The objective of hyperthermia cancer therapy is to elevate the tumor temperature to approximately 43degC while maintaining normal temperature in healthy tissue. This goal can be achieved through a waveform diversity method that optimizes the covariance matrix of the excitation signals applied to array elements. This paper presents the computer simulation of a cylindrical section ultrasound phased array using the waveform diversity method to heat a spherical tumor embedded in a 3D biological tissue model. With this hearing strategy, optimal excitation sequences are obtained and desirable power depositions and temperature distributions are achieved.
{"title":"P1B-1 Optimization of Power Distributions Produced by Ultrasound Phased Arrays through Waveform Diversity","authors":"Xiaozheng Zeng, R. McGough","doi":"10.1109/ULTSYM.2007.324","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.324","url":null,"abstract":"The objective of hyperthermia cancer therapy is to elevate the tumor temperature to approximately 43degC while maintaining normal temperature in healthy tissue. This goal can be achieved through a waveform diversity method that optimizes the covariance matrix of the excitation signals applied to array elements. This paper presents the computer simulation of a cylindrical section ultrasound phased array using the waveform diversity method to heat a spherical tumor embedded in a 3D biological tissue model. With this hearing strategy, optimal excitation sequences are obtained and desirable power depositions and temperature distributions are achieved.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"31 1","pages":"1290-1293"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74777100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Mienkina, C. Friedrich, J. Waldeck, K. Hensel, N. Gerhardt, C. Bremer, M. Hofmann, G. Schmitz
Photoacoustics (PA) combines the high contrast of optical imaging modalities with the high resolution of clinical ultrasound. Fluorescence mediated tomography (FMT), on the other hand, offers a very high molecular contrast specificity. Therefore, a combination of PA imaging and FMT might be fruitful: e.g. PA imaging could provide valuable a priori information for optical-tomography reconstruction algorithms thereby improving the resolution of FMT. The fusion of PA and FMT will be facilitated by contrast agents that are detectable by both modalities. This study investigates the usage of RGD-Cy 3 as a multimodal contrast agent specific for M21 and HT-1080 tumor cells in vivo (fluorescence reflectance imaging, FRI) and ex vivo (PA). 1.6 muM of RGD-Cy 3 was injected into tumor bearing mice (n=4 M21, n=6 HT-1080). The mice were subjected to in vivo FRI. The FRI showed a typical tracer washout time response, however a statistically significant difference between tumor tissue and muscle tissue could not be shown due to auto-fluorescence and hemoglobin absorption. Similar results were obtained 24 h after the injection of the tracer in biodistribution experiments conducted using harvested organs. Subsequently, the organs were PA imaged using a commercial ultrasound system (Sonix RP) and a Nd:YAG laser (532 nm). The kidney exhibited a mean contrast to the noise-floor of 23.97 dB (plusmn 2.65 standard error of the mean (SEM)), the hearts 23.45 dB (plusmn 0.63 SEM), and the native tumor 26.09 dB. RGD-Cy 3 labeled tumors showed a gain of 0.26 dB (26.35 dB plusmn 0.22 SEM) compared to unlabeled tumors, which was not statistically significant. These results were consistent with in vitro measurements of Cy 3-gelatine mixture phantoms that only showed a 9.4 dB gain compared to the noise- floor for a concentration 81 times higher than in vivo. These findings suggest that RGD-Cy 3 might not be a suitable contrast agent for in vivo PA imaging, although similar fluorochromes like Indocyanine Green were already successfully used for PA imaging.
{"title":"P6A-1 Photoacoustic Imaging of Fibrosarcoma Using RGD-Cy 3 as a Targeted Contrast Agent","authors":"M. Mienkina, C. Friedrich, J. Waldeck, K. Hensel, N. Gerhardt, C. Bremer, M. Hofmann, G. Schmitz","doi":"10.1109/ULTSYM.2007.606","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.606","url":null,"abstract":"Photoacoustics (PA) combines the high contrast of optical imaging modalities with the high resolution of clinical ultrasound. Fluorescence mediated tomography (FMT), on the other hand, offers a very high molecular contrast specificity. Therefore, a combination of PA imaging and FMT might be fruitful: e.g. PA imaging could provide valuable a priori information for optical-tomography reconstruction algorithms thereby improving the resolution of FMT. The fusion of PA and FMT will be facilitated by contrast agents that are detectable by both modalities. This study investigates the usage of RGD-Cy 3 as a multimodal contrast agent specific for M21 and HT-1080 tumor cells in vivo (fluorescence reflectance imaging, FRI) and ex vivo (PA). 1.6 muM of RGD-Cy 3 was injected into tumor bearing mice (n=4 M21, n=6 HT-1080). The mice were subjected to in vivo FRI. The FRI showed a typical tracer washout time response, however a statistically significant difference between tumor tissue and muscle tissue could not be shown due to auto-fluorescence and hemoglobin absorption. Similar results were obtained 24 h after the injection of the tracer in biodistribution experiments conducted using harvested organs. Subsequently, the organs were PA imaged using a commercial ultrasound system (Sonix RP) and a Nd:YAG laser (532 nm). The kidney exhibited a mean contrast to the noise-floor of 23.97 dB (plusmn 2.65 standard error of the mean (SEM)), the hearts 23.45 dB (plusmn 0.63 SEM), and the native tumor 26.09 dB. RGD-Cy 3 labeled tumors showed a gain of 0.26 dB (26.35 dB plusmn 0.22 SEM) compared to unlabeled tumors, which was not statistically significant. These results were consistent with in vitro measurements of Cy 3-gelatine mixture phantoms that only showed a 9.4 dB gain compared to the noise- floor for a concentration 81 times higher than in vivo. These findings suggest that RGD-Cy 3 might not be a suitable contrast agent for in vivo PA imaging, although similar fluorochromes like Indocyanine Green were already successfully used for PA imaging.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"189 1","pages":"2409-2412"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77550526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Sboros, E. Glynos, S. Pye, C. Moran, M. Butler, J. Ross, W. Mcdicken, V. Koutsos
The science of microbubble agents has expanded beyond imaging applications to biological targeting and drug/gene delivery. However, the majority of targeted microbubbles are manufactured without thorough characterisation of their targeting ability. Atomic Force Microscopy is capable of picoNewton force resolution, and is reported to measure single hydrogen bonds. The present study aims to introduce this nanosensor in the quantitative probing of the forces of interaction between cells and targeted microbubbles. In-house, lipid based, targeted ultrasound contrast agents that use the biotin-avidin chemistry to carry CD31 antibodies probed cultures of SkHepl cells with an Atomic Force Microscope. Tipless cantilevers were functionalised with poly-L-lysine and were immersed in a suspension of microbubbles in order to attach one at the end of each cantilever. This system then interrogated individual cells. In this initial study over 30 bubble-cell pairs were studied, producing over 200 force-distance curves. It was shown that the targeted microbubbles provide a significantly larger adhesion compared to control microbubbles. The average collective adhesion force was 0.68 plusmn 0.33 nN and was dependent on the depth of contact. As the spatial and force resolution of the AFM is of subnanometer and subnanonewton level, respectively, it is possible to spatially resolve the adhesion sites of targeted microbubbles and measure the forces of these single sites. A histogram analysis of these data demonstrating a single distribution of adhesion events present in all measurements with median at 89.2 pN. In conclusion, this system is capable of quantitative assessment of the avidity of targeted ultrasound contrast agents to cells, which is valuable information to the manufacturing process of such microbubbles.
{"title":"11A-5 Interrogation of the Targeting Mechanisms of Ultrasound Contrast Agent Microbubbles Using Atomic Force Microscopy","authors":"V. Sboros, E. Glynos, S. Pye, C. Moran, M. Butler, J. Ross, W. Mcdicken, V. Koutsos","doi":"10.1109/ULTSYM.2007.246","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.246","url":null,"abstract":"The science of microbubble agents has expanded beyond imaging applications to biological targeting and drug/gene delivery. However, the majority of targeted microbubbles are manufactured without thorough characterisation of their targeting ability. Atomic Force Microscopy is capable of picoNewton force resolution, and is reported to measure single hydrogen bonds. The present study aims to introduce this nanosensor in the quantitative probing of the forces of interaction between cells and targeted microbubbles. In-house, lipid based, targeted ultrasound contrast agents that use the biotin-avidin chemistry to carry CD31 antibodies probed cultures of SkHepl cells with an Atomic Force Microscope. Tipless cantilevers were functionalised with poly-L-lysine and were immersed in a suspension of microbubbles in order to attach one at the end of each cantilever. This system then interrogated individual cells. In this initial study over 30 bubble-cell pairs were studied, producing over 200 force-distance curves. It was shown that the targeted microbubbles provide a significantly larger adhesion compared to control microbubbles. The average collective adhesion force was 0.68 plusmn 0.33 nN and was dependent on the depth of contact. As the spatial and force resolution of the AFM is of subnanometer and subnanonewton level, respectively, it is possible to spatially resolve the adhesion sites of targeted microbubbles and measure the forces of these single sites. A histogram analysis of these data demonstrating a single distribution of adhesion events present in all measurements with median at 89.2 pN. In conclusion, this system is capable of quantitative assessment of the avidity of targeted ultrasound contrast agents to cells, which is valuable information to the manufacturing process of such microbubbles.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"1 1","pages":"965-968"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80459681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Physiologic motion corrupts measurements of induced tissue displacements and obscures tissue mechanical properties in radiation force ultrasound. Wall dilation and contraction with cardiac pulsation is especially disruptive to radiation force imaging the arterial system. We hypothesize that exploiting a rigid arterial wall model, which assumes long wavelength arterial pulse waves, will improve physiologic motion rejection in arterial radiation force imaging. Three rigid wall assuming filters (polynomial regression, principal component regression, and FIR high-pass filters) were compared to four filters that did not assume a rigid arterial wall (linear regression, quadratic regression, principal component regression, and FIR high-pass filters). The filters were tested using Field II generated data inclusive of simulated arterial wall motion combined with experimental acoustic radiation force impulse (ARFI) or shear wave elastography imaging (SWEI) displacement profiles. Performance metrics were sum of absolute differences (SAD) between original and filtered ARFI or SWEI displacement profiles in terms of total profile error, measured peak displacement error, measured recovery time error, and time-to-peak displacement error. Rigid wall assuming polynomial and principal component regression filters yielded the lowest SAD scores. The filters were also qualitatively compared on in vivo ARFI and SWEI data acquired in healthy pig iliac arteries.
{"title":"5C-5 A Rigid Wall Approach to Physiologic Motion Rejection in Arterial Radiation Force Imaging","authors":"R. Behler, T. Nichols, E. Merricks, C. Gallippi","doi":"10.1109/ULTSYM.2007.100","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.100","url":null,"abstract":"Physiologic motion corrupts measurements of induced tissue displacements and obscures tissue mechanical properties in radiation force ultrasound. Wall dilation and contraction with cardiac pulsation is especially disruptive to radiation force imaging the arterial system. We hypothesize that exploiting a rigid arterial wall model, which assumes long wavelength arterial pulse waves, will improve physiologic motion rejection in arterial radiation force imaging. Three rigid wall assuming filters (polynomial regression, principal component regression, and FIR high-pass filters) were compared to four filters that did not assume a rigid arterial wall (linear regression, quadratic regression, principal component regression, and FIR high-pass filters). The filters were tested using Field II generated data inclusive of simulated arterial wall motion combined with experimental acoustic radiation force impulse (ARFI) or shear wave elastography imaging (SWEI) displacement profiles. Performance metrics were sum of absolute differences (SAD) between original and filtered ARFI or SWEI displacement profiles in terms of total profile error, measured peak displacement error, measured recovery time error, and time-to-peak displacement error. Rigid wall assuming polynomial and principal component regression filters yielded the lowest SAD scores. The filters were also qualitatively compared on in vivo ARFI and SWEI data acquired in healthy pig iliac arteries.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"61 1","pages":"359-364"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80487707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the context of our on-going investigation of low-cost two-dimensional (2D) arrays, we studied the temperature-dependent acoustic properties of epoxy blends that could serve as a component in a lossy backing for a compact 2D transducer array. The acoustic impedance and attenuation of five epoxy blends - ranging from "soft" (low Tg) to "hard" (high Tg) - were analyzed across a 35degC temperature range. Fiberglass- and tungsten-filled samples were also fabricated and tested. We established that the hardest epoxy has a constant impedance (versus temperature) of 2.2 MRayl and constant attenuation of 1 dB/mm, while the softer epoxies are more temperature dependent. One soft epoxy has an impedance that declines from 2.7 to 2.0 MRayl and attenuation that increases from 5 to 10 dB/mm. In our application, unfilled epoxies could provide a 24 dB attenuation of backing block echoes, while filled epoxies may provide up to 40 dB attenuation. These materials may be machined (when chilled) or molded to form compact Z-axis conductive backing blocks with improved attenuation of echoes using existing methods.
{"title":"P3K-3 Investigation of Low Glass Transition Temperature Epoxy Resin Blends for Lossy, yet Machineable, Transducer Substrates","authors":"M. Eames, C.M. Rougely, J. Hossack","doi":"10.1109/ULTSYM.2007.483","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.483","url":null,"abstract":"In the context of our on-going investigation of low-cost two-dimensional (2D) arrays, we studied the temperature-dependent acoustic properties of epoxy blends that could serve as a component in a lossy backing for a compact 2D transducer array. The acoustic impedance and attenuation of five epoxy blends - ranging from \"soft\" (low Tg) to \"hard\" (high Tg) - were analyzed across a 35degC temperature range. Fiberglass- and tungsten-filled samples were also fabricated and tested. We established that the hardest epoxy has a constant impedance (versus temperature) of 2.2 MRayl and constant attenuation of 1 dB/mm, while the softer epoxies are more temperature dependent. One soft epoxy has an impedance that declines from 2.7 to 2.0 MRayl and attenuation that increases from 5 to 10 dB/mm. In our application, unfilled epoxies could provide a 24 dB attenuation of backing block echoes, while filled epoxies may provide up to 40 dB attenuation. These materials may be machined (when chilled) or molded to form compact Z-axis conductive backing blocks with improved attenuation of echoes using existing methods.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"78 1","pages":"1921-1924"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79059332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Mulé, A. de Cesare, O. Lucidarme, F. Frouin, A. Herment
The aim of this paper was to propose a robust method for estimating contrast agent attenuation in vivo in small animal studies from contrast-enhanced ultrasound images acquired in fundamental mode. A model of sound propagation was previously presented to take into account the presence of ultrasound contrast agent in the tissue. This model was solved by considering the microbubble backscatter-to-attenuation ratio gamma(k,t) constant on each A-line of an image. In this paper, an improvement of the model solving is proposed. At each time t, the microbubble backscatter-to-attenuation ratio gamma(k, t) is constrained to be homogeneous on the whole field of view around a predefined value gammamean(t), allowing regularized values of the ratio to be estimated. The predefined value gammamean(t) is estimated using an iterative process, starting from the value provided by the first approach. To test this new approach, twelve murine renal perfusion studies are considered. A large recovery of the signal in the deep regions is observed. Compared with the initial method, a higher signal-to-noise ratio is found. Moreover, the process is more robust.
{"title":"12A-6 A Method for the Regularized Estimation of Contrast Agent Concentration in Small Animal Contrast-Enhanced Ultrasound Studies","authors":"S. Mulé, A. de Cesare, O. Lucidarme, F. Frouin, A. Herment","doi":"10.1109/ULTSYM.2007.273","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.273","url":null,"abstract":"The aim of this paper was to propose a robust method for estimating contrast agent attenuation in vivo in small animal studies from contrast-enhanced ultrasound images acquired in fundamental mode. A model of sound propagation was previously presented to take into account the presence of ultrasound contrast agent in the tissue. This model was solved by considering the microbubble backscatter-to-attenuation ratio gamma(k,t) constant on each A-line of an image. In this paper, an improvement of the model solving is proposed. At each time t, the microbubble backscatter-to-attenuation ratio gamma(k, t) is constrained to be homogeneous on the whole field of view around a predefined value gammamean(t), allowing regularized values of the ratio to be estimated. The predefined value gammamean(t) is estimated using an iterative process, starting from the value provided by the first approach. To test this new approach, twelve murine renal perfusion studies are considered. A large recovery of the signal in the deep regions is observed. Compared with the initial method, a higher signal-to-noise ratio is found. Moreover, the process is more robust.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"101 1","pages":"1081-1084"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81519054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Failure analysis in industrial applications often require methods working non-destructively for allowing a variety of tests at a single device. Scanning acoustic microscopy in the frequency range above 100 MHz provides high axial and lateral resolution, a moderate penetration depth and the required non-destructivity. The goal of this work was the development of a method for detecting and evaluating connective defects in densely integrated flip-chip ball grid array (BGA) devices. A major concern was the ability to automatically detect and differentiate the ball-connections from the surrounding underfill and the derivation of a binary classification between void and intact connection. Flip chip ball grid arrays with a 750 mum silicon layer on top of the BGA were investigated using time resolved scanning acoustic microscopy. The microscope used was an Evolution II (SAM TEC, Aalen, Germany) in combination with a 230 MHz transducer. Short acoustic pulses were emitted into the silicon through an 8 mm liquid layer. In receive mode reflected signals were recorded, digitized and stored at the SAM's internal hard drive. The off-line signal analysis was performed using custom-made MATLAB (The Mathworks, Natick, USA) software. The sequentially working analysis characterized echo signals by pulse separation to determine the positions of BGA connectors. Time signals originated at the connector interface were then investigated by wavelet- (WVA) and pulse separation analysis (PSA). Additionally the backscattered amplitude integral (BAI) was estimated. For verification purposes defects were evaluated by X-ray- and scanning electron microscopy (SEM). It was observed that ball connectors containing cracks seen in the SEM images show decreased values of wavelet coefficients (WVC). However, the relative distribution was broader compared to intact connectors. It was found that the separation of pulses originated at the entrance and exit of the ball array corresponded to the condition of the connector. The success rate of the acoustic method in detecting voids was 96.8%, as verified by SEM images. Defects revealed by the acoustic analysis and confirmed by SEM could be detected by X-ray microscopy only in 64% of the analysed cases. The combined analyses enabled a reliable and non destructive detection of defect ball-grid array connectors. The performance of the automatically working acoustical method seemed superior to X-ray microscopy in detecting defect ball connectors.
工业应用中的故障分析通常需要非破坏性工作方法，以允许在单个设备上进行各种测试。在100 MHz以上的频率范围内扫描声学显微镜提供高轴向和横向分辨率，中等穿透深度和所需的非破坏性。这项工作的目标是开发一种检测和评估密集集成倒装芯片球栅阵列(BGA)器件中连接缺陷的方法。一个主要的问题是能否自动检测和区分球形连接和周围的下填体，以及在空隙和完整连接之间进行二元分类。利用时间分辨扫描声学显微镜研究了在BGA上有750 μ m硅层的倒装芯片球栅阵列。使用的显微镜是Evolution II (SAM TEC, Aalen, Germany)，结合230 MHz换能器。短声脉冲通过一个8毫米的液体层发射到硅中。在接收模式下，反射信号被记录、数字化并存储在地对空导弹的内部硬盘驱动器中。离线信号分析使用定制的MATLAB (The Mathworks, Natick, USA)软件进行。通过脉冲分离对回波信号进行顺序工作分析，确定BGA连接器的位置。然后用小波变换(WVA)和脉冲分离分析(PSA)对来自连接器接口的时间信号进行分析。此外，还估计了后向散射振幅积分(BAI)。为了验证目的，用x射线和扫描电子显微镜(SEM)对缺陷进行了评估。结果表明，含裂纹的球接插件在扫描电镜图像中显示小波系数(WVC)值减小。然而，与完整连接器相比，相对分布范围更广。结果表明，在球阵的入口和出口产生的脉冲分离与连接器的情况相对应。扫描电镜(SEM)图像验证了声学方法检测孔洞的成功率为96.8%。通过声学分析发现并经扫描电镜证实的缺陷，x射线显微镜只能在64%的分析病例中检测到。综合分析能够可靠且无损地检测球栅阵列连接器的缺陷。自动工作声学方法的性能似乎优于x射线显微镜在检测缺陷球连接器。
{"title":"9D-6 Signal Analysis in Scanning Acoustic Microscopy for Non-Destructive Assessment of Connective Defects in Flip-Chip BGA Devices","authors":"S. Brand, K. Raum, P. Czuratis, P. Hoffrogge","doi":"10.1109/ULTSYM.2007.209","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.209","url":null,"abstract":"Failure analysis in industrial applications often require methods working non-destructively for allowing a variety of tests at a single device. Scanning acoustic microscopy in the frequency range above 100 MHz provides high axial and lateral resolution, a moderate penetration depth and the required non-destructivity. The goal of this work was the development of a method for detecting and evaluating connective defects in densely integrated flip-chip ball grid array (BGA) devices. A major concern was the ability to automatically detect and differentiate the ball-connections from the surrounding underfill and the derivation of a binary classification between void and intact connection. Flip chip ball grid arrays with a 750 mum silicon layer on top of the BGA were investigated using time resolved scanning acoustic microscopy. The microscope used was an Evolution II (SAM TEC, Aalen, Germany) in combination with a 230 MHz transducer. Short acoustic pulses were emitted into the silicon through an 8 mm liquid layer. In receive mode reflected signals were recorded, digitized and stored at the SAM's internal hard drive. The off-line signal analysis was performed using custom-made MATLAB (The Mathworks, Natick, USA) software. The sequentially working analysis characterized echo signals by pulse separation to determine the positions of BGA connectors. Time signals originated at the connector interface were then investigated by wavelet- (WVA) and pulse separation analysis (PSA). Additionally the backscattered amplitude integral (BAI) was estimated. For verification purposes defects were evaluated by X-ray- and scanning electron microscopy (SEM). It was observed that ball connectors containing cracks seen in the SEM images show decreased values of wavelet coefficients (WVC). However, the relative distribution was broader compared to intact connectors. It was found that the separation of pulses originated at the entrance and exit of the ball array corresponded to the condition of the connector. The success rate of the acoustic method in detecting voids was 96.8%, as verified by SEM images. Defects revealed by the acoustic analysis and confirmed by SEM could be detected by X-ray microscopy only in 64% of the analysed cases. The combined analyses enabled a reliable and non destructive detection of defect ball-grid array connectors. The performance of the automatically working acoustical method seemed superior to X-ray microscopy in detecting defect ball connectors.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"76 1","pages":"817-820"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85747460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Mahmoud, D. Cortes, A. Abaza, H. Ammar, O. Mukdadi, M. Hazey, P. Ngan, R. Crout
This work is motivated by the lack of current imaging modalities to accurately predict the mechanical properties and defects in jawbone. Ultrasonic guided waves are sensitive to changes in microstructural properties and thus have been widely used for non-invasive material characterization. Guided waves propagating along the mandibles may exhibit dispersion behavior which depends on material properties, geometry and embedded cavities. In this work, we present the first theoretical and experimental study for the analysis of guided wave propagation in jawbone. Semi-analytical finite-element (SAFE) method is employed to analyze dispersion behavior of guided waves propagating in human mandibles. The cross section of the mandible is divided in two regions representing the cortical and trabecular bones. The experimental set-up for the guided waves experiment is described. Gabor Wavelet is used to calculate the experimental dispersion behavior from the ultrasound radio frequency (RF) signals. Results from both numerical analysis and guided waves experiment exhibit variations in the group velocity of the first arrival signal and also in the dispersion behavior of healthy and defected mandibles. These results shall provide a means to non-invasively characterize the jawbone and assess the bone mechanical properties.
{"title":"P5A-10 Assessment of Human Jawbone Using Ultrasonic Guided Wave: In Vitro Study","authors":"A. Mahmoud, D. Cortes, A. Abaza, H. Ammar, O. Mukdadi, M. Hazey, P. Ngan, R. Crout","doi":"10.1109/ULTSYM.2007.549","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.549","url":null,"abstract":"This work is motivated by the lack of current imaging modalities to accurately predict the mechanical properties and defects in jawbone. Ultrasonic guided waves are sensitive to changes in microstructural properties and thus have been widely used for non-invasive material characterization. Guided waves propagating along the mandibles may exhibit dispersion behavior which depends on material properties, geometry and embedded cavities. In this work, we present the first theoretical and experimental study for the analysis of guided wave propagation in jawbone. Semi-analytical finite-element (SAFE) method is employed to analyze dispersion behavior of guided waves propagating in human mandibles. The cross section of the mandible is divided in two regions representing the cortical and trabecular bones. The experimental set-up for the guided waves experiment is described. Gabor Wavelet is used to calculate the experimental dispersion behavior from the ultrasound radio frequency (RF) signals. Results from both numerical analysis and guided waves experiment exhibit variations in the group velocity of the first arrival signal and also in the dispersion behavior of healthy and defected mandibles. These results shall provide a means to non-invasively characterize the jawbone and assess the bone mechanical properties.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"52 1","pages":"2183-2186"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85884021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Seppanen, A. Kaskela, K. Mustonen, M. Oinonen, E. Haeggstrom
A few models have earlier been proposed to explain Al oxide breakage during US wirebonding as presented by L. Levine, but no widely accepted theory exists. We propose a model to describe the AlOx breakage mechanism during tangential US excitation at constant pressure in a wirebonder. The model is based on theoretical estimations and experimental measurements. We measure with a laser Doppler vibrometer the relative wire-base displacement and propose that stick-slip and micro-slip behavior is prevalent during ultrasonic bonding. Displacement was measured at rim of the rectangular 14 mum thick and 80 mum width Al wire and at the silicon microchip base. A rectangular shaped wire was used to have probe light good reflection. We combined displacement measurements, detailed SEM analysis of contact interfaces and FEM of the bond structure during the bonding process. We also made a synthesis of the current bonding process knowledge. As a synthesis we propose a two-step model, including early stage scrubbing and later microweld expansion. Validation of the proposed model is discussed. This work and the obtained results are steps towards a fundamental quantitative US bonding theory that is necessary to develop reliable bonding technologies towards finer-pitch and more reliable interconnections.
{"title":"P1E-5 Understanding Ultrasound-Induced Aluminum Oxide Breakage During Wirebonding","authors":"H. Seppanen, A. Kaskela, K. Mustonen, M. Oinonen, E. Haeggstrom","doi":"10.1109/ULTSYM.2007.347","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.347","url":null,"abstract":"A few models have earlier been proposed to explain Al oxide breakage during US wirebonding as presented by L. Levine, but no widely accepted theory exists. We propose a model to describe the AlOx breakage mechanism during tangential US excitation at constant pressure in a wirebonder. The model is based on theoretical estimations and experimental measurements. We measure with a laser Doppler vibrometer the relative wire-base displacement and propose that stick-slip and micro-slip behavior is prevalent during ultrasonic bonding. Displacement was measured at rim of the rectangular 14 mum thick and 80 mum width Al wire and at the silicon microchip base. A rectangular shaped wire was used to have probe light good reflection. We combined displacement measurements, detailed SEM analysis of contact interfaces and FEM of the bond structure during the bonding process. We also made a synthesis of the current bonding process knowledge. As a synthesis we propose a two-step model, including early stage scrubbing and later microweld expansion. Validation of the proposed model is discussed. This work and the obtained results are steps towards a fundamental quantitative US bonding theory that is necessary to develop reliable bonding technologies towards finer-pitch and more reliable interconnections.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"245 1","pages":"1381-1384"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76982077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Hammer, A. Jeays, W.T. Lee, D. Barber, R. Hose, W. Easson, P. Hoskins
Assessment of the severity of arterial disease is typically made using B-mode imaging for plaque evaluation and Doppler ultrasound for estimation of maximum blood velocity. Measurement of other blood velocity related quantities which are thought to be important in plaque development, such as wall shear stress, has proven difficult using conventional 2D ultrasound. This paper describes a 3D ultrasound system combined with computational fluid dynamics for estimation of 3D blood velocity and wall shear stress in arterial disease.
{"title":"P6B-14 A 3D Ultrasound System for Image Guided Modeling of Patient-Specific Artery Geometries","authors":"S. Hammer, A. Jeays, W.T. Lee, D. Barber, R. Hose, W. Easson, P. Hoskins","doi":"10.1109/ULTSYM.2007.621","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.621","url":null,"abstract":"Assessment of the severity of arterial disease is typically made using B-mode imaging for plaque evaluation and Doppler ultrasound for estimation of maximum blood velocity. Measurement of other blood velocity related quantities which are thought to be important in plaque development, such as wall shear stress, has proven difficult using conventional 2D ultrasound. This paper describes a 3D ultrasound system combined with computational fluid dynamics for estimation of 3D blood velocity and wall shear stress in arterial disease.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"8 1","pages":"2469-2472"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81219923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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