Scribing Gold-Coated PET Plastic

When manufacturing thin dielectric devices like some types of capacitors, a conductive surface coating is applied on a sheet of insulator material and then a pattern is scribed to create the desired capacitance effect when the component is fully formed. In this particular application involving flat sheets of polyethylene terephthalate (PET) film coated with a very thin layer of gold, the requirement was to laser scribe a series of circles so that the conductive gold coating was separated into two different charge regions.

Although gold is usually completely reflective at the 10.6 µm CO₂ laser wavelength, the gold coating on the PET substrate was thin enough that we were able to completely ablate, or remove, the gold coating off the PET due to the kinetic energy generated by the CO₂ beam hitting the surface.

A Synrad 30 W laser along with a Flyer marking head, equipped with a 125 mm focal length lens, and our WinMark Pro laser marking software was used for this project. This setup produced a focused spot size of 180 µm (0.007") on the gold-coated surface. The WinMark Pro mark file consisted of two circular objects measuring 6.35 mm (0.25") and 8.89 mm (0.35") in diameter connected by two polylines. The Power property for all of these objects was set to a duty cycle equivalent to 30 W and the Velocity was set to 1016 millimeters per second (40 in/sec.).

The resulting scribe mark, completed in a cycle time of only 50 milliseconds, cleanly removed the gold coating to expose the white PET surface underneath. After the laser ablation process, a conductivity test was performed to ensure full removal of the gold coating by verifying the conduction path between the separated regions was broken.

Cutting Layered Bandage Material

Most organic fabric materials can be cut very well with CO₂ lasers due to good absorption of the 10.6 µm wavelength. One of the main advantages of laser cutting is that there are no frayed edges unlike traditional knife cut edges. In addition, the edges of some materials can often be sealed due to the heating generated by the laser cutting process.

In this particular application, the requirement was to cleanly cut one inch squares out of a larger sheet of 0.2 mm (0.008") thick bandage fabric. The bandage material itself is a multi-layered composite, consisting primarily of poly-films and polyurethane foam. Initial testing confirmed the material was cut with almost pure vaporization and very little melting (no assist gas was required), so an FH Flyer marking head could be used to achieve the high-speeds demanded by the process.

The Synrad test setup consisted of a 60 W laser and an FH Flyer marking head (equipped with a 125 mm HP focal length lens)—all controlled by our WinMark Pro laser marking software. This setup produced a focused spot size of 180 µm (0.007") on the fabric surface. The mark file consisted of a rectangle object measuring 25 mm x 25 mm (1" x 1") with its Power property set to a duty cycle equivalent to 60 W and the Velocity property set to 305 millimeters per second (12 in/sec.).

The resulting cut was completed in only 330 milliseconds per square. As seen in the photo, the cut edges are clean and free of discoloration and fraying.

Firestar i401 Now Available

Orders are now being accepted for Synrad's latest 400 W laser, the single-tube Firestar i401, with production units currently being built for delivery in December.

The Firestar i401 laser with its all new high-performance, single-tube resonator design provides 400 watts of near-perfect beam quality with rise times less than 100 microseconds at duty cycles as low as 10% all the way up to 100% (full CW operation). Internal beam conditioning optics condition, align, and rotate the linearly polarized beam so the output plane of polarization is at a 45° angle to the baseplate. This feature means a simple, low-cost reflective phase retarding mirror is all that is necessary to create a circularly polarized beam at the work surface. The i401 is driven by four integrated field-replaceable RF modules that eliminates the need for RF cables and external amplifier units and simplifies installation on moveable gantries and robotic motion systems.

Not sure if an i401 is right for you? The Synrad Applications Lab is now equipped with the new Firestar i401 and is ready to process your samples. Contact your Synrad Regional Sales Manager to discuss sample submission for testing and how the i401's near-perfect beam quality and fast rise/fall times can help increase your throughput and product quality.

Click here to see detailed specifications or download the Firestar i401 Operator's Manual to get a head-start on integrating the i401 into your laser processing system.