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92 SMT007 MAGAZINE I AUGUST 2019 ductive paste with optimal rheology is jet dis- pensed (Paste C). Jet dispensing offers some significant advan- tages in terms of process controls as well as productivity when compared to auger valve dispensing. In addition to increased produc- tivity, jet dispensing also allows for smaller discrete dots of fluid to be dispensed. Lead- ing-edge technology in jet dispensing provides excellent control for the in-air stream width of the fluid and better enables further improve- ments for new trench-fill applications as the SiP packages continue to narrow the trenches and increase the depth to width ratio. With further improvements in fluid formu- lation to meet requirements for jetted line thickness, width, and surface adhesion, it is expected that jet dispensing will open the doors for further improving selectivity cover- age and enabling new packaging structures. It is also possible that jet dispensing conductive pastes will allow for more additive manufac- turing techniques and make possible for new applications such as flexible circuit trace print- ing or on-package antenna printing (Figure 9). Conclusion Sprayed EMI shielding has become a via- ble and attractive alternative to sputter coat- ing. Advancements in material formulations, as well as the methods of applying these mate- rials, allow for comparable performance and thickness as sputter coating. In addition, spray coating offers far more flexibility for different types of substrates that can be coated as well as allowing for greater selectivity for placement of the shielding material. Through optimiz - ing the spray coating process and patterning, spray can achieve a comparable or better cost per unit when compared to sputter coating. Spray coating further offers superior scalability for growing production capacity with low capi - tal investment. Lastly, further innovation in the dispensing of shielding materials is leading the way for highly precise shielded areas and con - ductive trace creation through jet dispensing. Acknowledgments The authors would like to recognize and thank the applications and engineering teams at the companies for generating test sam- ples and for your process optimization work in support of this paper. Specifically, we wish to thank Timothy Burner, Xinpei Cao, Noah Ekstrom, Juan Gomez-Garcia, Shawn Liang, Jaynie Park, Andrew Sun, and Mike Szuch for their contributions. SMT007 References 1. R. Urmi, N.J. Cho, Y.C. Kim, S.W. Yoon, W.K. Choi, P. Mari- muthu, "Packaging and Integration Strategy for mm-Wave Products," IMAPS 14 th International Conference and Exhi- bition on Device Packaging, 2018. 2. S. Djukic, "5G, From Anywhere: Overcoming The Challenges of Indoor Connectivity," Electronic Com- ponent News, May 7, 2018. 3. M. Szuch, A. Morita, G. Wong, M. Sakaguchi, H. Umeda, "EMI Shielding: Improving Sidewall Coverage With Tilt Spray Coating," IMAPS 13 th International Conference and Exhibition on Device Packaging, 2017. This paper was first presented at the IPC APEX EXPO 2019 Technical Conference and published in the 2019 Technical Conference Proceedings. Garrett Wong is senior product manager at Nordson ASYMTEK. Jinu Choi is market segment head, semiconductor packaging materials (AES), at Henkel Electronic Materials LLC. Figure 9: Jetted lines of conductive paste approximately 300 µm wide.