LED Red 2.0x1.25x0.7mm SMD Specification - 625-640nm - 1.8-2.4V - 20mA - 72mW - English Technical Document

1. Product Overview

The RF-RUB170TS-BD is a surface-mount red LED designed for general indication and display applications. It is fabricated using a high-efficiency red chip and comes in a compact 2.0mm x 1.25mm x 0.7mm package. This LED offers an extremely wide viewing angle of 140°, making it suitable for applications requiring broad light distribution. It is compatible with standard SMT assembly and reflow soldering processes, and meets RoHS compliance requirements. The moisture sensitivity level is rated as Level 3, requiring proper handling and storage to prevent moisture absorption.

2. Technical Parameter Interpretation

2.1 Electro-Optical Characteristics (at T_S=25°C)

Under a test current of 20mA, the LED exhibits the following characteristics:

• Forward Voltage (V_F): Available in three bins: B0 (1.8-2.0V), C0 (2.0-2.2V), D0 (2.2-2.4V). Typical value is 1.8V for B0 bin.
• Dominant Wavelength (λ_D): Ranges from 625nm to 640nm, sorted into bins F00 (625-630nm), G00 (630-635nm), H00 (635-640nm). Typical value is 625nm for F00 bin.
• Spectral Half Bandwidth (Δλ): 15nm typical.
• Luminous Intensity (I_V): Two intensity bins: 1GJ (20-40mcd) and 1BS (40-90mcd) at 20mA.
• Viewing Angle (2θ_1/2): 140° typical.
• Reverse Current (I_R): Maximum 10µA at V_R=5V.
• Thermal Resistance (R_THJ-S): Maximum 450°C/W.

These parameters are measured under the manufacturer’s standard test conditions. Allowable measurement tolerances are ±0.1V for voltage, ±2nm for wavelength, and ±10% for luminous intensity.

2.2 Absolute Maximum Ratings

Care must be taken to ensure that the actual operating conditions do not exceed these ratings, especially power dissipation and junction temperature, to avoid damage or accelerated degradation.

3. Binning System

The RF-RUB170TS-BD is characterized and binned by forward voltage, dominant wavelength, and luminous intensity to provide consistent performance for the end user.

• Voltage Bins: B0 (1.8-2.0V), C0 (2.0-2.2V), D0 (2.2-2.4V).
• Wavelength Bins: F00 (625-630nm), G00 (630-635nm), H00 (635-640nm).
• Intensity Bins: 1GJ (20-40mcd), 1BS (40-90mcd).

The bin code (e.g., F00 1GJ B0) is printed on the reel label to identify the exact performance group. This allows designers to select LEDs with tight parameter tolerances for uniform display panels or indicator arrays.

4. Performance Curve Analysis

4.1 Forward Voltage vs. Forward Current

The I-V curve shows a typical forward voltage around 1.8V at 20mA. At very low currents (below 5mA), the voltage drops below 1.5V. The curve is exponential, typical for a red LED.

4.2 Relative Intensity vs. Forward Current

Relative luminous intensity increases nearly linearly with forward current from 0 to 30mA. At 20mA, the intensity is approximately 80% of the maximum at 30mA. This relationship is useful for dimming applications via current adjustment.

4.3 Pin Temperature vs. Relative Intensity & Forward Current

As the pin (solder point) temperature rises, the relative intensity decreases. At 85°C, the intensity drops to about 85% of the value at 25°C. Similarly, the maximum allowable forward current must be derated at high temperatures to keep the junction temperature below 95°C. For example, at 100°C pin temperature, the forward current should be limited to approximately 10mA.

4.4 Wavelength Shift vs. Forward Current

The dominant wavelength increases slightly with forward current. At 30mA, the wavelength is about 1-2nm higher than at 5mA. This shift is small and usually acceptable for most indication applications.

4.5 Spectral Distribution

The typical spectrum peaks around 630-635nm with a half bandwidth of 15nm. The emission is narrow and concentrated in the red region, making it suitable for red indicators and displays.

4.6 Radiation Pattern

The radiation diagram shows a wide symmetrical pattern with half-intensity angle of ±70°, confirming the wide viewing angle of 140°. This makes the LED ideal for use in edge-lit or diffused lighting applications.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED package measures 2.0mm x 1.25mm x 0.7mm (L x W x H). The top view shows a centered lens with two terminals at the bottom side. The cathode is marked by a green ink dot on the top surface (as per latest version). The recommended soldering pad layout has dimensions: pad width 1.20mm, pad length 3.20mm, with a gap of 0.80mm between pads. All tolerances are ±0.2mm unless otherwise specified.

5.2 Polarity Identification

On the bottom view, pad 2 is the cathode as indicated by the polarity mark. On the top surface, a green ink dot (added in version E/3) indicates the cathode side. Designers should ensure correct orientation in the PCB layout.

5.3 Carrier Tape & Reel Dimensions

Components are supplied on 8mm wide carrier tape with 4mm pitch. Each reel holds 4000 pieces. The reel diameter is 178mm, with a hub diameter of 60mm and a tape width of 8.0±0.1mm. The carrier tape has a polarity mark indicating the feeding direction.

5.4 Label Information

Each reel carries a label containing: Part Number (RF-RUB170TS-BD), Spec Number, Lot Number, Bin Code (including wavelength, intensity, voltage bins), Quantity, and Date code. This traceability is essential for quality control.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

The recommended reflow profile for this LED (based on JEDEC J-STD-020) is:

• Preheat: 150-200°C for 60-120 seconds
• Time above 217°C (TL): 60-150 seconds
• Peak temperature (TP): 260°C max, with time within 5°C of peak not exceeding 30 seconds, and absolute peak time (tp) max 10 seconds
• Ramp-up rate: max 3°C/s from Tsmax to TP
• Cooling rate: max 6°C/s
• Total time from 25°C to peak: max 8 minutes

Reflow soldering must not be performed more than twice. If the interval between two soldering processes exceeds 24 hours, the LEDs should be baked before use due to moisture absorption.

6.2 Hand Soldering & Rework

If hand soldering is necessary, use a soldering iron with temperature below 300°C and contact time less than 3 seconds. Only one hand soldering operation is allowed. Rework after reflow should be avoided; if unavoidable, use a double-head soldering iron and pre-test to ensure no damage to the LED.

6.3 Storage & Moisture Handling

Before opening the sealed aluminum bag, store at ≤30°C and ≤75% RH for up to one year from the manufacturing date. After opening, the LEDs must be used within 168 hours (7 days) under conditions ≤30°C and ≤60% RH. If the storage conditions are exceeded or the desiccant has changed color, bake the LEDs at 60°C (±5°C) for more than 24 hours before use.

7. Packaging & Ordering Information

The standard packaging is 4,000 pieces per reel, 8mm tape, 178mm reel. Multiple reels are packed in a moisture barrier bag with desiccant and a humidity indicator card. The bag is then placed in a cardboard box for shipment. The box is labeled with product information and handling precautions.

8. Application Recommendations

8.1 Typical Applications

• Optical indicators on consumer electronics, home appliances, automotive interiors.
• Switches and symbol backlighting (e.g., buttons, logos).
• General purpose status indication and signage.
• Edge-lit lighting for small displays.

8.2 Design Considerations

• Always use a current-limiting resistor to keep the forward current below the absolute maximum rating (30mA). A small change in supply voltage can cause significant current variation; resistor tolerance should be considered.
• Thermal management is critical: ensure adequate heat dissipation through PCB copper pads and vias to keep junction temperature below 95°C. Derate the current at high ambient temperatures.
• Avoid applying reverse voltage as it may cause LED damage.
• ESD protection: use standard ESD-safe handling practices (grounded workstations, wrist straps).
• Note that the silicone lens is soft and may attract dust; avoid mechanical contact with the lens surface. Cleaning with isopropyl alcohol is recommended if needed. Ultrasonic cleaning is not recommended as it may damage the LED.
• Environmental compatibility: ensure the surrounding materials (e.g., potting, lenses, adhesives) do not contain high levels of sulfur ( >100ppm ), bromine ( >900ppm ), chlorine ( >900ppm ), or total halogens ( >1500ppm ), as these can cause chemical attack on the LED.
• Avoid using adhesives that outgas organic vapors, as they may condense on the LED and degrade performance.

9. Technical Comparison with Similar Products

Compared to other 2.0x1.25mm red LEDs, the RF-RUB170TS-BD offers a wide viewing angle of 140°, which is significantly broader than typical 120° or 110° parts. This makes it advantageous for applications requiring uniform illumination over a large area. The device also provides multiple wavelength bins covering 625-640nm, allowing designers to select the exact red hue for branding or aesthetic matching. Its thermal resistance (450°C/W) is moderate; for higher power applications, a larger package with better heat dissipation might be preferred.

10. Frequently Asked Questions

1. What is the maximum allowed storage time after opening the bag? 168 hours under ≤30°C and ≤60% RH. If exceeded, bake at 60°C for 24h.
2. Can I drive the LED at 30mA continuously? Yes, but ensure the junction temperature does not exceed 95°C. Derating may be required at high ambient temperatures.
3. What is the typical forward voltage at 20mA? Depending on bin: B0 ~1.8V, C0 ~2.1V, D0 ~2.3V.
4. Is the LED polarity marked? Yes, a green ink dot on the top surface indicates the cathode.
5. Can I use this LED in outdoor applications? The operating temperature range is -40 to +85°C, so it can be used outdoors if properly sealed against moisture and high temperature.
6. How to clean the LED after soldering? Use isopropyl alcohol. Do not use ultrasonic cleaning.

11. Practical Application Examples

Example 1: Status indicator on a home appliance panel. The wide viewing angle allows the indicator to be visible from any direction. Using a 330Ω series resistor with a 5V supply provides about 10mA current, ensuring long life and consistent brightness.

Example 2: Symbol backlighting in an automotive dashboard. The narrow wavelength bin (e.g., 630-635nm) ensures uniform red color across multiple switches. Proper thermal management via PCB copper pours keeps the LEDs cool even in hot cabin environments.

Example 3: Edge-lit display for a small signage. The low profile (0.7mm) allows the LED to be placed behind thin panels. Multiple LEDs can be arrayed along the edge with current set to ~15mA, giving even illumination.

12. Principle of Operation

The LED is a P-N junction diode made from a direct bandgap semiconductor (typically AlGaInP for red emission). When forward biased, electrons and holes recombine radiatively, emitting photons with energy corresponding to the bandgap. The dominant wavelength of 625-640nm corresponds to photon energies of approximately 1.98-1.94 eV. The efficiency of light extraction is enhanced by the transparent substrate and lens design. The 140° viewing angle is achieved by a hemispherical or flat-top lens that scatters light widely.

13. Development Trends

Current trends in red SMD LEDs include smaller package sizes (e.g., 1.6x0.8mm), higher efficacy (lm/W), and improved reliability for automotive and high-temperature applications. The RF-RUB170TS-BD represents a mature 2.0x1.25mm platform with good optical performance. Future developments may focus on reducing thermal resistance further and achieving better color consistency through tighter binning.