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Article
Publication date: 1 March 1987

S.T. Riches and G.L. White

GaAs electronic devices are becoming increasingly used in the microelectronics industry especially in solid state microwave, ultra high speed digital processing and…

Abstract

GaAs electronic devices are becoming increasingly used in the microelectronics industry especially in solid state microwave, ultra high speed digital processing and optoelectronic applications. However, in the manufacture of the GaAs devices, problems due to the inherent brittleness of the GaAs and batch to batch variability of the bond pad metallisation have commonly been experienced. This has resulted in some difficulties in wire bonding to GaAs devices with ultrasonic and thermocompression wire bonding techniques. This paper describes a programme undertaken to investigate Au wire bonding techniques to GaAs devices. Specifically, bonding trials have been performed on a range of GaAs substrates using pulse tip and continuously heated thermocompression bonding and ultrasonic bonding. The results of this work have shown that thermocompression and ultrasonic wire bonding techniques are cabable of producing acceptable bonds to GaAs devices, although some of the advantages and limitations of each technique have been demonstrated. Thermocompression bonding with a continuously heated capillary gave the most tolerant envelope of bonding conditions and highest bond strengths. Pulse tip thermocompression bonding gave a less tolerant envelope of acceptable bonding conditions, required a longer bonding time and the wire was weakened above the ball bond. Ultrasonic bonding did not require any substrate heating to give acceptable bonds. However, the choice of equipment can be critical if damage to the device is to be avoided.

Details

Microelectronics International, vol. 4 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 February 1987

R.L. Shook

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…

Abstract

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 wirebonding 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.

Details

Microelectronics International, vol. 4 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 September 1999

Chonglun Fan, Joseph A. Abys and Alan Blair

Palladium surface finishes are utilized on leadframes, printed wiring boards and automobile sensors. Their superior functional performance and the considerable…

Abstract

Palladium surface finishes are utilized on leadframes, printed wiring boards and automobile sensors. Their superior functional performance and the considerable environmental impact of plating lead‐free finishes for packaging processes have been increasingly recognized by the electronic industry. Wire bondable and solderable palladium finishes meet military and industrial standards at no extra cost in the overall assembly processes when compared to traditional packaging techniques. In addition to the development of palladium plating chemistries and technologies, the functional properties of the surface finishes including their wire bonding performance have also been investigated at Bell Laboratories. In this study, gold and aluminum wire bonding to palladium finishes was tested and the wire bond pull force and break position were examined in order to optimize the bonding processes. The results of the study are reported in this paper.

Details

Circuit World, vol. 25 no. 3
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 March 1990

S.T. Riches

Selection of the correct interconnection technique for high lead count integrated circuits is dependent on technical and economic factors, in particular in small batch…

Abstract

Selection of the correct interconnection technique for high lead count integrated circuits is dependent on technical and economic factors, in particular in small batch production of application specific devices (ASICs). This paper reviews some of the interconnection options and describes work where some advances in high density interconnection have been made.

Details

Microelectronics International, vol. 7 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 January 1994

J. Falk, J. Hauke and G. Kyska

Although wirebonding is an established and well‐known technique for micro‐joining on leadframes, direct die‐attach without housing on printed circuit boards has some new…

Abstract

Although wirebonding 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 wirebonding 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.

Details

Circuit World, vol. 20 no. 2
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 April 1998

J. Falk

The influence of process heat, with regard to wire‐ and substrate‐materials, on the adhesion of wirebonds was investigated. Temperature increases up to 200°C were…

Abstract

The influence of process heat, with regard to wire‐ and substrate‐materials, on the adhesion of wirebonds was investigated. Temperature increases up to 200°C were measured on the interface between surface and wire. This temperature is the basis for demonstrating the important influence of dissipated process heat on the cold welding process of wirebonding. Complementary calculations to evaluate the equation of thermal conductivity were carried out using the finite element (FE) method. Bonding tests were able to verify the calculations. These thermodynamical considerations give us a new method to optimize the construction and the choice of materials within the wirebond process.

Details

Microelectronics International, vol. 15 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 December 1999

Teo Kiat Choon and Victor G. Corpuz

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…

Abstract

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.

Details

Microelectronics International, vol. 16 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 2 May 2017

Hanmin Zhang, Ming Hu, Zhijie Wang, Qingchun He and Denghong Ye

The purpose of this paper is to attempt to study the failure mechanism of BGA (ball grid array) Cu wire bond ball lift and specifically focused on substrate outgassing’s…

Abstract

Purpose

The purpose of this paper is to attempt to study the failure mechanism of BGA (ball grid array) Cu wire bond ball lift and specifically focused on substrate outgassing’s impact on Cu wire bonding quality and reliability.

Design/methodology/approach

The Galvanic corrosion theory has been widely adopted in explaining the failure mechanism of Cu ball bond lift issue during reliability test or field application in the presence of moisture. In this study, ion chromatography was performed on BGA substrate halogen analysis. EDX (energy-dispersive X-ray spectroscopy) was also used to detect the contaminant’s element at the bottom surface of a window clamp. Further FTIR (Fourier transform infrared spectroscopy) analysis verified that the contamination is from substrate outgassing during wire bonding. A new window clamp design proved effective in reducing the negative impact from substrate outgassing during wire bonding.

Findings

The solder mask in a fresh substrate contains a chlorine element. The chlorine can be detected in the BGA substrate outgassing during wire bonding by FTIR and EDX analyses, which have a negative impact on the Cu wire bonding. The window clamp with a larger opening can reduce the negative impact of the Cu wire bonding from the BGA substrate outgassing.

Research limitations/implications

Because of the limitation of time and resources, bonding pad surface contamination from substrate outgassing and its correlation with Cu bonding ball lift failure after reliability test will be studied in depth later.

Originality/value

The BGA substrate outgassing has negative impacts on Cu wire bondability. A window clamp with a larger opening can reduce the negative impact from substrate outgassing.

Details

Microelectronics International, vol. 34 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 23 January 2009

Z.W. Zhong

This paper attempts to review recent advances in wire bonding using copper wire.

Abstract

Purpose

This paper attempts to review recent advances in wire bonding using copper wire.

Design/methodology/approach

Dozens of journal and conference articles published recently are reviewed.

Findings

The problems/challenges such as wire open and short tail defects, poor bondability for stitch/wedge bonds, oxidation of Cu wire, strain‐hardening effects, and stiff wire on weak support structures are briefly analysed. The solutions to the problems and recent findings/developments in wire bonding using copper wire are discussed.

Research limitations/implications

Because of page limitation of the paper, only a brief review is conducted. Further reading is needed for more details.

Originality/value

This paper attempts to provide introduction to recent developments and the trends in wire bonding using copper wire. With the references provided, readers may explore more deeply by reading the original articles.

Details

Microelectronics International, vol. 26 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 8 May 2009

Z.W. Zhong

The purpose of this paper is to review recent advances in fine and ultra‐fine pitch wire bonding.

Abstract

Purpose

The purpose of this paper is to review recent advances in fine and ultra‐fine pitch wire bonding.

Design/methodology/approach

Dozens of journal and conference articles published recently are reviewed.

Findings

The problems/challenges such as possible wire sweep and decreased bonding strength due to small wire sizes, non‐sticking, metal pad peeling, narrow process windows, wire open and short tail defects are analysed. The solutions to the problems and recent findings/developments in fine and ultra‐fine pitch wire bonding are discussed.

Research limitations/implications

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

Originality/value

This paper attempts to provide an introduction to recent developments and the trends in fine and ultra‐fine pitch wire bonding. With the references provided, readers may explore more deeply by reading the original articles.

Details

Microelectronics International, vol. 26 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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