Posts Tagged ‘flex PCB’

How to Make Your Flex PCB LED Design into Reality?

Thursday, March 6th, 2025

Flex PCB LED solutions keep expanding across industries as demand rises for products with creative shapes and compact structures. From automotive interiors to medical devices, these flexible boards blend functionality with space-saving benefits.

In this article, we’ll dive into what flex PCB LED means, explore its advantages, and share practical design and manufacturing processes. Whether you design products or source materials, this blog will help you understand why flex PCB LED continues to attract attention.

What is A Flex PCB LED?

A flex PCB LED is a thin, flexible circuit board designed to hold LED components while allowing the entire board to bend, twist, or fold during use. Unlike rigid PCBs, these boards are made from materials that stay reliable even after repeated bending.

Most flex PCB LED designs use polyimide or other flexible substrates that support surface-mount LEDs and small passive parts. These materials combine electrical performance with mechanical strength, helping the board withstand vibration and constant flexing without damage.

This flexibility helps designers install LED circuits into curved surfaces, folded product areas, or spaces too tight for traditional rigid boards. From flexible light strips to thin wearable screens, flex PCB LED technology supports creative designs while keeping circuits stable.

If your project need to be designed and produced, please feel free to contact Best Technology sales@bestpcbs.com. We devoted to provide you professional one stop flex pcb led solution and PCBA Service with competitive price and fast delivery, because we are equipped with advanced production and testing machines, and our engineer and production teams all have over 18 years of working experience in pcb industry. Looking forward to working with your project soon!

What Are the Advantages of a Flexible PCB?

Flexible adaptability

With a bend radius of less than 1mm, it adapts to curved and irregular spaces, supporting dynamic three-dimensional bending in space (such as foldable screens, wearable devices).

Lightweight design

Thickness less than 1mm, light weight, space saving and improved portability, suitable for mobile phone backlighting, car interior and other scenarios.

High reliability

High temperature resistance (the PI substrate can withstand temperatures above 260°C), strong vibration resistance, dynamic bending life exceeding one million times, suitable for harsh environments such as mechanical arms and automobiles.

Integration and Precision Supports

Multi-layer circuit stacking, capable of integrating drive modules or sensors; high precision copper wires ensure stable signal transmission, suitable for high-density wiring requirements (such as medical endoscopes). Thermal Dissipation and Safety Excellent thermal conductivity reduces component thermal damage; overall wire connections reduce assembly errors, enhancing system reliability.

All Details You Need to Know About Flex PCB LED

What Are the Disadvantages of a Flexible PCB?

Higher Cost

Due to the use of polyimide substrates and precision etching processes, the production cost is significantly higher than that of traditional rigid boards.

Difficult to Repair

If the lines are damaged after bending on a flexible substrate, it is difficult to repair locally and usually requires a complete replacement.

Complex Design

It is necessary to reserve stress relief areas to avoid line fractures at the bend; special processes are required for connecting the soft and hard parts, which increases the development cycle. Installation

Restrictions

Sharp bends or excessive stretching should be avoided to prevent delamination of the substrate or fracture of the copper foil.

Limited Application Scenarios

High costs and process limitations make them more suitable for high-value-added fields (such as aerospace and high-end consumer electronics), making it difficult to popularize in the low-end market.

What Are the Different Types of Flex LED PCB?

Single-Sided Flex LED PCB

Single-sided flex LED PCBs have just one conductive layer, perfect for simple circuits with basic LED arrays. These boards work well for backlighting, light strips, or decorative LED products.

Double-Sided Flex LED PCB

Double-sided versions add a second conductive layer, helping designers create more complex LED circuits in the same flexible space. These boards suit products where LEDs need more control, like tunable lighting or segmented displays.

Multi-Layer Flex LED PCB

Multi-layer designs stack several conductive layers, allowing advanced routing and high-density LED layouts. These boards support smart lighting, automotive displays, or complex wearables where space-saving matters.

What Is the Difference Between Flex and Non-Flex PCB?

Material

Flex PCBs use polyimide, PET, or other bendable substrates, while non-flex PCBs use fiberglass (FR4) or other rigid materials. Flexible materials let the board bend without cracking.

Thickness

Flexible boards run thinner than rigid boards, especially in wearable or lightweight designs. Rigid boards tend to be thicker for strength and easier handling.

Applications

Flex PCBs often serve in curved lighting strips, medical devices, or foldable gadgets. Non-flex PCBs dominate in flat devices like TVs, computers and so on.

Assembly

Rigid PCBs handle easier during assembly since they keep their shape. Flexible boards need extra care to avoid creases or trace damage. However, when correctly handled, flex PCB LED boards work just as well.

What Are the Manufacturing Processes of Flex PCB?

1. Material preparation and pretreatment

Substrate cutting

Cut the polyimide (PI) or polyester (PET) substrate into specific sizes according to design requirements. The thickness of the substrate is selected according to the application scenario (13μm for dynamic bending area and 25-50μm for static area.

Drilling and hole metallization

Mechanical or laser drilling forms through holes for subsequent electrical connections; metallize the inner wall of the hole through chemical copper plating (PTH process) or electroplating process to ensure conductivity.

2. Circuit pattern production

Dry film coating and exposure

On the surface of the substrate The surface is covered with a photosensitive dry film, and the circuit pattern is transferred to the dry film through ultraviolet exposure.

‌Development and etching‌

Development removes the unexposed part of the dry film to expose the copper layer. Acidic or alkaline etching solution etches away the excess copper layer to form the target circuit.

Demolding and surface cleaning‌

Peel off the remaining dry film, and clean and activate the etched circuit.

3.‌ Overlay and protective film processing

Cover film lamination

Align the PI or PET covering film with the substrate, and the thickness of the covering film needs to match the bending requirements (bending area ≤25μm).

High temperature pressing

In a clean room environment, the cover film and the substrate are pressed together as a whole through high temperature (150-200℃) and high pressure (10-15MPa).

4. Surface treatment and functional enhancement

ENIG

Deposit a nickel-gold layer (0.5-2μm nickel + 0.05μm gold) on the pad area to enhance solderability and corrosion resistance.

Character printing

Print identification text or symbols in non-functional areas to facilitate subsequent assembly identification.

5. Functional testing and finished product processing

Electrical testing

Test the circuit conductivity through a probe, Detect defects such as open circuit and short circuit.

‌Auxiliary material assembly

Add PI reinforcement sheet or steel sheet at the joint of connector or hard board to improve mechanical strength. Attach auxiliary materials such as adhesive tape and electromagnetic shielding film.

Appearance cutting

Use mold stamping or laser cutting to divide the whole board into the final finished product size.

6. ‌Final inspection and packaging

Full inspection (FQC)

‌Perform a comprehensive inspection of the appearance, size and electrical performance of the finished product to eliminate defective products.

Packaging and storage

Store at low temperature (<10℃) after vacuum anti-static packaging to prevent moisture absorption or oxidation of the material.

What Are the Material of a Flex LED PCB?

Substrate layer

Material type:

Polyimide (PI) film must be used in dynamic bending scenarios, which has a temperature resistance of more than 260°C and a bending life of more than 500,000 times, and is suitable for high-reliability scenarios such as folding screens and wearable devices.

Polyester (PET) film can be used for low-cost static scenarios, but it has poor temperature resistance (<100°C) and a bending life of less than 50,000 times.

Thickness selection:

The dynamic bending area requires a 13μm ultra-thin PI substrate to reduce stress concentration.

The static area can use a 50μm thick substrate to improve mechanical strength.

Conductive layer

Copper foil type:

The dynamic bending area must use rolled copper foil (RA copper), which has excellent ductility (long bending life) and avoids fatigue fracture.

Static scenes can use electrolytic copper foil (ED copper) to reduce costs.

Copper thickness parameters‌:

Conventional copper thickness is 18-35μm‌.

High-frequency or high-density lines require ‌9μm ultra-thin copper foil‌ to reduce signal loss‌.

Covering layer and protective film

‌Material matching‌:

The covering film must be consistent with the substrate (such as PI substrate with PI covering film) to avoid delamination caused by differences in thermal expansion coefficient‌.

Thickness control‌:

The thickness of the covering film in the bending area is ≤25μm, and the non-bending area can be increased to 50μm for enhanced protection‌.

The adhesive layer needs to use ‌high-temperature curing epoxy resin‌ to support welding processes (such as reflow soldering)‌.

Adhesives and Stiffener materials

‌Adhesion performance:‌

A low-flow epoxy adhesive is required to ensure the interlayer bonding strength and prevent bending delamination‌.

Stiffener strategy:‌

PI stiffener sheets or steel sheets need to be added to the soft and hard joints to enhance mechanical support‌.

Dynamic structures such as sliding covers are recommended to use ‌glue-free electrolytic copper‌ (better ductility)‌.

Adaptation to special scenarios

‌High-frequency applications:

Polytetrafluoroethylene (PTFE) substrate is required to reduce dielectric loss.

Medical/wearable devices:

The cover film must have sweat-proof and chemical corrosion-resistant properties (such as medical-grade PI materials)

Surface treatment:

The pads in the dynamic bending area need to be plated with a thin nickel-gold layer (0.5-2μm nickel + 0.05μm gold) to prevent bending and cracking.

How to Design a Flexible PCB for LED?

1. Material selection and basic design

Substrate selection

Polyimide (PI) substrate is preferred, as its high temperature resistance (above 260°C) and bending resistance can meet dynamic bending requirements‌. If cost is sensitive and the temperature resistance requirement is low (<100°C), PET film can be used‌.

Conductive layer design

Rolled annealed copper is used instead of electrolytic copper foil to improve the fatigue resistance of the bending area. The copper thickness is recommended to be 18-35μm‌.

‌Coating layer optimization

The covering film should be a polyimide protective film that matches the substrate. The thickness of the covering layer in the bending area is ≤25μm to avoid cracking caused by bending stress concentration‌.

2. Key points of layout planning

‌Component layout rules

All components such as LED lamp beads and driver ICs must be arranged in the hard board area or static bending area, and the distance from the soft-hard combination boundary is >1mm‌48. It is forbidden to place components in dynamic bending areas (such as the joints of wearable devices), and PI reinforcement sheets should be added to improve mechanical strength when the bending radius is ≤3mm. ‌

Power supply partition design

A star power supply topology is used, and the power line width is ≥0.3mm (1A current) to avoid voltage instability caused by impedance mutation due to bending.

3. Wiring process and structural optimization ‌Line direction control‌

The routing in the bending area must be perpendicular to the bending axis, and arc corners (radius ≥1.5 times the line width) are used instead of right-angle routing to reduce bending stress. ‌

Multi-layer board stacking strategy

Single-sided wiring is recommended for dynamic application scenarios, and double-sided wiring (with a 0.05mm PI adhesive layer in the middle) can be used for static scenarios, and the total thickness is controlled within 0.2mm.

‌Transition zone treatment

The soft and hard combination parts adopt a gradient line width design (line width change gradient ≤20%), and add anchor points (Via-in-Pad) to prevent delamination.

4. Production process and test verification

Etching precision control

The line tolerance needs to be ≤±10%, and the line spacing in the dynamic bending area must be ≥0.2mm to avoid short circuit caused by micro crack extension‌.

Welding process selection

Use low-temperature solder paste (melting point 138℃) or conductive silver glue welding to reduce the damage of thermal stress to the flexible substrate‌.

Reliability test

Dynamic bending test: After 100,000 bends (radius 1mm/frequency 1Hz), the resistance change rate is ≤5%‌.

Environmental test: Continuous operation for 500 hours under 85℃/85%RH conditions without performance degradation‌.

5. Design tools and engineering implementation

‌EDA tool settings

Use the Rigid-Flex module of Altium Designer to divide the soft and hard areas by defining the dividing line, and set the bending radius parameters (recommended ≥3 times the board thickness).

‌3D simulation verification‌

Simulate the bending state in software such as SolidWorks to check the component collision risk and line tensile deformation (allowable tensile rate ≤ 0.5%).

Conclusion

To sum up, Flex PCB LED technology offers powerful benefits for modern electronics, supporting thin, lightweight, and creative lighting designs. These boards help engineers build curved, wearable, or space-saving products where rigid boards simply cannot fit.

With the right materials, careful design, and proper handling, flex PCB LED circuits bring both reliability and creative freedom to industries from automotive to medical. Whether you need simple lighting strips or complex LED arrays, flexible boards open new design possibilities.

What are flexible PCBs made of?

Flexible PCBs are mainly made of polyimide or polyester film. These materials have good flexibility and insulation properties, which enable flexible PCBs to maintain stable working conditions in various bending and twisting environments.

The manufacturing process of flexible PCBs includes the following main steps:

Design phase: Use design software to create a prototype of the circuit board, determine the required lines, circuits and components, and design the shape and size of the flexible PCB according to the shape and size of the product.

Board making phase: Print the required lines and patterns on the plastic substrate, usually using photolithography techniques such as coating photolithography and inkjet printing.

Surface treatment and coating: Clean the circuit board and apply a protective coating to prevent chemical and mechanical wear, moisture, corrosion, etc.

Electroplating copper: Apply electroplating copper to certain parts of the flexible PCB to thicken the line.

Pattern chemical etching: Etch away the unnecessary parts of the circuit board and retain the required lines and components.

Molding and perforation: Cut the flexible PCB into the desired shape.

What is the difference between FR4 and flex PCB?

Material composition and performance

FR4: FR4 is the most common PCB substrate, mainly composed of glass fiber and epoxy resin. It has good electrical, thermal and mechanical properties.

Flexible PCB: Flexible PCB (FPC) is mainly made of materials such as polyimide (PI) and is flexible and bendable. They are often used in application scenarios that require frequent bending or limited space.

Application scenarios

FR4: Due to its rigidity and stability, FR4 is often used in applications that require high mechanical strength and stability, such as computer motherboards, mobile phone motherboards, etc.

Flexible PCB: Flexible PCB is often used in applications in car curves and corners, display screens and reverse cam screens, etc. due to its flexibility and bendability.

Manufacturing process and cost

FR4: The manufacturing process includes drilling, etching, copper plating, etc., with moderate cost, suitable for most consumer electronic products.

Flexible PCB: The manufacturing process is relatively complex and the cost is high, but it can meet the needs of specific applications.

In summary, FR4 and flexible PCBs have significant differences in material composition, performance and application scenarios. Choosing the right material depends on the specific application requirements.

What is the difference between a rigid PCB and a flexible PCB?

The main differences between rigid PCBs and flexible PCBs include softness, load-bearing capacity, durability, heat resistance and other aspects.

Softness: Flexible PCBs (FPCs) have good flexibility and can be easily twisted, bent and even folded, and are suitable for application scenarios that require flexible wiring. Rigid PCBs, on the other hand, are harder and cannot be bent, and are usually used in devices that require stability and high load capacity.

Load-bearing capacity: Flexible PCBs have relatively weak current carrying capacity and are suitable for applications with smaller currents. Rigid PCBs have stronger current carrying capacity and are suitable for high-load electronic devices.

Durability and heat resistance: Flexible PCBs can better absorb vibration and shock, have high durability and heat resistance, and can be used in extreme environments. Although rigid PCBs are thicker, they are easily damaged under the influence of high temperatures and chemicals.

Manufacturing process and materials: Flexible PCBs use flexible materials such as polyimide, and a cover layer process is used during the manufacturing process to protect the circuit. Rigid PCBs use thicker materials, usually made of glass-like materials, and require reinforcement.

Application scenarios: Flexible PCBs are widely used in modern smart devices such as smartphones, tablets, and wearable devices due to their flexibility and thinness. Rigid PCBs are often used in devices that require stability and high load capacity, such as laptops and desktop computers.

In summary, there are significant differences between rigid PCBs and flexible PCBs in terms of softness, load-bearing capacity, durability, heat resistance, and application scenarios. The selection of the appropriate type of circuit board should be determined according to specific application requirements.

What is the advantage of flex PCB?

Flexible PCB (Flexible Printed Circuit, FPC for short) has the following main advantages:

Flexibility: The main advantage of flexible PCBs is their elasticity and bending ability. They can be easily twisted, bent, and even folded, suitable for design requirements of various complex shapes.

Reduce weight and space: Flexible PCBs not only provide greater design freedom, but also have better space utilization and weight efficiency. Due to their thin and light characteristics, flexible PCBs can greatly reduce weight and space, especially for small devices.

Suitable for harsh environments: Flexible PCBs can be made of various corrosion-resistant materials and can withstand harsh environmental conditions.

Better thermal management: Flexible PCBs are made of polyimide, which has excellent thermal stability and can withstand extremely high heat.

Reduce costs: Flexible PCBs reduce assembly costs by reducing space requirements and the number of components. Since the need for wiring and connectors is reduced, testing and rework time is also reduced, improving productivity and efficiency.

In summary, flexible PCBs have significant advantages in flexibility, weight, space utilization, environmental adaptability and cost-effectiveness, making them an ideal choice for many high-tech products and applications requiring high reliability.

What are the disadvantages of flexible PCB?

The main disadvantages of flexible PCBs (FPCs) include:

High one-time initial cost: Since flexible PCBs are designed and manufactured for special applications, the cost of circuit design, wiring and photographic plates is high.

Difficult to change and repair: Once a flexible PCB is made, changes must start from the base map or the compiled photolithography program, so it is not easy to change. Its surface is covered with a protective film, which needs to be removed before repair and restored after repair, which is a relatively difficult task.

Size is limited: Flexible PCB is usually manufactured by intermittent process when it is not yet popular. Therefore, it is limited by the size of production equipment and cannot be made very long or wide.

Improper operation can easily cause damage: Improper operation by the assembly personnel can easily cause damage to the flexible circuit. Its soldering and rework require trained personnel to operate.

How thick is a flex PCB board?

The common thickness of flexible PCB board is 0.2mm. The thickening layer will be added behind the parts to be soldered. The thickness of the thickening layer is generally 0.2mm or 0.4mm12.

In addition, the thickness of flexible PCB board usually ranges from 0.1mm to 0.4mm, of which the thickness of 0.1mm to 0.4mm is called ultra-thin PCB board.

Where are flexible PCBs used?

Flexible PCB (Flexible Printed Circuit Board, FPC) is widely used in many fields, mainly including the following aspects:

Consumer electronics: Flexible PCB is widely used in consumer electronics such as smartphones, tablets, smart watches, etc.

Medical equipment: In medical equipment, flexible PCB can bend and adapt to specific shapes, and is often used in electrocardiographs, blood pressure monitors, monitoring equipment and medical sensors, etc.

Automotive electronics: Flexible PCB plays an important role in automotive electronic systems, connecting in-vehicle entertainment systems, navigation systems, dashboards, body control modules and safety systems, etc.

Aerospace: Flexible PCB is also widely used in the aerospace field, such as satellite communications, spacecraft control, etc.

Industrial control and automation: In the field of industrial control and automation, flexible PCB is used to connect sensors, actuators, control modules and data acquisition equipment, etc.

LED lighting: Flexible PCB is also used in LED lighting products to provide connection and signal transmission functions.

In summary, the material combination of flexible PCBs gives them unique properties and a wide range of application prospects. The flexible substrate provides bendability and durability, the conductive layer ensures efficient transmission of electronic signals, and the cover layer provides protection for the entire structure. The continuous innovation and optimization of these materials will continue to promote the development of flexible PCBs.