Flexible Printed Circuits

Flex circuits are flexible membrane switches made by either etching or screen-printing. Due to their thinness and ability to bend, they are often used in space-constrained applications where no other switches can fit. Flex circuits also help to solve interconnect challenges. Flex circuits eliminate the need for bulky, expensive wires and connectors, and offer a repeatable, reliable method of connecting things.

FPC provides two main types of flex circuits: Copper Flex and Silver Flex circuits.

Copper Flex Circuits

Copper Flex Circuit

Copper flex membrane switches are similar to normal membrane switches in that they are made of conductive metal traces on a thin film substrate. However, they differ in one major way: rather than directly printing the traces on, the traces are formed by chemically etching a copper-clad substrate. Chemical etching involves the use of harsh chemicals, hence copper flex circuits are much less environmentally friendly than screen-printed silver circuits. In addition, since more copper is used than needed (due to the lamination process), copper flex circuits lead to higher costs and greater wastage.

However, copper has significantly lower resistance than silver ink. Hence, copper traces can be made thinner, resulting in a much smaller, lighter, lower resistance switch. Copper flex membrane switches use either polyester (PET) or polyamide (Kapton) as the membrane substrate.

Silver Flex Circuits

Silver Flex Circuit

Silver flex circuits are flexible membrane switches made by screen-printing silver ink onto flexible polyester film sheets. Since silver flex circuits do not use an etching process, the use of harsh chemicals is eliminated, making silver flex circuits much more environmentally-friendly and more affordable than copper flex circuits.

However, silver flex circuits have a higher resistance than their copper flex counterparts, hence the decision to choose either option should be based on the needs of each individual application.

When Should I Choose Copper Flex Circuits?

You should choose copper flex circuits if you need:

Otherwise, we recommend choosing silver flex membrane switches instead, as they are significantly more environmentally-friendly and affordable option.

Features and Benefits of Silver Flex Membrane Switches