LTW-C181LDS5-GE SMD LED Datasheet - 1.6x0.8x0.55mm - 3.15V - 76mW - White - English Technical Documentation

1. Product Overview

The LTW-C181LDS5-GE is a surface-mount device (SMD) LED lamp designed for modern, space-constrained electronic applications. It belongs to a family of miniature components optimized for automated printed circuit board (PCB) assembly processes. The primary design goals for this component are miniaturization, compatibility with high-volume manufacturing, and reliable performance in a variety of consumer and industrial electronic devices.

1.1 Core Advantages and Target Market

This LED offers several key advantages that make it suitable for automated production lines. Its super-thin profile of only 0.55 mm in height is a critical feature for applications like ultra-slim mobile phones, tablets, and notebook computers where internal space is at a premium. The component is packaged in industry-standard 8mm tape on 7-inch diameter reels, which is fully compatible with automated pick-and-place equipment, streamlining the assembly process and reducing manufacturing costs. Furthermore, it is designed to be compatible with infrared (IR) reflow soldering processes, which is the standard for mass-producing surface-mount electronics. The target markets are broad, encompassing telecommunications equipment (e.g., cellular and cordless phones), office automation devices, network systems, home appliances, and indoor signage or display applications.

1.2 Features and Applications

The LED is constructed using an Ultra Bright InGaN (Indium Gallium Nitride) white chip. This semiconductor material is known for its high efficiency and ability to produce bright white light. The device is compliant with RoHS (Restriction of Hazardous Substances) directives, meaning it is free from specific hazardous materials like lead, mercury, and cadmium. Its I.C. (Integrated Circuit) compatibility indicates it can be driven directly by low-voltage logic circuits. Typical applications extend beyond simple status indicators to include functional lighting such as keypad or keyboard backlighting, micro-displays, and providing illumination for symbols or signals on control panels.

2. Package Dimensions and Mechanical Specifications

The physical outline of the LTW-C181LDS5-GE is defined by a standard EIA (Electronic Industries Alliance) package footprint. The lens color is yellow, while the light source itself is an InGaN white chip. The combination of the yellow lens with the white chip helps to shape the light output and potentially modify the color characteristics. All critical dimensions for the component body are provided in millimeters with a standard tolerance of ±0.1 mm unless otherwise specified. This precise dimensional control ensures consistent placement and soldering results during PCB assembly.

3. Ratings and Characteristics

This section defines the operational limits and performance parameters of the LED under specific test conditions.

3.1 Absolute Maximum Ratings

These ratings represent the stress limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C. The maximum power dissipation is 76 milliwatts (mW). The DC forward current should not exceed 20 mA for continuous operation. For pulsed operation, a peak forward current of 100 mA is allowed under a strict 1/10 duty cycle with a 0.1ms pulse width. The device can operate within an ambient temperature range of -20°C to +105°C and can be stored in temperatures from -40°C to +105°C. A critical rating for assembly is the infrared soldering condition, which is specified as withstanding 260°C for a maximum of 10 seconds, which aligns with typical lead-free (Pb-free) reflow profiles.

3.2 Suggested IR Reflow Profile for Pb-Free Process

A successful solder joint requires a specific temperature profile. For lead-free soldering, a pre-heat stage is recommended up to 150-200°C. The peak body temperature during reflow must not exceed 260°C, and the time above this peak temperature should be limited to a maximum of 10 seconds. It is crucial to note that different PCB designs, solder pastes, and oven types require profile characterization; the provided values are guidelines based on component-level verification testing.

3.3 Electrical and Optical Characteristics

These are the typical performance values measured at Ta=25°C and a forward current (IF) of 5 mA, which is a common test and operating condition. The luminous intensity (Iv), a measure of perceived brightness, ranges from a minimum of 112.0 millicandelas (mcd) to a maximum of 224.0 mcd. The viewing angle (2θ1/2), defined as the angle where the luminous intensity drops to half of its peak value, is 130 degrees, indicating a very wide beam pattern. The forward voltage (VF) typically falls between 2.70V and 3.15V at 5mA. The chromaticity coordinates on the CIE 1931 diagram are x=0.284 and y=0.272, which defines a specific point in the white color space. The reverse current (IR) is very low, with a maximum of 2 microamperes (μA) at a reverse voltage (VR) of 5V. Important notes clarify that the chromaticity coordinate tolerance is ±0.01, and the device is not designed for operation under reverse bias; the VR test is for informational purposes only.

4. Bin Rank System

Due to natural variations in semiconductor manufacturing, LEDs are sorted into performance bins to ensure consistency for the end-user. The LTW-C181LDS5-GE uses a three-dimensional binning system.

4.1 Forward Voltage (Vf) Rank

LEDs are grouped based on their forward voltage drop at 5mA. Bin Code A covers 2.70V to 2.85V, Bin B covers 2.85V to 3.00V, and Bin C covers 3.00V to 3.15V. A tolerance of ±0.1V is applied to each bin.

4.2 Luminous Intensity (Iv) Rank

This binning sorts LEDs by their brightness. R1 bin includes LEDs from 112.0 to 146.0 mcd, R2 from 146.0 to 180.0 mcd, and S1 from 180.0 to 224.0 mcd. A tolerance of ±15% is applied to the limits of each intensity bin.

4.3 Hue Rank (Chromaticity Coordinates)

This is the most complex binning, defining regions on the CIE 1931 chromaticity diagram to group LEDs by their precise shade of white. Multiple bins are defined (e.g., S1-2, S2-2, S3-1, S3-2, S4-1, S4-2), each specifying a quadrilateral area defined by four (x, y) coordinate pairs. This allows designers to select LEDs with very tight color matching for applications where consistent white appearance is critical. A tolerance of ±0.01 is applied to the (x, y) coordinates within each hue bin.

5. Typical Performance Curves

The datasheet includes a set of graphical representations that illustrate the device's behavior under varying conditions. These curves are essential for circuit design and thermal management. They typically include the relationship between forward voltage and forward current (V-I curve), which shows the nonlinear characteristics of the diode. The relationship between luminous intensity and forward current is also shown, indicating how brightness scales with drive current. Another crucial curve depicts the relative luminous intensity versus ambient temperature, showing how light output decreases as the junction temperature rises. This thermal derating information is vital for ensuring consistent brightness in the final application. Analysis of these curves allows designers to optimize drive current for a balance of brightness, efficiency, and longevity, and to understand the thermal constraints of their design.

6. User Guide and Assembly Information

6.1 Cleaning

If cleaning is necessary after soldering or due to contamination, only specified solvents should be used to avoid damaging the plastic package. The recommended method is to immerse the LED in ethyl alcohol or isopropyl alcohol at normal room temperature for less than one minute. Harsher or unspecified chemicals must be avoided.

6.2 Recommended PCB Attachment Pad Layout

A diagram is provided showing the optimal copper pad pattern on the PCB for soldering the LED. This layout ensures proper solder fillet formation, good mechanical strength, and correct thermal dissipation. Following this recommendation is key to achieving reliable solder joints and preventing tombstoning (where one end of the component lifts off the pad during reflow).

6.3 Tape and Reel Packaging Specifications

The component is supplied in a carrier tape system for automated handling. The tape width is 8 mm. The tape is wound onto a standard 7-inch (178 mm) diameter reel. Detailed dimensions for the tape pockets, cover tape, and reel hub are provided to ensure compatibility with feeder equipment. Key notes specify that empty pockets are sealed, each reel contains 5000 pieces, and the packaging conforms to ANSI/EIA 481 specifications.

7. Cautions and Reliability Information

7.1 Intended Application and Reliability

The LED is designed for use in ordinary electronic equipment. For applications requiring exceptional reliability or where failure could jeopardize life or health (e.g., aviation, medical devices, transportation safety systems), special consultation and qualification are required, as these are beyond the standard intended use.

7.2 Storage Conditions and Moisture Sensitivity

Proper storage is critical to prevent moisture absorption, which can cause package cracking during the high-temperature reflow process (known as \"popcorning\"). In its original sealed moisture-proof bag with desiccant, the LED should be stored at ≤30°C and ≤90% relative humidity (RH) and used within one year. Once the bag is opened, the storage environment must be ≤30°C and ≤60% RH. Components exposed to ambient air (out of the sealed bag) should be reflow-soldered within 672 hours (28 days), corresponding to Moisture Sensitivity Level (MSL) 2a. If this window is exceeded, a bake-out at approximately 60°C for at least 20 hours is required before assembly to remove absorbed moisture.

7.3 Soldering Guidelines

Detailed soldering parameters are reiterated. For reflow soldering: pre-heat to 150-200°C, peak temperature ≤260°C, time at peak ≤10 seconds, and a maximum of two reflow cycles allowed. For hand soldering with an iron: temperature ≤300°C, soldering time ≤3 seconds, and only one soldering cycle is permitted. Exceeding these limits can degrade the LED's performance or cause permanent damage.

7.4 Electrostatic Discharge (ESD) Precautions

The LED is sensitive to electrostatic discharge and electrical surges. Proper ESD control measures must be implemented during handling and assembly. This includes the use of grounded wrist straps, anti-static mats, and ensuring all equipment is properly grounded. Failure to observe ESD precautions can lead to latent or catastrophic device failures.

8. Design Considerations and Application Notes

When integrating this LED into a design, several factors must be considered. The wide 130-degree viewing angle makes it suitable for applications requiring broad area illumination or visibility from wide angles, such as status indicators on devices. The ultra-thin 0.55mm height is ideal for backlighting layers in stacked assemblies like mobile phone displays. The forward voltage range (2.7-3.15V) means it can often be driven directly from a regulated 3.3V logic supply with a simple current-limiting resistor, though a constant-current driver is recommended for optimal stability and longevity. The thermal rating of 76mW power dissipation must be respected; the PCB layout should provide adequate copper area for heat sinking, especially if operating near the maximum current. The comprehensive binning system allows for precise selection for color-critical applications, but designers should specify their required bins when ordering. For keyboard backlighting, multiple LEDs from the same intensity and hue bin would be used to ensure uniform brightness and color across all keys.