Flex Circuits
As you may already know, flex circuits are an ideal choice for high-reliability applications, such as medical imaging equipment, military missile guidance systems, video cameras and wearable electronics. The unique combination of flexibility and durability that rigid flex PCBs offer can deliver a significant benefit to your end-users, including decreased maintenance costs, reduced system downtime and enhanced product longevity.
When selecting a flex circuit manufacturer, you should work closely with them throughout the entire design process to optimize your design for manufacturability. This includes establishing clear communication and regular reviews of project progress, as well as seeking out their expertise to address any potential issues before they arise. This will help ensure a smooth, successful design and assembly process and ultimately a high-quality, cost-effective flexible circuit for your specific needs.
Whether you’re working on a static flex circuit or a dynamic flex application, there are important thermal considerations to keep in mind. Static flex circuits are designed to withstand a one-time bend to fit the assembly, while dynamic flex circuits must withstand multiple flexes over their lifetime. As a result, the trace routing and solder pad placement on these flex circuits must be carefully planned.
Thermal Considerations for Flex Circuits
A flex circuit’s core thickness is an important factor in how much it can withstand and transfer heat. A traditional 2-layer FR4 rigid PCB has a core thickness of 0.062″. In comparison, a flex circuit with a similar layer count can have a core thickness as thin as 0.008”. This allows for a larger surface area to volume ratio and significantly improves the ability to dissipate heat within the flex circuit.
The material used in a flex circuit is also an important factor to consider when it comes to its ability to transfer and disperse heat. Polyimide and Kapton films are popular options, as they have excellent insulation, mechanical strength, thermal stability and flame retardancy. These materials are also more thermally conductive than FR4. Aluminum PCBs, another highly effective choice, utilize a dielectric layer to absorb and transfer heat to the aluminum core where it is effectively dispersed.
In addition to these material choices, a rigid flex PCB can be laminated with a thermally-conductive Pressure Sensitive Adhesive (PSA) that helps to effectively disperse and dissipate the heat generated by the conductive copper layers. Additionally, aluminum flex PCBs can be designed with localized selective copper planes that provide an even greater level of heat dissipation.
Lastly, a good PCB manufacturing partner will have the tools to perform environmental testing on your flexible circuits to validate their suitability for their intended environment. This will include cyclic temperature and humidity testing as well as vibration and signal integrity measurements, which will identify any areas where additional attention or modification may be needed to maximize performance.
Choosing the right flex circuit manufacturer for your next project is essential to success. An experienced ECM with experience in all aspects of the design and assembly process, from CAD to CAM, can help you meet your exact specifications, budget and timeline. Levison Enterprises offers both rigid flex and dynamic flex PCBs, so get in touch with us today to learn more about our services or request a quote.
