LED Component Lifecycle Document - Revision 3 - Release Date 2014-12-11 - English Technical Specification

1. Product Overview

This document pertains to a specific revision of an LED component, identified as Revision 3. The lifecycle phase is designated as "Revision," indicating an updated version of the product. The release date for this revision is documented as December 11, 2014, at 19:03:32. The expired period is marked as "Forever," suggesting this document and the associated product data remain valid indefinitely unless superseded by a newer revision. This component is designed for integration into various electronic assemblies requiring reliable light emission.

The core advantage of this component lies in its documented and stable revision history, providing traceability and consistency for design and manufacturing processes. It targets markets and applications where long-term component availability and specification stability are critical, such as industrial lighting, automotive interior lighting, signage, and consumer electronics.

2. Technical Parameters Deep Objective Interpretation

While the provided excerpt focuses on administrative data, a comprehensive technical document for an LED would typically include the following parameter categories, which are essential for design engineers.

2.1 Photometric and Color Characteristics

Key photometric parameters define the light output and quality. Luminous flux, measured in lumens (lm), indicates the total perceived power of light emitted. Correlated Color Temperature (CCT), measured in Kelvin (K), describes the color appearance of white light, ranging from warm white (2700K-3000K) to cool white (5000K-6500K). Chromaticity coordinates (x, y on the CIE 1931 diagram) precisely define the color point. Color Rendering Index (CRI) measures the ability of the light source to reveal the colors of objects faithfully compared to a natural light source, with higher values (closer to 100) being better. Dominant wavelength or peak wavelength defines the color of monochromatic LEDs.

2.2 Electrical Parameters

Electrical specifications are crucial for circuit design. The forward voltage (Vf) is the voltage drop across the LED when operating at a specified forward current (If). It typically ranges from 2.8V to 3.6V for common white and blue LEDs. The forward current (If) is the recommended operating current, often 20mA, 60mA, 150mA, or higher for power LEDs. Maximum ratings for reverse voltage (Vr), forward current, and power dissipation must not be exceeded to prevent permanent damage. The electrostatic discharge (ESD) sensitivity rating (e.g., Class 1C, 2kV HBM) indicates the component's robustness against static electricity.

2.3 Thermal Characteristics

LED performance and lifespan are heavily influenced by temperature. The junction temperature (Tj) is the temperature at the semiconductor chip itself. The thermal resistance from junction to solder point (Rth_j-sp) or junction to ambient (Rth_j-a) quantifies how effectively heat is conducted away from the chip. Lower thermal resistance values are desirable. Maximum allowable junction temperature (Tj_max) is a critical limit; operating above this temperature drastically reduces luminous output and operational life.

3. Binning System Explanation

LED manufacturing yields variations. Binning groups LEDs with similar characteristics to ensure consistency in end products.

3.1 Wavelength/Color Temperature Binning

LEDs are sorted into bins based on their chromaticity coordinates or CCT. A typical bin structure on the CIE diagram might be defined by a small quadrilateral or ellipse. Tighter bins (smaller areas) offer better color uniformity but may have lower yield and higher cost.

3.2 Luminous Flux Binning

LEDs are categorized by their light output at a standard test current (e.g., If=20mA, T_sp=25°C). Bins are defined by minimum and/or maximum luminous flux values (e.g., 7-8 lm, 8-9 lm). This allows designers to select components that meet specific brightness requirements.

3.3 Forward Voltage Binning

LEDs are sorted by their forward voltage drop at a specified test current. Common bins might be Vf @ 20mA: 3.0-3.2V, 3.2-3.4V. Consistent Vf bins help in designing stable driver circuits and managing power distribution in arrays.

4. Performance Curve Analysis

4.1 Current-Voltage (I-V) Characteristic Curve

The I-V curve is non-linear. Below the threshold voltage, very little current flows. Once Vf is reached, current increases rapidly with a small increase in voltage. This is why LEDs are typically driven by a constant current source, not a constant voltage source, to prevent thermal runaway. The curve shifts with temperature; Vf decreases as junction temperature increases.

4.2 Temperature Characteristics

Luminous flux decreases as junction temperature rises. This relationship is often shown in a relative luminous flux vs. junction temperature graph. The forward voltage (Vf) also has a negative temperature coefficient. Understanding these curves is vital for thermal management design to maintain brightness and color stability.

4.3 Spectral Power Distribution

This graph shows the relative intensity of light emitted at each wavelength. For white LEDs (typically blue chip + phosphor), it shows a blue peak from the chip and a broader yellow/red emission from the phosphor. The SPD determines the CCT and CRI. It can shift slightly with drive current and temperature.

5. Mechanical and Packaging Information

5.1 Dimension Drawing

A detailed mechanical drawing provides all critical dimensions: length, width, height, lens shape and size, and lead/pad spacing. Tolerances are specified. Common surface-mount device (SMD) packages include 2835, 3528, 5050, etc., where the numbers often represent length and width in tenths of a millimeter (e.g., 2835 is 2.8mm x 3.5mm).

5.2 Pad Layout Design

The recommended footprint (land pattern) for PCB design is provided, including pad size, shape, and spacing. This ensures proper solder joint formation during reflow. Thermal pad designs, if present, are detailed to facilitate heat sinking.

5.3 Polarity Identification

Clear markings indicate the anode (+) and cathode (-). This can be a notch, a dot, a green marking, or a different lead length/shape. Correct polarity is essential for circuit operation.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A recommended reflow temperature profile is provided, including preheat, soak, reflow, and cooling zones. Key parameters are peak temperature (typically 245-260°C maximum), time above liquidus (TAL), and ramp rates. Exceeding these limits can damage the LED's plastic package, internal wire bonds, or phosphor.

6.2 Precautions

ESD precautions should be observed during handling. Avoid mechanical stress on the lens. Do not clean with solvents that may attack the silicone lens or plastic body. Ensure the PCB is clean and flux residues are compatible.

6.3 Storage Conditions

LEDs should be stored in a dry, dark environment at recommended temperature and humidity levels (often <30°C/85%RH). They are typically shipped in moisture-sensitive device (MSD) bags with desiccant and humidity indicator cards. If exposed to high humidity, baking may be required before reflow to prevent "popcorning."

7. Packaging and Ordering Information

7.1 Packaging Specifications

Components are supplied on tape and reel for automated assembly. The reel dimensions, tape width, pocket size, and component orientation are standardized (e.g., EIA-481). Quantity per reel is specified (e.g., 2000 pcs/reel, 4000 pcs/reel).

7.2 Label Description

The reel label contains information such as part number, quantity, lot number, date code, and bin codes for luminous flux, color, and Vf.

7.3 Model Numbering Rules

The part number encodes key attributes. A typical structure might be: Series Code - Package Size - Color/Flux Bin - Voltage Bin - Color Temperature - Special Option. This allows precise identification of the component's characteristics.

8. Application Suggestions

8.1 Typical Application Scenarios

Based on its implied specifications (common SMD LED), this component is suitable for backlighting units (BLU) in displays, general indicator lights, decorative lighting, automotive interior lighting (dashboards, switches), and signage.

8.2 Design Considerations

Always use a current-limiting resistor or constant-current driver. Consider thermal management early in the PCB layout; use thermal vias and adequate copper area for heat dissipation, especially for higher-power LEDs. For color-sensitive applications, specify tight color bins and consider feedback from color sensors. Account for forward voltage variation and thermal derating of light output in system brightness calculations.

9. Technical Comparison

Compared to previous revisions (e.g., Revision 2), Revision 3 may offer improvements such as higher luminous efficacy (more lumens per watt), better color consistency (tighter binning), enhanced reliability data, or updated packaging. The "Forever" expired period for this document suggests it represents a mature, stable product version with long-term support, unlike some rapidly evolving components where datasheets are frequently updated or deprecated.

10. Frequently Asked Questions

10.1 What does "Lifecycle Phase: Revision" mean?

It indicates this is not an initial release or an obsolete product, but an actively maintained and updated version of the component's documentation and specifications.

10.2 How should I interpret "Expired Period: Forever"?

This document does not have a planned expiration date. The specifications are considered valid indefinitely. However, always check for the existence of a newer revision that may supersede it.

10.3 Can I mix LEDs from different bins in my product?

Mixing bins can lead to visible differences in brightness or color within a single product, which is often undesirable. For uniform appearance, use LEDs from the same flux and color bin. For non-critical indicators, mixing may be acceptable.

10.4 Why is my LED dimmer than expected?

Common causes include operating at a current lower than specified, high junction temperature due to poor heat sinking, forward voltage variation affecting current in a simple resistor-driver circuit, or natural lumen depreciation over time.

11. Practical Use Case

Design Case: Panel Indicator Array
A control panel requires 20 white indicator LEDs arranged in a grid. Using the binning information, the designer selects all LEDs from the same luminous flux bin (e.g., 8-9 lm) and the same 3-step MacAdam ellipse color bin to ensure uniform brightness and color. A constant-current driver IC is selected to supply 20mA to each LED, arranged in a series-parallel configuration that accounts for the forward voltage bin (3.2-3.4V). The PCB layout includes a thermal relief pad under each LED connected to a ground plane via thermal vias to manage heat. The reflow profile from section 6.1 is programmed into the pick-and-place machine.

12. Principle Introduction

An LED is a semiconductor diode. When a forward voltage is applied, electrons from the n-type semiconductor recombine with holes from the p-type semiconductor in the active region, releasing energy in the form of photons (light). The wavelength (color) of the light is determined by the energy bandgap of the semiconductor material (e.g., InGaN for blue/green, AlInGaP for red/amber). White LEDs are typically created by coating a blue LED chip with a yellow phosphor; some of the blue light is converted to yellow, and the mixture of blue and yellow light is perceived as white. Different phosphor blends create different white tones (CCT).

13. Development Trends

The LED industry continues to evolve towards higher efficiency (more lumens per watt), achieving values exceeding 200 lm/W in labs. There is a strong focus on improving color quality, with high-CRI LEDs (CRI>90, R9>50) becoming more common for premium lighting. Miniaturization persists with ever-smaller package sizes for high-density applications. Smart and connected LEDs with integrated drivers and control circuits are a growing segment. Furthermore, research into novel materials like perovskites for LEDs and advancements in micro-LED technology for next-generation displays represent significant future directions. Reliability and lifetime under various operating conditions remain areas of continuous study and improvement.