LED encapsulation of more than 100 structures distinguish the complete

Time:2018-10-18 Views:935

There are three elements of LED packaging technology: design of packaging structure, selection of appropriate packaging materials and technology level.

At present, there are over 100 LED packaging structures, including over 40 Lamp series, over 30 SMD (chip LED and TOP LED) series, over 30 COB series, PLCC, high-power packaging, optical integrated packaging and modular packaging. The development of packaging technology should follow closely and meet the needs of LED application products.

The basic content of LED packaging technology

The basic requirements of LED packaging technology are: improving the efficiency of light emission, high-light color performance and device reliability.

(1) improve the light emission efficiency

LED packaging of light output efficiency can be 80-90%.

The packaging material with better transparency is chosen as the elastomer: the transparency is greater than 95% (1mm thickness), and the refractive index is greater than 1.5.

Instead of using high-excitation, high-dominant phosphor powder, the size of the particles is appropriate.

The backplate (reflecting cup) of the plate is designed with high reflectivity and high luminance.

Choose proper packaging technology, especially coating technology.

(2) highlight color performance

The main light-color technical parameters of LED are: height, glare, color temperature, color rendering, color tolerance, light scintillation, etc.

Color index CRI = 70 (outdoor), 80 (outdoor), 90 (art gallery, etc.)

Color tolerance

The packaging shall adopt multi-color combination to achieve, focusing on improving the spectral quantity distribution of LED radiation by SPD, which is close to the spectral quantity distribution of sunlight.We should pay more attention to the development and application of quantum dot phosphor to achieve better color quality.

(3) LED device reliability

LED reliability includes performance change of LED devices under different conditions and mechanism of various failure modes (LED packaging material degradation, influence of comprehensive stress, etc.), which is mainly mentioned as the characteristic value of reliability -- life. Currently, LED device life is generally 3-5 hours, which can reach 5-100 thousand hours.

Seal selects suitable packaging materials: high binding force, low stress, good match, good air tightness, temperature resistance, moisture resistance (low water absorption), uv resistance, etc.

The heat dissipation material for the package over the wall: the base plate with high thermal conductivity and high conductivity, the solid crystal material with high thermal conductivity, high conductivity and high strength, the stress is smaller.

Suitable packaging technology: assembly, pressure welding, packaging and other binding strength, stress should be small, the combination should match.

LED light integrated packaging technology

There are more than 30 types of LED light integrated packaging structure, which is gradually moving towards system integrated packaging, which is the development direction of future packaging technology.

(1) COB integrated packaging

COB integration encapsulation has more than 30 kinds of encapsulation structures, such as MCOB, COMB, MOFB, MLCOB, etc. COB encapsulation technology is becoming mature with the advantage of low cost.COB encapsulation accounted for about 40% of LED light source about the market now, photosynthetic efficiency up to 160 ~ 178 lm/w, thermal resistance of 2 ℃ / w, COB encapsulation is recently LED the trend of the development of the packaging.

(2) LED wafer level packaging

Wafer level packaging is made from epitaxial LED device as long as a chip, which is a form of multi-system integrated packaging for LED lighting light source. Generally, the substrate is made of silicon material, without solid crystal and pressure welding, and is shaped with dot glue to form system integrated packaging. Its advantages are good reliability, low cost, and it is one of the development directions of packaging technology.

(3) COF integrated packaging

COF package integration encapsulation is the flexible substrate assembly in the large area power LED chips, with high thermal conductivity, a thin layer of flexible, low cost, light evenly, high photosynthetic efficiency and can be curved surface light source, line source, the surface light source and the three dimensional light source all kinds of LED products, also can meet the requirements of modern LED lighting, personalized lighting, also can be used as a universal packaging components, market prospects look good.

(4) LED modular integrated package

Modular integrated packaging generally refers to the system integrated packaging of LED chips, drive power supply, control parts (including IP address), and parts, which is collectively referred to as LED module. It has many advantages such as material saving, cost reduction, standardized production and convenient maintenance, etc., and it is the development direction of LED packaging technology.

(5) wafer packaging technology

The overlaying technology is a space formed by chip, substrate and convex block. In this way, the encapsulated chip has the advantages of small size, high performance and short connection. Ceramic substrate, overlaying chip, eutectic process and direct pressing are adopted to meet the requirements of high power lighting performance.

The chip is pressed on the substrate with tin alloy to replace the previous silver glue technology, and the "direct pressing" replaces the "reflow welding" in the past, which has excellent conductive effect and heat conducting area.This packaging technology is an important development trend of high-power LED packaging.

(6) free packaging chip technology

The technology of free packaging is a kind of technology integration, which adopts invert chip and does not use fixed crystal glue, gold wire and bracket.

The light efficiency of PFC encapsulation-free chip can be improved to 200lm/w. The super-wide-angle all-around light design with the luminescence Angle greater than 300 degrees will not use the secondary optical lens, which will reduce the loss of light effect and reduce the cost, but it should be invested in expensive equipment.

The new PFC product is focused on the LED lighting market, especially in the candle lamp. It can not only simulate the shape of tungsten lamp, but also break the limit of heat dissipation volume.

(7) LED other packaging structures

Embedded EMC package structure: Embedded LED Chip will not see LED light directly.

(2) the EMC packaging technology (Epoxy Molding Compound) in Epoxy powder coating material for stent packaging technology, high heat, high integration, UV resistance, the advantages of small volume, but poor air tightness, is now mass production.

The package of the toy: an LED Chip is placed On a Glass substrate for packaging.

Martial QFN package technology: when the pixel unit of small distance screen is less than or equal to p.1, the package form adopted will replace PLCC structure, and the market prospect is promising.

V3d encapsulation technology: the technology of 3D encapsulation is under development.

The same power Frame encapsulation technology :(chip-in-frame Package) encapsulates the power LED Chip on a small Frame, and the industrialized light effect has reached 160~170 lm/w, which can reach more than 200 lm/w.

LED packaging material

There are many kinds of LED packaging materials, and they are developing continuously.

(1) packaging materials

Epoxy resin, epoxy plastic sealing material, silica gel, organosilicon plastics, etc., technically have requirements on refractive index, internal stress, binding force, air tightness, high temperature resistance, uv resistance, etc.

(2) solid crystal materials

Elastomer: resin and silica gel, the inner filling of metal and ceramic materials.

H eutectic: AuSn, rise /SnAgCu.

(3) substrate material: copper, aluminum and other metal alloy materials

Lu ceramic materials: Al2O3, AlN, SiC, etc.

Aluminum ceramic materials: called the third generation packaging materials AlSiC, AlSi, etc.

Materials for the metal substrate of the bronze SCB: multilayer die substrate, with good heat dissipation (heat conductivity 380w/m.k) and low cost.

The ceramic substrate is designed for fast heat transfer.

(4) heat dissipation materials: copper, aluminum and other metal alloy materials

Graphene composites with thermal conductivity of 200~1500w/ m.k.

PCT high temperature special engineering plastics (polyterephthalic acid 1, 4-cyclohexane dimethyl ester), ceramic fiber, high temperature resistance, low water absorption.

Thermal engineering plastics: non-insulating thermal engineering plastics, thermal conductivity 14w/m.k.

Insulating thermal engineering plastics, thermal conductivity 8w/m.k.