How much do you know about flip-chip eutectic LED technology?

Recently, the media has reported a lot about Flip Chip and its extended ELC, CSP, POD technologies that do not require packaging, which are likely to revolutionize "traditional packaging". In fact, Flip Chip eutectic technology has a long history in the semiconductor industry. Philips  Lumileds first introduced it to the LED field in 2006. Since then, Flip Chip eutectic technology has continued to develop and penetrate into chip-level packaging, giving rise to the concept of no packaging.

　　倒装结构，光从蓝宝石衬底取出，不必从电流扩散层取出，不透光的电流扩散层可以加厚，增加电流密度。晶粒底部采用锡(Sn)或金锡(Au-Sn)等合金作接触面镀层，晶粒可焊接于镀有金或银的基板上。当基板被加热至适合的共晶温度时，金或银元素渗透到金锡合金层，共晶层固化并将LED焊于基板上，打破从芯片到基板的散热系统中的热瓶颈，提升LED寿命。倒装共晶LED技术改善了金线虚焊、耐大电流能力不足、封裝硅胶热胀冷缩造成金线断裂、制程中金线影响良率等问题。

　　The excellent heat dissipation characteristics of high-current drive can only show its advantages in high-power devices. With the existence of the Droop effect, as the current increases, the light output efficiency of the LED will decrease, and the decrease will be severe. High-power devices are mainly used in high-power fields such as street lights, tunnel lights, and industrial and mining lights, and have high requirements for light efficiency. For example, 1-3W devices can pass 1000mA of current. In fact, for the needs of light efficiency, most of the use range is 350mA. In addition, based on conversion efficiency and cost considerations, LED driver power tends to have small current and high voltage, which is contrary to the high current and low voltage driving method represented by flip-chip eutectic. At present, the flip-chip eutectic technology involves expensive production equipment and materials, which makes its cost high, and the cost-effectiveness advantage is not reflected. Flip-chip LED technology has been on the market for a long time, but it has been slow to popularize due to many reasons.

　　At present, the products of flip-chip eutectic in the market are mainly from international manufacturers, such as CREE  XLamp XT-E, Philips Lumileds LUXEON-T series devices, and Taiwan New Century Optoelectronics launched AT. Since 2010, Nationstar Optoelectronics has been engaged in the research of flip-chip eutectic technology. The mass-produced ceramic eutectic 3535 devices have reached the level of 140lm/w, becoming one of the few domestic companies that master this technology. With the increasingly fierce market competition, flip-chip LEDs are gradually gaining attention in the lighting market. As more and more LED manufacturers invest in the field of flip-chip LED technology, their development in the field of semiconductor lighting applications will be accelerated in terms of technology and cost .