On the Microcontact Mechanism of Thermosonic Wire Bonding in Microelectronics: Saturation of Interfacial Phenomena

Jeng, Yeau-Ren; Chen, J. Y.

doi:10.1080/05698190590903114

Cited by 9 publications

(4 citation statements)

References 12 publications

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“…This process is achieved using an applied pressure at an elevated temperature usually in the range of 0.5-0.8T m , where T m is the absolute melting point of the material being joined. Cold welding [24], wire bonding [25], soldering, brazing, and welding [26] also use diffusion mechanisms. Polymer-to-polymer adhesion generally occurs through the inter-diffusion of molecules in the adhesive and the adherend [27,28].…”

Section: General Adhesion Mechanismsmentioning

confidence: 99%

Adhesion mechanisms of nanoparticle silver to substrate materials: identification

Joo

Baldwin

2009

Nanotechnology

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Nanoparticle silver (NPS) conductors are increasingly being investigated for printed electronics applications. However, the adhesion mechanism of the nanoparticle silver to substrate materials has not been identified yet. In particular, the adhesion of NPS to organic materials such as the widely used polyimide Kapton HN and Kapton FPC dry films is concerned with low adhesion strength because the processed polymer surface is chemically inert. Moreover, its adhesion to substrate materials such as benzocyclobutene (BCB), copper and aluminum was found to be very weak. Therefore, in this paper, the mechanisms of NPS adhesion to organic and inorganic materials are identified as the first step in improving NPS adhesion strength. Improving the adhesion strength of NPS will be the key issue for printed electronics applications. The adhesion of NPS to substrate materials was found to be mainly attributed to van der Waals forces based on particle adhesion mechanisms. This finding provides the initiative of developing an adhesion prediction model of NPS to substrate materials in order to provide guidelines for improving the NPS adhesion strength to the substrate materials used in printed electronics.

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Section: General Adhesion Mechanismsmentioning

confidence: 99%

Adhesion mechanisms of nanoparticle silver to substrate materials: identification

Joo

Baldwin

2009

Nanotechnology

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“…Jeng and Lin (2003) extended the original CEB friction model and developed frictional energy intensity to explain the influences of thermosonic wire bonding parameters to the ball shear test results. Jeng and Chen (2005) used frictional energy intensity calculations developed from CEB friction model to study the influences of wire diameter used during thermosonic wire bonding. Jeng and Horng (2001) used micro-contact mechanism and frictional energy intensity to study the ultrasonic wedge bonding process.…”

Section: Resultsmentioning

confidence: 99%

Effects of ball bond diameter on wire bond reliability for automotive application

Devarajan

Lee

Lacey³

2016

Microelectronics International

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Purpose – The purpose of this paper is to investigate the reliability of wire bonds with three varying ball bond diameters, which are ball bonded with three different sizes of gold wires in light-emitting diode (LED) package under high-temperature environment. In automotive applications, “lifted ball bond” issue is a potential critical point for LED device reliability, as the wire bonds are usually stressed under high operating temperature during their lifetime. Moreover, the reliability of wire bonds in recent LED production has fallen under scrutiny due to the practice of reducing wire diameters to cut down production costs. Design/methodology/approach – Three gold wires with sizes of 2, 1.5 and 1 mm were ball bonded on the LED chip bond pad via thermosonic wire bonding method to produce three different ball bond diameters, that is, 140, 120 and 100 μm, respectively. The reliability of these wire bond samples was then studied by performing isothermal aging at 200°C for the time interval of 30, 100 and 500 hours. To validate hypotheses based on the experimental data, COMSOL Multiphysics simulation was also applied to study the thermal stress distribution of wire bond under an elevated temperature. Findings – Experimental results show that the interfacial adhesion of wire bond degrades significantly after aging at 200°C for 500 hours, and the rate of interfacial degradation was found to be more rapid in the wire bond with smaller ball bond diameter. Experimental results also show that ball bonds randomly elongate along an axis and deforms into elliptical shapes after isothermal aging, and ball bonds with smaller diameters develop more obvious elongations. This observation has not been reported in any previous studies. Simulation results show that higher thermal stress is induced in the wire bond with the decrease of ball bond diameter. Practical implications – The reliability study of this paper provides measurements and explanation on the effects of wire diameter downsizing in wire bonds for automotive application. This is applicable as a reliability reference for industries who intend to reduce their production costs. Other than that, the analysis method of thermal stresses using COMSOL Multiphysics simulations can be extended by other COMSOL Multiphysics users in the future. Originality/value – To resolve “lifted ball bond” issue, optimization of the bond pad surface quality and the wire bond parameter has been studied and reported in many studies, but the influence of ball bond diameter on wire bond reliability is rarely focused. Moreover, the observation of ball bonds randomly elongate and deform more into elliptical shape, and ball bond with smaller diameter has the highest elongation after isothermal aging also still has not been reported in any previous studies.

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“…Chang et al (CEB model) [22] suggested an elastic-plastic microcontact model based on the volume conservation of plastically deformed asperities. The transition from an elastic to a fully plastic flow of the asperity is not modelled in the CEB model while the Zhao model [23] takes into account this point, and some papers [8,24] adopt the Zhao model to analyse the microcontact phenomena of thermosonic bonding. Ding et al [25,26] further suggest that the shear stress from ultrasonic vibration should be taken into account when calculating the real contact area.…”

Section: Calculation Methods Of Real Contact Areamentioning

confidence: 99%

Benefits of Flat Polymer Dielectric Surface Loading Organic Semiconductors in Field-Effect Transistors Prepared by Electrode-Peeling Transfer

Yasuda

Fujita

Nakashima

et al. 2003

Jpn. J. Appl. Phys.

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The theoretical equation of thermosonic bond strength involving interfacial deformation and microcontact phenomena is presented in this study. The constitutive equation of gold considering the ultrasonic softening mechanism was developed based on the thermosonic bonding experiments and coded into the FE software. The numerical model of bonding was established to estimate the surface exposure and the effective normal pressure. The real contact area was calculated by a microcontact model. Accordingly, the nominal bond strength can be obtained and verified by the experimental data. It is found that a better conjunction exists at the edge of the contact area because large surface exposure is produced there, which is also proved by the SEM image of a sheared ball bond. Increasing the bonding force or the ultrasonic power will increase the interfacial plastic deformation, the nominal and real contact areas, but decreases the effective normal pressure. The contact ratio increases to a maximum with the increase in the bonding force, and then decreases while it continues to decrease with the increase in the ultrasonic power. In addition, both the stress analysis and experimental result show that cratering and damage to the pad structure are easily produced below the edge region of the contact area under an excessive bonding force or ultrasonic power.

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On the Microcontact Mechanism of Thermosonic Wire Bonding in Microelectronics: Saturation of Interfacial Phenomena

Cited by 9 publications

References 12 publications

Adhesion mechanisms of nanoparticle silver to substrate materials: identification

Adhesion mechanisms of nanoparticle silver to substrate materials: identification

Effects of ball bond diameter on wire bond reliability for automotive application

Benefits of Flat Polymer Dielectric Surface Loading Organic Semiconductors in Field-Effect Transistors Prepared by Electrode-Peeling Transfer

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