0402 Red LED RF-RU0402TS-BC-B1 - 1.0x0.5x0.4mm - Forward Voltage 1.7-2.4V - Power 48mW - English Technical Datasheet

1. Product Overview

The RF-RU0402TS-BC-B1 is a miniature red SMD LED in a 1.0mm x 0.5mm x 0.4mm package, fabricated using a high-efficiency red chip. Designed for general-purpose visual indication, it offers an extremely wide viewing angle of 140°, making it suitable for applications where visibility from various angles is critical. The device supports standard SMT assembly and reflow soldering processes, and is RoHS compliant with a moisture sensitivity level of 3.

Key highlights include a low forward voltage range (1.7V to 2.4V at 5mA), a maximum forward current of 20mA, and a power dissipation of 48mW. The LED emits red light with dominant wavelengths between 625nm and 640nm, and luminous intensity bins ranging from 8 mcd to 65 mcd. The product is available in multiple intensity and wavelength bins, enabling fine-tuning for uniformity in large-scale applications.

2. Technical Parameter Analysis

2.1 Electrical & Optical Characteristics

At an ambient temperature of 25°C and a test current of 5mA, the LED exhibits the following typical characteristics:

• Forward Voltage (VF): The forward voltage is binned into several groups (A2 to D2), covering 1.7V to 2.4V in 0.1V steps. The measurement tolerance is ±0.1V.
• Dominant Wavelength (λD): Three wavelength bins (F00: 625-630nm, G00: 630-635nm, H00: 635-640nm) allow selection of precise red hue. Tolerance ±2nm.
• Luminous Intensity (IV): Six bins (A00: 8-12 mcd, B00: 12-18 mcd, C00: 18-28 mcd, D00: 28-43 mcd, E00: 43-65 mcd) cover a wide range of brightness options. Tolerance ±10%.
• Viewing Angle (2θ1/2): Typical 140°, ensuring wide dispersion.
• Reverse Current (IR): Less than 10 µA at VR=5V.
• Thermal Resistance (RTHJ-S): 450°C/W (junction to solder point).

2.2 Absolute Maximum Ratings

The device must not exceed the following limits to avoid permanent damage:

• Power Dissipation (Pd): 48 mW
• Forward Current (IF): 20 mA (DC); 60 mA peak for pulse (1/10 duty, 0.1ms width)
• ESD (HBM): 2000 V
• Operating Temperature (Topr): -40°C to +85°C
• Storage Temperature (Tstg): -40°C to +85°C
• Junction Temperature (Tj): 95°C

2.3 Thermal Characteristics

The thermal resistance of 450°C/W indicates moderate heat dissipation capability. In continuous operation at 20mA, the junction temperature rise above ambient is approximately 9°C (assuming good thermal management). Care must be taken to keep the junction below the 95°C limit, especially in high-density applications. The typical optical performance derating curves show that relative intensity decreases linearly with increasing ambient temperature (see Section 3).

3. Performance Curve Analysis

The datasheet provides several graphical relationships that aid in circuit design:

3.1 Forward Voltage vs. Forward Current

Fig 1-6 shows a typical exponential diode curve. At 2V forward voltage, the current is approximately 5mA. The curve becomes steeper above 2V, reaching 20mA around 2.5V. This nonlinearity emphasizes the need for current-limiting resistors.

3.2 Relative Intensity vs. Forward Current

Relative intensity increases linearly with forward current up to 20mA, then saturates slightly. At 5mA, relative intensity is about 0.4 (normalized to 20mA). This linear region allows easy brightness tuning via PWM or analog current control.

3.3 Temperature Effects

Fig 1-8 demonstrates that relative intensity drops approximately 15% when ambient temperature rises from 25°C to 85°C. Fig 1-9 shows the maximum permissible forward current decreases from 20mA at 25°C to about 8mA at 100°C pin temperature. These derating curves are crucial for thermal design.

3.4 Wavelength Stability

Fig 1-10 indicates that dominant wavelength shifts slightly (about 2nm) from 5mA to 15mA, remaining within the bin. This stability is acceptable for most indicator applications.

3.5 Spectral Distribution

The spectrum (Fig 1-11) shows a narrow peak centered around 630nm with a full width at half maximum (FWHM) of approximately 20nm, typical for AllnGaP red LEDs.

3.6 Radiation Pattern

Fig 1-12 presents a polar diagram illustrating a near-Lambertian emission pattern. Relative intensity drops to 50% at approximately 70° off-axis, confirming the 140° viewing angle.

4. Binning System

The RF-RU0402TS-BC-B1 employs a multi-dimensional binning system for color, brightness, and forward voltage:

• Wavelength Bins: F00 (625-630nm), G00 (630-635nm), H00 (635-640nm). Each bin ensures consistent color appearance.
• Luminous Intensity Bins: A00 through E00 (8-65 mcd range). Bins are non-overlapping, allowing precise matching for uniform backlighting or matrix displays.
• Forward Voltage Bins: A2 to D2 (1.7-2.4V, 0.1V steps). Voltage grouping helps in designing series/parallel circuits by minimizing current variation.

The combination of these bins is encoded in the part number label (e.g., BIN CODE field). Customers can request specific bin combinations for high-volume production to achieve tight uniformity.

5. Mechanical & Package Information

5.1 Package Dimensions

The LED uses an ultra-small 0402 footprint (1.0mm × 0.5mm × 0.4mm). The package has two terminals with a cathode mark (see Fig 1-4). The bottom view indicates pad dimensions: pad 1 is the anode, pad 2 is the cathode. The recommended soldering pattern (Fig 1-5) features 0.6mm × 0.6mm pads with 0.5mm spacing, allowing reliable solder joint formation.

5.2 Polarity & Handling

Polarity is clearly indicated by a marking on the top surface (cathode side). Incorrect polarity can cause reverse breakdown (max 5V) and damage the LED. The package is extremely small, so careful handling with vacuum tweezers or pick-and-place tools is recommended.

6. Soldering & Assembly Guide

6.1 Reflow Soldering Profile

The recommended reflow profile (Fig 3-1) follows IPC/JEDEC standards with a peak temperature of 260°C (max 10 seconds). Key parameters:

• Preheat: 150°C to 200°C for 60-120 seconds
• Time above 217°C (TL): 60-150 seconds
• Peak temperature (TP): 260°C (max 10 seconds)
• Cooling rate: ≤6°C/s

Do not exceed two reflow cycles. If more than 24 hours elapse between soldering operations, baking is required. Manual soldering with an iron should be limited to one side at ≤300°C for ≤3 seconds.

6.2 Handling Precautions

The LED is sensitive to moisture (MSL Level 3). Unused devices must be stored in a sealed moisture barrier bag with desiccant. After opening, storage time is limited to 168 hours at 30°C/60% RH. If the humidity indicator card shows excessive moisture, bake at 60±5°C for ≥24 hours.

Additionally, the silicone encapsulant is susceptible to chemical attack from sulfur, bromine, chlorine, and VOCs. The mating materials must contain less than 100PPM sulfur, <900PPM each of bromine and chlorine (total <1500PPM). Avoid adhesives that outgas organic vapors.

7. Packaging & Ordering Information

7.1 Packaging Format

The LEDs are supplied in 8mm wide carrier tape (4000 pcs per reel) with a 178mm diameter reel. The tape features polarity orientation and a cover tape for protection. Each reel is labeled with part number, spec number, lot number, bin code, quantity, and date code.

7.2 Storage & Shelf Life

Sealed bags can be stored at ≤30°C/≤75% RH for up to one year from the date of manufacture. Once opened, follow the MSL Level 3 floor life of 168 hours. If the desiccant has turned color or time has expired, baking is mandatory.

8. Application Guidelines

8.1 Typical Applications

The RF-RU0402TS-BC-B1 is ideal for status indicators, push-button backlighting, symbol illumination, and general-purpose visual feedback in consumer electronics, wearables, IoT devices, and automotive interior lighting. Its tiny footprint suits space-constrained PCBs.

8.2 Circuit Design Considerations

Always use a series resistor to limit current. For a 3.3V supply, a 150Ω resistor yields approximately 10mA (assuming 1.8V forward drop). In pulsed operation (e.g., 1/10 duty), peak current up to 60mA is allowed. For parallel arrays, consider using individual resistors per LED to avoid current hogging due to voltage bin variation.

8.3 Thermal Management

Despite low power, proper thermal design is recommended when many LEDs are clustered. Keep the solder pad temperature below 85°C; use thermal vias and copper pours to spread heat. In high ambient temperature environments, reduce the forward current (see derating curve in Fig 1-9).

9. Competitive Comparison

Compared to standard 0402 LEDs from other vendors, the RF-RU0402TS-BC-B1 offers a wider viewing angle (140° vs typical 120°) and tighter binning options (0.1V voltage bins, 2nm wavelength bins). The maximum rated forward current of 20mA is slightly higher than some competitors (often 18mA), allowing brighter output if needed. The ESD rating of 2kV (HBM) is comparable to industry norms. One unique advantage is the explicit guidance on material compatibility (sulfur, halogen limits) to prevent LED degradation, which is rarely provided in competitive datasheets.

10. Common Technical Questions

Q: What is the recommended operating current for maximum lifetime? A: For general applications, operating at 10mA provides a good balance between brightness and longevity. The junction temperature rise is minimal, and the LED can last over 50,000 hours.

Q: Can I drive this LED directly from a 3.3V logic pin? A: Yes, but only with a proper series resistor. A 150Ω resistor will limit current to approximately 10mA (assuming 1.8V VF). Many logic pins can source 20mA, but check the microcontroller datasheet.

Q: How should I clean the PCB after soldering? A: Use isopropyl alcohol (IPA) and avoid aggressive solvents that may attack the silicone. No ultrasonic cleaning is recommended unless tested for compatibility.

Q: What is the ESD sensitivity level? A: Class 1C (2000V HBM). Standard ESD precautions (grounded workstations, antistatic bags, wrist straps) should be used during handling and assembly.

11. Design Case Study

Case: Wearable fitness tracker with 4 status LEDs

Design requirement: Four red LEDs (heart rate, Bluetooth, activity, alert) must be visible in direct sunlight but not exceed a total power budget of 200mW. Using the RF-RU0402TS-BC-B1 in C00 brightness bin (18-28 mcd), each LED is operated at 8mA via a 2.0V supply (boost converter). The forward voltage is around 1.8V, so a 25Ω resistor is used. Total power: 4 × 1.8V × 8mA = 57.6mW, well within budget. The wide 140° viewing angle ensures visibility at watch tilt angles. ESD protection is integrated on the flex PCB. The device reliability test data (1000h life test at 5mA) gave confidence for a 2-year product warranty.

12. Operating Principle

This LED uses a red-emitting AllnGaP (Aluminum Indium Gallium Phosphide) semiconductor chip. When forward bias is applied, electrons and holes recombine in the active region, releasing photons with energy corresponding to the bandgap (≈1.95 eV, 635nm). The chip is mounted on a lead frame and encapsulated with epoxy or silicone to form a surface-mount package. The tiny lens shape (flat top) contributes to the wide emission angle. Heat is conducted through the backside terminal to the PCB.

13. Technology Trends

As IoT and wearable devices continue to shrink, demand for ultra-miniature LEDs like 0402 will grow. Trends include:

• Higher efficacy: Improvements in chip design will boost mcd/mA, enabling same brightness at lower currents for battery savings.
• Narrower binning: Customers increasingly require tight color and voltage groupings for uniform arrays. The 0.1V and 2nm bins offered here are already competitive.
• Enhanced reliability: Continued focus on sulfur/halogen resistance and extended lifetime testing (10,000h+).
• Integrations: Multi-color 0402 packages (RGB) are emerging, but the red alone remains a workhorse for status and safety indicators.

The RF-RU0402TS-BC-B1 is well positioned to meet these trends with its comprehensive binning, robust design, and clear application guidance.