Improves Efficiency of Rigid Flex PCBs
Rigid flex is a printed circuit board that incorporates rigid and flexible sections. It eliminates the need for extra connectors and cables, which improves efficiency, saves space and cuts costs. This is a crucial benefit in many applications, especially in electronics, automotive, aerospace and medical devices. However, there are certain design considerations that can affect signal integrity and electromagnetic interference (EMI). These include the material selection, conductive line routing for flex tolerance, and proper connector placement. To prevent these issues, it is essential to use a PCB design software that is optimized for rigid-flex design.
A rigid-flex PCB requires special construction techniques to maintain its flexibility and structural stability. To do this, a stiffener layer is created to add lateral strength to the flex section of the board. This layer can be made from FR4, polyimide or aluminum, and is bonded to the flex circuit using adhesive systems that are compatible with the underlying substrate. The stiffener should also have openings, perforations and connection points to facilitate component attachment and hardware placement.
The flex circuits are then constructed from multiple layers of conductive copper with padded through holes that connect the rigid and flexible sections. The number of layers varies from 6 to 12 based on the complexity of the board. A multilayer rigid-flex circuit typically has multiple power and ground planes. These can be solid copper pours, which may limit the board’s flexibility or they can be hatched-polygon, which is more flexible and reduces stress in the copper planes when the board is bent.
How Selective Soldering Improves Efficiency of Rigid Flex PCBs
When the rigid-flex circuit is ready for assembly, it is fluxed, preheated and soldered at one time with a dip selective soldering machine. The nozzles on this machine are designed one-to-one with the locations of the joints to be soldered, which improves the accuracy of the process. It also allows the flux to be applied with a finer spray than that used on a wave soldering machine, which helps reduce the risk of dross formation.
Selective soldering is the best way to ensure that all of the bare spots on a rigid-flex pcb are properly welded together. In addition, this method of soldering can help improve the performance of a rigid-flex pcb in harsh environments. The ability to solder a flex PCB at high temperatures and in harsh conditions can help to increase the lifespan of the product.
Although reflow ovens have replaced selective soldering machines in some manufacturing plants, it is still necessary for some production processes. This is particularly true when producing a large quantity of rigid-flex boards for consumer and commercial applications. A selective soldering machine is able to handle the large volumes of small, medium, and large-sized pads found on a rigid-flex circuit. This type of technology also has the added benefit of being a cost-effective alternative to other production methods, such as manual hand soldering. A nitrogen generator from Pneumatech can help manufacturers to optimize their selective soldering equipment by providing a continuous supply of pure, high-purity nitrogen. This can prevent dross and extend the lifetime of the nozzles.
