Where is the magic of CSP ceramic packaging in LED packaging technology?

When the size of the ceramic substrate is almost the same size as the size of the chip, it gradually loses the function of helping the LED to dissipate heat. On the contrary, if the ceramic substrate is removed, a thermal interface is removed, which facilitates the rapid conduction of heat to the circuit board. At the same time, as the flip chip matures, the function of the ceramic substrate as an insulating material for redistribution of PN electrode lines is no longer needed. In addition to the protection of the LED on the mechanical structure and thermal expansion mismatch, the important functions of the ceramic substrate on the chip's electrical isolation and heat conduction have been basically lost. The GGI or AuSn eutectic soldering that eliminates the need for a substrate and is a traditional ceramic encapsulation die can be changed to a low cost SAC solder. With the help of flip-chip, the gold wire and wire bonding steps are eliminated, reducing the packaging cost.

When major manufacturers and media promote CSP packaging, most of them can not bypass such a paragraph - traditional LED lighting production is divided into chips, packaging, lighting three links, the use of CSP package, you can save the packaging process, the chip factory can be directly The seamless connection with the luminaire factory greatly simplifies the production process and reduces the cost. The line between the lines seems to be expressed in the packaging process and will be removed from it. The packaging plant will have no way out. but it is not the truth. First of all, to popularize a concept, the so-called "chip-scale package", or "no package", "free package" is a positive solution is to use flip-chip directly sealed to the bottom of the package pad, no gold wire, no bracket, simplify production Flow, lower production costs, which can make the package size smaller, that is, can provide more power in the same package size.

In addition, the small size of the manufacturing process will result in high production process requirements. As a result, the level of production equipment and the level of control personnel will rise accordingly. At the same time, the level of production equipment determines the level of accuracy. Yield and cost will be the biggest considerations. In the entire CSP production process, every process step has high requirements for technology, equipment, and talent. The following difficulties are worth mentioning: 1. Distance control between the chip and the chip; 2. Chips The degree of positional matching between the substrates is controlled; 3. The control of the wavelength range of the epitaxial wafer; 4. The uniformity of the phosphor thickness; 5. The dispensing control technology; 6. The sealing property.

Over the past few years, the international giants of high-power LEDs have made efforts to improve the original ceramic packaging technology. With its advanced high-power flip-chip or vertical structure chip, gradually miniaturize the package to reduce the ceramic substrate and lower production efficiency. The cost pressure comes from and increases the chip's ability to withstand high current densities. The result is that without reducing or even increasing the luminous flux, they change the package from the original 3535 to 2525 and then reduce it to 1616 or even smaller, so that the size of the LED is approaching the size of the chip itself because it is close to the CSP. , hence the name Near Chip Scale Package, referred to as NCSP.

After the CSP package entered the country, in order to adapt to China's national conditions, eventually evolved into the NCSP, NCSP can be said to be based on the immature nature of CSP technology and the transition of the market demand. From the current development of LED, on the one hand, due to the intensification of the price war, companies have reduced the size of material costs by reducing the size, and the introduction of more cost-effective products, making the product size is becoming smaller, on the other hand, the new product CSP is Considered to be the latest generation of cost-effective products, and the current technology is not yet mature, thus creating a transitional product NCSP.

Then does CSP, which does not require ceramic substrates, form a revolutionary advantage and lead the entire market? If CSP becomes mainstream, then the manufacturing of ceramic substrates that have just emerged in China will be a considerable blow. Companies such as Sli- tun who bring up Chinese ceramic substrates will be severely hindered.

It is well known in the industry that the LED package connects the outer leads to the electrodes of the LED chip and protects the LED chip at the same time, and plays an important role in improving the light extraction efficiency. Reviewing the history of LED packaging, it can be mainly divided into LAMP, SMD, Display, POWER, and COB. At present, the most popular package types are SMD, POWER, and COB, and it is these mainstream packages that CSP packaging is designed to replace, which can replace the current mainstream LED2835, 3528, and 5050. Therefore, it should be noted that it does not affect the entire packaging industry, but is currently the mainstream form of the packaging industry. It belongs to the technical update of the chip link, not the encapsulated world.

For many small and medium enterprises in China, the development of CSP did not expand the industry's living space, nor did it reduce the pressure of industry competition. Even if it achieved 2,500 lm/$, it would not be of any use. At present, compared with the total lighting market and packaging market, the proportion of CSP packaging products is still very small, more applications in the field of backlight. In addition, most of the commercial lighting is still biased mainly in small and medium power, while the CSP is still mainly concentrated in high power. Until now, only a few companies such as Toshiba have introduced small and medium-power CSPs, and the technical difficulty is large and the yield rate is unknown. Therefore, it does not rule out technological breakthroughs and it can be applied more to small and medium power in the future. Therefore, the possibility of future CSPs in the field of lighting is unknown.

The CSP packaging technology is indeed a new technology and a good technology. It is a breakthrough in chip size packaging and should not be underestimated, but it is no better than the original "chip", so there is no need to deify it. As for ceramic substrate manufacturers like Slidon, there is no need to worry. After all, the era of CSP has not arrived yet and the application of ceramic substrates is not limited to LED alone.

Now that the giants are starting to exert force, according to the normal logic of new technology development, the CSP yield rate and cost problems will be resolved in the fastest half of the year, and the slowest time will only take one year. In the future, the boundary between the package and the chip and the boundary between the package and the assembly process will not be obscured, and the entire LED industry will become more clear and the situation will re-emerge. Please take the opportunity to capture signals and judge your own development pace. And moving.