White LED Ceramic Package 3535 Specification Sheet - Size 3.45x3.45x2.20mm - Voltage 2.6-3.4V - Color White - Power up to 6.8W - English Technical Document

1. Product Overview

This technical document details the specifications for a high-performance white light emitting diode (LED) designed for demanding lighting applications. The LED utilizes a ceramic package for superior thermal management and long-term reliability, making it suitable for a wide range of industrial and commercial uses.

1.1 General Description

The white light is generated through a combination of a blue semiconductor chip and phosphor materials. The emitted light spectrum can be tuned across various white color temperatures. The physical package is compact, with dimensions of 3.45mm in length, 3.45mm in width, and a height of 2.20mm, facilitating integration into space-constrained designs.

1.2 Key Features

• Ceramic Package Construction: Offers excellent thermal conductivity, mechanical strength, and resistance to environmental factors compared to traditional plastic packages.
• Wide Viewing Angle: A 120-degree half-intensity angle ensures broad and uniform light distribution, ideal for area illumination.
• Moisture Sensitivity Level 1 (MSL 1): This rating indicates the component can be stored in standard factory ambient conditions (≤ 30°C/60% RH) for an indefinite period without requiring baking prior to reflow soldering, simplifying logistics.
• Full SMT Compatibility: Designed for use with standard surface-mount technology assembly lines, including pick-and-place machines and reflow ovens.
• Tape and Reel Packaging: Supplied in industry-standard embossed carrier tape and reels to enable automated, high-speed assembly processes.
• RoHS Compliance: The product adheres to the Restriction of Hazardous Substances directive, ensuring it is free from specific hazardous materials like lead and mercury.

1.3 Target Applications

The combination of high luminous output, reliability, and compact size makes this LED suitable for numerous lighting segments:

• General & Architectural Lighting: Downlights, track lights, wall washers, and spotlights for residential, office, and retail spaces.
• Outdoor & Industrial Lighting: Street lights, area lights, high-bay lighting, and warning/signal lights.
• Specialty Lighting: Photographic and video fill lights, studio lighting, plant growth lighting, and landscape accent lighting.

2. In-Depth Technical Parameter Analysis

2.1 Electro-Optical Characteristics

All parameters are specified at a solder point temperature (Ts) of 25°C, providing a standardized baseline for comparison.

• Forward Voltage (VF): At a drive current of 350mA, VF ranges from a minimum of 2.6V to a maximum of 3.4V. This parameter is critical for designing the LED driver\'s output voltage range. A typical value often lies around 3.0V for such devices.
• Luminous Flux (Φ_v or IV): The total visible light output is model-dependent, categorized by flux bins. For example, one variant delivers 150-180 lumens at 350mA, scaling approximately linearly to 280-340 lumens at 700mA. This super-linear relationship is common but diminishes at very high currents due to efficiency droop.
• Correlated Color Temperature (CCT): Available in discrete bins from 2700K (warm white) to 6500K (cool daylight white). The specific CCT is fixed per model number, allowing designers to select the desired white point for their application\'s ambiance and functionality.
• Color Rendering Index (CRI or Ra): Specified with a minimum value of 70. This indicates the LED\'s ability to reveal the true colors of illuminated objects compared to a natural light source. A CRI of 70 is suitable for general lighting, while values above 80 are preferred for retail or studio applications.
• Viewing Angle (2θ_1/2): The full angle at which light intensity drops to half of its peak value is 120 degrees. This wide beam is characteristic of LEDs with a dome-less or minimally encased chip design.

2.2 Electrical Parameters and Absolute Maximum Ratings

These ratings define the operational limits that must not be exceeded to ensure device reliability and prevent permanent damage.

• Maximum Power Dissipation (P_D): 6800 mW. This is the maximum allowable power loss as heat within the LED package. Exceeding this limit risks thermal runaway and catastrophic failure.
• Maximum Continuous Forward Current (I_F): 2000 mA. The LED can be operated continuously at currents up to this level, provided the junction temperature is kept within safe limits through proper heatsinking.
• Maximum Peak Forward Current (I_FP): 3000 mA. This higher current is permissible only under pulsed conditions, defined here as a 0.1ms pulse width with a 10% duty cycle (1/10). This is useful for applications requiring short bursts of high brightness.
• Maximum Reverse Voltage (V_R): 5V. Applying a reverse voltage above this level can cause immediate damage due to the low reverse breakdown voltage of the semiconductor junction. Circuit design should include protection against reverse polarity.
• Reverse Current (I_R): Typically less than 10 μA when a 5V reverse bias is applied, indicating good junction quality.

2.3 Thermal Characteristics

Effective heat dissipation is paramount for LED performance and lifetime.

• Thermal Resistance Junction-to-Solder Point (R_θJ-S): Measured as 2.19 °C/W under specific conditions (I_F=700mA, T_a=85°C). This low value is a direct benefit of the ceramic package, which provides an excellent thermal path from the semiconductor junction to the PCB solder pads. It allows designers to calculate the expected junction temperature rise based on dissipated power: ΔT_J = P_D * R_θJ-S.

3. Binning System Explanation

To ensure consistency in lighting systems, LEDs are sorted (binned) according to key parameters after manufacture.

3.1 Color Temperature (CCT) Binning

The product family covers the full spectrum of white light. Each model variant corresponds to a specific nominal CCT: 2700K, 3000K, 3500K, 4000K, 4500K, 5000K, 5700K, 6000K, and 6500K. This allows precise selection for applications where color consistency is critical, such as in multi-LED fixtures or across different production batches.

3.2 Luminous Flux Binning

Flux is binned at standard test currents. For instance, a model might be guaranteed to produce between 170 and 200 lumens when driven at 350mA. This binning ensures predictable light output levels, enabling designers to accurately calculate the number of LEDs needed to achieve a target luminous flux for their product.

3.3 Forward Voltage (V_F) Range

While not explicitly separated into discrete bins in this document, the specified V_F range of 2.6V to 3.4V at 350mA is itself a form of electrical sorting. For designs using LEDs in series, it\'s important to consider the cumulative voltage drop variation. Parallel connections require attention to current sharing due to potential V_F mismatches.

4. Performance Curve Analysis

Understanding the LED\'s behavior under varying conditions is crucial for robust system design.

4.1 Current-Voltage (I-V) Characteristic

The I-V curve is non-linear, typical of a diode. The forward voltage increases with current. Operating at the higher end of the current range (e.g., 700mA vs. 350mA) will result in a higher V_F, increasing electrical power input and thermal load. Driver circuits must be designed to accommodate this voltage range.

4.2 Luminous Flux vs. Forward Current

Light output generally increases with drive current, but the relationship is not perfectly linear. Efficacy (lumens per watt) often peaks at a moderate current and decreases at higher currents due to efficiency droop, a phenomenon where internal quantum efficiency drops. Therefore, driving at 700mA may not yield double the flux of 350mA, as indicated by the parameter tables.

4.3 Thermal Effects on Performance

LED performance is highly temperature-dependent. As the junction temperature (T_j) rises:

• Luminous Flux Decreases: Light output can drop significantly. The ceramic package mitigates this by keeping T_j lower for a given power level.
• Forward Voltage Decreases: V_F has a negative temperature coefficient, typically around -2 mV/°C for blue/white LEDs. This can affect constant-voltage drive schemes.
• Color Shift May Occur: The peak wavelength of the blue chip and the conversion efficiency of phosphors can change with temperature, potentially causing a slight shift in CCT and chromaticity.

5. Mechanical and Package Information

5.1 Package Dimensions and Drawings

The LED has a square footprint of 3.45mm x 3.45mm with a nominal height of 2.20mm. Detailed drawings typically show top, side, and bottom views with critical dimensions such as pad size (e.g., 1.30mm x 0.85mm), pad spacing, and overall tolerances (generally ±0.2mm). These dimensions are crucial for PCB land pattern design (footprint) to ensure proper soldering and alignment.

5.2 Pad Design and Polarity Identification

The bottom of the package features two metalized solder pads. One pad is electrically connected to the anode (positive terminal), and the other to the cathode (negative terminal). Polarity is typically marked on the top or bottom of the component, for example, with a cathode indicator mark (like a notch, dot, or angled corner). Correct polarity must be observed during PCB assembly to ensure the LED functions.

6. Soldering and Assembly Guidelines

6.1 SMT Reflow Soldering Instructions

This LED is designed for lead-free (Pb-free) reflow soldering processes. A standard reflow profile with a peak temperature not exceeding 260°C is recommended. The ceramic package material can withstand these temperatures. Key profile stages include preheat (ramp-up to activate flux), thermal soak (to equalize board temperature), reflow (where solder melts, peak temp for 20-40 seconds), and controlled cooling. It is essential to follow the profile recommendations to avoid thermal shock or solder joint defects.

6.2 Handling and Storage Conditions

Due to its MSL 1 rating, no dry packing is required for storage. However, standard ESD (electrostatic discharge) precautions should be taken during handling, as the semiconductor chip is sensitive to static electricity. Use grounded workstations and wrist straps. Avoid mechanical stress on the package, especially on the lens/dome area if present. Store in a clean, dry environment.

7. Packaging and Ordering Information

7.1 Packaging Specifications

The LEDs are delivered in industry-standard packaging for automated assembly:

• Carrier Tape: Embossed plastic tape that holds individual LEDs in pockets. Dimensions of the tape pockets, pitch, and overall tape width are specified to be compatible with standard feeder systems.
• Reel: The tape is wound onto a reel. Reel dimensions (diameter, hub size, flange width) are standardized (e.g., 13-inch or 7-inch reels) to fit placement machines.
• Labeling: Each reel includes a label with information such as part number, quantity, lot number, and date code for traceability.

7.2 Model Numbering Rule

The part number (e.g., RF-AL-C3535L2K1**-M1) encodes key attributes. While the full decoding may require a separate guide, typical conventions include: \"C3535\" denotes the 3.45x3.45mm package size, \"L2\" may indicate a performance or flux level, and the \"K1**\" segment specifies the exact color temperature bin (e.g., 27 for 2700K, 30 for 3000K). The suffix \"M1\" often denotes a specific revision or material set.

8. Application Recommendations

8.1 Typical Application Scenarios

Based on its specifications, this LED excels in:

• High-Reliability Indoor Lighting: Office downlights and hotel ambient lighting where long life and consistent color are paramount.
• Thermally Challenging Environments: Enclosed fixtures or outdoor luminaires where the ceramic package\'s thermal performance prevents premature lumen depreciation.
• High-Current Drive Applications: Where maximum light output from a small source is needed, such as in compact spotlights or high-lumen modules, by leveraging its 2000mA continuous current capability with proper cooling.

8.2 Design Considerations

Successful implementation requires attention to several factors:

• Thermal Interface: Use a thermally conductive PCB (like metal-core or FR4 with thermal vias) and apply thermal paste or pads between the LED package and heatsink to minimize thermal resistance.
• Drive Circuitry: Employ a constant-current driver rather than a constant-voltage source. This ensures stable light output and protects the LED from current spikes. Match the driver\'s current and voltage compliance to the LED\'s V_F range and desired operating point.
• Optical Design: The 120-degree native beam may require secondary optics (reflectors, TIR lenses) to achieve specific beam patterns (narrow spot, wide flood).
• Electrical Layout: Keep driver traces short and wide to minimize voltage drop and inductance. Include reverse polarity protection diodes or circuit blocks if there\'s a risk of incorrect installation.

9. Technical Comparison

When evaluated against conventional mid-power LEDs with plastic packages (e.g., 3030, 2835 types), this ceramic-packaged LED offers distinct advantages:

• Superior Thermal Path: Ceramic (often aluminum oxide or aluminum nitride) has a thermal conductivity orders of magnitude higher than plastic molding compounds. This directly translates to a lower junction temperature at the same power, leading to higher sustained light output and longer projected lifetime (L70/B50).
• Enhanced Mechanical and Chemical Robustness: Ceramic is harder, more dimensionally stable, and less prone to yellowing or cracking under UV exposure or thermal cycling compared to silicones or epoxies used in plastic packages.
• Higher Maximum Drive Current: The improved thermal design allows for operation at continuous currents of 2000mA and beyond, enabling it to function as a high-power LED source, whereas many plastic packages are limited to currents below 1000mA.

10. Frequently Asked Questions

Q: What is the expected lifetime of this LED?
A: LED lifetime is typically defined as the point where luminous flux depreciates to 70% of initial output (L70). While not explicitly stated in this datasheet, LEDs with ceramic packages and proper thermal management often exceed 50,000 hours to L70 under recommended operating conditions.

Q: Can I drive this LED with a voltage source?
A: It is strongly discouraged. LEDs are current-operated devices. A small change in forward voltage (due to temperature or bin variation) can cause a large change in current, potentially leading to thermal runaway. Always use a constant-current driver.

Q: How does the 120-degree viewing angle affect my optical design?
A: It provides a very wide \"raw\" beam. If a narrower beam is required (e.g., for a spotlight), you will need to use a collimating lens or reflector. The wide angle is beneficial for applications requiring even, diffuse illumination without hotspots.

Q: Is there a derating curve for operating at high ambient temperatures?
A: While a specific curve isn\'t provided here, the absolute maximum ratings and thermal resistance data allow for calculation. The maximum allowable junction temperature (often 150°C) should not be exceeded. Using the formula T_j = T_s + (P_D * R_θJ-S), you can calculate the maximum permissible power dissipation for a given solder point temperature, which is influenced by ambient temperature and heatsinking.

11. Practical Use Cases

Case Study: High-Efficiency Commercial Downlight
A manufacturer designs a recessed downlight for office ceilings. They use 6 of these ceramic LEDs on a circular metal-core PCB (MCPCB). Each LED is driven at 500mA by a single, efficient constant-current driver. The ceramic package efficiently transfers heat to the MCPCB, which is itself attached to the luminaire\'s aluminum housing acting as a heatsink. This keeps junction temperatures low, ensuring stable light output (>100 lumens per watt system efficacy) and maintaining color consistency over a 50,000-hour lifespan, meeting stringent commercial warranty requirements.

Case Study: Durable Outdoor Wall Wash Light
For illuminating building facades, a linear fixture incorporates multiple LEDs spaced along an extruded aluminum channel. The ceramic package\'s resistance to moisture and UV radiation is crucial for outdoor durability. The wide 120-degree beam angle is ideal for creating a smooth, continuous wash of light up the wall surface. The high maximum current rating allows the designer to reduce the number of LEDs per meter while maintaining high brightness, lowering component count and cost.

12. Operating Principle Introduction

A white LED is a solid-state light source that converts electrical energy directly into visible light through electroluminescence. The core element is a semiconductor chip, typically made of indium gallium nitride (InGaN), which emits blue light when a forward current is applied across its p-n junction. To create white light, the blue chip is coated with a layer of yellow (or a mix of red and green) phosphor materials. Part of the blue light is absorbed by the phosphors, which then re-emit light at longer, yellow wavelengths. The human eye perceives the mixture of the remaining direct blue light and the converted yellow light as white. The specific ratio of blue to yellow emission determines the correlated color temperature (CCT) of the white light. The ceramic substrate serves as both the electrical interconnect platform for the chip and the primary path for heat dissipation.

13. Industry Trends

The LED industry is continuously evolving, with several key trends influencing products like this ceramic LED:

• Pushing Efficiency Limits: Research focuses on reducing efficiency droop at high currents and improving phosphor conversion efficiency to achieve higher lumens per watt (lm/W), reducing energy consumption for the same light output.
• Advanced Packaging: Innovations like chip-scale packaging (CSP) and flip-chip designs are being combined with materials like ceramics to create even smaller, more robust, and higher-performance light sources.
• Light Quality Emphasis: Beyond CRI (Ra), metrics like TM-30 (Rf, Rg) and standards for flicker-free and glare-free light are becoming important for human-centric lighting in wellness and productivity applications.
• Integration and Miniaturization: There is a trend towards integrating multiple functions (driver ICs, sensors, communications) closer to the LED package or onto the same substrate, enabled by the stability and real estate of ceramic packages.
• Sustainability and Circular Economy: Increased focus on designing LEDs for easier disassembly, recyclability of materials like ceramics, and further elimination of hazardous substances beyond RoHS.