The LED Encapsulation Technology And Structure (2)

The LED encapsulation technology and structure (2)

Product packaging structure type

Since the nineties of the last century, the LED chip and made a number of breakthroughs in material technology research and development, the transparent substrate trapezoidal structure, texture, surface structure, flip-chip structure, the commercialization of ultra-high brightness (1cd) red, orange, yellow, green, blue LED product after another asked the city, as shown in Table 1, the 2000 low, the luminous flux of special lighting applications. The LED on the midstream industry unprecedented attention to further promote the the downstream packaging technology and industrial development, the use of different packaging structure forms and sizes, different emission color die its two-color or three-color combinations, can produce a variety of series, varieties, specifications of the products.

LED product package structure of the type shown in Table 2, there are also classified according to the luminescent color, the chip material, the emission luminance, the size, etc. characterized. The single die typically constitutes a point light source, a plurality of die assembly typically may constitute a surface light source and the line light source, for information, status indication and the display, the light emitting display is also used a plurality of die, through the proper connection of the tube core (including series and parallel) with a suitable optical structure combination, constituting a light emitting section and a light-emitting point of the light emitting display. Surface Mount LED gradually replace the pin-LED application design is more flexible, occupy a certain market share, accelerate the development trend in the LED display. Solid-state lighting source, some of the products listed on the LED's in the future, the long-term development direction.

LED pin package

LED pin package with a lead frame for various pin package outline, first successfully developed market package structure, number of species range, a higher degree of maturity of the technology, the package structure reflective layer continues to improve. Standard LED most customers that is most convenient in the display industry, the most economical solution, a typical conventional LED placed in the can withstand the 0.1W input power encapsulating, 90% of its heat by the negative electrode pin distributing the frame to the PCB, and then released into the air, and how to reduce the temperature rise of the working pn junction is a packaging and application must be considered. Encapsulation materials, high-temperature curing epoxy resin, its excellent optical performance, process adaptability product * high, made of colored transparent or colorless transparent and colored the scattering or colorless scattering lens package different lens shape constitute a variety of shapes and sizes, for example, a circle divided by the diameter Φ2mm, Φ3mm Φ4.4mm, Φ5mm Φ7mm several different components of the epoxy resin can produce different glow. There are a variety of different color point light package structure: a ceramic base epoxy resin package having a better working temperature performance, the pins can be bent into a desired shape, small volume; the plastic reflector package metal base is an energy-saving light , suitable for power indication; flashing CMOS oscillator circuit chip LED die combination package themselves have a strong visual impact of the flashing light; two-color type die by two different emission color, encapsulated in the same epoxy resin lens, in addition to the two-color outside also get a third of the mixed color, large screen display system is an extremely broad subject package composed of a two-color display devices; voltage type constant current source chip LED die combination package a direct replacement for the 5-24V voltage indicator. The surface light source is a plurality of LED die sticky Song Xuan Wen on the predetermined position of the CB plates, the plastic reflector box cover and potting epoxy resin formed, different designs to determine the arrangement and connection of the outer leads of the PCB board, with double row Inline with single in-line structure. Point, the surface light source has been developed out of hundreds of package shape and size for the market and customers apply.

LED light emitting display by digital tube or rice-shaped pipe symbol tube moments Chen tube composed of a variety of a number of products into a variety of shapes and structures designed by actual demand. Digital tube reflector monolithically integrated, a single seven-segment, three package structure, connected common anode and common cathode two kinds, one is often said that digital tube, two more generally referred to as the display. Reflector with large fonts to assemble flexible hybrid package features material Province, made the seven-segment-shaped shell with reflective cavity, usually with white plastic, a single LED die bonding with seven reflector reflector cavity each other on a bit of the PCB, the bottom of the center position of each reflective cavity is a light emitting area formed by the die, and the bonding wires with the bonding method key dropwise within reflector, an epoxy resin, with good stick tube core PCB board bonding position, and then curing Serve. Reflector type is divided into two kinds of air sealing and real seal, the former scattering and dyestuff epoxy resin, used for units, double-bit devices; latter superstructure color filter with uniform film, and die The base plate coated on a transparent insulating plastic, to improve the light efficiency, generally used for more than four digital display. Monolithic integrated in the light emitting material on the wafer to produce a large number of the seven-segment digital display graphics die, and then dicing the housing is divided into a monolithic graphics die bonding, pressure welding, a package with a lens (commonly known as fish-eye lens). Single seven-segment will have a good production of large-area LED chips, plan to cut into the light bar containing one or more just core the same seven bond in the digital shape Kovar shelves, bonding, epoxy constitute resin encapsulation. Monolithic, single-characteristics of micro-miniaturization can be dual in-line package, mostly dedicated products. LED Bargraph display in 106mm length circuit board, placement of 101 frompeanuts.Just core (core) up to 201 just to belong to the high-density packaging, using the principle of optical refraction, to make the point light source through the transparent cover 13-15 Raster Imaging each tube core from the point to the line of the display, packaging technology is more complex.

A semiconductor pn junction electroluminescent mechanism decision LED is impossible to produce white light having a continuous spectrum, while the single LED is also impossible to produce two or more kinds of the high luminance monochromatic, only when the package by means of a fluorescent substance, blue or ultraviolet LED die coated with phosphor, indirectly produce broadband spectrum, synthetic white; die package of several (two or three, and a variety of) hair a different shade constitute a component of the housing by the shade of the mixed white LED. Both methods have made practical, the Japanese white LED production in 2000 amounted to 100 million, to develop into a stable glowing product, only white LED design and assembly of paired luminous flux less demanding local decorative role main, the pursuit of trendy electric light.