Flexible printed circuit boards are now prominently used in the electronics industry. Being one of the leading manufacturers of these circuit boards, Rigiflex provides 4 layer flex printed circuit boards. These circuit boards are being used in a variety of industrial applications, including power, medical devices, automobile components, and industrial control equipment.
These printed circuit boards have 4 conductive layers, and made from polyimide, rather than FR4. Being thermally stable material, polyimide allows it withstand extreme heat when used in high-temperature applications. The flexibility offered by polyimide makes surface mounting easier than hard boards, thereby helping in streamlining the design. This polyimide also helps in creating intricate designs, which are otherwise impossible with rigid printed circuit boards. Also, this material helps in reducing the overall weight of the PCB.
4 Layer flexible printed circuit boards comprises of 4 conductive layers usually of ployimide rather than FR4. These rigid flex PCBs have top layer, GND, VCC, and bottom layer. You can combine the layers of rigid printed circuit boards through buried or through holes.
Applications of 4 Layer Flex Circuits
Some common applications leveraging 4 layer flex PCB technology include:
Wearable devices – Smart watches, fitness trackers, AR/VR headsets.
Flexible displays – Edge or foldable displays, large LED video walls.
Automotive – In-car displays, lane departure systems, LiDAR.
Aerospace/Military – Helmet systems, communications, guidance systems.
Medical – Ultrasound transducers, implants, endoscopes.
Industrial – Flexible HMIs, robotic interconnects, motion control.
Consumer Electronics – Foldable phones, cameras, portable electronics.
Benefits of 4 Layer Flexible PCBs
Some key advantages of 4 layer flex PCBs are:
Maximum routing density – Complex, compact layouts with traces on 4 layers.
Embedded discrete passives – Buried resistor, capacitor and inductor integration.
Controlled impedances – Tight impedance control for matched high speed signals.
Integrated shielding – Entire layers can provide EMI/RFI isolation.
Higher component density – More components in a given area with multilayer escape routing.
Multilayer stacking – Can integrate other flex or rigid-flex layers.
Greater functionality – High density interconnects enable more capabilities and features.
Miniaturization – Ideal for complex circuits in small, lightweight products.
Lower assembly costs – Eliminates separate flexible cabling and connectors.
High frequency performance – Controlled impedances benefit RF applications.
Stack up/ Layout of 4 Layer Flex PCB
The manufacturing process of flexible printed circuit boards consists of two inner layers. They have sandwhich like appearance between two outer layers. Copper layer is usually a top layer. A copper layer in flexible printed circuit boards also refer to the signal layer. Bottom layer is also a copper layer.
Materials Used in Making 4 Layer Flex PCB
The materials are what which make your 4 Layer Flex PCB stand out and results in effective longevity. Materials enable your 4 layer flex PCB to cope up with usage demands. Materials that you can use in your 4 Layer Flex PCB have 3 different categories.
Base Material
In flexible circuit boards base material refers to the material which act as a foundation. In rigis flex PCBs it is a flexible polymer film. On the other hand polyimide film refers to the substrate. Polyimide is very flexible and can bear high temperature applications. The polyimide imparts all characteristics that your rigid flex PCB needs. Polyimide reduces the board thickness of your rigid flex pcb. Becuase of flexibility in polyimide slight bend prevent breakage such as in hard boards. Another characteristic of polyimide is that it does not need adhesive to copper attachment.
Adhesive
The role of adhesive is to form a bond. In case if the base material is polyimide in rigid flex PCBs, then adhesive serve its role in limiting the performance of laminate. Several issues come along with when you make use of polyimide adhesives. Adhesive of alternative polymer families serve thier purpose in this regard. In flex circuits adhesives have varying thicknesses. The kind of application determines the adhesive thickness in flex circuits.
Conductive Material
The conductive material is what make layer flex PCB suitable in industrial control equipment or industrial applications. In layer flex PCB the conductive material is Copper. The incredible electrical properties, copper thickness, and affordability are what make it desireable for layer flex circuit board. Copper foil has two main types, electrodeposited and rolled/ wrought. Beside these foils the foils with less copper thickness also in demand these days.
4 layer flex PCB technology enables innovative products with maximum routing density combined with dynamic flexing capabilities. To harness these benefits requires proper stackup configurations, controlled processes, and sound flex design techniques. Partnering with an expert flex PCB manufacturer having robust 4 layer technology maturity allows designers to fully leverage the advantages of 4 layer flex to develop cutting-edge solutions for flex electronics integration needs across industries.