Applications
Die Bonding systems from Dr. Tresky are the first choice wherever the highest demands are placed on positioning accuracy, the fastest implementation of a wide variety of assembly processes and a wide range of technologies.
Our customers and industries, for which we develop and offer joint solutions, are just as diverse as our die bonder systems. This also applies to the various construction and connection technologies that have to be implemented.
Our development laboratory is available for this, together with the most modern analysis methods. Together with our highly qualified and experienced specialist staff, we can offer you a perfectly coordinated overall package that is tailored precisely to you and your requirements.
Customized solutions for individual applications
General
Flip Chip Microelectronics Assembly describes the technique of mounting a flip-chip upside down (flip), i.e. face-down on a substrate, a printed circuit board or other carrier. The conductive chip bumps are precisely aligned with respect to the bump pad (chip bond pad) and then electrically connected in a eutectic process. In contrast to wire bonding, a technique used to electrically connect chips on the upper side (face-up) with a wire connection, a Flip-Chip Die Bonder from Dr. Tresky works with a beam splitting camera (Flip-Chip Ultra or Flip Chip Ultra MPA) to guarantee the highly precise alignment of the chip with respect to the substrate. Due to the high resolution, the multi-point alignment of the camera and the True Vertical Technology™ an accuracy of +-5µm (or better) is achieved, independent of the respective bond height.
Required technical data for Flip Chip applications:
- Accuracy: +-5µm (or better)
- Bond parameters: 20g – 100g bond force per bump depending on application
- Temperature: 120°C – 400°C depending on application
Various Processes
Process – C4 Soldering
In the C4 process (Controlled Collapse Chip Connection), the chip bumps are soldered onto the package substrate for electrical connection.
Process – Eutectic
Eutectic soldering process for Au/ Sn bumped dies, especially suitable for optoelectronic and RF devices.
Process – Adhesive Technology
In bonding processes, conductive and non-conductive adhesives (ACA, ICA, NCA) are applied to a substrate with a dosing device or by means of a stamp. The chip is aligned with a beam splitter camera, placed in the adhesive and then cured.
Process – Underfill
This process is used for bottom side encapsulated Flip-Chips to compensate for temperature differences and to increase the strength of the connection. In most cases an epoxy based material is used.
Process – Ultrasonic
During placement, the energy required for the welding process comes in the form of mechanical vibrations.
General
(Radio-frequency Identification) tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a (RF) signal, and other specialized functions. The second is an antenna for receiving and transmitting the signal. Tresky’s modular die bonding equipment delivers, once more, optimal perfomance in R&D and pre-production assembly as e.g.: Bonding of a Flip-Chip to Antenna.
Technical Parameters
Position Accuracy:
10micron (or less)
Bonding Parameters:
Force 20g – 400g and time up to 2-4sec. on final curing temperature.
Temperature:
Adjustable temp. profile for chip and antenna up to 200°C with ramping speed up to 18°C/Sec. for adhesive technologies only.
Flexibility
Tresky’s T-5000series allows different RFID bonding processes, such as adhesive or ultrasonic bonding. Process parameters can be easely adjusted for optimized results. Temperature, time and force can be adjusted respectively programed independently.
Various Processes
Process – Adhesive Tech. (ACP Anisotropic Conductive Paste)
Dispense ACP glue on antenna. Electroless bumped chip, aligned by beam splitter, placed into glue and cured.
Process – Adhesive Tech. (NCP Non Conductive Paste)
Dispense NCP glue on antenna. Stud bumped chip, aligned by beam splitter, placed into glue and cured.
Process – Ultrasonic
During placement, the ultrasonic energy is transfered to the chip contacts, where it is transformed into heat.
Die Bonding of Devices with Copper Pillar Bumps Application
Flip chip technology is keeping pace with the increasing connection density of the ICs and is capable of transferring semiconductor performance to the printed circuit board. The pitch is growing smaller, which means flip chip technology with solder bumps will unavoidably run up against its technical limitations. The reason for this is the spherical geometry of the bumps. The solution to this problem is copper pillars. In this contact technology for flip chip assembly, special cylindrical copper connections function with a solder deposit instead of the usual solder ball bumps to form the connecting element between semiconductor and substrate. The result: improved reliability and enhanced electrical and thermal connection characteristics, greater connection density with narrow pitching and RoHS conformity.
Introduction
Thermosonic flip-chip bonding is an advanced, solderless technology for area-array connections. The approach is used to join ICs with gold bumps, Figure 1, to gold plated pads on substrate. It is a simple, clean, and dry assembly process using a bonding mechanism, Figure 2, similar to thermo-compression bonding, but with lower bonding pressure and temperature due to the introduction of ultrasonic energy. The thermosonic process was mainly used for wire bonding but has also great advantages for die attach applications. The pure thermocompression welding typically requires interfacial temperatures of the order of >300°C. This temperature can damage packaging materials, laminates and some sensitive chips. The thermosonic process is a combination of thermo- compression and ultrasonic welding that optimizes the best quality of each for the microelectronics usage. Typically, the interface temperature and the bonding force can be much lower; between 100 to 160°C and 20 to 50g/ bump, which avoids above mentioned problems.
Highest Co-planarity and True-Vertical Technology™
Co-planarity and parallelism of the ultrasonic tool with respect to the substrate is a very important parameter to achieve a good bonding result. Misalignment can result an uneven force distribution which leads to joint on side A, and insufficient connection on side B, Figure 4. Tresky’s True Vertical Technology™ guarantees stable and accurate co-planarity and parallelism over the whole Z-stroke, Figure 5. In combination with the active force measurement, a good bonding result is achieved on every height, Figure 6.
Influence of bond parameters to the process
Force, time, temperature and Ultrasonic power are parameters that have a great influence to the process and can be programmed individually on Tresky systems. In general it can be said that; more bonding force, higher temperature, more ultrasonic power, (higher amplitude of ultrasonic vibration) and more vibrating time leads to more collapsed bump area and higher strength of the connection. However, when increasing these parameters, it is important to recognize the risk of an electric short between adjacent bumps as well as possible breakage of the die, Figure 7-9.
Process
The thermosonic process begins with the substrate sitting on a heated stage, held in position by vacuum. The chip is held by the vacuum pickup tool. After aligning with the beamsplitter optics, Figure 3, the chip with it’s Au stud bumps is brought into contact with the substrate. After the required bonding force is reached, ultrasonic vibration is applied for a predetermined length of time to complete the process.
Typical Process parameters
Heated stage (sustrate):
100°C to 160°C
Ultrasonic power:
100 to 200mW/ bump Bond force: 20 to 50g/ bump
