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This paper aims to analyze the effect of Au wire size and location of hook during wire pulling test to identify the variation of results obtained.

Two hook locations, namely, location A and location B were used to analyze the effect of hook location. Location A was the same as the hook location required by MIL-STD-883E standard, whereas location B was located near to the second bond. The correlation between new purposed failure modes and MIL-STD-883E standard was developed to reflect on the pull strength with the physical failure.

It was observed that fine pitch Au wire has higher variation and lower process capability of pull strength. Au wire pulled by the hook at location B provides a more representative result compared to that at location A. Fifty per cent or more of Au remnant is required to be considered as a good and reliable Au wedge bond based on the new purposed failure modes.

The evaluation of gold (Au) wedge bond requires a new proper wire pulling test method. This is due to the large variation obtained from the application of current practice of wire pulling test.

A study was undertaken to evaluate the thermosonic gold‐wire bonding capability to Ti‐Pd‐Cu‐Ni‐Au thin film metallisation on newly developed polymer hybrid integrated circuits (POLYHICs). (The POLYHIC technology incorporates alternating layers of polymer and metal added to conventional Hybrid Integrated Circuits which provide for increased interconnection density.) Destructive wire‐pull strengths were measured as a function of varying wire‐bonding machine operating parameters of wedge bond force, wedge bond time, temperature, and ultrasonic energy. All data were evaluated and compared with wire bonding under similar conditions to thin film circuits on Al2O3 ceramic. The results for wedge‐bond associated failures indicated that machine operating parameters of wedge bond force, time and ultrasonic energy similarly affected the average wire‐pull strength for both the ceramic and POLYHIC circuits. Pull strengths for equivalent metallisation schemes and bonding parameters were generally slightly higher and more tightly distributed for bonds made to metal films on ceramic. A strong correlation was found to exist between wire‐pull strengths and surface topography (as measured by a profilometer technique) of the thin film metallisation for the POLYHICs which had both smooth and rough metallisation surfaces for metal films on top of the polymer. The results indicated that rough metallisation bonded more easily and yielded much higher wire‐pull strengths. Also, rougher films were shown to effectively increase the parameter‐operating windows for producing reliable wire bonds. A semi‐quantitative analysis was developed to help explain this correlation. Surface topography effects were also found to be a key factor when evaluating wire bondability as a function of substrate bonding temperature. Wedge‐bond strength was essentially independent of temperature for bonds made to rougher metallisation while a strong temperature dependency was found when wire bonds were made to smoother films.

Although wire‐bonding is an established and well‐known technique for micro‐joining on leadframes, direct die‐attach without housing on printed circuit boards has some new requirements for the surface of the bond pads and the PCB itself. The best choice of material for the bond pads is a pure gold metallisation. The quality of the surface can be tested during wire‐bonding using the ultrasonic‐power process window. It will be shown that the surface and the PCB itself have a considerable influence on the ultrasonic and thermosonic bonding process.

In a plastic BGA package, the glass transition temperature of 170‐215°C for bismaleimide triazine (BT) substrate puts an upper ceiling to the usable wire bond temperature. To compensate for the limitation in thermal energy, high frequency thermosonic bonding was proposed and successfully demonstrated for plastic BGA wire bonding. Design of experiment (DOE) and response surface methods (RSM) for process optimisation were used; bonded areas were also analysed using scanning electron microscope (SEM). Of the four major bonding parameters were investigated, ultrasonic power and bond force appeared to be the most important control factor for wire pulls and ball shear force optimisation. The results show that bonding at low temperature is viable with the use of high frequency transducer wire bonder.

This paper aims to analyze the effect of surface roughness and hardness of leadframe on the bondability of gold (Au) wedge bond using in situ inspection of laser interferometer and its relationship with the deformation and wire pull strength.

The in situ inspection of ultrasonic vibration waveform through the changes of vertical axis (y-axis) amplitude of wire bonder capillary was carried out using laser interferometer to analyze the formation of Au wedge bond. The relationship between the changes of ultrasonic waveform of capillary with the deformation and the pull strength was analyzed to evaluate the bondability of Au wedge bonds.

It was observed that the changes in vertical axis amplitude of ultrasonic vibration waveform of wire bonder capillary can be used to describe the process of bonding formation. The loss of ultrasonic energy was exhibited in ultrasonic vibration waveform of wire bonding on leadframe that has higher value of roughness (leadframe A) as compared to that of leadframe that has lower value of roughness (leadframe B). The lower pull strength obtained by Au wedge bond further confirms the reduction of bond formation because of the higher deformation on leadframe A as compared to that of leadframe B.

The relationship between in situ measurement using laser interferometer with the bondability or deformation and wire pull strength of Au wedge bonds on different surface roughness and hardness of leadframes is still lacking. These findings provide a valuable data in analyzing the bonding mechanisms that can be identified based on the in situ measurement of ultrasonic vibration and the bondability of Au wedge bonds.

The purpose of this paper is to provide a systematic review on technical findings and discuss the feasibility and future of gold (Au) wirebonding in microelectronics packaging. It also aims to study and compare the cost, quality and wear-out reliability performance of Au wirebonding with respect to other wire alloys such as copper (Cu) and silver (Ag) wirebonding. This paper discusses the influence of wire type on the long-term reliability tests.

Literature reviews are conducted based on cost and wire selections of Au, Cu or Ag wirebonding. Detailed wear-out failure findings and wire selection with cost considerations are presented in this review paper. The future and the status of Au wirebonding in microelectronics packaging are discussed in this paper.

This paper briefly reviews selected aspects of the Au ball and other alternative bonding options, focusing on reliability performance, and discusses the future of Au wirebonding in the near future in semiconductor packaging.

The paper reveals the technical considerations when choosing the wire types for future microelectronics packaging.

The in-depth technical review and strategies of the selection of wire types (Au, Cu or the latest Ag alloy) in microelectronics packaging are discussed in this paper based on previous literature studies.

The challenge presented by advanced package development in the past five years has further accentuated the constant need for package quality and reliability monitoring through extensive laboratory testing and evaluation. As pin counts and chip geometries have continued to increase, there has been additional pressure from the military and commercial sectors to improve interconnect designs for packaged chips, including chips directly attached to the printed wiring board (PWB). One of the options employed has been tape automated bonding (TAB). However, this assembly technique also presents new standardisation, qualification and reliability problems. Therefore, at Rome Air Development Center (RADC), there is regular assessment (through in‐house failure analysis studies) of parts destined for military and space systems. In addition, Department of Defense (DoD) high tech development programmes, such as very high speed integrated circuits (VHSIC), have utilised all present screening methods for package evaluation, and have addressed the need for development of more definitive non‐destructive tests. To answer this need, two RADC contractual efforts were awarded on laser thermal and ultrasonic inspection techniques. Through these package evaluations, a number of potential reliability problems are identified and the results provided to the specific contractors for corrective action implementation. Typical problems uncovered are lid material and pin corrosion, damage to external components and adhesion problems between copper leads and polyimide supports, hermeticity failures, high moisture content in sealed packages and particle impact noise detection (PIND) test failures (internal particles). Further tests uncover bond strength failures, bond placement irregularities, voids in die attach material (potential heat dissipation problems), and die surface defects such as scratches and cracks. This presentation will review the specific package level physical test methods that are employed as a means of evaluating reliable package performance. Many of the tests, especially the environmental tests—e.g., salt atmosphere and moisture resistance—provide accelerated forms of anticipated conditions and are therefore applied as destructive tests to assess package quality and reliability in field use. In addition to a manufacturer's compliance with designated qualification procedures, the key to package quality lies in utilising good materials and well‐controlled assembly techniques. This practice, along with effective package screen tests, will ensure reliable operation of very large scale integration (VLSI) devices in severe military and commercial environment applications.

Tape automated bonding (TAB) is one technology which is becoming widely adopted for interconnecting integrated circuits to a substrate or package. Both destructive and non‐destructive test methods for evaluation of TAB bonds are analysed and criticised. The key parameters and general guidelines of a destructive beampull test set‐up are identified and presented. The key features of four different non‐destructive test methods are described and discussed. It is found that no universal solution exists for non‐destructive evaluation of TAB bonds although some methods may be more useful than others under certain conditions and constraints. Data and experimental procedure are presented for correlation of scanning laser acoustic microscopy and beampull data.

The purpose of this paper is to review recent advances in wire bonding of low‐k devices.

Dozens of journal and conference articles published in 2005‐2008 are reviewed.

The paper finds that many articles have discussed and analysed problems/challenges such as bond pad metal peeling/lift, non‐sticking on pad, decreased bonding strength and lower wire‐bond assembly yield. The paper discusses the articles' solutions to the problems and recent findings/developments in wire bonding of low‐k devices.

Because of the page limitation, only brief discussions are given in this paper. Further reading is needed for more details.

The paper attempts to provide an introduction to recent developments and the trends in wire bonding of low‐k devices. With the references provided, readers may explore more deeply by reading the original articles.

This paper reviews methods of quality control for the ultrasonic wire bonding process. It also covers the basic principles of the process, a model for the bonding mechanism, and the criteria which determine bond quality. In practice, quality control in production is mainly by batch destructive testing and by ensuring consistent performance of the bonding machine by, for example, periodic calibration. A more desirable approach is that of in‐process monitoring and control of every joint made. Although in‐process techniques have been extensively studied, they are currently little used because of the lack of a universal system, doubts on reliability and access problems. The in‐process monitoring and control techniques which have been studied have concentrated on methods which involve the detection of variations in the mechanical impedance of the bond zone; these are reflected back into the excitation system of the equipment during bond formation. It is believed that further development of these techniques, coupled with simultaneous monitoring of associated parameters, e.g., bonding wire deformation, offers hope of improved process control.