Six typical packaging structures
At present, there are more than 100 types of LED packaging structures, including more than 40 types of LAMP series, more than 30 types of SMD series, and more than 30 types of COB series. High power packaging, optical integration packaging, and modular packaging are among the main packaging types. The timely development of packaging closely follows the development needs of customer application products
The basic requirements of LED packaging technology are to improve light output efficiency, high light color performance, and device reliability. Hailongxing editor will talk about several typical LED bead packaging structures
1. Improve light output efficiency
The encapsulation efficiency can generally reach 80-90%
Choose packaging materials with better transparency: transparency greater than 95% (1mm thickness), refractive index greater than 1.5, etc
Select fluorescent powder with high laser emission efficiency and high dominance, with appropriate particle size
The mounting substrate (reflector cup) should have a high reflectivity and high light output optical design appearance
Choose appropriate packaging processes, especially coating processes
2. High gloss performance
The main technical parameters of LED light and color include: height, glare, color temperature, color rendering, color tolerance, and flashing light
Color rendering index CRI greater than 70, greater than 80, greater than 90
Color tolerance greater than or equal to 3SDCM greater than or equal to 5
Packaging companies should use multiple primary color combinations to achieve this, with a focus on improving the spectral distribution SPD of LED radiation, approaching the distribution of sunlight, and paying attention to the development and application of quantum dot phosphors,
LED reliability includes the performance changes and various failure modes of LED devices under different conditions, which mainly indicate the positive values of reliability. Currently, it is generally 3-5 hours and can reach 50000 to 100000 hours
Select appropriate packaging materials: high adhesion, low stress, good matching, good airtightness, temperature and humidity resistance (water absorption), UV resistance, etc
2. Packaging and heat dissipation materials: Solid crystal materials with high thermal conductivity and conductivity, high conductivity and high strength, and low stress
Suitable packaging process: strong bonding force, low stress, and matching bonding are required for lamination, soldering, and packaging
1COB integrated packaging
COB integrated packaging currently has more than 30 packaging forms, including MCOB, COMB, MOFB, MLCOB, etc. COB technology is becoming increasingly mature, with the advantage of low cost. COB packaging currently accounts for about 40% of the market for station LED light sources, with a light efficiency of 160-178IM/W
2. Traditional inline models
Due to its ease of mass production, simple use, low investment, complete set of supporting materials and equipment, and low price, direct insertion LED is widely used. The advantages of direct insertion LED are mature technology, simple application, easy to mass production, low investment in optical efficiency, and complete supporting equipment. Confirmed to have poor heat dissipation and fast decay, only suitable for currents below 20ma
2. The PIRANHA packaging model has mature technology, simple application, is conducive to mass production, low investment in optical efficiency changes, and complete supporting equipment. Disadvantage: Poor heat dissipation ability, generally suitable for currents below 70ma
3LImiLEDS packaging: The main application is to develop an LED bead for car headlights. By adopting patented TS chip technology, its luminous flux can reach 3-6lmIF-150MA. The application of red and yellow light is relatively complex, with high heat generation and UV epoxy resin technology packaging. Its advantages are that it can reach 150MA, has a large viewing angle, light intensity, and is easy for secondary light distribution. However, its disadvantages are thermal resistance of 60-80 ℃/w, and its heating is large and complex to use
4. OSRAM is mainly used in the field of backlighting. The advantages are small size, maximum current up to 50ma, large viewing angle, which is conducive to automated mass production, and easy to assemble and install. However, at the same time, it also has the disadvantage of poor thermal conductivity, high heat generation, and cannot withstand larger currents, unable to produce higher light output,
5. The structure of small chip bundle packaging uses ordinary 20ma chips, with a current of up to 240MA and a luminous flux of up to 70lm. Compared to other high-power chip packaging crystal structures, it is relatively simple to use and uses a series parallel connection method for chip connection. The difference in electrical parameters of the chip itself has a significant impact on product reliability, and its volume is large, which is not conducive to mass production, Strictly consider product heat dissipation
There are many welding methods for LED lamp beads on the chip, and the following is one of the commonly used methods for reference. First, use an electric soldering iron to heat some soldering tin on the positive and negative electrode pads of the lamp bead (the soldering tin must not be too much, otherwise, the positive and negative electrode pads will be connected once heated with a hot-air gun), then use a hot-air gun to heat the positive and negative electrode pads at the same time, after the tin melts, use tweezers to place the positive and negative electrodes of the lamp bead on the corresponding pad.
LED is the light emitting diode, which is a semiconductor solid light emitting device that converts electric energy into light energy. Its core is the PN junction. In addition to the forward conduction, reverse cut-off and breakdown characteristics of the general PN junction, it also has the light emitting characteristics under certain conditions. Its structure mainly includes the following parts: lead, bracket, encapsulation glue, bonding wire, LED chip, solid crystal glue and phosphor. The discoloration failure of LED lamp bead is closely related to its material, structure, packaging process and service conditions. The following will analyze the causes of its discoloration through specific cases.
LED lamp beads are also called light emitting diodes. It has a wide range of applications. Its luminous colors include red light, emerald green light, yellow green light, yellow light, purple light, blue light, white light and orange light. The above is monochromatic light. It can also be made into two or three colors.
The gold wire used to package LED lamp beads contains more than 99.99% gold. It is produced by drawing gold from this material. In addition to 99.99% gold, this gold also contains less than 1% other trace elements. One of the core components of LED lamp bead packaging is gold wire, which is the bridge connecting the luminous chip and the welding point, and plays a decisive role in the service life of LED lamp bead. So how to identify the purity of gold thread?