Flexible Printed Circuits (FPCs) are the backbone of modern electronics—powering smartphones, wearables, automotive infotainment systems, and medical devices. Their ability to bend, fold, and fit into compact spaces makes them irreplaceable, but FPC post-processing (reinforcement, drilling, surface treatment) is what transforms raw FPC substrates into reliable, long-lasting components. As a leading global FPC & PCB & Rigid-Flex ODM/OEM manufacturer, Shenzhen Huaruixin Electronics Co., Ltd. specializes in high-precision FPC post-processing, combining advanced technology, material expertise, and strict quality control to meet the demands of industries worldwide.

1. FPC Reinforcement Plate Lamination: Solving Flexibility vs. Rigidity Challenges

FPCs excel in flexibility, but FPC connector interfaces, solder pad areas, and component mounting zones require structural rigidity to withstand insertion forces, thermal stress, and mechanical wear. Without proper reinforcement, these critical regions are prone to bending, trace cracking, or delamination—leading to product failure. Huaruixin’s FPC reinforcement solution addresses this by bonding high-performance reinforcement materials to targeted areas, balancing flexibility with localized strength.

Our Precision Reinforcement Process

AOI-Guided Adhesive Dispensing: We use automated optical inspection (AOI) systems to precisely apply acrylic or epoxy-based FPC adhesives to pre-defined regions (e.g., USB-C connector ports, BTB connector pads). This ensures adhesive placement accuracy of ±0.03mm, avoiding FPC trace damage or adhesive overflow.

Controlled Thermal Bonding: Reinforcement plates (PI film, FR4 rigid sheets, or aluminum/steel foils) are aligned with the adhesive-coated FPC substrate using CCD vision alignment before thermal pressing. Our press machines maintain a consistent temperature of 120-150℃, pressure of 20-30kg/cm², and dwell time of 20-30 minutes—parameters optimized to achieve full adhesive curing and a peel strength of ≥7N/cm (exceeding IPC-6012 standards).

CNC Die-Cutting for Exact Fit: For reinforcement plates larger than the FPC outline, we use high-speed CNC die-cutting with custom steel rule dies to trim excess material. This eliminates burrs, ensures edge flatness (Ra ≤0.8μm), and guarantees compatibility with downstream FPC assembly processes.

Huaruixin’s Unique Advantages in FPC Reinforcement

Material Customization: We offer reinforcement materials tailored to application needs:

PI reinforcement (for low-profile, flexible-to-rigid transitions in wearables);

FR4 reinforcement (cost-effective option for consumer electronics like tablets);

Metal reinforcement (aluminum/steel for high-vibration environments, e.g., automotive FPCs).

Inline Quality Validation: After lamination, every FPC undergoes peel strength testing, AOI defect detection, and thermal shock testing (-40℃ to 125℃, 50 cycles) to ensure no delamination or weak bonding—critical for mission-critical applications like medical FPCs.

High-Volume Production Efficiency: Our automated reinforcement line processes up to 8,000 FPCs per shift, reducing lead time by 40% compared to manual lamination while maintaining a defect rate of <0.05%.

Key Considerations for FPC Reinforcement

Adhesive Compatibility: Ensure the adhesive matches the FPC substrate (e.g., polyimide, polyester) and reinforcement material to prevent chemical incompatibility or thermal expansion mismatch.

Trace Protection: Avoid covering FPC signal traces or vias with reinforcement plates—use CAD-driven design to define clear keep-out zones.

Assembly Compatibility: Design reinforcement thickness (0.1mm-0.5mm) to fit within the end product’s mechanical envelope, avoiding interference with connectors or housing.

2. FPC Drilling: Precision Holes for Vias & Component Mounting

Drilling is a make-or-break step in FPC manufacturing—microvias, through-holes, and mounting holes enable electrical interconnections between FPC layers and component attachment. Poor drilling quality (e.g., burrs, offset holes, or broken traces) leads to short circuits, open circuits, or failed solder joints. Huaruixin’s FPC drilling service combines laser and mechanical drilling technologies to achieve micron-level precision for diverse FPC designs.

Our Advanced FPC Drilling Process

UV Laser Drilling for Microvias: For FPCs requiring blind vias or microvias (diameter 0.05mm-0.1mm), we use high-power UV laser drilling machines with pulse width control. This non-contact method avoids mechanical stress on FPC substrates, ensuring clean hole walls (no burrs) and minimal heat-affected zones (HAZ ≤5μm)—critical for high-density FPCs (e.g., smartphone camera modules).

Mechanical Drilling for Larger Holes: For through-holes (diameter 0.1mm-2.0mm) or mounting holes, we use carbide drill bits with automatic tool changers. Our drilling machines feature Z-axis depth control (accuracy ±0.01mm) to prevent over-drilling and protect FPC coverlay layers.

Post-Drilling Deburring & Cleaning: After drilling, FPCs undergo ultrasonic cleaning in a neutral detergent solution to remove drill dust and debris. This is followed by plasma treatment of hole walls to improve copper plating adhesion—essential for reliable electrical connections.

Huaruixin’s Unique Advantages in FPC Drilling

Dual-Technology Capability: Our ability to combine laser and mechanical drilling allows us to handle complex FPC designs (e.g., rigid-flex boards with mixed hole sizes) in a single production run, reducing lead time and cost.

Real-Time Process Monitoring: Each drilling machine is equipped with machine vision systems that inspect hole position, diameter, and quality in real time. Any deviation from specifications triggers an automatic shutdown, preventing defective FPCs from entering downstream processes.

Compliance with IPC Standards: Our drilling processes meet IPC-6012/2223 standards for hole location accuracy (±0.1mm for mechanical holes, ±0.05mm for laser holes) and hole wall quality—ensuring compatibility with global electronics assembly requirements.

Key Considerations for FPC Drilling

Drill Bit Maintenance: Replace carbide drill bits after 500-1,000 holes (depending on material) to avoid dulling, which causes burrs or hole deformation.

Substrate Support: Use a backing material (e.g., aluminum sheet) during drilling to prevent FPC tearing, especially for thin substrates (≤0.1mm).

Hole Plating Readiness: Ensure hole walls are free of debris or oxidation before copper plating—poor plating adhesion leads to via failure under thermal cycling.

3. FPC Surface Treatment: Enhancing Reliability & Solderability

FPC surface treatment protects copper traces from oxidation, corrosion, and wear while improving solderability for component assembly. The right surface treatment can extend an FPC’s lifespan by 5-10 years, even in harsh environments (high humidity, salt spray, or temperature fluctuations). Huaruixin offers custom FPC surface treatment solutions tailored to application requirements, from consumer electronics to industrial automation.

Our FPC Surface Treatment Offerings

Electroless Nickel Immersion Gold (ENIG): Ideal for high-reliability FPCs (automotive, medical) requiring long shelf life (≥12 months) and excellent corrosion resistance. Our ENIG process deposits a nickel layer (50-100μm) for wear resistance and a gold layer (0.8-1.5μm) for solderability—tested to withstand 96 hours of salt spray (ASTM B117) without corrosion.

Immersion Silver (ImAg): A cost-effective option for consumer electronics (smartphones, tablets) with short production cycles. ImAg provides flat, solderable surfaces with low contact resistance (<10mΩ) and is compatible with lead-free soldering (RoHS compliant).

Organic Solderability Preservative (OSP): Perfect for FPCs used in low-temperature environments (e.g., wearables). Our OSP coating (thickness 0.5-1.0μm) forms a protective film on copper traces, maintaining solderability for up to 6 months of storage—no need for post-storage cleaning.

Hard Gold Plating: For FPCs with connector contacts (e.g., FPC-to-PCB connectors), we offer hard gold plating (gold thickness 1-3μm, cobalt alloyed) to withstand 10,000+ insertion cycles without wear.

Huaruixin’s Unique Advantages in FPC Surface Treatment

RoHS/REACH Compliance: All our surface treatment chemicals are RoHS 2.0 and REACH compliant, ensuring FPCs meet global environmental standards (EU, US, Japan).

Uniform Coating Control: We use automatic plating lines with pH, temperature, and concentration monitoring to ensure uniform coating thickness across the FPC—critical for high-density designs with fine-pitch components (0.3mm pitch or smaller).

Reliability Testing: Every surface-treated FPC undergoes solderability testing (IPC-J-STD-002), thermal cycling testing (-40℃ to 125℃, 100 cycles), and humidity testing (85℃/85% RH, 1,000 hours) to validate performance.

Key Considerations for FPC Surface Treatment

Coating Thickness: Avoid excessive coating thickness (e.g., >2μm gold in ENIG) as it can cause brittle joints or compatibility issues with fine-pitch components.

Cleanliness Before Treatment: Ensure FPCs are free of oil, flux residues, or finger prints before surface treatment—contaminants cause coating defects (pinholes, peeling).

Storage Conditions: Store surface-treated FPCs in dry, temperature-controlled environments (20-25℃, 30-60% RH) to preserve solderability and prevent oxidation.

Choose Huaruixin: Your Trusted FPC Post-Processing Partner

Shenzhen Huaruixin Electronics Co., Ltd. is more than an FPC manufacturer—we are a solutions provider for complex FPC challenges. Our post-processing services (reinforcement, drilling, surface treatment) are backed by:

A 10,000㎡ ISO 9001/14001-certified manufacturing base;

A team of 50+ FPC engineers with 10+ years of industry experience;

Customizable solutions for automotive, medical, consumer, and industrial FPCs;

Fast lead times (5-7 days for prototypes, 10-15 days for mass production).

Let’s Collaborate

Project Inquiries: Need high-quality FPC post-processing for your next project? Contact our team for a tailored quote.

Industry Insights: Visit www.hrxfpc.com to learn more about FPC technology, design guidelines, and post-processing best practices.

Technical Consultation: Email sales@hrxfpc.comfor expert advice on FPC reinforcement, drilling, or surface treatment—we’re here to help you optimize your FPC design for reliability and cost.

Elevate your electronics with Huaruixin’s precision FPC post-processing—where quality meets innovation.