How Do Flex Circuit Boards Impact Overall System Cost?
Flex Circuit Boards Impact Overall System Cost
Compared to rigid PCBs, flex circuit boards offer more flexibility. They can be made thinner and more dense, making them ideal for tight spaces and complex layouts. Additionally, they are capable of handling a wider range of thermal and mechanical stresses. This makes them a good choice for demanding applications, such as the flex-circuits used in mobile phones, laptops, and tablets (static application), or those where the board needs to bend frequently during use (dynamic application). Rigid-flex circuits are another example of a common flexible PCB, used in automotive and aerospace applications due to their ability to handle the stress of harsh conditions, such as high temperatures and vibration.
The main cost driver for flex circuit board is the complexity of the design, including layers, detailed traces, and vias. This makes the design and assembly process more time-consuming, labor-intensive, and expensive, which pushes up the overall cost. Additionally, specialized materials like polyimide and FR4 can add significantly to the final cost.
In addition to the complexity of the design, the quality of the flex circuits also impacts cost. This includes ensuring that the reference plane layer and signal traces are properly matched to the circuit board’s impedance characteristics. This prevents unwanted interference that can impact performance.
How Do Flex Circuit Boards Impact Overall System Cost?
Other factors that affect the cost of flex PCBs include materials, manufacturing processes, and volume. For example, a flex circuit’s conductor layers may be more expensive if the design requires thicker copper than standard FR4-grade material. This is because the thickness of the conductor is proportional to the number of layers it runs through.
For lower per-unit costs, it’s important to optimize the design of your flex circuit. This can be accomplished by simplifying the schematics, reducing the number of layers, and by using standard polyimide substrates rather than specialty alternatives. It’s also critical to review the bend radius requirements and choose a material that can sustain the necessary number of bends for the application.
Finally, it’s helpful to work with a flexible circuit manufacturer or assembler that offers transparent pricing based on your complete design specs and production volume requirements. Larger orders benefit from economies of scale and lower unit prices, while smaller, custom orders can be more expensive.
When comparing quotes from different manufacturers, keep in mind that NRE (non-recurring engineering) costs are independent of quantity and can increase or decrease the price per board. To lower your unit price, look for a supplier that offers NRE as part of the initial setup fees, and amortizes them over a larger production run. Additionally, look for a supplier that offers a variety of surface finishes. This includes ENIG, which protects the copper from corrosion and provides a solderable surface, as well as advanced options like ENEPIG. These surface treatments can reduce the amount of drilling needed and provide additional protection against harsh environmental conditions.