more (depending
a lot on optics used).
In order to see how much time is needed to LDI an pcb we must see how
much time should be exposed. Also on net I have seen that various
photoresists and soldermasks needs about 100 mJ/cm2 exposure (I have
seen some with 10mj and some with 200mj).

Considering such a laser diode focused on a 0.1 mm diameter spot
(that's other issue because a laser diode doesn't generate a circle
spot) means = 3.14*(0.05)^2 = 0.00785 mm2 =~
0.008mm2=0.000008cm2=8*10-5 cm2

100mJ/cm2 means equivalent 0.008mj/0.008mm2

0.008mj means 0.008mW-Second. the blueray diode has 60mW this would
mean that it could "expose" 7500 spot's per second.
a pcb of 320mm wide would be exposed with a speed of 0.2mm per second
if the pcb is 320mm long it would take 1600 seconds ~ 27 minutes.
A higher sensitivity resist would reduce the time.

If someone could tell me if I am wrong or what could go wrong in this
calculation please don't hesitate to contribute.
Until now I don't know if it is possible to focus that diode to
0.1mm2. In disc readers the track width it's more narrower.

Regards,
Daniel



--- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
<warrenbrayshaw@...> wrote:

>
> The following article may be of interest
>

http://www.circuitree.com/Articles/Column/18623649067d7010VgnVCM100000f932a8c0____