Single Sided Flex Circuits One single conductive layer, either bonded between two insulating lamination or uncovered on one side. | 
| Double Sided Flex Circuits Two conductive layers with an insulating layer between, plus cover layers on outer layers. They can be fabricated with or without Plated through holes (PTH). Plated through holes (PTH) provide connection. |
Multilayer Flex Circuits Three or more flexible conductive layers with flexible insulating layers between each one; which are interconnected by way of plated through holes (PTH). | | Multilayer Rigid-Flex Circuits Consisting of rigid and flexible substrates laminated together into a single package and electrically interconnected by plated through holes (PTH). Outer layers may have covers or exposed pads. Rigid-flex is differentiated from multilayer circuits with stiffeners by having conductors on the rigid layers. Plated through holes extend through both rigid and flexible layers. |
