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90 SMT007 MAGAZINE I AUGUST 2019 Furthermore, as illustrated in Figure 6, new spray shielding materials from Henkel also provide robust adhesion on various substrates commonly used across a wide range of elec- tronic design applications, including polyimide films used in flexible PCBs. Thus, spray coat- ing for EMI shielding can further be applied to a broader scope of applications than could pre- viously be considered. Cost Advantages of EMI Spray Coating As EMI shielding continues to expand into wider markets and applications, manufactur- ers are paying close attention to the costs for starting EMI shielding production and weigh- ing their options. One of the downsides of sputter coating is the significant cost of the capital equipment and associated floor space and operating cost. A typical sputter coating production line may require floor space on the order of 60 m 2 . Productivity with such equip- ment for a package that is 25 mm x 25 mm can roughly reach 1,500 units per hour (UPH). With the price of the equipment into the mil- lion-dollar range, the initial capital expenditure to start a production line and to further add capacity can easily be problematic for contract manufacturers with varying production load- ing from their end customers. By comparison, a spray coating process is far more scalable and flexible. A typical spray coating platform will require ~1 m 2 in floor space. A batch curing oven will typically run ~1 m 2 or an inline curing oven can be added for greater automation but at the trade-off of additional floor space. A single batch oven can typically serve curing parts from multiple spray coating platforms. Spray coating equip- ment with the batch oven can be sourced for a fraction of the cost of sputter coating equip- ment. A single spray coater can produce com- Figure 5: Adhesion testing and reliability of EMI spray shielding material. Figure 6: Substrate adhesion flexibility of spray shielding materials.