Lasers come in many different flavors and can be used for many different
purposes.
Basically lasers are a single wave length light beam which is typically
focused into a small spot. The shorter the wavelength the smaller the
theoretical minimum spot size, allowing for higher detail markings or
cutting. Higher power and/or a smaller spot increase the energy density.
With low energy density you can warm up the subject locally, with higher
density you can melt or burn it and with very high energy densities you can
ablate the material, which means that you explosively remove layers of the
material which is turned into dust. The properties of the materials and the
wavelength of the laser will make a difference in this process.
(1)Some marking can be done by placing a second temporary layer of material
on the subject and by using heat transfer some of that material onto the
subject.
(2) With higher power you can burn (or engrave) the desired information into
the material. This is commonly done on your stainless steel stencils and the
color difference between the raw material and the burned material allows you
to read the text.
(3) Ablating removes material cleanly and in homogenous material the text
may be hard to read. On the other hand if you have a white base material
with a dark coating you can locally remove the coating and get a nice high
contrast with minimum damage to the base material. On circuit boards you
could have a small area with solid silk screen in which you write the
desired text with minimal damage to the board.
Solutions 1 and 3 do not damage the circuit board, while solution 2 leaves
burnt marks in the board and possibly leaves conductive residue.
As for implementing any of this with existing equpment, I have no clue.
Have fun and choose wisely,
Ahne.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, 25 July, 2007 05:36
To: [log in to unmask]
Subject: Re: [TN] Laser marking for PWBs
Thank you! Any others care to respond on their experiences with laser
markers?
-----Original Message-----
From: Gumpert, Ben [mailto:[log in to unmask]]
Sent: Wednesday, July 25, 2007 6:16 AM
To: Stadem, Richard D.; TechNet E-Mail Forum
Subject: RE: Laser marking for PWBs
I wasn't too involved in the process, but we recently procured and are using
a system from Control Micro Systems
(http://www.cmslaser.com/pcb/html/pcbmarking.php). We validated its use on a
variety of board types and other materials. It's CO2, so it won't etch
metals, but if needed, a coat of ink can be applied to metal surfaces which
is then permanently 'cured' on where hit by the laser.
Ben
-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Wednesday, July 18, 2007 2:35 PM
Subject: Laser marking for PWBs
Hi folks,
I am looking at purchasing a laser marking system for the purpose of laser
etching the board serial number, part number, etc.
I have little experience with this type of process, and which systems are
better than others, etc.
Any feedback you care to share with me? Labels and ink stamping are not an
option in this case.
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