Can Flexible Circuits Be Recycled
A flexible circuit, also called a flex PCB, is similar to a standard printed circuit board (PCB) except it can bend. Its flexibility allows it to fold and conform to the shape of a device, which is important for some applications, such as portable medical devices.
There are a number of benefits that flex circuits offer. First, they provide a level of adaptability that is unmatched by rigid PCBs. They can be bent, twisted, and even rolled without causing electrical failure. They also allow for more components to be integrated in a small space, which is crucial for many devices. They are often used in consumer electronics like fitness trackers and smartwatches.
While the concept of flexible circuit has been around for decades, the technology only became possible with recent breakthroughs in materials and production methods. The 1940s saw the introduction of etching technologies that allowed for flexible electronic circuits, and the 1960s brought a material with a flexible base and high thermal stability to market known as polyimide. This made it possible to make flexible printed circuit boards, or flex PCBs, and gave rise to an industry that is now thriving.
Can Flexible Circuits Be Recycled at the End of Their Lifecycle?
Flex circuits feature conductive tracks on a non-conductive substrate, and can be made to replace bulky wires in several applications. This reduces assembly time and costs, while also lowering the overall product weight and size. In fact, a recent study found that flexible circuits can reduce SWaP requirements by up to 60%.
To create a flex PCB, manufacturers start with a layer of copper on a dielectric substrate. This is bonded together using either an adhesive or a heat and pressure process. The copper layer can range in thickness from very thin, rolled annealed copper to a thicker electro-deposited copper. The copper is then etched to expose the metal pads, which are then coated in a solder mask before being drilled. Drilling is also done on the back of the flex circuit, which creates positioning holes for component insertion and mounting.
Once a flex circuit is fabricated, it must be tested to ensure that all of its electrical paths work properly. This is done through the use of a test fixture that places the device under pressure, heat, and light to simulate real-world conditions. If there are any defects, the manufacturer can then repair the circuit by applying the necessary solder to the broken areas.
Lastly, the final step in creating a flexible circuit is to add the surface mount electronics. Depending on the design of the device, this can include LEDs, resistors, and other semiconductors. To ensure that the components are securely mounted on the flex circuit, manufacturers apply an overlay or coverlay to the surface of the circuit. This protects the conductive traces from mechanical stress and environmental damage. The final flexible circuit will then be finished with a choice of coatings, including tin or soft gold.
When a product reaches the end of its lifecycle, it is considered e-waste and can travel to a landfill, where chemicals in the electronics can bleed into the soil, or to an electronics recycling center. Fortunately, a new study has found that a flex circuit can be recycled by simply soaking it in a solution. This method is not only environmentally friendly, but will help to extend the lifespan of the circuit by reducing the risk of corrosion.
