线性调频激励的倒装芯片高频超声回波解卷积与缺陷检测  

High-frequency ultrasonic echo deconvolution and defect detection of flip chip with linear frequency modulated excitation

作　　者：宿磊 谢万隆 明雪飞 顾杰斐 赵新维 李可 PECHT Michael SU Lei;XIE Wanlong;MING Xuefei;GU Jiefei;ZHAO Xinwei;LI Ke;PECHT Michael(School of Intelligent Manufacturing,Jiangnan University,Wuxi 214122;Research Institute 58,China Electronics Technology Group Corporation,Wuxi 214000;Center for Advanced Life Cycle Engineering,University of Maryland,College Park,Maryland,USA 20742)

机构地区：[1]江南大学智能制造学院,无锡214122 [2]中国电子科技集团公司第五十八研究所,无锡214000 [3]马里兰大学CALCE中心,美国马里兰20742

出　　处：《声学学报》2025年第1期128-137,共10页Acta Acustica

基　　金：国家自然科学基金项目(52375099,U23B2044,51705203);中国博士后科学基金项目(2021T140279)资助。

摘　　要：针对倒装焊芯片高频超声检测回波微弱、信号混叠、受噪声影响大导致焊球缺陷难以准确检测的难题,提出一种基于预调制线性调频(LFM)激励和自回归谱外推法的高频超声检测方法。建立倒装焊芯片缺陷高频超声检测仿真模型,结合超声探头响应设计LFM信号作为探头激励信号,采用预调制LFM信号作参考信号对回波信号进行脉冲压缩,抑制噪声,信噪比平均提高12 dB;利用改进协方差法计算信号有效频带的自回归系数,对脉冲压缩后超声信号有效频带进行频谱外推,分离混叠回波信号;通过参数化扫描获取倒装焊芯片B扫描图像,对含噪声B扫描矩阵进行脉冲压缩、计算自回归系数矩阵及频谱外推,经滑动平均滤波进一步抑制噪声亮斑,对比分析无缺陷焊球模型和裂纹、孔洞焊球模型结果。仿真结果表明,该方法能够大幅提高B扫图时域分辨率,在-4 dB噪声影响下仍有较好效果。通过提取B扫图回波峰值所在时间,结合材料声速可计算缺陷预埋深度。在裂纹、孔洞缺陷焊球模型中预埋深计算误差均小于5%,可实现焊球缺陷识别与定位。Aiming at the problems of the weakness of echo,signal aliasing and the influence of noise,which make it difficult to detect the defects of the flip chip accurately,a high-frequency ultrasonic defect detection method based on liner frequency modulated(LFM)excitation and autoregressive spectrum extrapolation(ARSE)is proposed.A simulation model for high-frequency ultrasonic defect detection is established.Based on the response of ultrasonic probe,the LFM signal is designed as the probe excitation signal,and the pre-modulated LFM signal is used as the reference signal to compress the echo signal,suppress the noise,and increase the signal-to-noise ratio by 12 dB on average.Using the modified covariance method,the autoregressive coefficients of effective frequency band can be calculated.The effective frequency band of pulse compressed ultrasonic signal is extrapolated to separate the aliasing echo signal.The B-scan image of the flip chip is acquired through parametric scanning,followed by pulse compression to reduce noise in the B-scan matrix.Autoregressive coefficients are then computed and used for spectrum extrapolation.Additionally,a moving average filter is applied to further suppress noise bright spots.Compared to the simulation model of intact flip chips,as well as those with defects such as crack and bubble,the proposed method significantly enhances the time-domain resolution of B-scan images while maintaining good performance even under-4 dB noise interference.By considering the sound velocity of the material,the peak echo time of the B-scan matrix can be extracted to calculate the embedded depth of defects.The calculation error for determining the embedded depth of crack and bubble models of flip chip is less than 5%,enabling the identification and localization of solder bump defects.

关 键 词：倒装焊芯片 缺陷检测 高频超声 线性调频信号 自回归谱外推 

分 类 号：TN405[电子电信—微电子学与固体电子学]