COB LED assemblies combine multiple semiconductor elements into a compact emitting region. This creates a source geometry that differs from a board populated with widely separated packaged LEDs.
Source Geometry
A Concentrated Emitting Area
The closely grouped emitting region can act more like one larger source when viewed through a reflector or lens.
Source diameter, emitting area, mechanical holder, optical position, electrical contacts, and thermal interface all affect integration into the fixture.
Beam Formation
COB LEDs and Reflectors
Reflectors can collect light emitted from the COB source and redirect it into a controlled distribution.
The relative location of the emitting surface and reflector geometry can significantly influence the final beam.
Reflectors & Diffusers →Lenses
Secondary Optical Control
Lens systems can also be designed around a concentrated source to focus, collimate, or distribute the light.
Optical selection should account for the physical size of the COB rather than treating all sources as ideal points.
Optical Lenses →Heat Density
Thermal Design Around a Compact Source
Concentrating several emitting elements into one region can also concentrate thermal load. Mechanical design must provide a reliable path from the COB substrate into the larger heat-spreading structure.
Aluminum extrusions and machined housings are examples of structures that can provide both mechanical support and extended surface area for thermal management.
Mechanical Integration
Holders, Fasteners and Interfaces
The LED must remain positioned correctly relative to the optic while maintaining thermal contact. Holders, clamps, screws, insulating layers, thermal interfaces, and connector features can all be part of the assembly.
Electrical Operation
Driver Compatibility
COB devices should be operated with electronics suited to their electrical characteristics. Driver selection should consider the full lighting assembly rather than only nominal source output.
LED Drivers →Applications
Where COB Sources Can Fit
Concentrated sources can be useful where the lighting design needs a relatively compact optical origin for a reflector or lens system.
Whether a COB architecture is appropriate depends on fixture geometry, thermal conditions, optical requirements, electronics, and manufacturing constraints.
Selection