During the vacuum lamination of high-density Multilayer FPCs and Rigid-Flex PCBs, the step-height thickness drop at the rigid-flex junction represents a major mechanical challenge.
Rigid Tooling: Exerts extreme stress concentrations on rigid edges, fracturing tracks or prompting resin overflow.
Insufficient Pressure Windows: Leave micro-voids trapped within local geometric recesses, leading to inner-layer delamination during reflow.
Lixing Silicone Iron Pads resolve this engineering trade-off by chemically bonding a high-elasticity silicone layer directly onto a high-planarity alloy steel iron base plate.
Technical Core & Physical Mechanisms
1. Z-Axis Viscoelastic Compliance & Hydrostatic Pressure Equalization
Mechanism: Under high lamination clamping loads, the silicone matrix undergoes controlled 3D elastomeric flow, adapting to micro-scale step height variances.
Plain-Text Compliance Equation: Delta_z = (P0 * d_pad) / E_silicone (Delta_z: Z-axis kinetic displacement compensation; P0: Platen nominal hydraulic pressure; d_pad: Initial thickness of the silicone layer; E_silicone: Dynamic storage modulus of the polymer network at 200°C)
Benefit: Reconfigures perpendicular mechanical loads into uniform hydrostatic pressure, flattening local stress concentrations to arrest resin overflow.
2. Interfacial Fourier Heat Conduction & Delamination Defense
Mechanism: Thermal energy travels via steady-state Fourier conduction across the alloy plate core through the bonded polymer layer.
Plain-Text Fourier Equation: q = -k * (dT / dx) (q: Steady-state heat flux density; k: Alloy thermal conductivity constant; dT/dx: Perpendicular thermal gradient)
Benefit: Lixing matches the Coefficient of Thermal Expansion (CTE) between the fluoro-silicone matrix and the steel substrate. This minimizes interfacial shear stress, preventing high-temperature delamination between the iron base and the silicone face across thousands of cycles.
Industrial Applications
Rigid-Flex PCB Thermal Clamping: Cushioning large step-downs between rigid FR-4 zones and thin flexible polyimide tails with zero connector contamination.
Multilayer FPC Coverlay Bonding: Providing void-free trace encapsulation and mirror-plane finish across dense blind vias.
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