Phase Array Ultrasonic Transducer Based on a Flip Chip Bonding with Indium Solder Bump
Phase Array Ultrasonic Transducer Based on a Flip Chip Bonding with Indium Solder Bump
复制标题
基于铟焊料凸块倒装芯片接合的相阵超声波换能器
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
E. S. Kim
中科院分区：
文献类型：
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作者：
Jaehoon Lee;E. S. Kim
本文介绍了一种基于1 mm厚PZT(PZT)衬底，128个独立可访问电极的相控阵超声换能器的设计、仿真和制作工艺。研究了铟在空气、氮气、氢气、液态金属助熔剂和甲酸(H_2CO_2)中的回流过程。其中，甲酸被发现是形成铟凹凸的最好环境，因为它能最有效地去除氧化铟和清除残留物。此外，还测试了不同尺寸的凹凸金属化(UBM)和铟图案，测量了回流后铟凸块的高度，结果表明，UBM和铟图案之间的横向尺寸比为1：2.5时，UBM的润湿性最好，残留最小。
This paper presents the design, simulation and fabrication process of a phase array ultrasonic transducer based on 1mm-thick lead zirconate titanate (PZT) substrate with 128 independently accessible electrodes through flip chip bonding with indium solder bump. The reflow processes of indium have been explored under air, nitrogen, hydrogen, liquid metal flux, and formic acid (H2CO2). Among these, formic acid is found to be the best ambient for forming indium bump, as it removes indium oxide and clean out residuals most effectively. Also, different sizes of under bump metallization (UBM) and indium pattern have been tested, and the measured heights of indium bumps after a reflow show that the lateral dimension ratio of 1:2.5 between the UBM and indium patterns offers the best wettability over the UBM with the smallest residual.