Top 7 Cost Driving Factors of Flexible PCB Design and Layout

Top 7 Cost Driving Factors of Flexible PCB Design and Layout

Flexible printed circuit boards or PCBs are immensely popular and have been an integral part of electronics for a long time. These circuit boards are lightweight, mechanically flexible, and are used in 3D circuits and advanced devices like smartphones, cameras, and so on. Although flexible PCB designs and their processes have evolved over the years, there are still certain factors that may escalate the costs of flexible PCBs. Would you be intrigued to know what they are? The post offers insights on factors that may drive the costs of flexible PCB design and layout.

Know About Different Cost Drivers in Flexible PCB Design and Layout

Keeping an eye on the following cost drivers will help you save on the flexible PCB design and assembly.

• Layer Count: PCB layers are one of the key cost drivers in any PCB design and assembly and it is no different for flexible PCBs. The layers would require lamination, which will further add to the cost once the layer count goes on increasing. Additional time and materials are needed for circuits with higher counts, which would be another cost driving factor.
• Materials: Polyimide and copper combinations are a popular choice for flexible printed circuit boards. There are three types of copper/polyimide combinations – copper with acrylic adhesive + polyimide, copper with flame retardant adhesive + polyimide, and adhesiveless copper with polyimide. Of these, copper with acrylic adhesive + polyimide is easily available with most manufacturers and this allows you to save on costs. However, copper with flame retardant adhesive is ideal for high-temperature applications. You can save on this copper and polyimide combination if UL requirement is not necessary. However, it is not common, so, the prices can escalate a bit. Adhesiveless copper is expensive than the other two options. It is most suited for flexible PCB designs and layouts that have high layer counts.Polyimide coverlay and stiffeners are a few other materials that may add to the costs. You can choose between polyimide coverlay and flexible liquid photoimageable coverlay. Of these, polyimide coverlay is suited for flexible circuits, and is slightly costlier. Flexible liquid photoimageable coverlay is easy to handle and requires fewer efforts, which makes it popular with several PCB manufacturers. However, the choice will entirely depend on application requirements. Generally, polyimide or FR4 stiffeners are chosen for flexible circuit boards. Of these, FR-4 stiffeners are generally used to support the weight of components, and polyimide stiffeners are reserved for areas where additional thickness may be required. Adhesives used in these stiffeners generally drive their costs. These stiffeners are usually bonded to thermal set or pressure-sensitive adhesives. Pressure-sensitive adhesives are a popular choice for most flexible PCBs as they are less expensive and easy to work with.
• Circuit Class: Like any other electronics manufacturing, the flexible PCB design and layout can be distinguished into three classes – IPC 1 for general electronic products; IPC-2 for dedicated service electronic products; IPC-3 for highly reliable electronic products. The IPC -3 class flexible PCBs may have certain different requirements than IPC-2 and the costs will escalate as per these requirements.
• Panel Utilization: The utilization of panel will impact the costs. The shape and size of flex circuits also impact the panel utilization, which escalates the pricing.
• Drill Hole Count: This refers to mechanical holes, which are drilled on the panel to make connections. These mechanical holes can increase your tooling costs. Generally, 30,000 holes are considered normal, but anything beyond that may escalate your costs.
• ZIF Connectors: They are becoming a suitable alternative for wire and connector assemblies especially in rigid-flex circuits.
• Buried Vias: They are known to assure excellent layer to layer connectivity, and are known to enhance the current-carrying capabilities of the circuit. However, these vias may escalate the costs. So, it is only recommended to opt for high-speed circuits or circuits with stringent electrical requirements.

In addition to the above factors, it is important to partner with an experienced PCB assembly services provider and manufacturer who can further help you reduce costs in other areas. Twisted Traces is an experienced PCB assembly service provider and manufacturer specializing in flexible PCB design and layout. The company has helped their clients save on PCB assemblies without compromising on the quality. Twisted Traces also offers rigid and rigid-flex circuits in custom specifications.