Thick-film – a mature technology at the cutting edge of advances in the electronics industry

Abstract

For decades, thick-film technology has proven to be a dependable, cost-efficient method for highly reliable electronic circuitry and components. Hybrid microelectronics was the first major application for fired thick-film materials, finding its way into military and aerospace applications, where reliability is paramount. Inner and outer electrodes for passive components have been another traditional thick-film market. One of the main advantages of thick film is that it is an additive process, where the various conductor, resistor, and dielectric pastes are screen-printed and fired or cured in succession to form the circuit. This results in cost-efficient processing for the circuit manufacturer. Patterned screens are relatively easy to manufacture, allowing for flexibility in circuit design, and screen printing allows for flexibility in feature sizes from hundreds of microns down to 30 microns or less. The main drivers in electronics today are miniaturization – higher circuit density, adaptation to new forms such as 3D and flexible substrates, and ecological factors such as reduced energy consumption, waste reduction, and reduction in the use of toxic substances (RoHS – REACH). Thick film has evolved to address these main drivers and due to its reliability, flexibility, and adaptability, The technology has found new applications. 5G telecommunications utilizes highly conductive silver coatings on signal filters for low losses. Automobiles have historically used thick film technology in fuel/air sensors, air bag deployment sensors, and electronic control units (ECUs). Current vehicles have become computers on wheels and have multiple driver assistance sensors (ADAS), e.g. lane departure warning, blind spot monitoring, automatic braking, regenerative braking, and fully autonomous driving. Both fired and non-fired thick-film technology is enabling these developments. Also in the automotive space, applications include thick film heaters for cabin comfort, heaters keeping ADAS sensors free from frost and snow, and heaters for battery management systems (BMS) in electric vehicles. Polymer thick-film (PTF) pastes for cured (90 – 250o C) electronic circuitry on temperature sensitive polymers have also been around for decades, used in membrane touch-switch keypads and similar circuity. Recently, new applications have emerged for PTF in printed electronics, where the ability to develop flexible, highly durable pastes is enabling new applications in flexible displays, medical monitoring, and performance enhancement in sports. As the megatrends continue to drive the advancement in technologies, the versatility, reliability, and adaptability of thick-film technology is expected to continue to facilitate these advancements. Heraeus Electronics, with its extensive portfolio of thick-film pastes and matched systems, is primed to support these advancements.