LED Component Technical Documentation - Lifecycle Phase: Revision 2 - Release Date: 2014-12-06 - English

1. Product Overview

This technical document pertains to a specific revision of an LED component. The primary focus is on the established lifecycle phase of the product, indicating its maturity and stability within the manufacturing and supply chain. The core advantage of this revision lies in its finalized specifications and proven performance parameters, having undergone necessary updates and validations. The target market includes applications requiring reliable, long-term sourcing of lighting components for general illumination, signage, and indicator purposes where consistent quality and documented history are paramount.

2. Lifecycle and Revision Information

The document consistently identifies the component's status. The lifecycle phase is marked as \"Revision\", which signifies that the product design and specifications have been updated from a previous version and are now in a stable, released state. The revision number for this document is 2. The release date for this revision is clearly stated as December 6, 2014. Furthermore, the expired period is noted as \"Forever\", which typically indicates that this revision of the document and the product specifications it defines do not have a planned obsolescence date and are intended for indefinite use, barring any future fundamental changes or discontinuations.

3. Technical Parameters Deep Objective Interpretation

3.1 Photometric and Electrical Characteristics

While specific numerical values for luminous flux, wavelength, and forward voltage are not provided in the extracted snippet, a detailed technical document for an LED would typically include these. Photometric characteristics define the light output and color. Key parameters include dominant wavelength (for monochromatic LEDs) or correlated color temperature (CCT) and color rendering index (CRI) for white LEDs, measured in nanometers (nm) or Kelvins (K) respectively. Luminous flux, measured in lumens (lm), indicates the total perceived power of light. Electrical parameters are equally critical. The forward voltage (Vf) is the voltage drop across the LED when it is operating at a specified current. The rated forward current (If) is the recommended operating current for optimal performance and longevity. Exceeding this current can lead to accelerated degradation or failure.

3.2 Thermal Characteristics

The thermal performance of an LED is fundamental to its reliability and light output stability. The junction-to-ambient thermal resistance (RθJA), measured in degrees Celsius per watt (°C/W), quantifies how effectively heat is dissipated from the semiconductor junction to the surrounding environment. A lower thermal resistance value indicates better heat dissipation capability. Proper thermal management, often involving a heatsink, is essential to maintain the junction temperature within safe limits, ensuring long operational life and preventing color shift or lumen depreciation.

4. Binning System Explanation

LED manufacturing involves natural variations. A binning system categorizes LEDs based on key parameters to ensure consistency within a production batch. Wavelength or CCT binning groups LEDs according to their color output within a defined range (e.g., 2.5-step or 5-step MacAdam ellipses for white light). Flux binning sorts LEDs based on their luminous output at a standard test current. Voltage binning categorizes components by their forward voltage drop. This system allows designers to select LEDs from specific bins to achieve uniform color and brightness in their final application, which is crucial for multi-LED arrays or products requiring precise color matching.

5. Performance Curve Analysis

5.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve is a fundamental electrical characteristic of an LED. It is non-linear, showing a sharp increase in current once the forward voltage exceeds a certain threshold (the turn-on voltage). The curve is essential for designing the driving circuit, as it shows the relationship between the applied voltage and the resulting current. Operating the LED at a constant current, rather than a constant voltage, is the standard practice to ensure stable light output and prevent thermal runaway.

5.2 Temperature Dependence

LED performance is highly temperature-sensitive. As the junction temperature increases, the forward voltage typically decreases slightly. More significantly, the luminous flux output decreases. This relationship is often shown in a relative luminous flux vs. junction temperature graph. The spectral characteristics can also shift with temperature; for white LEDs, this may manifest as a change in CCT. Understanding these dependencies is vital for designing systems that maintain consistent performance across the intended operating temperature range.

5.3 Spectral Power Distribution (SPD)

For white LEDs, the SPD graph shows the intensity of light emitted at each wavelength across the visible spectrum. It reveals the composition of the light, whether from a blue pump LED combined with a phosphor or from a combination of different colored LEDs. The SPD directly determines the CRI and the quality of the white light. For colored LEDs, the SPD shows a narrow peak at the dominant wavelength, indicating the purity of the color.

6. Mechanical and Package Information

A detailed mechanical drawing would typically be included, showing the component's dimensions (length, width, height) in millimeters, often following a standard package naming convention like 2835 or 5050. The drawing specifies tolerances. It also clearly indicates the pad layout (anode and cathode) for surface-mount technology (SMT) assembly. Polarity identification is marked on the component itself, usually with a notch, a dot, or a different-shaped pad for the cathode. The package material (often a high-temperature plastic like PPA or PCT) and lens type (clear or diffused) are also specified.

7. Soldering and Assembly Guidelines

7.1 Reflow Soldering Profile

The document should provide a recommended reflow soldering temperature profile. This includes key parameters: preheat temperature ramp rate, soak time and temperature, peak temperature (which must not exceed the LED's maximum soldering temperature, typically around 260°C for a few seconds), and cooling rate. Adhering to this profile prevents thermal shock and damage to the LED package and internal die.

7.2 Precautions and Storage Conditions

Precautions include avoiding mechanical stress on the LED lens, preventing contamination of the optical surface, and ensuring proper alignment during placement. LEDs are sensitive to electrostatic discharge (ESD); therefore, ESD-safe handling procedures should be followed. Recommended storage conditions usually specify a temperature and humidity range (e.g., 5°C to 30°C, <60% relative humidity) to prevent moisture absorption, which can cause \"popcorning\" during reflow.

8. Packaging and Ordering Information

Packaging specifications detail how the LEDs are supplied. Common formats include tape-and-reel for automated SMT assembly. The reel size, tape width, pocket dimensions, and orientation are specified. The label on the reel or box includes critical information: part number, revision code, quantity, bin codes (for flux, color, voltage), lot number, and date code. The model naming rule deciphers the part number, indicating package type, color, flux bin, voltage bin, and other attributes through a specific alphanumeric sequence.

9. Application Suggestions

9.1 Typical Application Scenarios

Based on common LED packages, potential applications include backlighting units for LCD displays, general ambient lighting (bulbs, panels, tubes), architectural accent lighting, automotive interior lighting, signage and channel letters, and status indicators in consumer electronics and appliances.

9.2 Design Considerations

Key design considerations involve selecting an appropriate constant-current driver matched to the forward voltage and current requirements of the LED or LED string. Thermal management design is non-negotiable; the PCB layout and possible external heatsink must keep the junction temperature low. Optical design, including secondary optics like lenses or diffusers, shapes the light output. For arrays, ensuring uniform current distribution, often through appropriate circuit topology, is necessary for consistent brightness.

10. Technical Comparison

While a direct comparison with other products is not possible from the given data, the advantages of this specific revision (Rev. 2) would generally be based on its finalized and validated parameters. Compared to earlier revisions or prototype stages, it offers guaranteed performance specifications, improved manufacturing yield consistency, and resolved issues identified during development. Compared to alternative technologies (e.g., incandescent or CFL), LEDs offer superior energy efficiency, longer lifetime, better durability, and smaller form factors.

11. Frequently Asked Questions (FAQ)

Q: What does \"Lifecycle Phase: Revision\" mean?
A: It indicates the product design and specifications have been updated and finalized. This revision (Rev. 2) is the stable version released for production and use.

Q: The expired period is \"Forever\". Does this mean the LED will last forever?
A: No. \"Forever\" refers to the validity period of this document revision, not the product's operational life. The LED's lifetime (often defined as L70 or L50) is a separate parameter, typically tens of thousands of hours.

Q: How do I interpret the release date?
A: The release date (2014-12-06) is when this specific revision of the technical documentation was issued. It serves as a reference for the version of the specifications.

Q: What is the most critical parameter for driving an LED?
A> The forward current (If). LEDs are current-driven devices. Operating them at their specified constant current is essential for correct brightness, color, and longevity.

12. Practical Use Case

Consider designing a linear LED light fixture for office lighting. The designer selects this LED component based on its documented specifications (Rev. 2). They use the luminous flux bin to calculate the number of LEDs needed to achieve the target illuminance. The forward voltage and current specifications are used to design a series-parallel array and select a suitable constant-current driver. The thermal resistance data informs the design of the aluminum PCB and heatsink to ensure the junction temperature remains below 85°C for maximum lifespan. The reflow profile from the document is programmed into the SMT assembly line. The bin codes from the reel labels are recorded for traceability and to ensure color consistency across multiple production batches of the fixture.

13. Principle Introduction

An LED (Light Emitting Diode) is a semiconductor device that emits light when an electric current passes through it. This phenomenon is called electroluminescence. When a voltage is applied in the forward direction, electrons recombine with holes within the semiconductor material (commonly based on gallium nitride (GaN) for blue/white/green, or aluminum gallium indium phosphide (AlGaInP) for red/amber), releasing energy in the form of photons. The wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material. White LEDs are typically created by coating a blue LED chip with a yellow phosphor; the combination of blue and yellow light appears white to the human eye.

14. Development Trends

The LED industry continues to evolve towards higher efficacy (more lumens per watt), improving energy savings. There is a strong focus on enhancing color quality, including higher CRI values (CRI90+) and improved color consistency (tighter binning). Miniaturization of packages while maintaining or increasing light output is an ongoing trend. Smart and connected lighting, integrating LEDs with sensors and controls, is a significant growth area. Furthermore, research into novel materials like perovskites and quantum dots aims to achieve even better color performance and efficiency. The industry also emphasizes sustainability through improved recyclability and reduction of hazardous materials.