Once the design parameters for the project are talked through, electrical engineers at BTI begin to design the flexible circuits. They consider things like how much electrical current is going to be needed to run the device. Electrical engineers use the design parameters to create the circuit as fine lines or as wide as required. Typically flex circuits used in membrane switches are pretty wide. On the other hand, fine line circuits are designed for products like printed sensors and antennas.
BTI can produce FHE circuits that are 1 or 2-sided with multiple layers per side achieved by incorporating thru-hole and blind vias. Once the circuit is fabricated, a highly functional device can be created by placing surface mount components and connectors.
Common materials used in flexible circuit design are heat stabilized polyester or PET, synthetic paper, polyimide, and thermoplastic polyurethane or TPU. Inks are selected based on conductive requirements. Usually, the inks in a flexible circuit are silver, carbon, copper, PEDOT, and dielectric or insulating. Some products also require a carbon overprint for added durability and to prevent any silver ink from moving. Also, depending on the design, there are specialty inks like PTC or FSR carbon ink.
BTI can print very fine line traces and spaces, allowing for high-density, flexible circuitry through Vility CCD registration screen printer equipment. The smallest traces can be as fine as 50 microns, which is smaller than the text on a penny!
