Multilayer Rigid Flex PCB Blog Tg170 FR-4 And Polyimide

What is a rigid-flex PCB?
A rigid-flex PCB (Printed Circuit Board) is a type of circuit board that combines the features of both rigid and flexible PCBs. It consists of a flexible circuit board that is integrated with one or more rigid circuit boards. The flexible portion of the PCB is made up of a thin, flexible substrate material, such as polyimide, that can bend and twist to fit into tight spaces or to conform to complex shapes.

The rigid portion of the PCB is made up of a more traditional circuit board material, such as FR-4 or a metal core, that provides the necessary support and stability for components that cannot be mounted directly on the flexible substrate.

Rigid-flex PCBs are commonly used in applications that require both flexibility and durability, such as aerospace, medical devices, and consumer electronics. They can reduce the amount of space required for a circuit board and increase reliability by eliminating the need for connectors and cables.

The example from bicheng
The PCB features a Tg170 FR-4 and Polyimide material with a lead-free process, making it eco-friendly and suitable for various applications. It can operate in a temperature range of -40℃ to +85℃, making it ideal for applications that require a wide range of operating temperatures.

The stackup configuration of the PCB is a 4-layer rigid-flex PCB with a finished copper of 35um, FR-4 Tg170 dielectric, and a Polyimide core adhesiveless. The stackup has been optimized to ensure optimal signal quality and reduce noise and crosstalk between components. The use of Polyimide in the core of the PCB provides flexibility, making it suitable for applications that require bending or flexing.

The construction details of the PCB have been carefully selected to ensure optimal performance and reliability. The board dimensions are 121mm x 126mm with a tolerance of +/- 0.15mm. The minimum trace/space is 7/8 mils, and the minimum hole size is 0.2mm. The finished board thickness is 1.5mm for the rigid part and 0.25mm for the flexible part, making it suitable for applications that require both rigidity and flexibility. The finished Cu weight is 1 oz (1.4 mils) for all layers, and the via plating thickness is 1 mil.

The surface finish of the PCB is ENIG (Electroless Nickel and Immersion Gold), providing excellent solderability and a flat surface for mounting components. The PCB has undergone 100% electrical testing to ensure its quality and reliability.

Impedance matching is not required for this project, with a tolerance of +/- 10%. The PCB has a total of 66 components and 152 pads, with 18 thru-hole pads, 64 top SMT pads, and 70 bottom SMT pads. There are 87 vias and 26 nets. A panelized solder paste stencil is supplied for the top side, and three fiducial marks are provided on tooling strips.

The type of artwork supplied for this PCB is Gerber RS-274-X.

In conclusion, the rigid-flex PCB introduced in this article offers a high-performance solution for modern electronics. Its use of Tg170 FR-4 and Polyimide material with a lead-free process and a temperature range of -40℃ to +85℃ ensures optimal performance and eco-friendliness. Its stackup configuration and construction details are carefully selected to ensure optimal signal quality, reduce noise and crosstalk, and provide both rigidity and flexibility. The PCB has undergone 100% electrical testing to ensure its quality and reliability.