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Led Structure
May 31, 2016

Core of the LED light emitting portion is made of p-type and n-type semiconductor pn junction consisting of core, when most carriers injected minority carriers of pn junction with compound, emits visible light, ultraviolet light or near-infrared light. Pn junction region of photons sent from non-directional, is fired in all directions have the same probability, so not all the light tube core can be released, mainly depends on the quality of semiconductor materials, core structure and geometry, package structure and encapsulation materials, improve internal and external quantum efficiency of LED application requirements. General 5mm LED package is a square with side length 0.25mm die bond or sintered on the lead frame, die the positive by spherical contact point and the gold bonding wire connected with a PIN, negative through reflection glass and lead frame connected to another pin, then top with epoxy resin coating. Reflective glass collection tube core side, is the role of the light interface, launch to the desired angle. Top Department package seal of epoxy resin made must shape, has such several role: protection tube core, not by outside erosion; used different of shape and material nature (mixed or not mixed bulk color agent), up lens or diffuse lens function, control light of divergent angle; tube core refraction rate and air refraction rate difference too big, led tube core internal of full reflection critical angle is small, its has source layer produced of light only small was out, most easy in tube core internal by times reflection and was absorption, easy occurred full reflection led to too much light loss, Choose the corresponding refractive index of epoxy resin as a transitional, improved pipe core light emitting efficiency. Used as a form of shell-and-tube epoxy resin shall be resistant to moisture, insulation, mechanical strength, and core refractive index and high transmittance of light. Select packaging materials of different refractive index, package geometry effects on the efficiency of photon emission is different, luminous intensity distribution and core structure, used for light output, the package lens material and shape. If they are sharp-shaped resin lens, light can be focused to the axis of the LED, the corresponding angle smaller if resin lens at the top of a round or flat, and its corresponding angle will increase.

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