Bergquist™ Gap Pad® VO is part of a product line of thermally conductive materials including VO Soft, VO Ultra Soft, and VO Ultra Soft-B. The Bergquist Gap Pad VO product is a three layer material consisting of a main layer of silicon that is placed between a rubber coated fiberglass carrier and an EPDM release liner. Bergquist Gap Pad VO is available in a variety of thicknesses from 0.50mm to 6.35mm thick. The 1.0mm thick Bergquist Gap Pad VO was selected for laser testing. A diagram depicting the Bergquist Gap Pad VO material is shown in Figure 1.
Figure 1. Bergquist Gap Pad VO diagram showing the rubber and fiber glass carrier located on top of the main silicone layer with an EPDM release liner on the bottom. The pink carrier layer on top measures 108µm and the blue release liner on the bottom measures 95µm. The silicone layer measures 875µm thick.
Bergquist Gap Pad VO is electrically isolating, thermally conductive, and has the ability to maintain its physical and mechanical properties over a wide range of temperatures, particularly high temperatures, making it a good candidate for laser processing. The delicate nature of this material makes it difficult to process with traditional mechanical methods. The non-contact nature of laser cutting provides a method of processing Bergquist Gap Pad VO without mechanically deforming the material. Universal Laser Systems makes it simple to consistently and repeatedly process this material to a high degree of dimensional accuracy, as the non-contact nature of laser processing eliminates material deformation during processing.
Laser Processing Notes
Bergquist Gap Pad VO was tested to assess laser processing compatibility and determine the best configuration of peak laser power and wavelength. The three layers of the Bergquist Gap Pad VO absorb 9.3µm energy more efficiently than other wavelengths available from Universal Laser Systems, producing a processed edge with minimal heat affects. This means that the laser cutting of this material can be performed at higher speeds with minimal discoloration, further reducing the heat-affected zone. With the configuration of 150 watts of 9.3µm laser energy, laser cutting of Bergquist Gap Pad VO produces a consistent edge. Laser processing of Bergquist Gap Pad VO produces a nominal amount of debris along the processed edge, requiring minimal post-processing. A microscopy image taken at 300x and a 3D-rendered image illustrating the contour of the processed edge of the Gap Pad VO is shown in Figures 2 and 3, respectively.
Figure 2. Microscopy image (300x) of the edge after laser cutting Bergquist Gap Pad VO post-processing. The heat affected zone measures 125µm. The material was processed with both liners in place.
Figure 3. 3D-rendered microscopy image (300x) of the edge after laser cutting Bergquist Gap Pad VO.
Bergquist Gap Pad VO was also tested with an alternate system configuration of a 150 watt 10.6µm laser. The results of these tests were compared by analyzing the heat effects, quality of the processed edge, and post-processing requirements. The results of the comparison of these system configurations are listed in tabular form in Table 1 and shown photographically in Figures 4 and 5. The 9.3µm wavelength configuration produces a noticeably better edge when cutting this material and is the recommended configuration.
Table 1. System Configuration Comparison
System Configuration
Heat-Affected Zone
Process Characteristics
Post-Processing Requirements
9.3µm (Recommended)
Minimal heat-affected zone of approximately 126µm
This configuration results in a smooth edge that exhibits minimal heat effects and discoloration
Post-processing requirements include the removal of slight deposition from the surface using light abrasion
10.6µm
Increased heat-affected zone of approximately 175µm.
This configuration results in increased discoloration and heat effects along the processed edge
Figure 4. Microscopy image (300x) of the edge quality produced with the 9.3µm laser. The heat-affected zone measures 126µm. The material was processed with both liners in place.
Figure 5. Microscopy image (300x) of the edge quality produced with the 10.6µm laser. The heat-affected zone measures 175µm.
Processing Example
Bergquist Gap Pad VO applications requiring fine geometry and intricate detail without degrading the physical properties of the material can be accomplished with Universal Laser Systems technology. An example demonstrating the results of laser processing Bergquist Gap Pad VO material is shown in Figure 6.
Figure 6. Example of the geometry possible with laser cutting of Bergquist Gap Pad VO.
Conclusion
Bergquist Gap Pad VO is suitable for laser processing and was extensively tested to determine the best processing configuration. Through this testing it was determined that laser cutting is a viable with this material and that the 150 watt 9.3µm CO2 laser is the best configuration for the processing of this material. The Bergquist Gap Pad VO efficiently absorbs the 9.3µm wavelength laser energy to produce a processed edge that has minimal heat-affected zone and discoloration.
