Rigid Flex Be Used in MEMS Devices
A rigid flex is a type of printed circuit board that uses a rigid base with flexible copper foils. This circuit board is often used in electronic devices that require high-performance and durability, including wearable electronics, medical diagnostic equipment, and military aircraft instrumentation. Rigid flex can also be found in vehicle infotainment systems and industrial automation.
The most common rigid flex applications use the conductive foils as electrodes, with a rigid substrate supporting the conductive layers. The electrodes can be driven by electrostatic, piezoelectric, or thermal actuation. The drive mechanisms influence the voltage, response time, life cycles, and other properties of the device.
One of the main benefits of rigid flex is that it can be made with low-cost materials and processes. This makes the technology more accessible for manufacturers who want to produce flexible MEMS devices. However, there are some limitations to using rigid flex for these devices.
Can Rigid Flex Be Used in MEMS Devices?
For example, rigid flex is not ideal for high-performance MEMS that require a high-precision bending and twisting operation. This is because these devices can easily get damaged by a high amount of stress on the circuit board. This could lead to shorts and potential fires, which can be very dangerous for the device users.
Another limitation is the rigidity of the rigid flex. While this does not affect the performance of a MEMS device, it can make it difficult to design an enclosure for the rigid-flex PCB. This can impact the device’s shape, which in turn impacts how heat is dissipated and the mechanical structure of the device.
To overcome these challenges, manufacturers must choose a rigid-flex material with high tensile strength, high dielectric constant, and good electrical properties. In addition, they must ensure that the rigid-flex PCB has enough room to accommodate the MEMS actuators and sensors. The best option for this is to use a multi-layer rigid-flex design.
Creating a rigid-flex PCB involves combining rigid sections with a flex section in a sandwich configuration. The flex section can be routed as required by the application. Rigid-flex circuit boards must also include plated-through holes (PTH) for both the flex and rigid sections, which will connect to mounting components on both sides of the assembly.
Rigid-flex circuits can be cut to size by a process called blanking. In high-volume production, this can be done with a hydraulic punch and die set, which has fairly expensive tooling costs. For prototypes and lower-volume runs, a blanking knife is used. The blade is bent into the shape of the flex circuit outline and affixed to a routed slot on a backing board, which is usually MDF or plywood. The blanking knife is then pressed against the flex circuits to cut them out.
Whether you’re designing for a flexible MEMS device or a standard PCB, you need the right design tools. Look for a PCB software package that supports both rigid-flex and full layer stack management, and can show you a graphical representation of your layered assembly. This way, you can keep track of the link between rigid and flex sections, even during manufacturing. Altium Designer is the only PCB design platform that offers these powerful features. Try it for yourself with a free trial today.
