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84 SMT007 MAGAZINE I AUGUST 2019 Feature by Garrett Wong NORDSON ASYMTEK, and Jinu Choi HENKEL ELECTRONIC MATERIALS LLC Abstract Shielding electronic systems against electro- magnetic interference (EMI) has become a hot topic. Technological advancements toward 5G standards, wireless charging of mobile elec- tronics, in-package antenna integration, and system-in-package (SiP) adoption are driving the need to apply more effective EMI shield- ing and isolation to component packages and larger modules. For conformal shielding, EMI shielding materials for exterior package sur- faces have mostly been applied with a physical vapor deposition (PVD) process of sputtering, leveraging front-end packaging technologies to back-end packaging applications. However, sputtering technology challenges in scalabil- ity and cost along with advancements in dis- pensable materials are driving considerations for alternative dispensing techniques for EMI shielding. The authors will discuss the development of a spray coating process to apply EMI shielding materials to the exterior surfaces of individ- ual components on strips and larger SiP pack- ages. Using newly developed and enhanced materials and equipment for this industry, a process was demonstrated that provided uni- form coating on packages in the sub-10-μm thickness range with consistent coating thick- nesses around package corners and package sidewalls, producing a top surface-to-side- wall thickness ratio of 1:1. Further investiga- tion showed decreased production costs for applying EMI shielding to component pack- ages by increasing spray-coating productivity and by selectively applying the coating to spe- cific areas of packages. Additionally, low capi- tal-equipment expense and shorter lead times for spray coating equipment improved the abil- ity to scale up production capacity compared to sputtering equipment. In mobile electronics packaging, several SiP- module manufacturers are challenged to iso- late components within the SiP from each other and from their exterior for EMI shield-

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