Rework of LED dies using debonding solution from Tresky Automation

In times of limited availability of components and materials, reworking takes on a very special significance. This also applies to LED manufacturing, where irregularities in processed LEDs are immediately visible at first sight.

Reworking faulty or incorrectly placed components is one of the more demanding tasks in electronics production. If the components are particularly small or fragile, this work is even more complex. If LEDs are used, a perfect light pattern is usually a prerequisite. For reasons of extremely important quality assurance, it may be necessary to rework LED dies. "Defective LED dies are a real challenge. These sensitive, easily fragile and very small components are usually processed in tight packing densities and can only be removed and reworked with a lot of knowledge, experience, a lot of tact and the right tools. With the right technology, however, this is possible," explains Daniel Schultze, Managing Director of Tresky Automation.

For this purpose, Schultze and his team adapted a process known from component manufacturing at the request of a customer. "Our die bonding automation system allows LED dies to be easily and successfully removed in the rework configuration without damaging adjacent LED dies or affecting the solder and its surroundings," Schultze continues. For this purpose, the debonding process is carried out with the help of a modified scrubbing function, whereby the adhesion between the LED die and the solder is broken with the help of the heating temperature. "Once the LED die is separated from the solder, it is carefully picked up by a pick-up tool," explains Schultze. A new die can then be inserted in the same Tresky Automation machine. Since the die bonding systems are designed for high-precision processes, the entire reworking process of the LED dies is carried out according to the specifications of the semiconductor production and is therefore not only exact, but also controlled and reproducible.

Tresky offers DIE bonding prototyping and small series production

In the prototyping phase and when producing small series or batch size 1, many companies shy away from investing in their own Die-Bonder. Often, the final design process has not yet been completed, so downstream changes to the product or even to the manufacturing processes may be necessary. Therefore, the Die-Bonder manufacturer Tresky GmbH from Berlin now offers contract manufacturing of prototypes and small series.

Investments are not always made based on the respective project and development status. At the same time, many customers want to be able to produce the prototypes and small series as quickly as possible and without any loss of quality. In these cases, they rely on service providers who can take over the production of the sensitive electronic components with extensive experience and detailed knowledge. "That is why, with our technical know-how and based on our years of experience, we are now manufacturing prototypes and small series for our customers from the very first piece on our equipment. Because we can also implement all the necessary processes in our demo centre, our customers have the full manufacturing spectrum at their disposal," says Daniel Schultze, managing owner of Tresky GmbH. In addition to epoxy/adhesive DIE bonding, Tresky offers UV DIE bonding, ultrasonic bonding (US bonding), thermocompression bonding (TC bonding), sintering, DIE stacking, flip chip bonding, DIE sorting and eutectic bonding as a service process.

 

Especially in a time of high demand for components, the use of these services can be crucial for component manufacturers. That's why Tresky helps its customers reduce time-to-market with its range of services. As an external partner, the company can also quickly produce small series on demand. On the customer's side, it is therefore not necessary to build up additional production capacities, to use existing resources or even to interrupt series production. "This way, our customers get the products they need and can also use the production process to test the performance of our die bonders. Furthermore, we can demonstrate our reliable process capabilities. Customers thus receive an individual demonstration including a production record, which can also facilitate the decision for a machine for subsequent series production," Schultze continues.

Air-bearing bond head, new vibrating feeders and a new wafer handling system

Tresky GmbH will showcase three new options for its die bonders during SMTconnect in Nuremberg, Germany, May 10-12, 2022, in Hall 4A, Booth 234: a new precision placement head, a vibrating feeder and a new wafer handler.

 

With the air-bearing bond head developed by Tresky GmbH, highly sensitive components can be placed powerfully. Finally, newly developed semiconductor chips are becoming smaller and thinner due to the continuous miniaturisation in the electronics industry. In addition, new materials are being used to manufacture chips. In the past, for example, silicon (Si) or germanium (Ge) were mostly used to manufacture semiconductors. Particularly driven by the development of new generations of laser, LED, diode or transistor semiconductors, materials such as gallium arsenide (GaAs), gallium nitride (GaN) or, for example, silicon carbide (SiC) are now also being used. Some of these compound semiconductors, such as gallium arsenide (GaAs), have the disadvantage, in addition to their positive electrical properties, of not being very stable mechanically and breaking quickly. This leads to enormous challenges in packaging technology during chip bonding.

 

In order to minimise the contact forces during bonding, the engineers at Tresky GmbH have developed a bonding head with air bearings. This enables a backlash- and friction-free vertical movement when placing the chip. The air bearing is kept in a floating state by vacuum or compressed air and is controlled by a proportional valve that can operate from vacuum to atmospheric pressure. The bond head recognises changing weights and can thus maintain the floating state at all times. This results in a weight compensation of the component. By changing the proportional valve from vacuum to pressure, a defined weight force can now be applied in a vertical direction to the semiconductor component to be placed or picked up with an exact force.

 

Furthermore, Tresky presents a new vibrating feeder. By means of vibration technology, this universal feeding system feeds components delivered as bulk material to the processing stage. The design of the feeder makes it possible to position components in a vibrating, small open container in such a way that the head camera recognises the individual components clearly and precisely. At the same time, the vibrations position the components so that the top of the component faces upwards. In addition, 99% of all component geometries are compatible with this vibrating feeder. Depending on the quantity of components, different hopper sizes are available. From there, the components are transferred to the vibratory container. The feeder can be easily integrated into all existing die bonding systems from Tresky without any major changeover time.

 

A new wafer handling system allows precise and reliable wafer feeding. It can accommodate 300 mm wafers with a maximum weight of up to 1 kg. Vacuum, edge and customised end effectors are available to the end user for the pick-up. In addition, a pre-align function can also be integrated as an option.