Four advances in LED packaging industry in 2011

, COB package

At present, LED package method can be divided into lens type (Lens-type) and reflection cup (Reflector-type), which can be molded lens molding (Molding) or lens adhesive molding; reflection cup type chip is by glue mixing, dispensing, packaging and molding; in recent years, epitaxial wafer fixing and packaging design mature, chip size and structure of LED by small, high power single chip power up to 1~3W, even more than 3W, when the LED power is rising, cooling and heat load for the LED chip circuit version and system requirements, more and more strict.

In insulation, insulation, heat and heat resistance into consideration, to become one of the important materials of ceramic substrate chip adhesion technology. The technology can be divided into thick film process (Thick film), low temperature co firing process (LTCC) and thin film process (DPC), etc.. However, thick film technology and low temperature co firing process, using screen printing technology and high temperature sintering process, easy to produce line, not accurate, and rough alignment of the contraction ratio, if the product for LED high power line is more and more detailed, or require accurate eutectic or flip chip technology for the production of LED products co fired ceramic substrate, thick film and low temperature, has no use.

Therefore, high coefficient of heat transfer film ceramic substrate, using sputtering, electrical / chemical deposition and photolithography technology, with metal line precision, material system stability, the development trend for high power, small size, high brightness LED, more is to solve the eutectic / flip chip packaging technology on ceramic substrate metal line resolution and accuracy of the stringent requirements. When the LED chip ceramic as a carrier plate, radiating LED module is transferred to the bottleneck of the system circuit board, the heat from the LED chip to the cooling fins and the atmosphere, with the gradual promotion of the LED chip functional materials, has gradually changed from FR4 to metal core printed circuit board (MCPCB), but with the progress of high power the demand for LED, heat transfer coefficient of MCPCB material (2~4W/mk) cannot be used for higher power products, therefore, ceramic circuit board (Ceramic circuit board) the demand will gradually spread, in order to ensure the stability of material in high power LED products under the operation and light stability, ceramic as heat and metal wiring board trend has become clear. At present, the cost of ceramic material is higher than MCPCB. Therefore, how to use the high coefficient of heat dissipation coefficient of ceramic to save the area of material to reduce the cost of production has become one of the important indicators of the development of ceramic LED. Therefore, in recent years, the design and integration of polycrystalline materials packaging and system circuit with ceramic material COB has been paid more and more attention to the packaging and system manufacturers.

COB, in the electronic manufacturing industry is not a new technology, refers directly to the bare wafer adhesive on the circuit board, and the wire / wire soldered directly to the gold line on the PCB, also known as the wire (Wire bonding), and then through the sealing technology. The packaging steps in the production process of IC directly transferred to the circuit board assembly. In the LED industry, because the products of modern science and technology more and more exquisite light and high portability, in addition, in order to save a plurality of LED chip design system in space, in the demand of high power LED system, we developed the chip can be directly adhered on the system board COB technology.

COB is advantages: cost-effective, simple circuit design, system board to save space, but also the existence of technical threshold harmonic chip integrated brightness, color temperature and system integration. Taking 25W LED as an example, the traditional light source LED high power 25W, should be used in 25 1W LED chip package into 25 LED components, and COB package LED chip package is 25 1W in a single chip, so the two optical lens needs from the 25 reduced to 1, a help to narrow the source area, reduce material, system cost, and simplify the two optical design of light system and save manpower cost assembly. In addition, the high power COB package requires only a single high power LED can replace more than 1 watts (including) more than LED package, prompting the product volume is more light and short.

It is understood that the current COB packaging ball bulb has occupied the LED bulb around 40% of the market, many companies in Japan and China are beginning to go COB package mode. Insiders predict that COB packaging will become the inevitable trend of future development.

Although the voice of the COB package is very large, obvious signs of temperature, but the outlook does not seem clear. In two or three years, COB packaging technology can not be the mainstream of the Zhejiang billion meters Photoelectric Technology Co., Ltd. R & D Department of Dr. Zou Jun. He added, because most domestic enterprises still use the traditional way of packaging, technology and cost constraints in various conditions, and also need time to spread incoming foreign technology, COB packaging technology can quickly occupy the trend, but it is undeniable that COB packaging technology is a strong development direction.

An embarrassing situation lies in the current application of the enterprise COB integrated packaging needs. Due to the failure of the last round of investment, resulting in many lighting companies do not dare to use this package. It is understood that the bottleneck of COB packaging technology is how to improve the reliability of light source, and the environment of the trial, however, packaging companies currently on the market to production of COB light source is not much, and most of the use of aluminum as substrate materials. The aluminum substrate COB due to its thermal resistance is high, the reliability is not high, prone to decay and death light phenomenon. Although the ceramic matrix is one of the ideal materials of COB, but the cost is high, the cost is higher when the power is less than 2W