In the dynamic landscape of Flexible Printed Circuit (FPC) and Printed Circuit Board (PCB) manufacturing, the FPC stripping process stands as a make-or-break step for ensuring circuit performance, reliability, and long-term durability. As devices grow smaller (e.g., wearables, IoT sensors) and more complex (automotive ADAS modules, medical implants), the demand for precision in photoresist removal and flexible substrate protection has never been higher. However, manufacturers worldwide grapple with persistent challenges that hinder efficiency and quality.

Shenzhen Huaruixin Electronics Co., Ltd. – a global ODMOEM for FPC, PCB, and Rigid-Flex Printed Boards with state-of-the-art R&D labs and large-scale 

manufacturing facilities – has redefined industry standards by addressing these pain points head-on. This blog dives deep into the critical challenges of the FPCPCB stripping process, Huaruixin’s unique technical solutions, and actionable insights to boost your production. For businesses seeking reliable FPC manufacturing partners or technical resources, visit www.hrxfpc.com or email sales@hrxfpc.com for personalized support.

1. Core Challenges in FPC&PCB Stripping Process (and Their Impact on Production)

The stripping process involves eliminating photoresist (dry film or wet film) from copper-clad laminates (CCL) post-etching, leaving clean, precise flexible circuit traces or rigid PCB pads. Below are the most pressing challenges and their consequences for FPCPCB quality

1.1 Incomplete Photoresist Stripping & Residue Buildup

A top pain point for FPC manufacturers is leftover photoresist residue on PI substrate (polyimide substrate) or FR-4 boards. This issue arises from

Mismatched stripping agents for high-temperature photoresists (used in automotive FPCs).

Inadequate ultrasonic agitation in stripping tanks for fine-pitch FPCs (line widthspace  50μm).

Residues disrupt subsequent steps like solder mask application and electroplating, leading to poor solder joint integrity, short circuits, or costly rework (up to 15% of batches in unoptimized processes).

1.2 Over-Stripping & Flexible Substrate Degradation

Excessive exposure to stripping chemicals (e.g., strong alkalis) often damages

PI film flexibility Critical for foldable devices or FPCs in robotics.

Copper trace integrity Thinning of traces reduces current-carrying capacity, risking overheating in power-sensitive PCBs.

For rigid-flex PCBs – a Huaruixin specialty – over-stripping can separate the rigid FR-4 and flexible PI layers, rendering the board useless.

1.3 Inconsistency in High-Volume FPC Production

Global clients demand batch-to-batch uniformity, but factors like

Fluctuations in ambient temperature (affecting chemical reactivity).

Variations in photoresist thickness (from different suppliers).

lead to inconsistent stripping quality. This increases lead times and erodes trust – a major barrier for manufacturers targeting automotive FPC or medical PCB markets (where compliance with IATF 16949 or ISO 13485 is mandatory).

1.4 Environmental Compliance for Stripping Agents

Traditional PCB stripping chemicals (e.g., VOC-rich solvents) conflict with global regulations

EU’s RoHS 3.0 (restricting hazardous substances).

China’s “Dual Carbon” goals (limiting industrial emissions).

Waste disposal costs for non-compliant agents can add 20% to production expenses, while non-compliance risks fines and market exclusion.

2. Huaruixin’s Unique Solutions Redefining FPC Stripping Excellence

Shenzhen Huaruixin Electronics combines FPC-specific R&D, intelligent automation, and green manufacturing to solve these challenges – making us a trusted partner for 500+ global clients in consumer electronics, automotive, and medical industries.

2.1 Customized Stripping Formulations for FPC Substrates

Huaruixin’s R&D team has developed low-VOC, PI-friendly stripping agents tailored to

High-temperature FPCs (used in engine bays) Resists thermal degradation while removing photoresist in 60–90 seconds.

Ultra-fine pitch FPCs (for wearables) Ensures 99.8% residue-free stripping even for 3030μm traces.

These formulations reduce copper etching by 40% compared to generic agents, preserving circuit trace conductivity and extending FPC lifespan.

2.2 AI-Powered Process Control for Stripping Consistency

Our manufacturing lines integrate Industry 4.0 technologies

Real-time pHconductivity sensors Adjust stripping agent concentration dynamically to avoid overunder-stripping.

Machine vision inspection Post-stripping, high-resolution cameras (200x magnification) scan for residues, flagging defects with 99.9% accuracy.

MES (Manufacturing Execution System) Links stripping data (time, temperature, chemical batch) to product serial numbers for full traceability – critical for automotive PCB clients requiring end-to-end compliance.

2.3 Automated Stripping Lines for Rigid-Flex & FPCs

Huaruixin’s custom-built automated stripping equipment addresses substrate-specific needs

For FPCs Soft-grip robotic arms prevent PI film creasing during loadingunloading.

For rigid-flex PCBs Dual-chamber tanks (one for rigid FR-4, one for flexible PI) ensure uniform stripping across both layers.

This automation cuts processing time by 30% and reduces human error – key for meeting high-volume orders (e.g., 100k+ FPCsmonth for smartphone manufacturers).

2.4 Green Stripping Compliance & Cost Savings

We’ve implemented a closed-loop stripping agent recycling system

Waste liquids are filtered, neutralized, and reused (85% water recovery rate).

VOC emissions are reduced by 70% vs. industry averages, complying with RoHS 3.0 and China’s environmental standards.

This not only lowers disposal costs but also positions clients as sustainable partners – a competitive edge in today’s eco-conscious market.

3. Critical Best Practices for FPC&PCB Stripping (From Huaruixin’s Experts)

To optimize your stripping process, follow these actionable steps

Pre-Stripping Substrate Preparation

Clean copper-clad PI laminates with mild detergents to remove oil or dust – contaminants are the #1 cause of residue. For PCBs, ensure etchants are fully rinsed to avoid chemical reactions with stripping agents.

Match Stripping Agent to Photoresist Type

Use alkaline agents for dry film photoresists (common in rigid PCBs) and solvent-based (low-VOC) agents for wet film (used in flexible FPCs). Huaruixin offers free sample testing to help clients select the right formulation – contact sales@hrxfpc.com to request.

Post-Stripping Validation

Conduct adhesion tests (per IPC-TM-650 standards) to ensure solder mask bonds properly. For FPCs, perform bending tests (180° cycles) to verify PI substrate integrity post-stripping.

Train Teams on EHS Protocols

Ensure operators understand how to handle stripping agents safely (e.g., using PPE, responding to spills). Huaruixin provides on-site training for clients adopting our processes.

Partner with Huaruixin Your Trusted FPC&PCB Manufacturing Expert

Whether you need custom FPCs for wearable tech, high-reliability PCBs for industrial control, or rigid-flex boards for aerospace applications, Huaruixin’s expertise in the stripping process ensures consistent, high-quality results. Our certifications (ISO 9001, IATF 16949, UL) and global supply chain capabilities make us a one-stop solution for your manufacturing needs.

Learn More Visit www.hrxfpc.com to explore our FPCPCB technologies, case studies, and industry resources.

Get a Quote Email sales@hrxfpc.com with your project specs (substrate type, trace width, volume) for a personalized proposal.

Technical Support Our engineers are available 247 to answer questions about stripping processes or FPC design optimization.

Elevate your FPC&PCB production with Huaruixin – where precision meets innovation.