COB Light Strip Production Process

COB Light Strip Production Process

COB light strip is a new type of high-brightness linear light strip. It boasts an exquisite appearance, highly consistent color rendering, uniform, soft yet bright light output, and multi-level waterproof performance. Adopting flip-chip packaging technology, it features outstanding heat dissipation, low heat generation, long service life and many other superior properties.

Within the modern lighting industry, COB (Chip-on-Board) light strips stand out for their high brightness, even light distribution, energy efficiency and eco-friendliness. They have become an essential component widely applied in all kinds of lighting fixtures. The manufacturing of COB light strips involves multiple precise processes. Let us walk through the full production workflow behind this brilliant lighting product.

COB Light Strip Complete Manufacturing Flow

As a professional COB light strip manufacturer, we strictly implement standardized production procedures with full quality inspection at every stage to ensure high luminous uniformity, low heat decay, stable voltage performance and long service life of all COB flexible light strips. The whole production workflow is divided into 12 core processes as follows:

1. Raw Material Inspection & Preparation

All incoming raw materials go through 100% incoming quality control (IQC) before production launch. Key materials include:

＊Flexible FPC substrate (2oz/3oz copper foil, double-sided heat-conductive PI film)

＊High-brightness COB LED chip wafers (2700K-6500K CCT, CRI≥90 optional)

＊High thermal conductivity silver glue, insulating white glue, encapsulation PU glue

＊Solder paste, conductive gold wire, copper connecting terminals, silicone waterproof sleeves

＊Accessories: double-sided adhesive tape, end caps, wire connectors, PVC outer sleeves

Inspection items: FPC bending resistance, chip luminous efficiency, glue thermal conductivity, wire tensile strength, color temperature consistency of LED chips. Unqualified raw materials will be returned to suppliers directly without entering production lines.

2. FPC Substrate Cutting & Punching

According to customized light strip length specifications, large roll FPC base material is cut into fixed-size single boards via automatic cutting machines. The equipment completes edge trimming, positioning hole punching and terminal slot punching in one step.

＊Control dimensional tolerance within ±0.1mm to avoid assembly deviation

＊Deburr all cutting edges to prevent copper foil short circuit during later wiring

＊Classify FPC boards by voltage type (12V/24V low voltage, 110V/220V high voltage COB strips) and transfer to cleaning station.

3. FPC Surface Plasma Cleaning

Plasma surface activation cleaning is adopted to remove oil stains, dust and oxidation layers on FPC copper pads. This step greatly improves the adhesion between silver glue, LED chips and the substrate, preventing chip peeling and light failure under long-term bending.

Cleaning parameters are fixed for different FPC thicknesses to guarantee uniform surface tension of each circuit board.

4. Silver Glue Dispensing (Die Attach Preparation)

Automatic high-precision dispensing machines apply thermally conductive silver glue evenly on the pre-designed chip mounting positions of FPC.

＊Accurate glue volume control to avoid excessive glue overflow causing short circuits or insufficient glue leading to poor heat dissipation

＊Silver glue is stored at constant low temperature, and mixing proportion is strictly recorded to ensure consistent thermal conductivity batch by batch

After dispensing, FPC boards are transferred to low-temperature pre-baking ovens to remove tiny bubbles inside silver glue.

5. COB LED Chip Die Bonding

Automatic die bonder equipment picks single LED chips from wafer trays and attaches them precisely onto silver glue positions with micron-level positioning accuracy.

＊Chips are arranged in dense linear arrays, the core advantage of COB strips for uniform shadow-free lighting

＊Real-time CCD camera monitoring to reject tilted, offset or damaged chips instantly

Finished bonded boards enter medium-temperature curing ovens to fully solidify silver glue, locking chips firmly on FPC and forming stable heat conduction channels.

6. Wire Bonding (Gold Wire Interconnection)

Ultrasonic wire bonder connects electrodes of adjacent LED chips with fine gold wires to form continuous series-parallel circuit loops.

＊Use 0.8mil high-purity gold wire with excellent conductivity and anti-fatigue performance

＊Each bonding point undergoes tension testing; weak solder joints are marked and reworked manually

After wire bonding, an insulating white protective glue is dispensed on all gold wire positions to isolate circuits and prevent wire breakage during bending. Secondary baking is conducted to cure white glue completely.

7. Pre-Encapsulation Electrical Testing

Before full encapsulation, semi-finished COB boards pass automatic lighting testing racks. Technicians check:

7.1 No dead chips, dim light or flickering points

7.2 Consistent brightness and color temperature of all chips on one strip

7.3 No open circuit, short circuit or leakage current

Defective products are picked out for repair: replace faulty chips or re-broken gold wires; qualified semi-finished products flow to the glue encapsulation process.

8. PU Silicone Full Encapsulation & Molding

Two optional encapsulation processes based on customer requirements: surface thin glue coating and full wrap waterproof molding.

8.1 Indoor non-waterproof COB strips: Uniform thin layer of transparent PU glue coated on chip surface, soft and scratch-resistant, high light transmittance

8.2 IP65/IP67 waterproof COB strips: Full surrounding silicone extrusion molding, completely wrapping chips, wires and FPC circuit

All encapsulation glue adopts anti-yellowing formula, resisting UV aging for long-term indoor and outdoor use. Encapsulated strips go through segmented temperature baking tunnels for slow curing to eliminate internal glue bubbles.

9. Fixed Length Cutting & Terminal Soldering

Fully cured long COB strip rolls are cut into customer required lengths (1m/5m/custom length) according to cutting marks reserved on FPC during early design.

Automatic soldering machines weld positive and negative copper terminals on both ends of each light strip, with tin thickness standardized to ensure stable plug-in connection with power adapters. Manual reinforcement soldering is applied for high-power long strips to avoid loose terminals.

10. Secondary Aging & High-Low Temperature Cycling Test

All finished light strips enter aging test rooms for 4-hour continuous lighting aging under rated voltage. Meanwhile, high-low temperature alternating cycling test (-40℃ to +60℃) is carried out to simulate extreme usage environments.

Test judgment standards: No brightness attenuation, no dead lights, no glue cracking, no terminal falling off after aging cycle. Unqualified products are eliminated centrally.

12. Final FQC Inspection & Outer Packaging

Final full inspection covers appearance, lighting effect, waterproof grade, length, CCT, CRI and packaging integrity. Qualified reels are labeled with specification stickers (voltage, power, length, color temperature, IP rating), then packed into neutral white boxes or customized color cartons. Moisture-proof desiccant bags are added into every package to avoid circuit dampness during sea or land transportation.

Core Advantages of Our Standardized COB Production Line

Full-automatic equipment from chip mounting to packaging, minimizing manual error and improving batch consistency

Multi-layer heat dissipation design in production process, greatly reducing light decay

Strict multi-stage testing links to lower defective rate below 0.3%

Flexible customization support: adjustable chip density, waterproof grades, color temperatures, lengths and packaging solutions for architectural lighting, home decoration, cabinet lighting, commercial display and outdoor landscape lighting.