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74 DESIGN007 MAGAZINE I APRIL 2020 can be stored to prepare for assembly because cured Mina™ remains stable, or the boards can go straight through the component assembly process wherein solder will be printed onto the pads, followed by loading of components in the pick-and-place and then reflow. Mina™ activates during the reflow cycle and ensures a good solder joint to the core aluminum. The unique thing is that the solder selec- tion depends on the substrate. A common use of aluminum is associated with aluminum on PET substrates or Al-PET substrate. PET can- not withstand high temperatures for an ex- tended time, so low temperatures solders be- come the only option. Dunn: This appears to significantly simplify the current standard process. Are there other ben- efits of Mina™ that we should be aware of? Kadiwala: Yes, there are several benefits to us- ing Mina™. It is green because it eliminates several wet chemistry process steps that would otherwise be needed to solder to an aluminum pad. It also widens the scope for the use of Al- PET substrates. These are often limited to in- expensive applications like RFIDs that are as- sembled using silver epoxy. With the ability to solder components, Al-PET substrates can now replace single layer copper-based circuits for applications like smart tags, LEDs, and other applications. Overall, aluminum is about one- third of the cost of copper, and when com- bined with the cost-benefit of PET film over polyimide, it is one-eighth the cost of copper on a usage basis. This is a significant cost sav- ings. From a performance perspective, soldered joints are electrically superior and more reliable than those made using conductive epoxies. Dunn: What industry segments do you see as the early adopters of this technology? Kadiwala: From our conversations, I expect that the early adopters will be those indus- tries that are already using Al-PET substrates. Again, these include smart tags, LEDs, auto- motive, RFIDs, and those using aluminum for EMI shielding and similar applications. Once these adopt, we will start targeting other con- ventional copper-based circuits that will be driven to aluminum for its cost advantages. Dunn: Is Mina™ commercially available at this time? Kadiwala: Yes, it is available now. It has been qualified for use by some customers and is un- der testing at others. Dunn: What type of testing and development has been completed? Kadiwala: The testing and development are always specific to the end application of the product. Mina™ has passed the surface insu- lation resistance (SIR) test. This was done at an independent lab per IPC specifications. We routinely do shear tests to confirm adhesion while qualifying new solders. We get shear val- ues that are greater than 15 N/mm2, and typi- cally, failure mode is between the aluminum and PET film. We also examine the joints using X-ray to examine for voids. The voids are con- sistently within expected norms of less than 30%. It has been tested and qualified for use in soldering to aluminum for an EMI shield- ing application. Further, it is undergoing test- ing for LEDs, smart tags, and automotive ap- plications. Dunn: Will there be any specialized equipment, or storage or handling procedures that will need to be addressed before bringing this into a manufacturing environment? Kadiwala: Mina™ is very simple to use and re- quires no special handling other than com- mon PPE per best practices when handling a Mina™ activates during the reflow cycle and ensures a good solder joint to the core aluminum.

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