Four-layer flex PCBs represent a significant step up in capability for applications requiring dedicated power planes, complex routing, or superior signal integrity. With four conductive layers, designs gain the flexibility to separate power, ground, and signal layers while maintaining the mechanical advantages of flex circuits.
The 4-layer configuration is often the starting point for rigid-flex applications where the flexible section must carry multiple signal groups between rigid areas. It's also the go-to choice for designs requiring controlled impedance stripline configurations or comprehensive EMI shielding.
Our 4-layer flex service includes advanced via options including blind and buried vias, tight impedance control, and HDI capability. We support both all-flex and rigid-flex configurations to meet your specific mechanical and electrical requirements.
Separate power and ground planes enable optimal power distribution and signal integrity. Shield sensitive signals between ground layers.
Blind vias, buried vias, and microvias enable sophisticated layer-to-layer connections. Full HDI capability for high-density designs.
Stripline and embedded microstrip configurations with controlled impedance. Shield layers contain EMI for sensitive RF and high-speed digital.
Ideal layer count for rigid-flex designs. Flex sections carry complex signal groups while rigid areas support components.
4-layer flex PCBs enable applications requiring advanced electrical performance.
Complex systems like cameras, medical devices, and aerospace electronics use 4-layer flex sections to connect rigid boards with full signal integrity.
DDR memory interfaces, PCIe connections, and other high-speed buses benefit from dedicated ground planes and impedance-controlled striplines.
Wireless modules and antenna systems use 4-layer flex for controlled impedance feeds and integrated shielding to contain RF emissions.
Designs requiring both power distribution and signal routing benefit from dedicated power planes while maintaining compact form factor.
Implantables and diagnostic equipment use 4-layer flex for complex signal routing in miniaturized, flexible packages.
4-layer flex stackup design requires balancing electrical performance with mechanical flexibility.
Signal-Ground-Ground-Signal or Signal-Ground-Power-Signal configurations are common. Stackup selection depends on impedance requirements and routing needs.
Individual dielectric thicknesses are controlled to achieve target impedance. We work with you to optimize layer thicknesses for your electrical requirements.
In flex areas, consider using only the two outer layers for routing to improve flexibility. Inner layers can be used primarily in rigid or stiffened zones.
Balance copper on opposite sides of the neutral axis to minimize flex circuit warping. This is especially important for longer flex sections.
For best flexibility and reliability, adhesiveless polyimide construction is recommended. Adhesive-based construction is available for cost optimization.
Via selection and placement significantly impact both manufacturability and design flexibility.
Standard plated through-holes connect all four layers. Most economical option but create routing obstacles on middle layers.
Connect outer layer to adjacent inner layer. Enable routing over vias on the opposite outer layer. Increase design density.
Connect inner layers without affecting outer layers. Maximum routing flexibility but add cost and process complexity.
Multiple lamination cycles enable buried via structures. Required for complex HDI designs with maximum density requirements.
Minimize vias in flex regions. Use through vias when possible for cost. Blind and buried vias where density requires. Our design review identifies optimization opportunities.
Miniaturized 4-layer flex for medical endoscope with HD video, LED illumination, and control signals routed through 3mm diameter flex section.
Rigid-flex 4-layer assembly connecting flight controller, GPS, and sensor modules. Controlled impedance for high-speed serial buses.
4-layer flex connecting 77GHz radar MMIC to antenna array. Controlled impedance with integrated shielding for automotive radar system.
Consider 4-layer when you need dedicated power/ground planes, controlled impedance stripline structures, shielding between signal layers, or routing density that can't be achieved with two layers.
4-layer flex typically costs 2-3x more than double layer due to additional lamination, drilling, and plating steps. The exact ratio depends on design complexity and via structure.
Yes, but with more constraints than 1-2 layer designs. Larger bend radius is required (typically 6x thickness minimum), and design optimization in the flex region is critical.
Yes, we support both blind and buried via structures for 4-layer designs. Additional lamination cycles are required which affects cost and lead time.
Standard tolerance is ±10%, with ±5% available for critical applications. Stripline configurations in 4-layer flex provide excellent impedance stability.
