Economic Observer reporter Zheng Chenye

Entering this track now, I think the time is just right. "Recently, when talking about the timing of TCL Huaxing's entry into glass based packaging, the company's CEO Zhao Jun told Economic Observer reporters," We will make rapid and substantial industrial investment on the premise of increasingly mature technology, processes, equipment, and materials. TCL Huaxing is a semiconductor display subsidiary of TCL Technology (000100. SZ).

Glass based packaging is a new link in the AI computing power supply chain. In the past two years, there has been a wave of cross-border competition among manufacturing enterprises around the hardware demands derived from AI computing power, such as packaging, optical interconnection, PCB (printed circuit board), liquid cooling, etc. For example, Lansi Technology (300433. SZ), which produces glass covers for Apple phones, has obtained supplier certification from Nvidia through acquisition, while Dongshan Precision (002384. SZ), which produces precision metal parts, has entered the field of optical modules through acquisition.

In fact, TCL does not lack assets related to AI computing power, nor does it lack interfaces to enter the AI computing power supply chain. For example, the company Tianjin Pulin (002134. SZ) within the system produces PCBs, Zhonghuan Leading produces semiconductor silicon wafers, and TCL Huaxing's panel technology can be extended to packaging substrates. But in the face of the rise of the AI computing power industry chain, TCL gives the market the feeling of "slow response and low volume".

There is a representative view in the market that TCL has focused more on the adjustment of photovoltaics and the technological transformation of panels in the past two years, with relatively less investment in AI direction. For example, an analyst from a large securities firm in southern China told reporters that as an industrial group, TCL's technological transformation in photovoltaics and panels has indeed taken up a lot of management energy and capital, and it is unfair to compare it with companies that only do a single business. "However, even considering this, TCL's presence in the AI computing power supply chain is indeed weak.

Regarding this, Wang Cheng, CEO of TCL Technology (000100. SZ), responded that TCL is seeing and actively embracing the trend of technological change. "Zhonghuan is leading the investment in the Shenzhen project of semiconductor large silicon wafers for integrated circuits, and TCL Huaxing has achieved global integration in new display fields such as printing, while also entering the field of glass based advanced packaging semiconductors with same source technology.

Recently, reporters from the Economic Observer interviewed Wang Cheng, Zhao Jun, and Liao Qian, Senior Vice President and Secretary of the Board of Directors of TCL Technology, in an attempt to understand the layout logic and actual progress of TCL Huaxing in the fields of optical communication and glass based packaging.

Extend from display light source to information light source

TCL Huaxing used to produce LEDs (Light Emitting Diodes) mainly to make the screen light up, but now they need to use the same "light" to transmit data.

In the field of display, LED is an important light source for LCD (Thin Film Transistor Liquid Crystal Display). Traditional LCD backlighting typically uses tens to hundreds of LEDs, while Mini LED (submillimeter light-emitting diode) TVs use thousands or even more LED chips. TCL Huaxing has accumulated capabilities in LED epitaxy (the process of growing semiconductor materials layer by layer on a substrate), chip manufacturing, and Micro LED (micro light-emitting diode) related to display applications.

Zhao Jun told reporters that TCL Huaxing completed the acquisition of Fujian Zhaoyuan Optoelectronics this year and renamed it as Huazhao Optoelectronics, further improving TCL Huaxing's capabilities in LED chips and strengthening our layout in upstream optoelectronic device and chip manufacturing.

Micro LED is the next generation form of LED technology, with a size reduced to below 100 microns. Each LED itself is a pixel and does not require backlighting or liquid crystal layers. Its brightness, contrast, response speed, and lifespan are superior to existing LCDs and OLEDs (organic light-emitting diodes).

The current main application directions of this technology are AR (augmented reality) glasses, car displays, and large-sized splicing screens. The difficulty in mass production mainly lies in the large-scale transfer process, which involves accurately transferring millions of micrometer sized LED chips onto the substrate. At present, the yield and cost have not yet reached the requirements of the consumer market.

In Zhao Jun's view, there are two main paths from display light sources to information light sources: one is Micro LED optical communication. Micro LED is small in size, fast in response, and can transmit data through high-speed flashing. It has strong continuity with TCL Huaxing's existing LED and Micro LED technologies and is expected to be applied in short distance high-speed interconnection within data centers in the future; The other is laser optical communication, which is also a more mature technology route in the current high-speed optical communication field.

Laser optical communication solves the problem of data transfer in AI computing power clusters. The computing power of GPUs is doubling with each generation, but the bandwidth growth of data transmission between chips and servers cannot keep up. The principle of optical communication is to convert electrical signals into optical signals, transmit them through optical fibers, and then convert them back into electrical signals at the receiving end. The optical module is the core component that completes this conversion, and the optical chip is the core component of the optical module. Indium phosphide laser chip is currently the main current solution for high-speed optical modules.

At present, we are extending the long-term accumulated semiconductor luminescence capability from display light sources to information light sources. On the one hand, we are exploring new opportunities for Micro LEDs in high-speed optical interconnection, and on the other hand, we are focusing on the layout of indium phosphide laser chips and optoelectronic integration capabilities. These directions are closely related to AI computing power, high-speed interconnection of data centers, and next-generation information infrastructure. ”Zhao Jun told reporters.

Wang Cheng also told reporters that TCL Huaxing will actively evaluate and layout related technology reserves, industrial cooperation, and commercialization opportunities based on its accumulation in optoelectronic materials, chip technology, micro nano processing, and manufacturing management.

So, how far is the distance between LED chips and indium phosphide laser chips? Both belong to compound semiconductors (semiconductor materials composed of two or more elements, different from elemental semiconductors such as silicon), which deposit materials layer by layer on a substrate using epitaxial growth technology. Both require micro nano processing (the process of processing device structures at the micro and nano scales) to create chip structures; The difference between the two lies in the material system and device design. LEDs use gallium nitride or gallium arsenide, while laser chips use indium phosphide. The resonant cavity of a laser (a structure that oscillates light back and forth between two reflecting surfaces to generate laser light) is much more complex than that of an LED.

In Zhao Jun's view, what Huazhao Optoelectronics has added to TCL Huaxing is the epitaxial and manufacturing capabilities of LED chips. Extending from this foundation to indium phosphide laser chips requires a re establishment of material systems and device design capabilities.

But on this route, TCL can no longer be considered a pioneer. Sanan Optoelectronics (600703. SH) is one of the largest LED chip manufacturers in China. Public information shows that the company has extended from LED chips to indium phosphide optical chips. 400G and 800G optical chip products have been shipped in bulk, and 1.6T products have also been sent to customers for sampling.

The process difficulties of glass based packaging

Glass based packaging solves the load-bearing problem of AI chips as they become larger.

In order to enhance computing power, chip design manufacturers need to integrate more computing cores and storage units into one package. The packaging size of AI chips is also increasing, and traditional organic packaging substrates are approaching their limits in terms of flatness, thermal stability, and interconnect density. The larger the chip, the more prominent the problems of warping and thermal deformation become.

The flatness and thermal stability of glass substrates are far superior to organic materials, and can support higher density interconnection. Intel announced its technology roadmap for glass substrate packaging as early as 2023, and since then, Samsung, SK Group, and TSMC have followed suit.

Zhao Jun divided packaging technology into two categories based on substrate material - silicon-based packaging and panel level packaging. Silicon based packaging uses wafers as carriers, and the size is limited by the wafer diameter; Panel level packaging uses large-sized panels as carriers, which can process more chips simultaneously on a larger area.

Panel level packaging, also known as glass based packaging, currently appears to be an important direction for advanced semiconductor packaging in the future, especially in AI and high-performance computing. ”Zhao Jun told reporters that TCL Huaxing's accumulation of thin film deposition, photolithography and etching processes in panel manufacturing "has a high degree of synergy with glass based packaging in the processing of large-sized glass substrates, precision film formation, photolithography, etching, detection and automated handling processes".

Panel manufacturing originally involves micrometer level processing on large-sized glass, and panel level packaging also requires micrometer level processing on large-sized glass. The equipment, processes, and supply chains of the two overlap to a considerable extent. Regarding this, Liao Qian also told reporters that "some of the process capabilities accumulated by display manufacturers such as TCL Huaxing in the manufacturing of display panels have the feasibility of migrating to the packaging field, which will help shorten the exploration cycle of Know how (proprietary technology).

However, partial overlap in craftsmanship does not necessarily mean that it can be directly reused. Liao Qian mentioned three process difficulties - copper filling for TGV (glass via), stress control for multi-layer structure, and deep processing of glass substrates - each of which is related to panel manufacturing but not entirely the same. TGV is a process of creating micrometer sized holes on a glass substrate to connect the upper and lower circuits. The holes should be made thin and straight, and then copper should be filled into the holes. If the holes are not filled enough, it will affect conductivity, and if they are filled too much, it will generate stress; Multilayer films stacked on glass, each with a different coefficient of thermal expansion, generate stress when temperature changes, and can also warp or crack if not handled properly; In addition, glass itself is relatively brittle, and cutting and grinding during deep processing can easily produce microcracks.

Regarding this, Zhao Jun also emphasized that "glass based packaging has some unique processes, such as glass through-hole capability and copper deposition capability, as well as high-density and high-precision through-hole detection capability, which are all unique to advanced packaging; in addition to the inherent technology we already have, we also need to build our capabilities in new technology fields

Liao Qian told reporters that TCL Huaxing has formed a professional team to conduct technical exchanges and joint research with target customers around the key process difficulties mentioned above. They plan to launch relevant samples in the second half of the year and initiate the construction of a pilot R&D platform. In the future, they will collaborate to promote the adaptation of upstream glass materials and the validation of key equipment such as through holes, electroplating, CMP grinding (chemical mechanical polishing), etc.

Regarding the timeline for large-scale production of glass based packaging, Zhao Jun told reporters, "The current industry consensus is around 2028, and we are steadily making relevant technical preparations according to this timeline

Zhao Jun also emphasized, "Compared to our existing business scale, the capital expenditure in this field is completely controllable

(Author Zheng Chenye)