As technology evolves, the demand for innovative and flexible electronics is growing across industries, including automotive, healthcare, and consumer products. These sectors often need circuits that feature increased flexibility, better thermal stability, and improved electrical performance, handle frequent bending, and withstand harsh application environments. This is where thermoformed flex PCBs come in—an advanced solution that offers the flexibility of standard flexible circuits and the stability of a formed structure to meet specific design requirements. Would you like to learn more about these special flexible printed circuit board types? If yes, continue reading the post.
An Overview of Thermoformed Flex PCBs
Thermoformed flex PCBs are mechanically bent into a desired static bend radius during the manufacturing process. Unlike traditional flexible PCBs, which are made to bend repeatedly during their lifetime, thermoformed flex PCBs are molded into a fixed shape to fit intricate housings or enclosures. They are made using a thermoforming process, which makes them highly reliable as it ensures that the shape does not change or move once it is integrated into a device. These PCBs find immense applications – including the car’s dashboard or the latest wearable health monitor – that demand a specific, stable shape to fit into compact spaces.
Designing Thermoformed Flex PCBs
Designing thermoformed flex PCBs involves thoughtful planning and several precise steps. Manufacturers of these PCBs must focus on several crucial elements, especially regarding material selection, physical stress, and thermal dynamics during formation. Check out the major steps involved in designing these specialized PCBs.
- Choosing the Right Materials: As the making of boards involves heating and shaping, materials should withstand varying temperature levels without warping or compromising their structural stability. Polyimide is a popular choice among the several materials available due to its outstanding thermal resilience and flexibility. It can endure the necessary heat for thermoforming while maintaining its characteristics. Next comes the choice of adhesive. The right choice is equally important, as it must maintain its strength throughout the thermoforming process.
- Configuring the Layer Stack-Up: The stack-up of layers in a thermoformed flex PCB should be planned wisely for optimal flexibility. These boards have fewer layers than rigid PCBs, making them easier to shape. The design of copper traces is another critical consideration. Straight traces with rounded edges distribute mechanical stress more evenly.
- Bend Radius: Having the right bend radius plays a critical role in maintaining the integrity of the copper traces and overall board structure when it comes to flex circuits. The minimum bend radius is finalized after carefully analyzing the material’s thickness and the number of layers. If the bend radius is too tight during thermoforming, it can create stress that risks damaging the conductive elements.
- Creating the 3D Model: In the design phase, a 3D model of the circuit is made to ensure accuracy in the final product. The model created using Computer-Aided Design (CAD) software allows the designer to visualize how it will fit into the intended space and accurately predict the bends and folds needed for the thermoformed board.
Fabrication Process of Thermoformed Flex PCBs
Once the design phase is completed, manufacturing a thermoformed flex PCB begins. The following are the key manufacturing processes involved in making these flexible printed circuit boards.
- Fabrication: The fabrication process begins with the traditional methods to form a flexible PCB. Copper traces are etched, and polyimide layers are laminated to produce a flat, flexible board. In this stage, protective layers, such as solder masks, shield the copper from environmental exposure and other elements. At this phase, the board remains flat, similar to any typical flex PCB.
- Heating and Forming: One of the unique aspects of thermoformed flex PCBs is thermoforming, where the board is shaped into its final desired form. The flat PCB is heated to make the polyimide flexible enough to be molded. The softened board is then placed into a pre-designed mold that reflects the final shape. With applied pressure, the board conforms to the mold and is allowed to cool, thereby retaining its new, permanent shape.
- Quality Testing: Now, considering the rigidity requirements of specific applications, certain parts of the thermoformed PCBs go through additional reinforcements. Stiffeners or extra layers are added as required. After these processes, the finished board undergoes rigorous testing – majorly flying probe testing – to ensure it works as designed.
Advantages of Thermoformed Flex PCBs
Thermoformed flex PCBs offer several benefits that make them ideal for advanced applications across industries.
- By forming the PCB into a fixed shape, there is minimal movement during use, which prevents mechanical stress and extends the life of the board.
- Thermoformed PCBs are ideal for compact devices, as they can be molded to fit precisely into tight or odd-shaped units.
- Since the PCB maintains its specific form, it fits more easily into its designated position during product assembly, which minimizes the complexity and cost of assembly.
Typical Applications of Thermoformed Flex PCBs
A few of the many applications of thermoformed PCBs include:
- Automotive: These PCBs find applications in tight dashboard spaces and in-car sensors.
- Medical: The PCBs are utilized in instruments that need to fit into small, curved enclosures in surgical instruments and medical imaging equipment.
- Electronics: They are used in wearables and portable devices including infotainment systems, dashboard displays, and augmented reality (AR) headsets, among others.
Thermoformed flex PCBs represent a significant innovation for industries and by utilizing these PCBs, designers can create products that are both high-performing and resilient, even in challenging environments. If you’re looking to integrate thermoformed flex PCBs into your next project, connect with a skilled PCB manufacturer like Rigiflex, who has the right team, capabilities and experience to handle the complexities of thermoforming.
