China Rigid Flex PCB Manufacturers & Pricelist

The minimum bend radius is governed by whether the application is static (flex-to-install) or dynamic (continuous flexing), along with the number of flexible conductive layers and copper foil metallurgy. Per IPC-2223 guidelines, for a single-layer flexible section in a static installation, the bend radius R must be at least 6× to 10× the overall flex thickness (T). For double-sided flexible cores, the static minimum bend radius increases to 10× to 12× T. In high-cycle dynamic flexing applications (such as robotics or medical camera gimbals), a single-sided flex core should be maintained wherever possible, and the bend radius must expand to at least 20× to 40× the total flex thickness. Additionally, dynamic designs must specify rolled-annealed (RA) copper instead of electro-deposited (ED) copper, keep the copper grain structure oriented along the bend direction, avoid placing plated through-holes or coverlay terminations within 50 mil (1.27mm) of the bend transition, and use cross-hatched ground copper rather than solid pours to retain mechanical flexibility.

Adhesived flexible laminates utilize a layer of acrylic or modified epoxy adhesive (typically 12.5µm to 25µm thick) to bond the copper foil to the dielectric polyimide film. While less expensive, adhesived laminates present major thermal and electrical drawbacks: the adhesive layer has a low glass transition temperature (Tg < 150°C), absorbs significant moisture during lead-free soldering cycles, and exhibits high z-axis thermal expansion, which increases stress on plated through-hole (PTH) barrels. In contrast, adhesiveless flexible laminates (such as DuPont Pyralux AP or Shengyi SF305) cast the polyimide resin directly onto the rolled-annealed copper foil or utilize ultra-thin seed metal vacuum sputtering. Adhesiveless materials deliver a higher continuous operating temperature rating (Tg > 220°C), superior dimensional stability (shrinkage <0.05%), reduced total stack-up thickness, and improved resistance to microvia barrel cracking during multiple 260°C lead-free reflow operations. Adept PCBA uses adhesiveless polyimide laminates as the default for all multi-layer and high-reliability rigid-flex builds.

Resin management at the rigid-to-flex transition boundary is one of the most critical challenges in rigid-flex fabrication. Standard FR-4 prepregs liquefy and flow under autoclave lamination pressure; if this resin flows uncontrolled onto the exposed flexible arm, it creates stress concentrators that lead to brittle polyimide failure during bending. Conversely, if insufficient resin flows up to the rigid cap edge, internal voids and delamination pockets can form. Our CAM and process engineers resolve this using no-flow or low-flow prepregs (such as 106NF or 1080NF styles) with carefully controlled resin rheology profiles. Furthermore, the prepreg is CNC router-cut or laser-profiled with an engineered relief cut back from the rigid-to-flex transition interface. We also enforce an overlap design rule: the flexible polyimide coverlay must extend at least 0.8mm (30 mil) inside the rigid board section, and outer rigid prepreg cores must terminate with a structural step transition to ensure smooth stress dissipation without mechanical micro-cracking.

To provide a precise quote and comprehensive DFM report, we require: (1) Gerber RS-274X or ODB++ files including all copper routing layers, soldermasks, coverlay opening layers, silkscreens, drill files (specifying plated vs non-plated through-holes, blind/buried microvias), and router route paths; (2) An explicit layer stack-up drawing detailing the rigid regions versus flexible zones, specifying core thicknesses, copper foil weights (1/3oz, 1/2oz, 1oz), prepreg glass styles, coverlay thicknesses, and any stiffener requirements (FR-4, polyimide, aluminum, or stainless steel); (3) A comprehensive fabrication master drawing noting IPC inspection classes (IPC-6013 Class 2 or Class 3), controlled impedance targets with referenced trace widths/geometries, surface finish specs (ENIG, ENEPIG, Immersion Silver), and mechanical tolerances; and (4) If turnkey assembly is required, a clean Bill of Materials (BOM) in Excel format with manufacturer part numbers (MPN), reference designators, and package footprints, alongside centroid pick-and-place XY coordinates.

Yes. We routinely fabricate rigid-flex HDI boards utilizing staggered, stacked, and copper-filled laser microvias (VIPPO - Via-In-Pad Plated Over) in configurations such as 1+N+1, 2+N+2, and any-layer HDI structures. In these designs, UV and CO2 laser drill systems create microvia diameters down to 75µm (3 mil) with blind aspect ratios of 1:1. However, good DFM practice avoids placing laser microvias directly within dynamic flexing zones, as localized rigid plating increases copper strain under flexure. Instead, microvias are concentrated within the rigid SMT lands, while the inner flexible layers transition into smooth, unpierced, teardrop-filleted copper routing arms. When blind vias must interface with flexible layers, our plating lines utilize specialized DC pulse plating baths to ensure clean, void-free copper fill and uniform planar surfaces across component lands.

Standard prototype lead times for a 4-layer to 6-layer rigid-flex board typically run 5 to 8 business days after final DFM and CAM sign-off. For quick-turn R&D projects requiring rapid functional verification, we offer expedited 72-hour and 96-hour turns on select stack-ups when standard stocked materials (such as DuPont Pyralux and Shengyi high-Tg cores) are specified. Complex multi-layer HDI rigid-flex builds (8 to 16 layers with multiple lamination cycles and laser blind/buried microvias) generally require 10 to 14 business days. Medium- to high-volume production batches (ranging from 1,000 to over 50,000 units) maintain production cycle times of 16 to 22 business days, supported by automated optical inspection (AOI), 100% electrical flying probe or dedicated bed-of-nails e-testing, and vacuum moisture-barrier packaging.

Electroless Nickel Immersion Gold (ENIG) is our most frequently requested finish, providing a planar surface for fine-pitch BGAs (0.4mm pitch) along with solid oxidation resistance (gold thickness 1–3 µ-inches over 120–240 µ-inches of electroless nickel). However, when flexible contact fingers must withstand repetitive insertions into Zero Insertion Force (ZIF) connectors, immersion gold can wear through. In those cases, we specify Electrolytic Hard Gold (typically 15 to 30 µ-inches of hard gold over 150 µ-inches of nickel), which offers superior abrasion and wear resistance. For high-density mission-critical medical and aerospace electronics requiring wire bonding or protection against nickel-corrosion "black pad" risks, we recommend ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold). The intermediate palladium layer (2–4 µ-inches) acts as a reliable barrier against nickel diffusion, ensuring robust solder joint shear strength under high vibration.