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40 PCB007 MAGAZINE I MARCH 2021 Dunn: ank you. Let's start the conversation with aluminum. What are the benefits of alu- minum over other metals? Kadiwala: Aluminum is the most abundant metal in the earth's crust. is makes it more easily available and less expensive compared to other metals. It has different benefits when compared to other metals based on the field of use. For example, in automobiles, its superior strength at lower weight is a significant ben- efit against iron and its common alloy—steel. But in the field of printed electronics, its main competitor would be copper. Aluminum is more than three times light- er than copper. It has 68% of the conductivi- ty of copper but has only 30% of the weight of copper. is means that a bare wire of alumi- num weighs half as much as a bare wire of cop- per that has the same electrical resistance. is makes it the metal of choice for high voltage transmission cables. Also, it is three times less expensive than copper on an equal weight ba- sis and six times less expensive on an actual us- age basis. is is the biggest advantage that alu- minum has over copper. Dunn: Interesting. Why do you think aluminum is attractive specifically for automotive appli- cations? Kadiwala: Aluminum has been a boon for the automobile industry. Like any industry, the automobile industry has evolved due to various geo and politi- cal reasons over its 100-plus-year his- tory. Whether it's the oil embargo of the 1970s or global warming due to climate change, it has been constant- ly under pressure to improve fuel effi- ciency standards. e easiest way to improve fuel effi- ciency is to reduce the dead weight of the automobile and improve the effi- ciency of the internal combustion en- gine. Aluminum helps reduce an auto- mobile's body weight by providing su- perior strength at lower weight when com- pared to steel and other alloys of iron. It also helps improve engine efficiency by providing better performance at lower weight. Since most automobiles have their body and chassis made of aluminum, the integration of onboard electronics to aluminum is critical. Averatek's Mina can provide a soldered con- nection to aluminum without any plating or surface finish. It can help ease manufacturing and reduce costs. Dunn: Aluminum has historically been difficult to assemble to. What are the challenges of sol- dering to aluminum? Kadiwala: Aluminum PC boards, whether rig- id or flex, are limited in use due to challeng- es associated with soldering components to aluminum pads. is is because all aluminum surface is covered with a layer of aluminum oxide. Although self-limiting, this oxide layer cannot be overcome by flux in existing solder systems during reflow. It thus prevents the for- mation of a metal-to-metal bond. Even if this oxide layer is removed using etchants and flux- es, a new layer forms in situ upon exposure of clean aluminum to the atmosphere. is pre- vents the use of conventional SMT methods for attaching SMDs to assemble PC boards. An example of aluminum over copper.