3M Electrically Conductive Adhesive Transfer Tape 9707

Laser Processing of 3M™ Electronically Conductive Adhesive Transfer Tape 9707

Introduction

3M™ 9707 Electrically Conductive Adhesive Transfer Tape (ECATT) is part of a product line of similar materials including 9703, 9705, 9706, 9709, 9709S and 9709SL. The 9707 ECATT product consists of a 50µm thick acrylate adhesive layer, filled with conductive fillers that provide electrical continuity through the thickness (Z-axis) and in the plane of the adhesive (X-Y planes). The acrylic adhesive layer itself is protected with a 50µm thick transparent PET release liner on both the top and bottom surfaces. A diagram depicting the layers of the 9707 material is shown in Figure 1.

3M Electrically Conductive Adhesive Transfer Tape 9707 Layers

Figure 1. ECATT 9707 diagram showing PET liners located on top and bottom of the acrylate adhesive layer. PET layers measure 50µm thick and the acrylate adhesive layer measures 50µm thick.

3M ECATT materials are flexible adhesive tapes. The delicate tacky nature of these materials makes them difficult to process, resulting in deformation of the materials when processed with traditional mechanical methods. The non-contact nature of laser processing overcomes this difficulty, which enables the processing of applications with fine geometry and intricate detail. 3M ECATT materials are only suitable for laser cutting, which produces smooth laser-processed edges and minimal heat-affected zones without degrading the physical properties of the materials. Other laser processes are not suggested as they are not conducive to the intended use of these materials. Universal Laser Systems makes it simple to consistently and repeatedly process these materials to a high degree of dimensional accuracy because the non-contact nature of laser processing eliminates material deformation during processing.

Laser Processing Notes

3M 9707 ECATT was tested to assess laser processing compatibility and determine the best system configuration of laser peak power and wavelength. The PET liners absorb 9.3µm energy more efficiently than other wavelengths, meaning less peak power is necessary to produce good results with minimum heat affects. The acrylic adhesive layer also absorbs the 9.3µm wavelength efficiently with clean edges free of heat affects along the processed path. Microscopy images taken at 400x magnification of the processed edge of the 9707 post-processing, with the liners in place and the liners removed, are shown in Figures 2 and 3, respectively. In these images it is shown that the PET liners contain most of the heat affects and discoloration, while the acrylic adhesive layer itself is relatively free of heat effect and discoloration.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 2

Figure 2. Microscopy image (400x) of the laser-processed edge of 3M ECATT 9707 with the PET liners in place. The heat-affected zone measures 125µm.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 3

Figure 3. Microscopy image (400x) of the laser-processed edge of 3M ECATT 9707 with the PET liners removed from the material. The heat- affected zone measures 25µm.

Further inspection of the material shows that the acrylic adhesive layer is cleanly processed along the path of the laser with a 30 watt 9.3µm CO₂ laser source. Figures 4 and 5 depict 3D-rendered microscopy images of the surfaces shown in Figures 2 and 3. Figure 4 depicts how the PET layer reacts to the laser energy by forming a “wave” of melted material along the top surface of the edge. In Figure 5, the PET liners are removed from the material, showing the smooth flat surface and edge of the acrylic adhesive layer, free of adverse heat effects.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 4

Figure 4. 3D-rendered microscopy image (400x) of the laser-processed edge of ECATT 9707 with the PET liners in place.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 5

Figure 5. 3D-rendered microscopy image (400x) of the laser-processed edge of ECATT 9707 with the PET liners removed.

3M 9707 ECATT was also tested with an alternate system configuration of 10.6µm laser energy at equivalent laser power level for comparison and determination of the effectiveness of each system configuration. 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 Figure 6. Both system configurations appear viable but with some reduction in results quality for the 10.6µm 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 125µm	The 9.3µm laser energy has the advantage of better absorption by the material resulting in a consistent edge along the processed path with a reduced heat-affected zone	Processing of the 3M 9707 material with either the 9.3µm or the 10.6µm configuration did not require additional post-processing
10.6µm	Increased heat-affected zone compared to 9.3µm wavelength, approximately 170µm	This configuration produces a slightly rougher processed edge on the adhesive layer and an increased heat-affected zone in the PET liners when compared to the 9.3µm configuration

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 6a

Figure 6a. Comparison microscopy images (400x) of the processed edge resulting from 9.3µm processing. The PET liners were left in place for both samples.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 6b

Figure 6b. Comparison microscopy images (400x) of the processed edge resulting from 10.6µm processing. The PET liners were left in place for both samples.

Processing Example

3M ECATT adhesive tape applications requiring fine geometry and intricate detail without degrading the physical properties of the material can be achieved with Universal Laser Systems technology. An example demonstrating the results of laser cutting the 3M ECATT 9707 material is shown in Figure 7.

3M Electrically Conductive Adhesive Transfer Tape 9707 Figure 7

Figure 7. Example of the fine geometry possible with laser cutting 3M ECATT 9707.

Conclusion

3M 9707 ECATT is suitable for laser processing and was extensively tested to determine the most efficient processing configuration. Through this testing it was determined that laser cutting is viable with this material and a 30 watt 9.3µm CO₂ laser source is the best configuration of wavelength and power for the processing of this material. The PET liners and acrylate adhesive layer efficiently absorb the 9.3µm wavelength laser energy, and, coupled with the peak power of the 30 watt laser source, produce a clean smooth edge that has minimal heat-affected zone and discoloration. Other materials in this ECATT product line are expected to process similarly.