Analysis of the three main schools of LED chip technology"

Review: now for more than ten years of my experience with LED technology to share with you, especially in the upper reaches of the technical aspects.

I mentioned last year, LED competition is the competition of technology in the past two years will be, but cannot do without the two laws: "more and more advanced technology, especially enhance the optical efficiency; the cost will be more and more low", especially in the chip, reduce packaging and power cost, and of course the lamp assembly how can automation, reduce the manpower cost. In the LED industry for almost 16 years I saw a blue chip by a five dollars (in 1998) to one thousand now 5 dollars (5RMB/k), the industry progress too fast, even faster than the integrated circuit, I witnessed its growth, I also participated in his step. Now for more than a decade of my experience with LED technology to share with you, especially in the upper reaches of the technical aspects.

I put the GaN LED technology school is divided into three parts: the first one is the vertical structure, second is sent (flipChip), flip third is certainly the sapphire substrate structure, the mainstream of the current LED, almost every company based on this structure make great improvement, said 16 years of progress is always to one thousand times. This structure continues to improve. The three schools have their own advantages and disadvantages:

Vertical structure

A bit like Ming or sun moon god feeling, always is not the mainstream, but also have unique technology, to achieve the ultimate if like CREE or silicon carbide technology with mainstream contend, in Jin Yong's novels, whether it is Yang up Zhang Wuji, imprisoned or they can meet as equals to Invincible Eastern, Shaolin Wudang, but still not the mainstream or like a meteor disappeared. Vertical structure is the case, it has always been in the non mainstream line, has been published in the new technology, but in the market has always been difficult to find them. In addition to the vertical structure of silicon carbide and homogeneous substrate, need to process very complex to manufacture, regardless of silicon substrate or the metal substrate, and gallium nitride thermal mismatch problem has not been resolved, the structure yield is very low, although the good thermal conductivity, substrate than sapphire cheap, light emitting area is relatively large, but always not sapphire in the structure of cost and technology competition opponent.

Because the upper and lower electrodes, the application is limited, especially not satisfy many requirements in the lamp circuit design need to string and can make high voltage chip, so the vertical structure of the chip can be used only in specific market street price is high, the general lighting and back light of the two mainstream chip vertical structure not always a lot of intervention. We will ask me whether there is room for price cuts? My answer is yes, but limited, currently only two kinds of mainstream GaN substrate approach, HVPE and heat ammonia amonothermalmethod by hydride vapor phase epitaxy, estimated to be reduced to 100 dollars will be competitive, but five years in accordance with the current technology are not up to.

Flip chip

A bit like Wudang, Shaolin Wudang is created after Zhang Sanfeng left school, as extension of flip chip technology is actually sapphire technology, but is the sapphire structure of flip chip attached to the substrate thermal conductivity is relatively high, if the substrate plus two zener diodes, he can resist the impact of electrostatic electron the device is most afraid of, a bit like the feeling of Killing with Kindness Wudang Tai chi. The flip is the dress structure of everyone in the focus of attention, especially the packaging factory rush to lower cost in time, because the heat transfer path without sapphire, directly into the heat radiating substrate, flip chip eutectic technology has become mature in technology, more and more high yield, the yield rate has been close to the suit. Flip has three advantages is the dress will never be able to catch up, welding process and high current driving light, fluorescent powder coating uniform, so the current packaging factory of flip is love and hate, love is that he can save the cost of welding wire, flip chip packaging diode can add high current, 1 when 2 or 3 teeth with fluorescent powder can be coated evenly and send out light is pretty uniform. Hate is a lot of Companies in the development of packaging process (CSP:chipScalePackage), the packaging process of the core segments are finished, skip the package delivery to the application vendors, many packaging factory in case CSP has become mainstream in the future, they will lose everything before investment.

This is what I have been concerned about the technology, I still can not judge whether it is possible, as we look at Jin Yong novel, has always been unable to determine whether it is a powerful Wudang shaolin.

Sapphire pie

In my mind the Shaolin twenty years has always been standing, whether or epitaxial chip technology, is gradually in accordance with the law of Heinz (Haitz 'sLaw) rising, like Shaolin Kung Fu, constantly through practicing internal strength, complete the sublimation of martial arts masterpiece. The dress is Mr. Nakamura Shuji out of the development process, the main reason is the dress made of sapphire substrate is not conductive to the negative electrode in the same lighting surface, he has inherent drawbacks, as long as you can overcome these shortcomings, accomplish a great improvement. Sapphire and Gan lattice mismatch low-temperature buffer layer, P type gallium nitride high resistance by annealing solution, nickel gold transparent conductive layer penetration rate is too low for indium tin oxide ITO to replace the diamond knife cutting, low yield, high cost of diamond knife by UV laser scribing, UV brightness loss by femtosecond laser scribing invisible cutting or hot acid corrosion solution, reduce the defect density, reduce the total reflection with PSS patterned substrate instead of planar substrate. A promotion is accomplished through new materials and new technology, like Shaolin martial arts, through the solid basic skills, martial arts will step by step to complete the upgrade, the sublimation of martial arts masterpiece, no tricky is no shortcut. Every time he was challenged to use a solid foundation to resolve, so has been the mainstream of LED, estimated in the next few years will be the case.

Some people will ask me, who will be the mainstream of technology in the future, I think Mr. Jin Yong has given us the answer, in the novels of Jin Yong, those factions are standing still, those are instantaneous storm, the moment passed. The long run, with the flip of Wudang Shaolin dress is the mainstream, like other technologies, is a novel inside the sun moon god, Zoroastrianism, in a time of wind wave, but never is the mainstream.