SMD 3528 Reverse Mount RGB LED

Dongguan Zhiding Electronics Technology Co., Ltd. is one of the most reliable manufacturers and suppliers of smd 3528 reverse mount rgb led in China, also supports customized service. If you're going to wholesale advanced smd 3528 reverse mount rgb led made in China, welcome to get quotation from our factory. Also, 2 years warranty is available.

SMD 3528 Reverse Mount RGB LED - Bottom Emitting Tri-Color Chip (AL-S3528RGBC Series)

3.5x2.8mm compact footprint with reverse-mount (bottom-view) lens​ for edge-lit and side-firing designs. Integrated Red/Green/Blue chips in water clear package. Optimized for SMT reflow, narrow channel lighting, and space-limited PCB backlighting.

Engineering Notes for Bottom-Emitting RGB Integration​
When transitioning from standard top-view to reverse-mount 3528s, pay close attention to the PCB cutout depth. Because the light exits from the underside, a 0.5mm to 1.0mm gap between the PCB and the light guide plate is critical for preventing hotspots. Our water-clear lens is tuned to disperse the R/G/B mix evenly across a 120° arc, making it suitable for single-layer aluminum boards where space prohibits secondary optics.

Why Reverse Mount for RGB?

In conventional top-view SMDs, the epoxy lens captures die light and projects upward. For Reverse Mount 3528, the emitting surface is oriented toward the board.
Edge Lighting Efficiency: When mounted along the edge of a light guide plate or acrylic channel, the bottom-emission couples light directly into the medium without secondary reflectors.
Low Profile Design: Eliminates the need to tilt the PCB or use right-angle modules in <5mm depth enclosures.
RGB Uniformity: The central lens position on the underside maintains consistent mixing distance relative to the PCB surface, reducing color shadows in close-range viewing.
Assembly Note: Pay attention to the orientation silkscreen. Reversed mounting will direct light away from the intended illumination zone.

Driving the Red AlInGaP die at 20mA typically yields 700 mcd​ within a dominant wavelength of 615-630nm. The InGaN-based Green and Blue channels exhibit higher Vf ranges (2.6~3.4V) compared to Red (1.8~2.6V), necessitating independent constant-current drive circuits for optimal color mixing. All three emitters share a uniform 120° beam angle​ from the bottom lens, ensuring even dispersion in edge-lit configurations.

PWM Dimming & Color Mixing Technical Notes
Unlike monochrome white LEDs, this 3528 RGB reverse mount requires PWM (Pulse Width Modulation)​ control to achieve accurate color mixing. The human eye's photopic response peaks at 555nm, meaning green light appears significantly brighter than red or blue at equal radiant flux. We recommend applying a gamma correction curve (γ ≈ 2.2)​ to the PWM duty cycle of the green and blue channels via your MCU firmware.
Drive Circuit Considerations:
The Red AlInGaP die operates at 1.8~2.6V VF, while Green/Blue InGaN dies require 2.6~3.4V. Use independent constant-current drivers per channel to prevent over-driving the Red die during full-brightness white mode.
Provide separate ground returns​ for each color on your PCB layout to avoid voltage drop interference between channels during simultaneous operation.
ESD rating for InGaN channels: 2000V HBM. Handle with standard ESD precautions during assembly.

Notes:
Tolerance: Luminous Intensity ±15%; Forward Voltage ±0.1V; Dominant Wavelength ±1nm.
Reverse Mount Structure: Light emission originates from the bottom side​ of the package. Ensure correct PCB orientation during SMT placement to align the emitting surface with the target illumination area.
ESD Sensitivity: InGaN chips (Green/Blue) feature an ESD rating of 2000V (HBM). Handle with standard ESD precautions.

Thermal Shock Warning for InGaN Chips:
While the Red (AlInGaP) die exhibits robust thermal stability, the Green and Blue (InGaN) channels are sensitive to rapid thermal transuspension. During hand soldering, avoid dwelling on the leads for more than 3 seconds. Multiple heat cycles on the same pad can cause micro-cracking in the phosphor layer of the green die, leading to chromaticity shifts not present in standard white LEDs.

About ZHIDINGLED – Precision in Specialized SMD Packaging
We: Dongguan Zhiding Electronics Technology Co., Ltd is an LED manufacturer located in Dongguan City, Guangdong Province, providing LED products and PCB processing services to global customers. Our factory has ISO 9001 certificate. Products have ROHS and REACH certificates, as well as other patent certificates.

Frequently Asked Questions
Q: Can I drive this RGB LED with a single PWM signal?​
A: No. Each color channel (R/G/B) requires an independent PWM output from your controller. The Red die (AlInGaP) has a lower forward voltage (1.8~2.6V) than the Green/Blue InGaN dies (2.6~3.4V), so a shared drive will result in Red over-saturation.
Q: Why does my RGB LED show color shift after reflow?​
A: Ensure peak temperature does not exceed 260℃ for more than 10 seconds. The InGaN dies are sensitive to thermal shock. If you see chromaticity drift, check your reflow profile's preheat phase (must be 140~160℃ for ≤2 min).
Q: What's the minimum PCB pad size for reverse mount?​
A: We recommend following our land pattern diagram (downloadable in the Datasheet). The reverse-mount pads are symmetrical to standard 3528, but the solder mask opening should be 0.05mm larger​ on the emission side to avoid blocking bottom light output.

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