| Laser
Marker Applications
A.
Uses of Laser Markers - Handler, X-Y, & Shoot Down
Laser markers are proliferating in industry. They are used to put
part numbers, lot codes, date codes, performance codes, expiration
dates, etc. on all sorts of materials. Usually, these markers are
integrated into the production line for mass-produced materials.
In the electronics industry, laser markers are gaining acceptance
for marking bare wafers and finished packaged I.C.s. Exatron is
targeting this last application for its most intense marketing
efforts.
Our gravity-feed handlers integrate laser markers for scribing
part numbers, lot codes, performance ratings, etc. on the tops
of integrated circuit packages. Currently, the 8000, Stacker, and
900
have a laser
marker.
Exatron also manufactures a manual-load x-y table marker. This
is for marking I.C.s in standard JEDEC trays - mainly QFP, PQFP
and TSOP parts. The moving tray mount adjusts the position of the
tray under the stationary laser. Given that the laser currently
can mark in a two-inch square field, it is possible to mark several
I.C.s without moving the tray.
Finally, Exatron manufactures "shoot down" lasers for integration
into existing or newly manufactured production lines. The typical
application would be an automated PCB fabrication or stuffing line.
As PCBs move from one station to another, they could move under
the laser and be marked. Please keep in mind that Exatron's small
shoot-down laser can be used in non-I.C. applications, including
food packaging, wood burning, etc.
B. Types of Marking
Systems - Scribing v. Stencil
| Scribing |
|
Stencil |
| Slower
operation |
|
Very fast
operation |
| Much more
flexible |
|
Inflexible |
| Does not
require stencils |
|
Needs
a supply of pre-cut stencils |
Uses low-power lasers
- less expensive to purchase
- lower power consumption
- less expensive to operate
- less expensive to maintain
|
|
Uses higher power lasers
- more expensive to purchase
- higher power consumption
- more expensive to operate
- more expensive to maintain
|
There are two main types of laser markers: Scribing and Stencil.
Of these types, Exatron only produces scribing laser marking systems.
A scribing laser system uses a thin beam of light the point of
which is moved on the surface of the target. Scribing lasers employ galvanometer-mounted
mirrors to move the laser beam.
Stencil markers use a stencil through which a wide-area laser
beam is projected to mark the image of the stencil on the target.
Scribing lasers are much more flexible. Scribing lasers can change
their marks "on the fly" which means that every time the laser
shoots, it can write something different. Scribing lasers can efficiently
mark date codes, performance results, serial numbers, and other
items which will change often as no pre-cut stencils are employed.
The ease with which scribing laser marks can be changed is very
helpful in production environments where small lots are regular.
Given that a scribing laser uses a beam with a fine point, the
amount of power it requires to mark a given surface is less than
a stencil laser whose beam is much less focused. Thus, the power
consumption and safety of a scribing system are superior.
The disadvantage of the stencil marker is the high power required
to run the laser, and the need for stencils. Every time the mark
changes, a new stencil is required. The use of stencils precludes
marking date codes, lot numbers, performance results, etc.
The main advantage of a stencil system is the speed with which
it can operate. The stencil system takes only one burst of the
laser to mark its stencil; this is much faster than a scribing
laser which must write out each character.
C. Types of Lasers
- CO2 and Nd:YAG
Exatron uses two types of lasers in its scribing marking systems
at present. These are the Carbon Dioxide gas
laser (CO2) and the Diode-pumped Nd:YAG solid
state laser. Each has its advantages and disadvantages. Please
refer to Section IV. for a description of the differences between
these two lasers. Section V explains the difference between the
old-fashioned Flashlamp YAG
and the new style Diode-pumped YAG.
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