Flexible printed circuit boards are equally popular as their rigid counterparts. When compared with rigid PCBs, the flexible printed circuit boards assure major cost savings in terms of weight and small footprint. Although the technique of flexible circuit board manufacturing has evolved over the years, there are certain factors that you need to address while building your first PCB. What are these factors? How do they contribute to the functioning of the PCBs? Read this post to know the answers.
Top 6 Factors That You Need to Address During the Manufacturing of Flexible Circuit Boards
There are several minute details that you need to address and take care of while designing a printed circuit board. However, these six factors are quite important because the performance of your PCBs will be influenced by them.
- Address the Flexibility and Bendability: Although flexible PCBs are bendable and flexible, they may impose limitations in certain applications. These limitations may result in breakage of the PCB or jeopardizing the performance of the electronic circuit. To avoid this, it is important to address the flexibility and bendability of the PCB. You need to determine the number of times, the PCBs will flex or bend. Based on this, you can decide in favor of the dynamic or static boards. Generally, the static boards can be bent only at the time of installation and they can withstand bending up to 100 times during their entire lifetime. Against this, dynamic boards can support flexing and bending the unlimited number of times. These dynamic boards are considered perfect for PCBs used in mission-critical applications.
- Know the Material to Be Used: Polyimide is used for both coverlay layers as well as flexible core layers. This material maintains uniform thickness throughout the PCB. The polyimide flex cores comprise rolled annealed copper or electro-deposited copper, which is quite thin. This makes it suited for static and dynamic applications. You can find two types of flexible polyimide materials – an adhesive-based material where the copper is bonded to the polyimide using an acrylic adhesive, and an adhesive-less material where the copper is cast directly on the polyimide. Each of these materials possesses their advantages and disadvantages, so you need to choose them wisely.
- Address the Flex Trace Routing: The layout of the circuit plays a key role in the functioning of the PCB. It can make or break a PCB. You can choose between angular traces and curved traces. Curved traces are considered better over angled ones because they cause less stress to the board. It is recommended to reduce I-beaming or avoid it altogether to minimize the stress on the boards.
- Protect the Flexible Layers: The flexible layers of flexible circuit boards can be protected by placing them at the center of the stack-up. This helps avoid exposure of the layer to the plating of the outer layer. This placement of a flexible layer in the middle of the stack-up also helps simplify the overall manufacturing procedure, as well as improve control and impedance.
- Secure the Vias: Several reasons lead to the failure of flexible PCBs, and the presence of vias is one of them. It is known to tear down the PCB design. To avoid this, it is always recommended to use tear-dropped vias.
- RF and EMI Shielding Options: Flexible circuit boards may be subjected to emitting or receiving radio frequency (RF) and electromagnetic (EM) waves. To avoid this, additional external copper layers are added. They can be added as cross-hatched or solid hatched planes, which are connected to the ground, and signal layers are sandwiched between them. You can also use shielding films and silver ink shield layers to minimize RF and EMI interferences. Each of these components has their own benefits and disadvantages, which need to be understood and the right decision must be made.
By now you may have realized how different factors contribute to the performance of these flexible circuit boards. You can get these factors right by partnering with a trusted and experienced PCB manufacturer. Owing to the popularity of these components, today, it is quite easy to find PCB manufacturers and assemblers specializing in PCB assembling; however, all may not serve your purpose. PCBHERO is one of the leading manufacturers of flexible circuit boards in the China and has been serving clients across industries like medical, military, and defense, and commercial electronics by offering them performance-driven PCBs. The company also provides rigid and rigid-flex PCBs. The experts at the company will guide you on these important factors irrespective of whether you are building the PCB for the first time or nth time.