SMD LED 12-21/BHC-AN1P2/2C Datasheet - Blue - 3.5V - 25mA - English Technical Document

1. Product Overview

The 12-21/BHC-AN1P2/2C is a surface-mount device (SMD) light-emitting diode (LED) utilizing InGaN chip technology to produce blue light. This component is designed for modern, compact electronic assemblies, offering significant advantages in board space utilization and automated manufacturing processes.

1.1 Core Advantages and Target Market

The primary advantage of this LED is its miniature 12-21 package footprint, which is considerably smaller than traditional lead-frame type LEDs. This enables the design of smaller printed circuit boards (PCBs), higher component packing density, reduced storage requirements, and ultimately, more compact end-user equipment. Its lightweight construction makes it particularly suitable for portable and miniature applications. The product is compliant with key industry standards including RoHS, EU REACH, and is halogen-free (Br <900 ppm, Cl <900 ppm, Br+Cl < 1500 ppm), making it suitable for a wide range of consumer and industrial electronics.

1.2 Applications

Typical applications include backlighting for instrument panels, switches, and symbols; indicator and backlighting in telecommunication devices such as telephones and fax machines; flat backlighting for liquid crystal displays (LCDs); and general-purpose indicator use.

2. Technical Parameter Deep Dive

This section provides a detailed, objective interpretation of the key electrical, optical, and thermal parameters specified in the datasheet.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or beyond these limits is not recommended.

• Reverse Voltage (V_R): 5V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Continuous Forward Current (I_F): 25 mA. The maximum DC current that can be continuously applied.
• Peak Forward Current (I_FP): 100 mA. This is permissible only under pulsed conditions (duty cycle 1/10 @ 1kHz) and must not be used for DC operation.
• Power Dissipation (P_d): 110 mW. The maximum power the package can dissipate, calculated as forward voltage multiplied by forward current, considering thermal limitations.
• Electrostatic Discharge (ESD) Human Body Model (HBM): 150V. This is a relatively low ESD tolerance, indicating the device is sensitive to static electricity. Proper ESD handling procedures are mandatory during assembly and handling.
• Operating & Storage Temperature: -40°C to +85°C (operating), -40°C to +90°C (storage). This wide range ensures reliability in various environmental conditions.
• Soldering Temperature: Reflow soldering is specified at 260°C peak temperature for a maximum of 10 seconds. Hand soldering should be limited to 350°C for 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These parameters are measured at a standard test condition of 25°C ambient temperature and a forward current (I_F) of 20 mA, unless otherwise stated.

• Luminous Intensity (I_v): Ranges from 28.5 mcd (minimum) to 72 mcd (maximum), with a typical value unspecified. The actual value is determined by the binning group (see Section 3). A ±10% tolerance is noted.
• Viewing Angle (2θ_1/2): 120 degrees (typical). This wide viewing angle is characteristic of the water-clear resin dome, providing a broad emission pattern suitable for area illumination and indicators.
• Peak Wavelength (λ_p): 468 nm (typical). This is the wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λ_d): 470 nm (typical). This is the single wavelength perceived by the human eye, defining the color. A tolerance of ±1 nm is specified.
• Spectral Bandwidth (Δλ): 35 nm (typical). This defines the width of the emitted spectrum at half the maximum intensity (FWHM).
• Forward Voltage (V_F): 3.5V (typical), 4.0V (maximum) at I_F=20mA. A tolerance of ±0.1V is noted. This parameter is crucial for designing the current-limiting circuitry.
• Reverse Current (I_R): 50 µA (maximum) at V_R=5V.

3. Binning System Explanation

The LEDs are sorted (binned) based on key optical and electrical parameters to ensure consistency within a production lot. This allows designers to select parts that meet specific application requirements.

3.1 Luminous Intensity Binning

LEDs are grouped into four intensity bins, identified by codes N1, N2, P1, and P2. The intensity range for each bin is clearly defined, with P2 representing the highest output group (57.0 - 72.0 mcd). The tolerance for luminous intensity in the binning table is noted as ±11%.

3.2 Dominant Wavelength Binning

The blue color is controlled through dominant wavelength binning. LEDs are grouped into four bins: A9 (464.5-467.5 nm), A10 (467.5-470.5 nm), A11 (470.5-473.5 nm), and A12 (473.5-476.5 nm). This ensures color consistency within a defined range. The tolerance is ±1 nm.

4. Mechanical and Package Information

4.1 Package Dimensions

The datasheet provides a detailed dimensional drawing of the 12-21 SMD package. Key dimensions include the overall length, width, and height, as well as the pad spacing and size. All unspecified tolerances are ±0.1 mm. The polarity is indicated by a marking on the package, which is essential for correct orientation during assembly.

4.2 Packaging Format

The LEDs are supplied in moisture-resistant packaging. They are housed in 8mm wide carrier tape, which is wound onto 7-inch diameter reels. Each reel contains 2000 pieces. The packaging includes a desiccant and is sealed within an aluminum moisture-proof bag to protect the components from ambient humidity during storage and transport.

5. Soldering and Assembly Guide

Proper handling is critical to ensure reliability and prevent damage to these sensitive components.

5.1 Storage and Moisture Sensitivity

This product is moisture-sensitive. The unopened bag must be stored at 30°C/90%RH or less. Once opened, the components have a "floor life" of 168 hours (7 days) under conditions of 30°C/60%RH or less. If not used within this time, or if the desiccant indicator shows saturation, the LEDs must be baked at 60 ± 5°C for 24 hours before use to remove absorbed moisture and prevent "popcorning" during reflow soldering.

5.2 Reflow Soldering Profile

A detailed Pb-free reflow soldering temperature profile is provided:

• Pre-heating: 150-200°C for 60-120 seconds.
• Time Above Liquidus (217°C): 60-150 seconds.
• Peak Temperature: 260°C maximum, held for a maximum of 10 seconds.
• Heating Rate: Maximum 6°C/second.
• Time Above 255°C: Maximum 30 seconds.
• Cooling Rate: Maximum 3°C/second.

Reflow soldering should not be performed more than two times. Stress on the LED body during heating must be avoided.

5.3 Hand Soldering and Repair

If hand soldering is necessary, it should be performed with a soldering iron tip temperature below 350°C, applied for no more than 3 seconds per terminal. The soldering iron power should be 25W or less. A minimum interval of 2 seconds should be left between soldering each terminal. Repair after soldering is strongly discouraged. If absolutely unavoidable, a double-head soldering iron must be used to simultaneously heat both terminals, preventing thermal and mechanical stress on the LED chip.

6. Application Suggestions and Design Considerations

6.1 Current Limiting is Mandatory

The datasheet explicitly warns that an external current-limiting resistor is required. LEDs exhibit a non-linear, exponential current-voltage relationship. A small increase in forward voltage beyond the typical value can lead to a large, potentially destructive increase in current. The resistor value (R) can be calculated using Ohm's Law: R = (Supply Voltage - V_F) / I_F. Always use the maximum V_F from the datasheet for a conservative design.

6.2 Thermal Management

While the package is small, power dissipation (up to 110 mW) generates heat. For optimal longevity and stable light output, ensure adequate thermal relief in the PCB design. This includes using appropriately sized copper pads and, if possible, thermal vias to dissipate heat to other board layers.

6.3 ESD Protection

With an ESD HBM rating of only 150V, this component is highly sensitive. Implement ESD-safe workstations, use grounded wrist straps, and transport components in conductive containers. Consider adding transient voltage suppression (TVS) diodes or other protection circuits on the PCB if the LED is connected to external interfaces prone to ESD events.

7. Technical Comparison and Differentiation

The 12-21 package offers a balance between size and ease of handling. Compared to larger SMD LEDs (e.g., 3528, 5050), it saves significant board space. Compared to smaller chip-scale packages (CSP), it is generally easier to assemble and inspect visually. Its wide 120-degree viewing angle differentiates it from narrower-beam LEDs, making it better suited for area illumination rather than focused spot lighting. The water-clear resin, as opposed to diffused resin, provides higher light output efficiency but may appear as a brighter point source.

8. Frequently Asked Questions (Based on Technical Parameters)

8.1 Can I drive this LED at 30 mA for higher brightness?

No. The Absolute Maximum Rating for continuous forward current (I_F) is 25 mA. Exceeding this rating will reduce the LED's lifespan and may cause immediate failure due to overheating or electromigration within the semiconductor junction.

8.2 Why is the forward voltage 3.5V when other blue LEDs are around 3.0V?

The forward voltage is a characteristic of the semiconductor material (InGaN) and the specific epitaxial structure of the chip. A V_F of 3.5V is within the typical range for blue InGaN LEDs. This must be accounted for in the power supply design.

8.3 What happens if I don't follow the moisture sensitivity instructions?

Ignoring the MSL (Moisture Sensitivity Level) instructions can lead to "popcorning" or delamination during reflow soldering. Absorbed moisture rapidly turns to steam when heated, creating internal pressure that can crack the LED resin or damage the internal wire bonds, resulting in immediate or latent failure.

9. Practical Design and Usage Case

Scenario: Designing a status indicator for a portable device. The 12-21 LED is an excellent choice due to its small size and low power consumption. The designer selects bin P1 for luminous intensity (45-57 mcd) to ensure good visibility, and bin A10 for dominant wavelength (467.5-470.5 nm) for a consistent blue color. A 3.3V system voltage is used. Calculating the series resistor: R = (3.3V - 4.0V_max) / 0.020A. This yields a negative value, indicating 3.3V is insufficient to overcome the maximum V_F. Therefore, a higher supply voltage (e.g., 5V) must be used: R = (5.0V - 4.0V) / 0.020A = 50 Ohms. A standard 51-ohm resistor is selected. The PCB layout includes ESD protection diodes on the indicator signal line and thermal relief pads connected to a ground plane.

10. Operating Principle and Technology Trends

10.1 Basic Operating Principle

This LED is based on a semiconductor p-n junction made from Indium Gallium Nitride (InGaN). When a forward voltage is applied, electrons and holes are injected into the active region where they recombine. The energy released during this recombination is emitted as photons (light). The specific composition of the InGaN alloy determines the bandgap energy and thus the wavelength (color) of the emitted light, which in this case is in the blue spectrum (~470 nm).

10.2 Industry Trends

The trend in SMD LEDs continues towards higher efficiency (more lumens per watt), smaller package sizes, and improved reliability. There is also a focus on tighter binning tolerances for color and intensity to meet the demands of applications requiring high color consistency, such as full-color displays and architectural lighting. The drive for miniaturization supports the development of even smaller packages and chip-scale packaging (CSP) technologies. Furthermore, integration of control electronics directly with the LED die (e.g., intelligent LEDs) is an ongoing area of development.