Lifespan of Flex PCBs
The lifespan of a flex PCB is incredibly high compared to rigid PCBs. In fact, a typical flex circuit board can withstand up to 500 million bending cycles during the lifespan of an electronic device. Moreover, these boards can also resist a variety of harsh environmental conditions such as heat, humidity, moisture, chemicals, shocks, and vibrations. However, the longevity of a flex circuit board depends on several factors, including its material properties and manufacturing processes. To ensure the highest quality, manufacturers should choose a qualified PCB shop that produces a high-quality quick-turn PCB on a regular basis.
When designing a flex PCB, you must keep in mind the fact that these boards are usually more complex than their rigid counterparts. As a result, they require more precise engineering and fabrication processes. During the design phase, it is important to consider the number of layers, material type and thickness, as well as the layout and routing of traces in the board. It is also important to make sure that the board is not too long, as it could cause a bend during manufacturing.
Choosing the right material for a flex pcb is crucial to its success and reliability. A copper-clad laminate (CCL) is a common choice because it offers exceptional thermal control. This helps prevent the copper foil from softening due to temperature extremes and increases the lifetime of the product. It is also recommended to use a polyimide resin for the CCL because it can provide exceptional flexibility and elasticity.
What is the Lifespan of Flex PCBs?
In addition to the CCL, a flex circuit requires a base material that is both flexible and durable. Previously, manufactures used adhesives to attach these materials to the cladding layer, but this method decreased the product’s reliability. To resolve this issue, they developed a new material called PI, which attaches to the copper without an adhesive and has a lower risk of via breakage.
Another key factor in a flex circuit’s durability is the thickness of its copper. The thickness of the conductive lines must be sufficient to ensure that it can withstand the stresses and bending of the PCB. The thickness should be at least 2 oz. In addition, the copper should be plated with a thicker finish. This will improve etch yields and help maintain a consistent impedance in the conductor traces.
Lastly, it is vital to know that a flex PCB should have stiffeners for areas that need additional mechanical stability. These stiffeners can be made from a variety of materials, including FR4, metal, and a combination of both. Using stiffeners will increase the cost of the flex PCB, so it is best to consult a fabricator during the design phase and ask about this option.
Another important factor in a flex PCB’s durability is the drill-to-copper distance. Since flex materials are more likely to move and compress during production, it is important to have a large enough distance between the drill and copper. The ideal drilling gap is at least 8 mils. Additionally, it is also recommended to stagger the traces near bend areas to avoid stress on the holes.
