The jabil optics advanced process development team has extensive experience in using both wire bonding and acf bonding. Process quality improvement in thermosonic wire bonding by jaesik lee a thesis. With each new wire material, the bonding process is. Optimize wire bonding small mesa chips with superior process development and wire bond tool customization. With its upgraded and enhanced subsystems, it is engineered to deliver all the capability you will need for wire bonding today, plus tomorrow. The criteria for good bonds are described, along with pre and postbonding inspection techniques. On the left is a list of several problems affecting wire bonds. The wire bonding process involves two items, namely, the wire bonder and the bonding wire i. Copper cu 26 silver ag 7, and alloyed wires 8 have emerged as potential replacement to au in recent years. Although less common, wire bonding can be used to connect an ic to other electronics or to connect from one printed circuit board pcb to another. Wirebonder machine this paper describes the multiobjective optimization of the wirebonder driven by a linear lorentzs force actuator fig. It is recommended to first carry out conventional pull force optimization followed by. Wire bonding process is the key driver of the package assembly yields.
Iterative optimization of tail breaking force of 1 mil wire. Bonding parameters are extremely important because they control the bonding yield and reliability directly4. Wire bonding is a solid phase welding process, where the two metallic materials wire and pad surface are brought into intimate contact. Evaluation of wire bonding performance, process conditions, and metallurgical integrity of chip on board wire bonds daniel t.
This chapter discusses the evaluation of wire bonding performance. Evaluation of wire bonding performance, process conditions. Design of experiments doe four key inputs to the gold ball bonding process are ultrasonic transducer power, bond tool force, bond time, and stage heat. The following is a basic procedure for wire bond process optimization. Small precision tools wire bonding process optimization. The parameter of wire bonding machine requires precision with properly designed and operated equipment 3. Things to consider about the bonding surface include the metal. Process optimization approach in fine pitch cu wire bonding. Some of the variations that challenge wire bonding are.
Wedge tool cleaning with manual adjusted installation. Copper wire bonding challenges and solutions of small. Battery connections with ultrasonic wire bonding ultrasonic wire bonding is one of the most flexible and beneficial joining technique of batteries in the production of battery packs for emobilty applications. The use of a crossbonding tool can help reduce the extent of ultrasonic cupping problems. Failure modes in wire bonded and flip chip packages. Optimization of the cu wire bonding process for ic assembly using taguchi methods chaoton sua. Statistical software namely minitab is used to analyze. Wirebonding ultrasonic transducer lever moving voice coil linear lorentzs force actuator r 2 r 1 x 1 x 2 figure 1.
Fortunately, overcoming these limitations is possible and that process begins with the optimization of a 3d stereo imaging system for the inspection of bonding wires. In recent years, there are increasing research efforts in the quantitative understanding of the wire bonding process. Dec 10, 2010 with normal production expectations of fast bonding and good quality performance on flimsy leadframe, copper wire challenges of small outline packages were incredible. A sturdy mechanical structure, process camera, quiet linear motors, 0. The olp method is known to speed up bonding program creation process and improve accuracy of bond program created 6,9. Optimization of the cu wire bonding process for ic assembly.
Wire bonding is generally considered the most costeffective and. Jun 12, 2012 the basic process flow is shown in fig. Optimization of ultrasonic aluminum wire bonding on chromium. Optimization of the cu wire bonding process for ic. However, the high price of au has been pushing the wire bonding industry to look for alternative bonding wire materials. It turned out that the range of optimal process windows for bonding. The process optimization defines a process parameter window for ball and wedge bond quality. Jun 02, 2017 wire bonding processes on challenging overhang devices are developed using this new optimization software. Process optimization of gold stud bump manufacturing using. The cartoon shows a wire bonding process from a bond pad on a chip to a lead of a package. Advanced wire bonding capillaries pi series the transition from finepitch fp to ultra fine pitch ufp volume production, and the emergence of stackeddie, csp and ultra low loop bonding has increased the level of difficulties in wire bonding process. For gold wire, heat is added to increase interatomic diffusion and accelerate bond formation.
High frequency bonding and the bonding to soft substrates are given special attention. A wire bond process optimization is essential for bonding process stability. Design of experiments approach for improving wire bonding quality international journal of innovation, management and technology, vol. Author links open overlay panel chaoton su a chengjung yeh b. Using design of experiments to optimize wire bond processes. The iconn plus is designed to meet all leading edge wire bonding challenges. When implemented in the wire bonding process, this unique bonding tool provides greater control in wire loop height and shape stability, significantly. Doe is normally conducted for any new devices, new capillary design or changes made to the wire or substrate. Process characterization and trials parameter optimization. The gold stud bumping process is originally derived from the modified wire bonding process harman, 1997. This has accelerated a decrease in the pitch and size of interconnects. The criteria for good bonds are described, along with pre and post bonding inspection techniques.
Pdf in this paper, a transient nonlinear dynamic finite element framework is developed, which integrates the wire bonding process and the. It requires a lot of manpower and cost to perform the bonding process optimization before the ic chips and substrates with the said bond pads may be put into production. The first bond of a wedge bond is capable of bonding closer to the package wall, and often is more reliable than a ball bond in this type application. Today, most wire bond machine vendors have their own version of olp programs. Iterative optimization of tail breaking force of 1 mil. Wire bonding process optimization is normally performed through design of experiment doe to further understand how changes affect the outputs. Furthermore, this method may not be sensitive enough, especially for some bond pads that already have bond pad lift issues, since. In order to enjoy full saving of material cost, there was no loss expected on yield, quality, throughput, and machine efficiency. Wire bond functionality tests, such as bond accuracy tests, electrical resistance measurements, and material characterization of wire bonds, are covered. Workshop wire bonding for mems technology cluster september 2012 jan eite bullema 2. Hesse mechatronics partners with cad design software fremont, california, december 15, 2015 hesse mechatronics, inc.
The bond force initially deforms the wire and couples the ultrasonic energy into the wire and scrubs the wire into the pad. In consequence, the tool touches the substrate and the ultrasonic power is not applied into the joining area. Though high quality wire bond tools are available additional tool customization and optimizations may be necessary to meet speed and yield requirements of a wire bond process. Introduction optoelectronic packages are classic hybrids with some new optomechanical variations. The wire bond process wire bonding is an electrical interconnection technique using thin wire and a combination of heat, pressure andor ultrasonic energy. Wire bonding is a widely used technology for the first level interconnection in microelectronic devices. This paper discusses the bonding process optimization carried out in order to solve this issue and to. The unit operations of processing a gold stud bump with double bumping modes include the forming of a free air ball fab, the first bumping mode, and the second bumping mode, as illustrated in fig. Proper optimization and process window development for wire bonding is essential to minimize nonstick on pad, lifted or broken wire bonds. Contents work shop wire bonding jan eite bullema introduction wire bonding 2 introduction equipment metallurgy shear testing process parameters demonstration in the lab 3. The key variables for wire bonding include bonding force and. Process optimization of gold stud bump manufacturing using artificial neural networks. The fab was skew and coarse with very small diameter when.
The wire bonder is provided by the equipment supplier. Since bonding wire diameter may range from a few microns to a few hundred microns, optical resolution is highly application dependent, and developers must carefully consider. Fully automatic wire bonder for bonding today, plus tomorrow iconn plus is a stateoftheart in fully automatic wire bonding. Optimizing a wire bond process begins with a clear understanding of the bonding equipment, machine setup, the response. The proper bond pad cleanliness also contributes to reliable wire bonds. Todays leading edge production devices are gold ball bonded with 60. Iterative optimization of tail breaking force of 1 mil wire thermosonic ball bonding processes and the influence of plasma cleaning. Process quality improvement in thermosonic wire bonding.
Design of experiments approach for improving wire bonding quality. The system for automatic optical wire bond inspection bondaoi s6053bov. The principal bonding process parameters such as bonding time, normal force, resonant frequency, ultrasonic power, and the amplitude of the tool can affect the bonding quality 22. Define ball and wedge bond specifications to be use as target response in optimizing a given application. Copper wire bonding capability for thin top metal device has been established by bond pad design and wirebond parameter optimization. Modeling and simulation of the ultrasonic wire bonding process. This paper investigated the process optimization of electronic flameoff efo which was the melting of a wire tip by an electrical spark to form a free air ball fab for 1.
It is also utilized for wire bonding process optimization and process control during assembly manufacturing. Ultrasonic wire bonding is an indispensable process in the manufacturing of. Among wire bonding technologies, thermosonic wire bonding is one of the most commonly used processes in electronics packaging due to its stability, flexibility and cost effectiveness. How to optimize wire bonding small mesa chips semigen. Using 3d stereo vision to inspect bonding wires vision. As shown from the result, copper bonding on thin top metal with circuit under pad technology is achievable. Wire bonding occurs at the end of the assembly process after the lowest melting temperature solder alloy has already.
Peter majewicz, program manager jonathan pellish, deputy manager. Lowk, multitier and stackeddie wire bonding capillaries. Furthermore, situation became worse when new copper wire process was found requiring additional bonding time and mechanism due to harder material properties. The gold stud bumping process is originally derived from the modified wire bonding process harman. The setup of a wire bonding process can be tedious and dependent on the skill of the process engineer. Jan 02, 2014 the cartoon shows a wire bonding process from a bond pad on a chip to a lead of a package. Wire bonding looping solutions for high density systemin. The capillary 10 guides a length of bonding wire 12 and is operative to connect the bonding wire 12 to bond pads of electronic devices. Many terms related to the process, such as loop height an wire. Four key inputs to the gold ball bonding process are ultrasonic transducer power, bond tool force, bond time, and stage heat. Experimenting with these parameters is time well spent, and is an important step toward developing a robust wire bond process. Pdf thermosonic wire bonding process simulation and bond.
Pdf process optimization approach in fine pitch cu wire bonding. Wire bonding is an important technique in highdensitypackaging. Doe is normally conducted for any new devices, new capillary design or changes made to the wire or substrate, whereby a new process window need to be defined. Wire bonding is the method of making interconnections between an integrated circuit ic or other semiconductor device and its packaging during semiconductor device fabrication.
This has a negative impact on the process stability and. To some extent there must be an intermetalic region with at least a few thousand atoms thickness between the wire and the pad. Design of experiments approach for improving wire bonding. Us patent for bond pad assessment for wire bonding patent. These include design of experiment and response of. Though often overlooked during the development of a wire bond process, the bonding surface condition is also vital in determining the optimum wire bond tool configuration. The process optimization of efo for copper wire bonding. Copper wire bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes. Using design of experiments to optimize wire bond processes tj. Furthermore, the wire clearance against various components in the package can also be assessed. Advanced ultralowloop wire bonds bob chylak, lee levine. Chapter 4 cu crescent bonding process optimization and. The recent development in fanout wafer level packaging fowlp lowers package cost, achieves thinner packages with higher electrical.
Optimization of the cu wire bonding process for ic assembly using taguchi methods. Copper wire bonding challenges and solutions of small outline. Wire properties are considered along with the changing bond shapes and sizes as the number of chips inputs and outputs increase. Under these stringent requirements, development of copper wire bonding process requires full considerations and optimization of all possible root causes, with targeted performance matching gold wire bonding process. The use of a cross bonding tool can help reduce the extent of ultrasonic cupping problems. Validated simulation of the ultrasonic wire bonding process. Process quality improvement in thermosonic wire bonding by.
Reliability of the wirebonded interconnect is explored along with testing and control methods designed to improve bond quality. May 29, 20 this chapter discusses the evaluation of wire bonding performance. Additional challenges include parallel vertical wire spacing and shadow e ffects fortunately, overcoming these limitations is possible and that process begins with the optimization of a 3d stereo imaging system for the inspection of bonding wires since bonding wire diameter may range from a few microns to a few hundred microns, optical resolution is highly application dependent, and. Development of a fast method for optimization of au ball. The system for automatic optical wire bond inspection. Investigation of ultrasonic vibrations of wirebonding.
Since led wire loops tend to be short and low, the nordson dage wire pull cartridge provides 360 rotation of the test hook in addition to a variety of tools to meet various geometries. The wire bonding process requires the wire to become welded to the pad both semiconductor or connection pad. Wire bonding is a solid state welding process, where two metallic materials are in intimate contact, and the rate of metallic interdiffusion is a function of temperature, force, ultrasonic power, and time. Through continuous improvements, wire bonding remains the dominant interconnection method. Contents work shop wire bonding jan eite bullema introduction wire bonding 2 introduction equipment metallurgy shear testing process parameters demonstration in. Wire bonding process optimization small precision tools. Wire bond tool variables the wire bond process variable categories associated with the wire bond tool include the tool, bonder, and work holder. Surface cleanliness and bond pad metallurgy is critical. Typical wire bond process optimization small precision tools. This means you get optical components that can be trusted to deliver superior image quality at all times.
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