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Papers by Yingfeng Yu

Research paper thumbnail of Monitoring extent of curing and thermal–mechanical property study of printed circuit board substrates

Microelectronics Reliability, 2014

ABSTRACT Precise control of curing conversion for epoxy-based printed circuit board (PCB) substra... more ABSTRACT Precise control of curing conversion for epoxy-based printed circuit board (PCB) substrates and clarification of curing–property relationship are critical for the performance and reliability assessment, and for the design optimization of electronic systems. In this article, various epoxy composites for PCB substrates were analyzed by infrared spectroscopy (IR), differential scanning calorimetry (DSC), rheometry, dynamic mechanical analysis (DMA), and scanning electron microscope (SEM). Compared with mid-IR and DSC, near-IR (NIR) is found to be a reliable method for the characterization of curing conversion process by detecting the consumption of epoxy groups. And DMA is a powerful method for measuring the conversion of PCB materials by testing glass transition temperatures (Tg) and viscoelastic properties. The curing behaviors of a variety of epoxy composites show distinct differences in both curing rate and activation energy, and the growth tendency of Tg with curing conversion also changed depending on the material compositions. Correlation of curing conversion versus thermal properties shows that the activation energy of curing at different stage by DSC resembles the tendency of Tg transitions tested by DMA. Mechanical properties of the composites show close relationship with the curing conversions. Peel strength, the indicator of adhesion strength between copper foil and epoxy composites, was tested on all the specimens of different curing conversions, and the results showed a maximum value at curing conversion between ca. 90 and 95%.

Research paper thumbnail of A METHOD FOR SYNTHESIS OF A 3D FACE USING A SINGLE 2D IMAGE

Handbook of Pattern Recognition and Computer Vision, 2009

Research paper thumbnail of State-of-the-art of 3D facial reconstruction methods for face recognition based on a single 2D training image per person

Pattern Recognition Letters, 2009

Research paper thumbnail of Face recognition subject to variations in facial expression, illumination and pose using correlation filters

Computer Vision and Image Understanding, 2006

Research paper thumbnail of Monitoring extent of curing and thermal–mechanical property study of printed circuit board substrates

Microelectronics Reliability, 2014

ABSTRACT Precise control of curing conversion for epoxy-based printed circuit board (PCB) substra... more ABSTRACT Precise control of curing conversion for epoxy-based printed circuit board (PCB) substrates and clarification of curing–property relationship are critical for the performance and reliability assessment, and for the design optimization of electronic systems. In this article, various epoxy composites for PCB substrates were analyzed by infrared spectroscopy (IR), differential scanning calorimetry (DSC), rheometry, dynamic mechanical analysis (DMA), and scanning electron microscope (SEM). Compared with mid-IR and DSC, near-IR (NIR) is found to be a reliable method for the characterization of curing conversion process by detecting the consumption of epoxy groups. And DMA is a powerful method for measuring the conversion of PCB materials by testing glass transition temperatures (Tg) and viscoelastic properties. The curing behaviors of a variety of epoxy composites show distinct differences in both curing rate and activation energy, and the growth tendency of Tg with curing conversion also changed depending on the material compositions. Correlation of curing conversion versus thermal properties shows that the activation energy of curing at different stage by DSC resembles the tendency of Tg transitions tested by DMA. Mechanical properties of the composites show close relationship with the curing conversions. Peel strength, the indicator of adhesion strength between copper foil and epoxy composites, was tested on all the specimens of different curing conversions, and the results showed a maximum value at curing conversion between ca. 90 and 95%.

Research paper thumbnail of A METHOD FOR SYNTHESIS OF A 3D FACE USING A SINGLE 2D IMAGE

Handbook of Pattern Recognition and Computer Vision, 2009

Research paper thumbnail of State-of-the-art of 3D facial reconstruction methods for face recognition based on a single 2D training image per person

Pattern Recognition Letters, 2009

Research paper thumbnail of Face recognition subject to variations in facial expression, illumination and pose using correlation filters

Computer Vision and Image Understanding, 2006

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