Circuit boards have been a staple in electronics for many years. With evolving demands and increasing complexity, these boards have undergone constant upgrades, progressing from traditional rigid PCB to flexible PCB, and now gaining popularity, rigid flex PCB. Apart from variations in craftsmanship and materials, cost considerations hold significant importance for users. In this article, TechSparks will analyze the cost components of rigid flex PCB and provide guidelines to enhance project profitability.
Why Use High Cost Rigid Flex PCB
In similar situations (size, thickness, processing), the cost of a rigid flex PCB is the highest among the three circuit types. This is due to its utilization of more materials and the need to combine both rigid and flexible circuits. However, despite its higher cost, rigid flex PCB offers essential advantages and characteristics:
- Rigid-flex PCB combines the strengths of both circuits, enabling them to perform exceptionally well in extreme environments characterized by large temperature differences, high humidity, and significant vibrations.
- Their application in three-dimensional spaces provides enhanced reliability while reducing overall volume.
- While bare boards are more expensive to manufacture, they are considered beneficial to the overall project.
Cost Components of Rigid Flex PCB
Board Size
The size of a rigid flex PCB plays a crucial role in determining its price as it directly correlates with the amount of material used. However, larger size does not necessarily translate to better performance; rather, it should be chosen based on the specific requirements of the project. TechSparks presents common usage sizes for board:
- 21 X 24 inches (533 x 610 mm)
- 18 X 21 inches (457 x 533 mm)
- 18 X 24 inches (457 x 610 mm)
Circuit Layers
As electronics become more advanced, there is a growing demand for multi-layer circuit structures to enhance circuit density and functionality. However, considering multi-layer circuits as the sole standard is a misconception. It is crucial to assess the project’s specific requirements before opting for multi-layer circuits, as they come with increased manufacturing complexity and higher failure rates, which can ultimately impact the customers.
Moreover, incorporating flexible circuits into multi-layers can pose additional challenges. Even expert flexible PCB manufacturers may face limitations, typically restricting them to ten layers. Below is a list showing the relationship between rigid-flex PCB circuit layers and their corresponding prices:
- 20 – 30%: 10L to 12L
- 20 – 30%: 8L to 10L
- 30 – 35%: 6L to 8L
- 30 – 40%: 4L to 6L
- 35 – 40%: 2L to 4L
- 35 – 40%: 1L to 2L
Material Costs
In circuit boards, the substrate material plays a critical role in influencing various aspects, including mechanical behavior, signal performance, and thermal performance of the final product. Rigid flex PCB, designed for extreme environments, demands the utilization of advanced materials for both rigid and flexible portions, which can contribute to higher costs. These common materials include:
Strategies to Reduce Rigid Flex PCB Costs
Avoid losses caused by failures
Indeed, rigid flexible PCB poses unique challenges in their manufacturing process. Collaborating with professional manufacturers who possess expertise in producing flexible PCB or excel in specific fields can help avoid losses due to mistakes. Entrusting your project to experienced craftsmen ensures that they can leverage their past experiences, leading to cost savings on materials and minimizing identification errors.
Optimize circuit design
To optimize the project’s requirements, it is advisable to minimize the number of circuit layers and substrate thickness while ensuring functionality. Additionally, opting for rigid laminates rather than additional non-flowing prepregs when increasing thickness can be a beneficial approach. This strategy aims to strike a balance between performance and cost-effectiveness, ultimately resulting in an efficient and cost-efficient solution.
Flexible arm terminates in rigid plate
Designers often opt to integrate flex cables into the rigid section of a rigid flex PCB, facilitating compatibility with ZIF connectors and other devices. However, achieving this functionality requires the utilization of a technique called “bag-forming” during the outer layer manufacturing process to safeguard the flexible cable segment. This technique necessitates a considerable amount of additional handwork and the application of stress-relief beads in the rigid-flex transition area. To streamline the manufacturing process and reduce costs, it is beneficial to terminate all flex cables on a rigid board, eliminating the need for intricate bag-forming and simplifying the assembly process.