Automated Flex Rigid PCB Manufacturer
Rigid-flex PCBs combine the benefits of both rigid and flexible circuit boards in one unified design. They are used in the bending areas of mobile phones, screen signal connection in tablets and laptops, and many other products that require high-quality electronic components. They are also used in medical, military, and aerospace equipment, including wearable health monitoring devices and rotation axis control panels for satellites.
Like rigid PCBs, flex-rigid boards must meet specific requirements to achieve functional and reliable performance. These include material selection, component placement, and impedance matching between rigid and flex sections. They must also meet a minimum bending radius requirement to avoid damage, while providing adequate flexibility.
The fabrication process for a flex rigid pcb manufacturer begins with the application of photo resist film to the bare copper layers of the board. This step is typically performed on an automated conveyor line, and may be followed by etching to remove the photoresist and expose the copper to create circuit traces. The etching process must be carefully controlled to ensure that the required copper is etched away, and the remainder of the photoresist remains intact.
Once the copper layers have been etched, the remaining photoresist is stripped using solvents to expose the underlying circuit traces. The traces must then be soldered, which requires careful temperature management to prevent thermal stress that could result in oxidation or delamination of the copper pads. The finished flex-rigid circuit board is then laminated with the rigid-board section, forming a single unified structure.
Automated Flex Rigid PCB Manufacturer – The Typical Process
A flex-rigid PCB must also be covered with a protective layer to shield the delicate conductive copper and dielectric layers from damage. This coverlay is usually an additional polyimide or liquid crystal polymer (LCP) film with adhesive, although there are also non-adhesive options. For boards with components mounted on flex sections, this coverlay may also serve as the solder mask layer.
For efficient and accurate production of a flex-rigid circuit board, the fabricator must have a clear and complete set of documentation from the designer. This includes a layer stack diagram that clearly marks the flex and rigid sections with different pattern-fill patterns. It’s important to minimize overlap between the flex and rigid sections, to avoid confusion during assembly.
For example, it’s recommended that the flex-to-hardboard transition areas use a circular arc rather than a straight segment. This will prevent issues with scalability and performance in dynamic applications, where the arc will need to be much larger than the straight segment. It’s also important to provide a minimum bending radius of at least 1mm for the flex-to-hardboard segments. This will help to protect the conductive copper from fatigue, and to ensure that the bending radius is adequate for the dynamic applications required.
Next, the manufacturing process moves to material selection and preparation. High-quality substrates, such as FR-4 for rigid portions and polyimide for flexible areas, are chosen based on the intended application and performance specifications. These materials undergo precise cutting and cleaning to ensure optimal bonding and adhesion during fabrication. Once the materials are prepared, the circuit patterns are transferred onto the substrate using methods like etching or printing. This step requires precision to achieve accurate circuitry and proper alignment between rigid and flexible sections.
