Tresky GmbH from Hennigsdorf near Berlin will present its newly developed pre-sintering processes at this year's pcim EUROPE in Nuremberg. As assemblies with high-performance semiconductors represent a key technology for the global energy turnaround and electromobility, Tresky has been working on these manufacturing processes for some time and will present further product and process innovations in 2023 as part of additional development steps.

"At pcim EUROPE, we will present the pre-sintering process and the associated components we have developed to the German expert audience for the first time," explains Daniel Schultze, Managing Director of Tresky GmbH. During the sintering process, the chip is not only electrically but also thermally very well bonded to the substrate by means of silver and copper paste. This is done with the help of heat and pressure. In this process, the silver or copper particles are bonded together by diffusion processes. "The advantage over normal soldering processes is the very high thermomechanical stability, which is particularly needed in power electronics," Schultze continues.

"The service life and energy efficiency of these assemblies essentially determine the efficiency and economic success of the process in which the assembly fulfils its function. State-of-the-art assembly and connection technology is the solution to today's problems in the production of power electronic assemblies," Schultze continues. In copper and silver sintering, the paste application and the application of the semiconductor are the most important process steps. "We have developed a process that combines these two important steps, the sequential two-dimensional application of the Cu or Ag sintering paste to the substrate and the placement of the power semiconductor in one machine," Schultze continues. This combination, paired with the already established Tresky process modules, enables a cycle-time-optimised production in which reproducible results are guaranteed.

Furthermore, the sintering process can be combined with additional options, such as processing wafers, pressing components with high pressure as well as dispensing a tacking agent that supports the positioning and fixation of the DIE on the substrate provided with sintering paste.

From 09 to 11 May 2023, Tresky will present itself at pcim Europe in Nuremberg in Hall 6, Booth 434.

Assemblies with high-performance semiconductors are key components for the global energy transition and electromobility. For this reason, Tresky GmbH from Hennigsdorf near Berlin has been working on this key technology for some time and will present further product and process innovations in 2023 as part of additional development steps.

DIE Attach or DIE Bonding is the generic term for the process of permanently bonding a semiconductor DIE to a substrate, package, wafer or other component. In the sintering process, the DIE is very well bonded to the substrate not only electrically but also thermally by means of silver and, more recently, copper paste. This is done with the aid of heat and pressure. In this process, the silver or copper particles are bonded together by diffusion processes. The advantage over normal soldering processes is the very high thermomechanical stability, which is required above all in power electronics.

"The service life and energy efficiency of these assemblies essentially determine the efficiency and economic success of the process in which the assembly fulfills its function. State-of-the-art assembly and joining technology is the solution here to today's problems in the production of power electronic assemblies," says Daniel Schultze, managing director of Tresky GmbH. In copper and silver sintering, the paste dispensing and the placement of the semiconductor are the most important process steps. "We have developed a process that combines these two important steps, the two-dimensional application of the Cu or Ag sintering paste to the substrate, and the placement of the power semiconductor in one system," Schultze continues. This combination, coupled with the already established Tresky process modules, enables cycle-time-optimized production in which reproducible results are guaranteed.

Furthermore, the sintering process can be combined with additional options, such as the picking from wafer, the bonding of components with high force, and the dispensing of a tacking agent. The latter supports the positioning and fixing of the DIE on the substrate provided with sintering paste. This avoids the need to press the DIE during the assembly process, which is otherwise used to fix the semiconductor prior to vacuum soldering. For this purpose, four dispensing points are set before the DIE is placed, which fix the component in place. "This gives our customers a clear advantage in terms of their time to market, as development and series production can be implemented quickly and reliably," says Schultze.

Particularly when it comes to the highest precision requirements, machine builders from different industries like to rely on a material that is thousands of years old, from the depths of the earth: granite. Particularly when the components to be processed are extremely small, precision comes into even stronger focus, as in the semiconductor industry with DIE bonding.

The German bonder manufacturer Tresky GmbH swears by the rock from the earth's core. "Granite is a deep rock, formed from magma within the earth's crust, which enables high accuracy due to its material composition. We therefore offer a whole range of DIE bonders based on a pure granite chassis," explains Daniel Schultze, managing owner of Tresky GmbH. Due to its specific properties, granite is the optimal material for the precision bonders Made in Germany. Thus, the DIE Bonder T-8000-G, with the granite gantry designed for highest accuracy, offers a large working area of 590 mm x 560 mm, in which, among other things, 12-inch wafers can also be processed. The bonding system therefore combines the placement accuracy of 2.5 μm @ 3 sigma with versatility and speed.

The low coefficient of thermal expansion and the very good vibration-damping properties of granite were the very reasons why Schultze and his development team chose the natural material as the chassis base. "This enables high precision in the micro range, which is very important especially for our international customers. Because due to the use of granite, our DIE Bonders also work with high precision in warm, subtropical regions and non-air-conditioned production centres," Schultze continues.

Due to its low thermal conductivity and higher heat capacity, granite reacts much more sluggishly to temperature changes than metallic materials, such as a machine chassis made of steel or aluminium. Temperature differences, especially when they occur for a short time, as in a soldering process that can be carried out inside the DIE Bonder, lead to permanent geometry changes in steel and grey cast iron. Vibration damping was also a decisive criteria, because even if the DIE Bonders travel at low speeds in X and Y, the high precision requirements in the semiconductor industry mean that unnecessary natural and external vibrations should be avoided. So there is a lot to be said for granite being the optimal material for Tresky GmbH's precision machines.

Alternatively, concrete-based, high-strength concepts were also available for selection during the development phase of the DIE Bonder. Even though the UHPC concrete (Ultra High Performance Concrete) used here is becoming increasingly important in mechanical engineering, it fell off the grid for Tresky in terms of manufacturing. "Basically, with mineral casting, a new mould has to be created for each casting, which makes the manufacturing process very time-consuming. The subsequent machining of the material is also not easy due to our precision requirements. This leaves only granite as a material. We import it and have it manually processed and polished to such an extent that it meets our specifications and guarantees precision in production on the end customer's side," Schultze explains the manufacturing process.

Furthermore, the energy and CO2 balance of granite is also positive compared to concrete and steel, as the extraction of the granite blocks in the quarry, including transport, causes less energy expenditure than the production of steel and concrete. "Granite is therefore very important to us and we will continue to develop further machines based on this natural material in the future. So we can justifiably claim that a rock from the earth's interior is responsible for the accuracy and functionality of digital systems in our modern times," says Schultze.

The DIE bonding process Thermosonic Bonding (TSB) combines the novel thermocompression bonding with ultrasonic welding (UW).

Ultrasonic welding can reduce bonding pressure and temperature. This improves the bonding process, which is particularly advantageous in semiconductor production. For example, in flip-chip bonding. Here, solderless DIE bonding technology enables area array connections. With this process, an array of gold bumps located on the underside of an IC can be connected to gold-plated pads on a substrate. In particular, thermocompression bonding is used in this simple, clean and dry assembly process.

The TSB process starts with a substrate placed on a heated support and held in position by vacuum. The chip is held by a pick & place tool with a die collet designed for thermosonic bonding applications. Once the Tresky pattern recognition system has aligned the chip with the substrate, the Gold-Stud bumps are contacted to the substrate. Once the required bonding force is achieved, the current of the ultrasonic welding is applied for a defined period of time.

The vertical technology offered by Tresky guarantees stable and precise coplanarity and parallelism over the entire Z-axis stroke. "In combination with force control, an excellent joining result can be achieved at any height, whereby decisive parameters such as force, temperature, power of ultrasonic welding and process time can be individually programmed," assures Daniel Schultze, Managing Director of Tresky GmbH.

In addition to an IP collet (inverted pyramid (IP)), the use of an additional channel type collet (CH)) is advisable as soon as access to the tool is restricted or it has to be aligned through two sides of the chip. Whether a collet is suitable for the TSB can be determined by factors such as the cyclic movement of the collet during the US process, the sensitive surface of the chip and heat transfer.

Tresky's next generation thermosonic bonding allows US power and collets to be used to create an excellent bond between a chip and a substrate. Because Tresky's Pick & Place system offers excellent coplanarity and parallelism along the Z-axis, it can ensure accurately bonded chips.

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.

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.

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.

Tresky GmbH won the State at Brandenburg 2021 Innovation Award 2021 in the metal category. The manufacturer of innovative die bonders from Hennigsdorf near Berlin has prevailed against the competition with the newly developed air-bearing bond head, which will be presented to the professional public for the first time at Productronica 2021.

In order to achieve minimal contact force during bonding, Tresky GmbH has developed an air-bearing bond head that enables clearance and friction free vertical movement when the chip is placed. The air bearing is kept suspended by vacuum or compressed air and controlled by a proportional valve that can operate from vacuum to atmospheric pressure. The bond head recognizes changing weights and can therefore maintain its 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 exerted in the vertical direction on the semiconductor component and be placed or absorbed with an exact force.

With the air-bearing bond head for force-controlled placement of highly sensitive components, Tresky has developed a pioneering tool for future semiconductor production. Due to the advancing miniaturization in the electronics industry, newly developed semiconductor chips have to become smaller and thinner. This leads to enormous challenges in chip bonding assembly and connection technology, the materials required for this are becoming more and more sensitive. In addition, new materials are used that also have to be treated with great care. “In the past, silicon (Si) or germanium (Ge) were used in most cases to manufacture semiconductors.

Especially driven by the development of new generations of laser, LED, diode or transistor semiconductors, materials such as gallium arsenide (GaAs), gallium nitride (GaN) or e.g. silicon carbide (SiC) are now being used,” explains Schultze. However, some of these compound semiconductors, such as gallium arsenide (GaAs), have the disadvantage of their positive electrical properties of being mechanically not very stable and brittle.

The Brandenburg Innovation Award is a project by the State of Brandenburg on behalf of the Ministry of Economics, Labor and Energy. With the Innovation Award, Brandenburg honors innovative developments and processes that simplify manufacturing processes or make them more efficient. Tresky is awarded in the categories of metal, plastics and chemistry as well as the food industry. The Award ceremony will take place on November 18, 2021.