Flex PCB Design Tips and Tricks
4 min
Flexible printed circuit boards (Flex PCB) are a type of printed circuit board that is made from a flexible material, such as polyimide. FPCBs are used in a wide variety of applications, including consumer electronics, medical devices, and automotive electronics.
flex PCB from jlcpcb
Designing FPCBs can be challenging, as there are a number of unique considerations that must be taken into account. In this article, we will discuss some of the most important flex PCB design tips and tricks.
The outline of a flex PCB refers to the final shape of the board. When designing the outline, it is important to consider the following:
- The outline layer must be unique. Typically, this layer is represented by GM1 or GKO.
- Non-metallic hole annuli or slot frames should also be placed on the outline layer.
- The outline layer should not contain any miscellaneous lines.
- The FPC outline cannot have internal right angles or sharp corners. It must also be closed, and cannot be open.
Outline design example 1
Outline design example 2
Outline design example 3
Outline design example4
Outline design example 5
Ground Copper Design for Flex PCB
The ground copper design is another important consideration for flex PCBs. When designing the ground copper, it is important to avoid large areas of copper, as this can reduce the flexibility of the board. It is also important to design the ground copper in a grid pattern, with a line width of 0.2mm and spacing of 0.2mm.
Ground Copper Design Example 1
Issue: Bubbles during lamination
Cause: Large areas of ground copper with few openings in the solder mask can trap air, which can react with the copper surface during lamination, causing oxidation spots.
Solution: Add solder mask openings or change to a grid copper design.
Ground Copper Design Example 2
Issue: Reduced flexibility
Cause: Large areas of ground copper can reduce the flexibility of the board.
Solution: Design the ground copper in a grid pattern, with a line width of 0.2mm and spacing of 0.2mm.
Ground Copper Design Example 3
Issue: Misalignment of components or insufficient solder during SMT
Cause: Ground copper covering between IC pads or gold finger pads can result in several pads connecting together.
Solution: Do not cover excess copper between pads.
Ground Copper Design Example 4
Issue: Solder bridging and short circuits during soldering
Cause: Thick traces or ground copper on component pads can decrease the spacing between pads.
Solution: Avoid designing thick traces or ground copper on similar pads.
Flex PCB Soldering Gold Finger Design
Soldering gold fingers are used to connect flex PCBs to other components. When designing soldering gold fingers, it is important to consider the following requirements
- Soldering fingers must have pads designed on both the top and bottom layers.
- The lengths of the pads on the upper and lower layers need to be staggered by 0.5mm, and the corresponding solder mask openings should also be staggered by more than 0.5mm.
- The solder mask needs to cover the pad by 0.5mm (this can be achieved by extending the pad).
- Design half-holes at the front of the gold fingers; also design a hole on the finger pad, with an inner diameter of 0.3mm and an outer diameter of 0.5mm.
- The through-holes on the pads need to be staggered and should not be aligned in a single row.
Additional Tips
In addition to the tips discussed above, there are a few other things to keep in mind when designing flex PCBs:
- Use a flexible material that is appropriate for the application.
- Consider the bend radius of the flex PCB.
- Use a solder mask that is compatible with the flexible material.
- Test the flex PCB thoroughly before using it in a production environment.
- By following these tips, you can design flex PCBs that meet your specific needs and requirements.
By following these tips, you can design flex PCBs that meet your specific needs and requirements.
Keep Learning
6 Critical PCB Design Mistakes That Delay or Fail Your Custom PCBA
While ordering a custom PCBA is more accessible than ever, a simple design oversight can quickly lead to costly production delays, frustrating board failures, or, in the worst cases, a complete and expensive redesign. The transition from a schematic to a physical, assembled board is filled with potential pitfalls that can trap even experienced engineers. This article will detail the six most common and impactful design mistakes that engineers encounter when preparing a project for custom PCB assembly.......
Blank PCB and Parts : Building on Empty Boards
A blank PCB refers to an unpopulated circuit board with no components assembled. A blank PCB is an empty circuit board, manufactured from a copper-clad substrate, drilled, masked, and finished. It’s the canvas engineers use for prototypes, experiments and hobby builds. Blank boards are simple PCBs without components. Let’s dig deeper into the article to find out some standards and technologies used in the industry. Universal Blank Boards vs Pre-routed Prototyping Boards Universal blank boards are copp......
Amplifier PCB Design: Building Nosie-free Hi-Fi Boards
Designing a high-fidelity audio amplifier PCB requires balancing physics principles with modern techniques.We must maintain a pure signal and ensure the board is manufacturable. An audio amplifier circuit should start with a clean power supply and proper filtering. Use a low-noise input stage with correct biasing and an input coupling capacitor. We will see some design techniques on how to include bypass and decoupling capacitors. Ensuring proper grounding to reduce hum. Adding stability networks, suc......
PCB Art : Jaw-Dropping Designs & How to Make Your Own
Usually, PCBs are designed to replicate complex circuits on a small board consisting of traces. All this is done to connect different components. However, when it comes to the aesthetics and functionality of a printed circuit board, various applications also exist, such as coloured PCBs and PCB cards. The rise of PCB art isn’t a fluke. And by the introduction of JLCPCB, this art became easier to fabricate. A community that loves to flex creativity and RGB. Engineers who want their work to be both func......
Master PCB Board Circuit Diagrams: From Zero to Reading & Drawing Like a Pro
When designing a circuit for real applications, it is better to use PCBs. PCBs are the formal electrical representation of an electronic system. If you don't want the wires to be hanging with components and messy systems, it's better to turn it into a circuit board. To design a PCB board, there are 2 steps: first, the schematic design. The schematic shows how components such as ICs, capacitors, resistors and other components are interconnected. The schematic is the blueprint through which we can gener......
PCB Impedance Control: Ensuring Signal Integrity in High-Frequency Circuits
Impedance measures the opposition of an electric circuit when alternating current is applied to it. It is the combination of the capacitance and the induction of an electric circuit at high frequency. Impedance is measured in Ohms, similar to resistance. If the impedances are different, reflections and attenuation occur that deteriorate the signal. For high-frequency analog or digital circuits, it is essential to protect the signals that propagate on the PCB from being damaged. In fact, signals above ......