When creating a circuit board, it’s essential to know exactly the process for making Rigid-Flex PCBs. While the design process is relatively straightforward, you must complete the different steps to get the finished product you need. Therefore, a good team of PCB engineers is key to the success of a rigid-flex PCB project. Whether working on a simple board or a more complex multi-board design, you’ll need to understand how to make rigid-flex PCBs.
The Rigid-Flex design technique incorporates multiple layers of flexible substrates attached to a rigid board. This technique provides stability and flexibility for installation in hard-to-reach places. It also enables a higher level of precision and repeatability in circuit design. This PCB is ideal for electrical components and is also helpful in ensuring safe connections to other electrical components. Additionally, Rigid-Flex PCBs are designed to withstand extreme temperatures and environments and are therefore ideal for use in electronics.
The Rigid-Flex design process starts with a flexible substrate cut to the required size and shape. Then, it goes through two common process steps: die-set cutting and hydraulic punch cutting. These two processes involve cutting multiple flexes with high precision and accuracy. The Rigid-Flex board is then laminated between two rigid layers and electrically tested. With the Rigid-Flex design process, designers can quickly and efficiently create products and designs. In addition, cadence’s PCB solutions support the modern IPC-2581 industry standard.
Altium Rigid-Flex
A flexible board can have several features that make it ideal for designing circuit boards with multiple stacked layers. With this new feature, you can define any number of sub-stacks from one master layer stack. These sub-stacks are named and ready to be used for rigid-flex design. Using Altium Designer, you can design circuit boards with a rigid-flex structure by simply placing a layer stack in the desired location.
When designing a rigid-flex PCB, it is essential to remember that the process of making the board rigid is a complex one. This method is prone to making it difficult to solder or assemble components. Besides, the parts of the rigid-flex toolset are very tight, which makes it challenging to align components and make the board fit correctly. Therefore, you should take note of the process before starting the design.
Altium provides three basic packages, each with varying costs. The basic package costs around $200 per year. It offers a few essential tools, including a design library, but you can only design a limited number of boards with the basic package. It is important to note that this toolkit does not require purchasing the latest parts, as you can use older designs. In addition, you will be able to use all Altium’s tools and parts, but the content of each board will decrease over time.
Flex circuits have many applications in wearable electronics. This technology is ideal for wearables like health monitors and fitness trackers. Flex printed circuit boards help maintain thermal stability and reliability, simplify assembly, and lower costs. Additionally, flex circuits can be helpful in foldable wearables, such as medical devices or fitness monitors. Finally, flex circuits are often necessary for products that require bending capabilities.
Designing an Altium Rigid-Flex PCB
The editor has a powerful 3D rendering engine, enabling you to present your circuit board’s realistic three-dimensional representation. It supports the rigid-flex circuits as well, and you can view the design in either its fully-folded or flat state with Fold State slider. This feature is available in the PCB design software, and the manufacturer has included detailed documentation.
Board shape
The main goal to design a rigid-flex PCB is to minimize the amount of mechanical stress on the circuit. A rigid-flex PCB has a lot of potential for bending, but careful planning is necessary. To avoid permanent bends, you must ensure that the bend radius exceeds the circuit thickness. The bend radius should be at least 15:1 for a single-layer, double-sided circuit, or multi-layer design to achieve the best flexibility. In addition, you should aim for a 20 to 40:1 bend ratio in dynamic applications.
The next step is to set the rigid-flex design mode. Altium offers two rigid-flex modes, the standard and the advanced. The standard rigid-flex mode is suitable for simple rigid-flex designs, but you can also choose the advanced mode for complex designs. The advanced mode supports overlapping flex regions, and you can define custom splits and bookbinder-type structures. You can also choose the flex mode by clicking on the Advanced Rigid-Flex Mode menu in the Layer Stack Manager.
Layer stackup
When designing your rigid-flex PCB, it’s vital to consider the requirements for multiple layers. In the Altium Designer, you can use the Layer Stack Manager to define the required number of layers for the board. In addition to the number of layers, you can define bending zones for each layer, allowing you to balance the board’s mechanical and electronic design areas. This helps ensure that your design meets fabricator requirements and complies with the required thickness and dielectric material.
PCB layer stackup is critical for determining the impedance of surface layers. The Altium Designer integrated Simberian field solver allows you to perform accurate impedance calculations. You can also set the calculated widths and clearances as electrical design rules, which enforce the impedance target for routing vias and applying teardrops.
Coverlay
The Coverlay tool in Altium helps to ensure flexibility in flexible circuits. Its graphical editing capabilities allow users to change the shape and location of coverlay polygons. This tool will enable users to insert or remove coverlay polygons from a design directly on the workspace. This tool is an essential part of the design process for flexible circuits. It improves the functionality of bending areas.
A coverlay is a polyimide material that covers the exposed traces and protects them from exposure to abrasion and environmental elements. These materials are available in various colors but most commonly use black. When applying the coverlay, careful consideration must be given to the “C” marking line and pads.
Challenges
A successful rigid-flex PCB design involves careful stackup and trace designs and detailed coordination with a board fabricator. 3D design tools can simplify this task, allowing designers to use open real estate and easily identify potential design issues. In addition, because flex circuits are thin, they are more likely to suffer accidental damage during manufacturing, which can negatively affect yield and per-item cost. Fortunately, Altium’s leading PCB design software can assist designers in this process by automating many design tasks.
In addition to helping designers design rigid-flex PCBs, Altium provides a powerful tool for a multi-board design that allows them to work on a single board or multi-board design simultaneously. Furthermore, the software’s 3D functionality will enable engineers to pass board changes between the mechanical and electronic domains. The Altium Guidebook provides an overview of this technology and a step-by-step process for designing rigid-flex PCBs.
Summary
If you’re looking for an easy way to create rigid-flex PCB designs, you’ll be happy to know that Altium Designer comes with an integrated 3D design tool and standard routing and layout tools. These tools are available in the software’s unified design model, enabling you to easily design and modify devices, components, stackup, and more. With Altium Designer, rigid-flex PCB designs are easy to create, and the software is compatible with multiple boards and other electronic devices.
