SMD LED LTW-C181DS5-GE2 Datasheet - Super Thin 0.55mm Height - White InGaN - 20mA - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a surface-mount device (SMD) Light Emitting Diode (LED). This component belongs to a family of miniature LEDs designed specifically for automated printed circuit board (PCB) assembly processes and applications where space is a critical constraint. The LED utilizes an InGaN (Indium Gallium Nitride) semiconductor material to produce white light, offering high brightness in a compact form factor.

The primary design philosophy behind this product is to provide a reliable, high-performance lighting solution that integrates seamlessly into modern electronic manufacturing workflows. Its compatibility with infrared (IR) reflow soldering processes and automatic pick-and-place equipment makes it suitable for high-volume production environments. The ultra-thin package height is a key feature, enabling its use in increasingly slim consumer and industrial electronics.

1.1 Features

• Compliant with the Restriction of Hazardous Substances (RoHS) directive.
• Extremely low profile with a package height of only 0.55 millimeters.
• Utilizes an ultra-bright InGaN white light chip.
• Supplied in industry-standard packaging: 8mm tape on 7-inch diameter reels.
• Conforms to Electronic Industries Alliance (EIA) standard package outlines.
• Electrically compatible with integrated circuit (IC) logic levels.
• Designed for compatibility with automated component placement systems.
• Withstands standard infrared reflow soldering profiles.

1.2 Applications

This LED is engineered for a broad spectrum of electronic equipment. Its key application areas include:

• Telecommunications Equipment: Status indicators on routers, modems, and handsets.
• Office Automation: Backlighting for keypads, keyboards, and control panels in printers, scanners, and copiers.
• Consumer Electronics & Home Appliances: Power, mode, or function indicators in devices like smart speakers, televisions, and kitchen appliances.
• Industrial Equipment: Machine status, fault, or operational mode indicators in control systems.
• Indoor Signage & Micro-Displays: Illumination for symbols, icons, or small informational displays.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed. All values are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd): 76 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (I_F(PEAK)): 100 mA. This is the maximum allowable current under pulsed conditions, specified at a 1/10 duty cycle and a 0.1ms pulse width. It is significantly higher than the continuous current rating.
• DC Forward Current (I_F): 20 mA. This is the maximum recommended continuous forward current for reliable long-term operation.
• Operating Temperature Range (T_opr): -20°C to +105°C. The ambient temperature range within which the LED is designed to function correctly.
• Storage Temperature Range (T_stg): -40°C to +105°C. The temperature range for non-operational storage.
• Infrared Soldering Condition: 260°C for 10 seconds. The maximum thermal profile the package can withstand during reflow soldering.

2.2 Electro-Optical Characteristics

These are the typical performance parameters measured under standard test conditions (Ta=25°C, I_F=5mA unless noted).

• Luminous Intensity (I_V): Ranges from 112.0 mcd (millicandela) to 224.0 mcd. Measured using a sensor filtered to match the CIE photopic eye-response curve. The actual value is binned (see Section 3).
• Viewing Angle (2θ_1/2): 130 degrees. This is the full angle at which the luminous intensity is half of the intensity measured at 0 degrees (on-axis). A wide viewing angle like this provides broad, diffuse illumination suitable for backlighting and status indicators.
• Chromaticity Coordinates (x, y): Typical values are x=0.304, y=0.3005 on the CIE 1931 chromaticity diagram. These coordinates define the perceived color point of the white light. Tolerance and binning apply (see Section 3).
• Forward Voltage (V_F): Ranges from 2.70V to 3.15V at 5mA. This is the voltage drop across the LED when conducting current. It is binned into specific ranges (see Section 3).
• Reverse Current (I_R): Maximum of 2 μA at a Reverse Voltage (V_R) of 5V. This parameter is primarily for IR test purposes; the device is not intended for operation in reverse bias.

3. Bin Ranking System Explanation

To ensure consistency in mass production, LEDs are sorted (binned) based on key parameters. This allows designers to select parts that meet specific performance windows for their application.

3.1 Forward Voltage (V_F) Rank

Binning at I_F = 5mA. Each bin has a tolerance of ±0.1V.

• Bin Code A: V_F = 2.70V to 2.85V
• Bin Code B: V_F = 2.85V to 3.00V
• Bin Code C: V_F = 3.00V to 3.15V

3.2 Luminous Intensity (I_V) Rank

Binning at I_F = 5mA. Each bin has a tolerance of ±15%.

• Bin Code R1: I_V = 112.0 mcd to 146.0 mcd
• Bin Code R2: I_V = 146.0 mcd to 180.0 mcd
• Bin Code S1: I_V = 180.0 mcd to 224.0 mcd

3.3 Hue (Chromaticity) Rank

Defined by boundaries on the CIE 1931 (x, y) chromaticity diagram at I_F = 5mA. Each bin has a tolerance of ±0.01 in both x and y coordinates. The datasheet lists specific quadrilateral boundaries for bins like S1-2, S2-2, S3-1, and S4-1. This binning ensures color consistency across multiple LEDs in an assembly.

4. Mechanical and Package Information

4.1 Package Dimensions

The LED features a super-thin package design. The key dimension is the height, which is 0.55 mm. All other package dimensions are provided in the detailed mechanical drawing within the source document, with a standard tolerance of ±0.1 mm unless otherwise specified. The lens color is yellow, while the light source itself is an InGaN white chip.

4.2 Recommended PCB Attachment Pad Layout

A suggested land pattern (footprint) for the printed circuit board is provided to ensure proper soldering and mechanical stability. Adhering to this recommended layout helps achieve reliable solder fillets and prevents tombstoning or misalignment during reflow.

4.3 Polarity Identification

Correct polarity is crucial for LED operation. The datasheet includes a diagram identifying the anode and cathode terminals on the package. Typically, this is indicated by a marking on the component body or an asymmetry in the package footprint.

5. Soldering and Assembly Guidelines

5.1 Infrared Reflow Soldering Parameters

For lead-free (Pb-free) solder processes, a specific thermal profile is recommended. The critical parameter is a peak body temperature of 260°C, which should not be exceeded for more than 10 seconds. The profile includes a pre-heat stage. It is emphasized that the optimal profile depends on the specific PCB design, components, and solder paste used, and should be characterized for each application.

5.2 Hand Soldering

If hand soldering is necessary, it should be performed with extreme care. The recommendation is to use a soldering iron tip at a maximum temperature of 300°C, with the soldering time limited to 3 seconds per pad. This should be done only once to prevent thermal damage to the LED chip and package.

5.3 Cleaning

If cleaning after soldering is required, only specified solvents should be used. Acceptable methods include immersing the LED in ethyl alcohol or isopropyl alcohol at normal room temperature for less than one minute. The use of unspecified chemicals can damage the LED package material.

6. Packaging and Handling

6.1 Tape and Reel Specifications

The components are supplied in an 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Standard reel quantities are 5000 pieces per reel. The packaging conforms to ANSI/EIA-481 specifications. Key handling notes include: a maximum of two consecutive missing components are allowed, and the minimum orderable quantity for remnants is 500 pieces.

6.2 Storage Conditions

Sealed Package: LEDs in their original, unopened moisture-proof bag (with desiccant) should be stored at ≤30°C and ≤90% Relative Humidity (RH). The recommended shelf life under these conditions is one year.
Opened Package: Once the moisture barrier bag is opened, the components are exposed to ambient humidity. They should be stored at ≤30°C and ≤60% RH. For components meeting Moisture Sensitivity Level (MSL) 2a, it is recommended to complete the IR reflow process within 672 hours (28 days) of exposure. Components exposed for longer periods should be baked at approximately 60°C for at least 20 hours before soldering to remove absorbed moisture and prevent \"popcorning\" damage during reflow.

6.3 Electrostatic Discharge (ESD) Precautions

The LED is sensitive to electrostatic discharge and voltage surges. Proper ESD control measures must be employed during handling and assembly. This includes the use of grounded wrist straps, anti-static gloves, and ensuring all equipment and work surfaces are properly grounded.

7. Application Notes and Design Considerations

7.1 Current Limiting

An external current-limiting resistor is mandatory when driving the LED from a voltage source. The resistor value (R_limit) can be calculated using Ohm's Law: R_limit = (V_supply - V_F) / I_F. Using the maximum V_F from the datasheet (e.g., 3.15V) in the calculation ensures the current does not exceed the limit even with a higher-voltage bin part. For reliable operation, driving the LED at or below the typical 5mA test current is advisable unless high brightness is specifically required.

7.2 Thermal Management

Although the power dissipation is low, proper thermal design extends LED lifespan and maintains light output. Ensure the PCB pad design provides adequate thermal relief according to the recommended layout. In high-ambient-temperature applications, derating the forward current may be necessary to stay within the junction temperature limits.

7.3 Optical Design

The 130-degree viewing angle produces a wide, Lambertian-like emission pattern. For applications requiring a more focused beam, secondary optics (lenses or light guides) would be needed. The yellow lens acts as a color-converting phosphor for the InGaN blue chip to create white light, and its properties are integral to the final chromaticity.

8. Technical Comparison and Differentiation

The primary differentiating feature of this LED is its 0.55mm ultra-thin height. This makes it a compelling choice for modern ultra-slim devices like smartphones, tablets, and wearable electronics where z-height is severely constrained. Compared to standard LED packages which may be 0.6mm or taller, this component offers a direct reduction in assembly thickness. Furthermore, its combination of high brightness (up to 224 mcd at 5mA) and wide viewing angle in such a thin package is a significant engineering achievement, balancing optical performance with mechanical minimalism.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum rated DC forward current. For longest lifetime and stable performance, operating at a lower current like 5-10mA is recommended.

Q: What is the difference between the R1, R2, and S1 intensity bins?
A: These bins represent different ranges of luminous output. S1 is the brightest bin (180-224 mcd), R2 is mid-range (146-180 mcd), and R1 is the standard bin (112-146 mcd). Selecting a higher bin ensures greater light output for a given current.

Q: How critical is the 672-hour floor life after opening the bag?
A: It is very important for reliability. Exceeding this exposure time without a bake cycle prior to reflow can lead to internal package delamination or cracking due to rapid vaporization of absorbed moisture during soldering (the \"popcorn\" effect).

Q: Why is the reverse current rating only for test purposes?
A: The LED is a diode and is not designed to be operated in reverse bias in a circuit. The 5V reverse voltage rating is a test condition to verify leakage current, not an operational guideline. Always ensure correct polarity in the circuit.

10. Operational Principles

This LED operates on the principle of electroluminescence in a semiconductor p-n junction. The active region is composed of InGaN. When a forward voltage exceeding the diode's turn-on voltage (V_F) is applied, electrons and holes are injected into the active region where they recombine. In a white LED, this recombination in the InGaN layer typically produces blue light. A phosphor coating (contained within the yellow lens) absorbs a portion of this blue light and re-emits it as yellow light. The mixture of the remaining blue light and the converted yellow light is perceived by the human eye as white light. The specific ratios and phosphor composition determine the exact chromaticity coordinates (x, y) on the CIE diagram.

11. Industry Trends

The development of this component reflects several key trends in optoelectronics: Miniaturization continues to be a dominant driver, pushing package heights below 0.5mm. Increased Efficiency is perpetual, with newer chip designs and phosphors delivering higher lumens per watt (lm/W). Color Consistency and Binning have become more sophisticated, with tighter bins (like the defined hue quadrilaterals) enabling better color matching in multi-LED arrays for displays and lighting. Finally, manufacturing compatibility remains essential, with components being optimized for fully automated, high-speed SMT lines and robust enough for lead-free reflow profiles, as evidenced by the detailed soldering guidelines provided.