Ceramic 3535 Series 1W Blue LED Datasheet - Dimensions 3.5x3.5x?mm - Voltage 3.2V - Power 1W - English Technical Document

1. Product Overview

This document details the specifications for a high-power 1W blue LED encapsulated in a robust ceramic 3535 package. Ceramic packages offer superior thermal management compared to traditional plastic packages, making this LED suitable for applications requiring high reliability and stable performance under demanding thermal conditions. The primary target markets include professional lighting, automotive lighting modules, and specialized industrial applications where consistent color output and long-term durability are critical.

1.1 Core Advantages

The ceramic substrate provides excellent heat dissipation, which directly contributes to lower junction temperatures, enhanced luminous efficacy maintenance, and extended operational lifespan. The package design ensures good mechanical stability and resistance to thermal stress. The LED features a wide 120-degree viewing angle, making it versatile for various optical designs requiring broad illumination.

2. Technical Parameters and Objective Interpretation

2.1 Absolute Maximum Ratings (T_s=25°C)

• Forward Current (I_F): 500 mA (Continuous)
• Forward Pulse Current (I_FP): 700 mA (Pulse Width ≤10ms, Duty Cycle ≤1/10)
• Power Dissipation (P_D): 1700 mW
• Operating Temperature (T_opr): -40°C to +100°C
• Storage Temperature (T_stg): -40°C to +100°C
• Junction Temperature (T_j): 125°C
• Soldering Temperature (T_sld): Reflow soldering at 230°C or 260°C for 10 seconds maximum.

These ratings define the operational limits. Exceeding these values may cause permanent damage. The pulse current rating allows for brief overdrive in applications like strobes or pulsed sensing.

2.2 Typical Electro-Optical Characteristics (T_s=25°C)

• Forward Voltage (V_F): Typical 3.2V, Maximum 3.4V at I_F=350mA.
• Reverse Voltage (V_R): 5V (Maximum).
• Peak Wavelength (λ_d): 460 nm (Typical).
• Reverse Current (I_R): Maximum 50 µA.
• Viewing Angle (2θ_1/2): 120 degrees (Typical).

The forward voltage is a key parameter for driver design. The typical value of 3.2V at 350mA indicates the nominal operating point. Designers must account for the maximum V_F to ensure the current source can provide sufficient voltage.

3. Binning System Explanation

The LED is sorted (binned) according to key performance parameters to ensure consistency within a production batch. This allows designers to select LEDs that meet specific application requirements.

3.1 Luminous Flux Binning (at 350mA)

Blue LEDs are sorted by their light output. The bin code, minimum (Min), and typical (Type) luminous flux values are as follows:

• Code 1C: Min 14 lm, Type 16 lm
• Code 1D: Min 16 lm, Type 18 lm
• Code 1E: Min 18 lm, Type 20 lm
• Code 1F: Min 20 lm, Type 22 lm
• Code 1G: Min 22 lm, Type 24 lm

The luminous flux tolerance is ±7%. Selecting a higher bin code guarantees a higher minimum light output, which is crucial for achieving target brightness levels in a design.

3.2 Forward Voltage Binning

LEDs are also binned by their forward voltage drop at a test current to ensure uniform current distribution when multiple LEDs are connected in series. The bins are:

• Code 1: 2.8V to 3.0V
• Code 2: 3.0V to 3.2V
• Code 3: 3.2V to 3.4V
• Code 4: 3.4V to 3.6V

The voltage measurement tolerance is ±0.08V. Using LEDs from the same or adjacent voltage bins in a series string minimizes current imbalance and potential overdriving of LEDs with lower V_F.

3.3 Dominant Wavelength Binning

For color-critical applications, the dominant wavelength is tightly controlled. The available bins for blue are:

• Code B2: 450 nm to 455 nm
• Code B3: 455 nm to 460 nm
• Code B4: 460 nm to 465 nm

This allows for precise color matching, which is essential in applications like display backlighting or multi-color mixing systems.

4. Performance Curve Analysis

The datasheet provides several key graphs that illustrate the LED's behavior under different conditions.

4.1 Forward Voltage vs. Forward Current (V_F-I_F) Curve

This curve shows the non-linear relationship between voltage and current. It is essential for understanding the dynamic resistance of the LED and for designing constant-current drivers. The curve typically shows a sharp increase in current once the forward voltage exceeds the diode's threshold.

4.2 Relative Luminous Flux vs. Forward Current Curve

This graph illustrates how light output scales with drive current. While output increases with current, the efficacy (lumens per watt) often decreases at higher currents due to increased heat generation. This curve helps optimize the trade-off between brightness and efficiency for a given application.

4.3 Relative Spectral Power vs. Junction Temperature Curve

This curve demonstrates the effect of junction temperature (T_j) on the LED's spectral output. For blue LEDs, the peak wavelength may shift slightly with temperature (typically 0.1-0.3 nm/°C). Maintaining a low T_j is crucial for color stability in sensitive applications.

4.4 Spectral Power Distribution Curve

This plot shows the intensity of light emitted across the visible spectrum. A blue LED will have a narrow, pronounced peak around its dominant wavelength (e.g., 460 nm). The full width at half maximum (FWHM) of this peak indicates the color purity of the LED.

5. Mechanical and Packaging Information

5.1 Outline Drawing and Dimensions

The LED uses a standard ceramic 3535 footprint, measuring approximately 3.5mm x 3.5mm. The exact height is not specified in the provided excerpt. The drawing includes critical dimensions such as pad spacing and overall package size with associated tolerances (e.g., .X: ±0.10mm, .XX: ±0.05mm).

5.2 Recommended Pad Pattern and Stencil Design

The datasheet provides recommended land pattern and solder stencil designs for PCB layout. Adhering to these recommendations ensures proper solder joint formation, reliable electrical connection, and optimal thermal transfer from the LED's thermal pad to the PCB. The stencil design controls the volume of solder paste deposited.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

The LED is compatible with standard reflow soldering processes. The maximum allowable soldering temperature is 230°C or 260°C for a duration not exceeding 10 seconds. It is critical to follow a temperature profile that preheats the assembly adequately to minimize thermal shock and ensures the peak temperature does not exceed the specified limit.

6.2 Handling and Storage Precautions

LEDs are sensitive to electrostatic discharge (ESD). Proper ESD precautions (e.g., grounded workstations, wrist straps) should be observed during handling. The devices should be stored in their original moisture-barrier bags in a controlled environment (specified storage temperature: -40°C to +100°C) to prevent moisture absorption and oxidation.

7. Packaging and Ordering Information

7.1 Carrier Tape Specifications

The LEDs are supplied on embossed carrier tape for automated pick-and-place assembly. The datasheet includes detailed drawings of the carrier tape pocket dimensions, pitch, and spooling direction to ensure compatibility with standard surface-mount technology (SMT) equipment.

7.2 Reel Packaging

The carrier tape is wound onto standard reels. The reel type, quantity per reel, and outer packaging should be specified according to the manufacturer's standard or customer requirements to facilitate efficient production line feeding.

7.3 Part Numbering System

The model number follows a structured format that encodes key attributes: series, package type, chip configuration, color, and performance bins (e.g., luminous flux, voltage). Understanding this nomenclature is essential for correctly specifying the desired LED variant. For example, a code indicates a ceramic 3535 package, a single large-power die, blue color, and specific flux/voltage/wavelength bins.

8. Application Suggestions

8.1 Typical Application Scenarios

• Architectural and Commercial Lighting: Used as a primary blue source in RGB color-mixing systems for tunable white or colored lighting.
• Automotive Lighting: Suitable for daytime running lights (DRLs), signal lights, or interior lighting where high reliability is required.
• Specialty Illumination: Applications requiring high-power blue light, such as medical devices, curing systems, or entertainment lighting.
• Backlighting: Can be used in high-brightness LCD backlight units, often combined with phosphors to create white light.

8.2 Design Considerations

• Thermal Management: Despite the ceramic package's advantages, effective heat sinking is mandatory. The PCB should have a thermal pad connected to internal ground planes or an external heatsink to keep T_j below 125°C.
• Current Driving: Always use a constant-current driver. The recommended operating current is 350mA, but it can be driven up to 500mA with appropriate derating for temperature.
• Optical Design: The 120-degree viewing angle may require secondary optics (lenses, reflectors) to achieve the desired beam pattern. The ceramic surface may have different reflectivity properties than plastic packages.
• Binning Selection: For multi-LED arrays, specify tight bins for luminous flux, voltage, and wavelength to ensure uniform appearance and performance.

9. Technical Comparison and Differentiation

Compared to standard plastic 3535 packages, this ceramic LED offers distinct advantages:

• Superior Thermal Performance: Ceramic material has higher thermal conductivity than plastic, leading to a lower thermal resistance from the junction to the solder point (R_th-Js). This results in a lower operating junction temperature at the same power level, which directly translates to higher light output maintenance (L70, L90 lifetime) and better color stability.
• Enhanced Reliability: Ceramic is inert and does not degrade or yellow under high-temperature or high-UV exposure, unlike some plastics. This makes it ideal for harsh environments.
• Mechanical Robustness: The ceramic substrate is more rigid and less prone to cracking under thermal cycling stress.
• The trade-off is typically a slightly higher unit cost compared to plastic packages.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 What is the difference between the continuous current (500mA) and the typical operating current (350mA)?

The absolute maximum continuous current rating (500mA) is the highest current the LED can withstand without immediate failure. The typical operating current (350mA) is the recommended current for achieving the specified performance (luminous flux, efficacy) while maintaining a safe operating margin for junction temperature and long-term reliability. Operating at 350mA typically offers a better balance of performance and lifespan.

10.2 Why is voltage binning important?

When LEDs are connected in series, the same current flows through each one. If the forward voltages vary significantly, the total voltage required by the string increases. More importantly, LEDs with lower V_F will dissipate less power as heat for the same current, but the driver must supply enough voltage for the highest V_F LED. Using closely matched V_F bins ensures predictable system voltage and uniform power distribution.

10.3 Can I drive this LED with a constant voltage source?

No. LEDs are current-driven devices. Their forward voltage has a negative temperature coefficient and can vary from unit to unit. A constant voltage source would lead to uncontrolled current, potentially exceeding the maximum rating and causing rapid failure. A constant-current driver or a current-limiting circuit is always required.

10.4 How do I interpret the luminous flux binning?

The bin code (e.g., 1E) defines a guaranteed minimum light output (18 lm) and a typical value (20 lm) when measured at 350mA and 25°C case temperature. When designing a light fixture, using the \"Min\" value for calculations ensures the final product will meet the minimum brightness target even with unit-to-unit variation.

11. Practical Design Case Study

Scenario: Designing a high-reliability underwater diving light requiring a pure blue beam.

Implementation:

1. LED Selection: Choose this ceramic 3535 blue LED for its robustness and thermal performance. Select a tight wavelength bin (e.g., B3: 455-460nm) for consistent blue color and a high luminous flux bin (e.g., 1G) for maximum output.
2. Thermal Design: The light housing is machined from aluminum, acting as a heatsink. The PCB is a metal-core PCB (MCPCB) with a high-thermal-conductivity dielectric layer. The LED's thermal pad is soldered directly to a large copper area on the MCPCB, which is then tightly mounted to the aluminum housing with thermal paste.
3. Electrical Design: A waterproof, efficient constant-current buck driver is designed to provide a stable 350mA from a lithium-ion battery pack. The driver includes protection against over-voltage, reverse polarity, and thermal shutdown.
4. Optical Design: A secondary TIR (Total Internal Reflection) collimating lens is used over the LED to narrow the beam from 120 degrees to a 10-degree spot for long-distance penetration in water.
5. Result: The final light achieves high brightness, stable color output even after extended use, and excellent reliability in a challenging environment, leveraging the ceramic LED's inherent advantages.

12. Operating Principle Introduction

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current passes through it. This phenomenon is called electroluminescence. In a blue LED, the semiconductor material (typically based on indium gallium nitride - InGaN) is engineered with a specific bandgap. When electrons recombine with electron holes within the device, energy is released in the form of photons. The wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material. The ceramic package serves as a mechanical support, provides electrical connections via wire bonds to the anode and cathode, and most importantly, acts as an efficient pathway to conduct heat away from the semiconductor junction, which is critical for performance and longevity.

13. Technology Trends and Developments

The high-power LED market continues to evolve with several clear trends:

• Increased Efficiency (lm/W): Ongoing improvements in epitaxial growth, chip design, and light extraction techniques steadily push the luminous efficacy higher, reducing energy consumption for the same light output.
• Improved Color Quality and Consistency: Tighter binning tolerances and advanced phosphor technologies enable LEDs with superior color rendering index (CRI) and more consistent color points across production batches.
• Advanced Packaging: Ceramic packages, like the one used here, are becoming more prevalent for high-end applications. Further trends include chip-scale packages (CSP) and package-level integration (e.g., COB - Chip-on-Board) to reduce cost and improve optical density.
• Higher Power Density: LEDs capable of operating at higher current densities are being developed, allowing for smaller light sources with equivalent or greater output, enabling more compact and innovative luminaire designs.
• Smart and Connected Lighting: Integration of control electronics and communication interfaces directly with LED modules is a growing trend, facilitating IoT-enabled lighting systems.