Medium and small batch production of rigid-flex PCBs (typically 100-5,000 units) requires a balance between efficiency, flexibility, and cost control, leveraging specialized processes to adapt to varying order sizes while maintaining consistency. These processes differ from mass production by prioritizing adaptability and reducing setup times.

The production starts with flexible substrate preparation. For small batches, laser cutting is preferred for its precision and quick setup—digital designs are directly converted to cutting paths, eliminating the need for expensive dies. The flexible layers (polyimide with copper cladding) are cleaned and treated with adhesion promoters to ensure strong bonding with rigid layers. For medium batches, panelization is optimized to fit 20-50 boards per panel, maximizing material usage without excessive waste.

Lamination is a critical step, with modified processes for smaller runs. Instead of large-scale automated lamination lines, batch-specific lamination presses with programmable temperature and pressure profiles are used. This allows customization for different layer counts—for example, a 4-layer rigid-flex board requires 2-3 lamination cycles, each tailored to the thickness of rigid and flexible materials. The lamination of rigid FR-4 and flexible polyimide layers uses thermosetting adhesives, with curing times adjusted to 30-60 minutes per batch to ensure proper bonding without overprocessing.

Drilling and plating are adapted for variable volumes. Mechanical drilling is used for larger holes in rigid sections, while laser drilling handles microvias in flexible areas, with quick tool changes between batches. Electroless copper plating ensures uniform coverage of holes, with batch-specific current settings to accommodate varying board sizes. For small batches, manual inspection supplements automated systems to catch defects, while medium batches use AOI for efficiency.

Component assembly for medium and small batches often combines automated pick-and-place for standard components with manual placement for large or irregular parts. Reflow soldering uses batch-specific profiles, with separate zones for rigid and flexible sections to prevent overheating. Post-assembly testing includes bend cycle tests (5,000-10,000 cycles) for flexible areas and electrical testing to ensure connectivity, with batch-specific test fixtures designed for quick setup. These adapted processes enable efficient production of medium and small batches while maintaining the quality and reliability of rigid-flex PCBs.