Surface-Mount LEDs: Package Size 3528 (3.5×2.8mm), CRI 70-90

Component Specifications

Definition

Surface-mount LEDs (SMD LEDs) are solid-state lighting components that utilize semiconductor materials to emit light when current flows through them. These components feature flat, pad-style terminals that allow direct soldering onto PCB pads without through-hole mounting. They are characterized by standardized package sizes (e.g., 0603, 0805, 1206, 3528, 5050), precise optical characteristics, and compatibility with high-speed pick-and-place assembly systems. SMD LEDs provide superior thermal management through direct PCB contact, enabling higher current operation and better lumen maintenance compared to through-hole alternatives.

Working Principle

SMD LEDs operate on electroluminescence principle where semiconductor materials (typically gallium arsenide phosphide or indium gallium nitride) emit photons when electrons recombine with electron holes across the p-n junction. Forward bias voltage (typically 2-3.5V) injects carriers into the active region, where radiative recombination produces light with wavelength determined by the semiconductor bandgap. The emitted light is extracted through epoxy or silicone encapsulation with precise optical shaping.

Materials

Semiconductor: GaAsP (red/orange/yellow), InGaN (blue/green/white); Substrate: Alumina ceramic or FR4; Encapsulation: Epoxy resin or silicone with phosphor coating for white LEDs; Electrodes: Copper alloy with nickel/gold plating; Bond wires: Gold or aluminum.

Technical Parameters

Parameter	Typical range	Notes & selection driver
CRI	70-90
Package Size	3528 (3.5×2.8mm)
Viewing Angle	120 degrees
Forward Current	20mA (typical), 30mA (max)
Forward Voltage	2.8-3.4V
Color Temperature	3000K-6500K (white LEDs)
Luminous Intensity	6000-8000 mcd
Thermal Resistance	200-300 K/W
Operating Temperature	-40°C to +85°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 9001, IEC 62031, JEDEC JESD22, IPC-A-610

Parent Products

This component is used in the following industrial products

LED Strip Lights

Flexible circuit boards with surface-mounted LEDs for decorative, accent, and task lighting.

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Engineering Analysis

Risks & Mitigation

Electrostatic discharge damage during handling
Thermal degradation from insufficient heat sinking
Moisture absorption in encapsulation materials
Solder joint fatigue from thermal cycling
Color shift over operational lifetime

FMEA Triads

Trigger: Excessive forward current
Failure: Catastrophic junction overheating and bond wire melting
Mitigation: Implement constant current drivers with overcurrent protection, design PCB with adequate thermal vias, use LEDs with appropriate current rating

Trigger: Poor solder joint formation
Failure: Intermittent electrical connection causing flickering or complete failure
Mitigation: Optimize reflow profile (preheat, soak, reflow, cooling), maintain proper pad design with solder mask definition, implement automated optical inspection post-assembly

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.1mm placement accuracy, ±5% forward voltage variation, ±10% luminous intensity variation within production batch

Test Method

IEC 62031 LED modules safety requirements, LM-80 lumen maintenance testing, TM-21 lifetime projection, IPC-J-STD-001 soldering requirements

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Surface-Mount LEDs

Manufacturer profiles associated with Surface-Mount LEDs.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the difference between SMD 3528 and 5050 LEDs?

SMD 3528 LEDs measure 3.5×2.8mm with single diode per package, typically producing 6-8 lumens. SMD 5050 LEDs measure 5.0×5.0mm with three diodes per package, producing 18-22 lumens with RGB capability. 3528 is more compact and energy-efficient for basic lighting, while 5050 offers higher brightness and color mixing.

How are SMD LEDs tested for quality control?

Automated optical inspection verifies placement accuracy and orientation. Electrical testing measures forward voltage, current, and luminous intensity. Thermal cycling tests validate reliability under temperature stress. Spectroradiometry ensures color consistency and chromaticity coordinates meet specifications.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Surface-Mount LEDs