Ever since the creation of the first television, we have always sought better options, resulting in the initial-colored TV, more recently to LEDs, and in the future, mini and micro Light Emitting Diodes (LED), which offer a high-resolution viewing experience.

Mini and micro LEDs are becoming the go-to next-generation materials due to their ability to be applied to pliable materials in creating transparent monitors because they retain high aperture ratios and are more energy efficient than traditional LED screens due to their auto luminescence.

Mini and micro LEDs have broader and more diverse applicability as monitors and are bringing about a revolutionary era for screen technology and markets.

Contrel Technology Co., Ltd. has been actively involved in developing equipment to manufacture liquid crystal displays (LCD) since 1999 and, in 2003, developed the first laser repair machine, ushering in the zero bright-dot era for the LCD industry and providing the audience with the best graphics.

The company further established a laser testing lab in 2015 to pursue the research and development (R&D) for applied uses of lasers that would help address possible issues that clients may experience.

Like most LED developers on the market, Contrel is searching for an answer on how to bring down costs and make micro LEDs more accepted on the market.

This year (2022) has marked Contrel’s use of lasers on the mass transfer and mass repair of micro LEDs and, in so doing, has served to integrate the technologies behind mini LEDs, Micro LEDs, mass transfer, mass repair, metal repair and momentary processing.

This new technology, which Contrel has named 6M+, covers all micro LED manufacturing processes, providing more effective solutions for critical procedures that have proven to be bottlenecks in manufacturing procedures before.

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Contrel Mass Transfer Master	Contrel Laser Trimming Master

Contrel R&D Center Director Kevin Tsai said, “Mass transfer technology for micro LEDs has continually evolved over the last few years, starting from the pick and place method to the now-common laser-based mass transfer technology. Contrel has always excelled in laser technology and developed equipment by applying the use of lasers through fused optical couplers.”

The heat-bound method carries the downside in that the stamp head that grabs the diode is made of viscous, macromolecular material and runs the risk of degrading viscosity from repeated heating and pressure.

The high temperature to which the stamp head is subject warps the macromolecule’s shape, causing the stamp head to become uneven, decreasing yield rates and requiring constant replacement, driving up overhead costs.

Contrel has integrated all functions necessary to conduct inspections and counter-positioning during the mass transfer process into an automated manufacturing process using lasers.

When the stamp head applies pressure to the LEDs, the lasers will, over a very brief amount of time, conduct localized welding across the display, freeing the LEDs from the stamp head.

The lack of contact between lasers and the stamp head minimizes physical deterioration and reduces attrition during manufacturing. Furthermore, the place and bonding function provided by the mass transfer technology has the added benefit of decreasing overhead and increasing production efficiency, allowing clients’ micro LED products to maintain the advantage of being low-cost-to-produce with high production efficiency.

Dr. Tsai said the most significant problem facing micro LEDs is that millions of LEDs across the red, green and blue spectra are on a module plate of LEDs that is 10-inches in size. Therefore, when calculating yield rates rationally, there will inevitably be at least several thousand LEDs that have been damaged or are faulty.

This is the primary reason micro LED monitor yield rates have been unable to grow, and the main reason micro LED displays retain a high price.

Contrel’s 6M+ solution includes automated optical inspection (AOI) technology, which uses AI software to automatically pinpoint hundreds, if not thousands, of damaged LEDs, allowing for batch repairs of damaged LEDs in one go and providing the company with 100 percent yield rate panels in a short time.

“The most common repair method on the market is selective mass addressable repair technology, which selects a particular section of broken LEDs, then proceeds to line a temporary carrier with all the still-functioning LEDs. However, as each carrier only corresponds to a small section of the panel and is junked after that section is repaired, the method is not only time-consuming and also material-heavy,” Dr. Tsai said.

Contrel’s solution has redefined micro LED repairs. Recognizing that malfunctioning or faulty LEDs on each panel will be located in different areas, Contrel programs its stamp head to grab large amounts of LEDs in one go. Once the software has completed its computation, the stamp head can identify which panel parts have faulty LEDs and use laser technology for selective welding to complete mass repairs.

The solution is repeatable and can repair multiple areas on a panel, allowing maximum repair efficiency. 

Each LED takes less than a millisecond to solder and employing laser technology for mass transfer or mass repairs is an ongoing trend that will soon be the mainstream technology used in the manufacturing of micro LEDs. Compared with laser technology from other brands, Contrel’s equipment has a longer life, uses fewer materials and is more efficient after removing extraneous processes.

The standard method of gauging productivity for micro LEDs is the unit per hour (UPH) method or the number of LEDs transferred per hour. Contrel’s 6M+ solution has 5 times the UPH of its competitors at comparative resolutions. A 10” LED panel that used to take two hours to assemble would now take less than ten minutes if using Contrel’s 6M+ solution.

Contrel Metal Repair Master	Contrel LED Repair Master

Contrel Chief Operation Officer Simon Yeh said, “According to the industry’s analysis, a stronger foundation for mass transfer and mass repair technologies, as well as gradually declining costs for LED production, will see a 5-10 percent decrease in overhead for micro LED manufacturing by 2025.”

Unlike laser mass transfer and mass repair solutions which require special or unique consumables and accessories leading to a higher cost, Contrel’s 6M+ solution has fewer limitations. It adopts a more straightforward approach to manufacturing processes. This simplification reduces the use and waste of consumable resources while offering shorter transfer times and greater efficiency.

In addition, Contrel is planning to upgrade its production lines with automation, allowing itself to conduct mass transfer operations, AOI functions, LED trimming, mass repair processes and panel assembly on one production line. 

Creating a one-stop production for micro and mini LEDs provides clients with more options and creates a more significant profit margin for the company, allowing the company to maintain a steady footing in the micro and mini LED market. In addition, the ability to decrease significantly overhead cost and manufacture time will create a higher standard and facilitate the transfer into the next LED generation.

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About CONTREL TECHNOLOGY CO., LTD. 
https://www.contrel.com.tw/

Contrel Technology is the equipment leader in FPD and semiconductors.
It’s also been dedicated to laser equipment repair with 23-years of experience. Products include: Panel and Semiconductor automation product lines, Optical inspection equipment, and Laser application equipment. It is also able to provide factory turnkey solutions of TFT-LCD manufacturing starting from array, cell, to LCM process. Furthermore, a smart factory could be built as per customers’ request.

Contrel intends to make AI function a primary focus of its product development in response to the smart manufacturing trend e.g., defects in panels could be identified automatically and the repair path could then be planned instantly. Furthermore, since Micro LED is emerging as the next-generation in displays, the company has been involved in the Mini/Micro LED display market and has successfully debuted its equipment for the market. The custom equipment is developed successfully for rollable Mini LED emissive display featuring active matrix (AM) driving technology for the customer. Contrel also provides other diverse equipment.