| Co-Investigator(Kenkyū-buntansha) |
SAKA Masumi Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (20158918)
SOYAMA Hitoshi Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (90211995)
SASAGAWA Kazuhiko Hirosaki University, Faculty of Science and Technology, Associate Professor, 理工学部, 助教授 (50250676)
OGURA Yukio Hitachi Engineering Co. Ltd., Senior Engineer, 検査部門, 技師長(研究職)
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| Research Abstract |
1.Development of the generation and detection system of THz wave
A pulsed laser beam generated by a fs laser was separated into a pump and a probe beam by a beam splitter. The pump beam was then focused on a nondoped GaAs wafer. Due to the photoconductive effect, a pulsed THz beam was generated from the GaAs emitter. Moreover, the THz beam was focused on a ZnTe crystal white the probe beam was also focused on the ZnTe sensor, through a time delay. Due to the Pockels effect, a phase variation of the probe beam was induced by the electro-optic modulation. By using a pair of balanced photodiodes, the phase variation which varies with the electric field of the THz wave was detected.
2.Construction of the tomography system
The generated THz beam was focused on the inspected sample, and the reflected THz wave which carries the information of the sample was focused on the ZnTe sensor. The probe beam was synchronized with the reflected THz beam at the ZnTe sensor. In the same time, the sample was moved in the x and y direction by an electric stage. Therefore, by adjusting the time delay as a time gate, the amplitude of the reflected THz wave from a cross section of the sample was recorded, and a tomograph was generated.
3.Nondestructive evaluation of delamination in electronic packages
For the practical use of the THz wave tomography, the generation of the 3D image of delamination between the chip and the encapsulant resin in the mounted electronic packages, and the establishment of nondestructive evaluation method of mounted electronic packages on an assembly line, are being promoted.
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