Introduction to LED Display Technology

Modern LED Display Screens rely on semiconductor electroluminescence, where InGaN/GaN chips emit blue light (450nm) converted to white via phosphor coating. High-end displays achieve 16-bit grayscale, 3840Hz refresh rates, and 5,000 nits brightness for outdoor applications.

Raw Materials and Components

1. LED Chips

• Type: InGaN blue chips (2835/1010 packages)

• Specifications:

• Wavelength: 450±2nm

• Forward Voltage: 2.8-3.4V @20mA

• Luminous Efficacy: ≥180 lm/W

2. Encapsulation Materials

3. Substrates

• Aluminum PCB: Thermal conductivity ≥2.2W/m·K, Cu thickness 35±5μm

• Ceramic PCB: AlN substrates (24W/m·K) for high-power LED arrays

LAMP LED Production Workflow

1. Die Bonding

• Adhesive: Silver epoxy (80% Ag content)

• Curing: 150℃/1hr, bond line thickness 25±5μm

• Accuracy: Placement error ≤±15μm

2. Wire Bonding

• Wire: 99.99% Au, diameter 1.0mil

• Parameters: Ultrasonic power 50W, force 30g, cycle time 0.3s

3. Encapsulation

• Process: Vacuum potting (≤1kPa, 30min degassing)

• Curing: 135℃/4hrs, bubble diameter ≤30μm

4. Final Assembly

• Pin Forming: Shear cutting ±0.1mm tolerance

• Binning: Wavelength ±2nm, luminous intensity ±5%

SMD LED Manufacturing Process

1. Solder Paste Printing

• Stencil: Laser-cut stainless steel, 0.12mm thickness

• Solder: SAC305 alloy, volume 80-120μm (SPI monitored)

2. Component Placement

• Machine: High-speed pick-and-place (30,000 CPH)

• Precision: ±0.03mm (X/Y), ±0.5° (θ)

3. Reflow Soldering

• Profile:

• Preheat: 1-2℃/s to 150℃

• Peak: 245℃ (60s above 217℃)

• Atmosphere: Nitrogen (O₂ <1,000ppm)

4. Molding and Dicing

• Molding: Transfer process @8-12MPa, 150℃/180s

• Laser Cutting: 355nm UV laser, 5W power, 100mm/s speed

Mini/Micro LED Advanced Processes

1. Mass Transfer Technology

• Laser Lift-Off (LLO):

• Transfer rate: 99.99% (R&D), 99.9% (production)

• Accuracy: ±1.5μm placement

2. Chip-on-Board (COB)

• Pixel Density: 100-200 PPI

• Encapsulation: Black epoxy fill (ΔE <1.5)

3. Automotive-Grade Standards

• AEC-Q102: -40℃ to 125℃ operation, 85℃/85%RH/1,000h

• Vibration Test: 50G shock (MIL-STD-883 Method 2002)

Quality Control Systems

1. In-Process Inspection

• AOI: Defect detection ≥99.9% (solder bridges, missing parts)

• X-Ray: Voiding <15% in solder joints

2. Environmental Testing

3. Photometric Testing

• Integrating Sphere: CCT tolerance ±150K, CRI ≥80

• Viewing Angle: ≥140° horizontal/vertical, ≤50% brightness drop

Packaging and Logistics

1. Moisture Protection

• MSL Level: Level 3 (72hrs floor life @30℃/60%RH)

• Dry Packaging: <10% RH with desiccant

2. Shock/Vibration Resistance

• ISTA 3A: Survives 1.2m drops, 50G impacts

3. Compliance Documentation

• Safety: UL/cUL, CE, CCC

• Environmental: RoHS 2.0, REACH SVHC <0.1%