FPC materials include both circuit substrates and lamination process aids. Buyers may describe this process aid as a buffer pad silicone sheet. Before reusing a gold silicone buffer pad, separate three jobs: the buffer pad conforms to thickness variation and transfers pressure, release material isolates potential resin bleed, and the carrier plate provides flat support. Then inspect contamination, scratches, warpage, and the prior process record instead of relying on cycle count alone.
Why the release surface needs its own check
The official FPC Lamination Silicone Buffer Pad page identifies a PTFE nano-coating as the anti-stick layer and describes a multilayer construction using elastic fluororesin fiber fabric, heat-resistant thermally conductive fluororesin, and high-tensile fiber fabric. The coating manages release at the interface, while the composite body handles cushioning and pressure transfer. One visual pass cannot validate both functions.
Buffer pad, release material, and carrier plate roles
- Buffer pad: conforms to stack and trace-height variation while transferring lamination pressure; inspect thickness, flatness, and permanent set.
- Release material: separates surfaces that may contact resin; inspect residue, wrinkles, and surface damage.
- Carrier plate: supplies a rigid, flat reference; inspect plate contamination, warpage, and loading position.
The site’s FPC process and lamination-products overview provides broader context for process-aid roles. This article narrows the decision to whether a coated buffer pad is fit for another run.
Formula: use work of adhesion to understand wetting
The Young–Dupré relation is W_A = gamma_L x (1 + cos theta). W_A is the work required to separate liquid and solid (J/m²), gamma_L is liquid surface tension (N/m), and theta is equilibrium contact angle. A peer-reviewed treatment of sessile-drop adhesion shows that, for a smooth clean surface at equilibrium with saturated vapor, a larger contact angle corresponds to lower ideal work of adhesion. The relation only explains wetting. Roughness, contamination, resin cure, pressure, thermal cycling, and peel rate alter real release behavior, so it cannot predict product life or yield.
Four checks before the next press run
- Contamination: under consistent lighting, look for resin residue, particles, and oily films; do not apply an unverified solvent to the coating.
- Scratches: record abrasion, local haze, or coating loss and determine whether it lies inside the active lamination area.
- Flatness: inspect warpage, folds, and local dents so a carrier-plate or stack problem is not mislabeled as release failure.
- Process history: bind temperature, pressure, dwell time, resin system, and cleaning method to the individual pad record; revalidate when conditions change.
How official specifications fit the decision
The official page lists 85–90 Shore A hardness, 280°C temperature resistance, pressure capacity above 45 kg/cm², and applications including PCB, FPC, rigid-flex, and IC-substrate lamination. These ratings still need to be checked against press settings, stack construction, resin, and inspection method; they do not guarantee the result of an individual run. For sampling, return to the gold silicone buffer pad specifications and inquiry page.
Conclusion: base reuse on condition and records
When dents or bubbles appear, troubleshoot by function: check conformity and flatness at the buffer pad, residue and wrinkles at the release layer, and rigidity and surface condition at the carrier plate. If evidence points to the anti-stick interface, compare contamination, damage, and the previous run record. This creates a traceable engineering decision without turning a nominal cycle count into a guarantee.
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