Wire bonding dynamics monitoring by wavelet analysis

Han, Lei; Gao, Rong-Zhi; Zhong, Jue; Li, Han-Xiong

doi:10.1016/j.sna.2007.02.041

Cited by 13 publications

(7 citation statements)

References 12 publications

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“…In contrast, at the time interval of 10.5 ms until 16 ms, it is shown that the capillary velocity is gradually reduced both for the leadframes A and B as shown in Figures 6(a) and 7(a). This is because of the decrement of the atomic diffusion process at the bond interface (Han et al, 2007;Hu et al, 1998;Li et al, 2007). Apparent characteristic that can be noted in Figure 6(a) is that there is a fluctuation of ultrasonic vibration velocity envelop for the case of leadframe A.…”

Section: Resultsmentioning

confidence: 86%

Effect of surface roughness and hardness of leadframe on the bondability of gold wedge bonds

Zulkifli

Harun

Jalar

2019

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Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

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Section: Resultsmentioning

confidence: 86%

Effect of surface roughness and hardness of leadframe on the bondability of gold wedge bonds

Zulkifli

Harun

Jalar

2019

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“…Lei Han [5] reported that in his wavelet analysis, that there was significant high frequency (256-512kHz) vibration in the initial 10ms of the die bonding process that correlated well with the variation in bonding pressure when observing the vibration in the x-axis direction. The largest vibrations occurring with a low bonding pressure (12.2N), and almost indistinct at high bonding pressures (18.8N).…”

Section: Discussionmentioning

confidence: 89%

“…The results of this study show a distinct variation in the power input in the 1 st harmonic with the variation of power input and contact force. Lei Han [5] studied the movement on the head and tip of the capillary along the x axis for wedge bonders, then using the process of wavelet analysis, looked for significant variations in the vibration characteristics as the bonding pressure was varied. Separating the signal into different frequency packets, small but significant vibrations at the start of the bonding process in the 256-512 kHz band correlated well with the variation of the bonding pressure.…”

Section: Introductionmentioning

confidence: 99%

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An investigation of capillary vibration during wire bonding process

Gao

Kelly

Yang

et al. 2008

2008 International Conference on Electronic Packaging Technology &Amp; High Density Packaging

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As the bond pitch size decreases, understanding the behaviour of the capillary tube and monitoring bond quality becomes increasingly important. This paper uses Finite Element Analysis (FEA) and Laser Doppler Interferometer to study the vibration of the capillary tube during the wire bonding process. Using a laser Doppler interferometer, the vibrations were measured along the x, y and z axis under two different conditions, when the capillary was vibrating against a hard surface (low friction) and during wire bonding operations (higher friction). The head of the capillary was shown to describe a circular path when the friction was low and an elliptical path when there was more frictional resistance at the capillary tip. The forces acting on the capillary tube were studied and it was shown that the reason for the vibration in the y-axis was the horizontal reaction due to the frictional resistance when the capillary was not aligned with the x-axis. The path described by the tip of the capillary is discussed. The significance of these results is discussed and using the forces acting on the capillary in the deformed shape, the difference between the circular and elliptical paths is explained. FE analysis is then used to further understand and demonstrate the behaviour of the capillary. The conclusions of the paper show that when the capillary vibrates in a stable condition, the deformed shape does not change, but revolves around the central vertical z-axis.

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“…Therefore, continuous wavelet transform (CWT) has been widely used for frequency decomposition in objective of fault detection, pattern recognition, and material characterization. [17][18][19][20] WT has been widely addressed in the literature to remove the noise in the image used in diameter and hairiness measurements involving image processing technique of unfolded yarns, [21][22][23] while in studies based on optical techniques it has been discussed, for diameter measurement, 24 nep detection, 25 and irregularity determination, 26 by smoothing the yarn signal with the help of decomposed wave packets. In this paper, it has been proposed that the continuous determination of the twist characteristic of fancy yarns with respect to local frequency changes of yarn signal along the yarn surface by using wavelet analysis.…”

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confidence: 99%

Characterization of twist of fancy yarns using wavelet analysis of sensor signal

Süle

2020

Textile Research Journal

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Yarn twist variations may cause stripes in the direction of weft yarns or local defects on a fabric surface. Since fast Fourier transform and time analysis cannot directly detect local frequency variations of yarn signal and defect sensors are designed to detect the diameter decreases without considering frequency analysis, no data associated with twist-related frequency changes can be obtained when inspecting Chenille yarn (Cy) defects. This study proposes the prediction of twist level ( T) and twist variations ( ΔT) of Cy whose twist changes in accordance with the spatial period of pile density by using wavelet analysis, allowing localized frequency variations to be obtained. Complex-valued Paul wavelet was used to determine the ΔT of signals with small frequency fluctuations, while Morlet wavelet was addressed for signals with high frequency change. The relation of the signal frequency to the pile yarn density and, correspondingly, twist was modeled by equations. To prevent discontinuities in wavelet cross-spectrum (WCS), the twist simulation signal was generated by equalizing twist oscillation amplitudes without changing their phase. To compare ideal twist to the local twist, another simulation signal demonstrating the ideal twist at sample-specific frequency was generated. The WCS of the simulation signals allowing the segmentation of variation intervals was used for determining ΔT and yarn portions, where the twist is compatible with ideal twist, by establishing correlation between scales and twists. For yarn samples with various T and ΔT types, the T and ΔT results obtained by the proposed wavelet-based algorithm showed the mean absolute relative percentage errors of 1.617% and 37.062%, respectively.

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Wire bonding dynamics monitoring by wavelet analysis

Cited by 13 publications

References 12 publications

Effect of surface roughness and hardness of leadframe on the bondability of gold wedge bonds

Effect of surface roughness and hardness of leadframe on the bondability of gold wedge bonds

An investigation of capillary vibration during wire bonding process

Characterization of twist of fancy yarns using wavelet analysis of sensor signal

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