微电路封装产品内部水汽含量的分析与控制方法

为了使我所微电路封装产品能广泛满足航空、航天及其他特殊领域对内部水汽含量的要求(≤5000ppm),提出了降低金属或陶瓷结构封装的微电路封装产品内部水汽含量的控制方法和工艺要求。     

Development and characterization of the thermal behavior of packaged cascode GaN HEMTs

This study investigates the heat generation behavior of packaged normally-on multi-finger AlGaN/GaN high electron mobility transistors (HEMTs) that are cascoded with a low-voltage MOSFET (LVMOS) and a SiC Schottky barrier diode (SBD). By foremost carrying out electro-thermal simulation and related thermal measurements with infrared thermography and Raman spectroscopy for basic 5 mm GaN HEMTs, the location of hot spot in operating device can be obtained. Based on the outcome, further packaged cascode GaN HEMT is analyzed. A hybrid integration of the GaN-HEMT, LVMOS, and SiC SBD are assembled on a directly bonded copper (DBC) substrate in the four-pin metal case TO-257 package. The metal plate is used as both the source terminal and heat sink. The analytical results of thermal investigation are confirmed by comparing them with the infrared thermographic measurements and numerical results obtained from a simulation using Ansys Icepak. For a power dissipation of less than 11.8 W, the peak temperature of the GaN HEMTs is 118.7 °C, obtained from thermal measurements.     

RF-LDMOS器件宏模型研究

射频器件模型是射频电路仿真的基本要素之一。为了解决射频横向双扩散金属氧化物半导体晶体管（RF-LDMOS）缺乏准确SPICE模型的问题。此处提出了一种适用于带封装结构的RF-LDMOS器件宏模型建模及提模方法,并采用MBP软件进行验证分析。结果表明该宏模型建模方法能够很好的实现数据拟合,直流特性和射频特性的误差均在5%范围内,能够准确地反映器件的电学特性。     

Rapid detection of Escherichia coli contamination in packaged fresh spinach using hyperspectral imaging

A rapid method based on hyperspectral imaging for detection of Escherichia coli contamination in fresh vegetable was developed. E. coli K12 was inoculated into spinach with different initial concentrations. Samples were analyzed using a colony count and a hyperspectroscopic technique. A hyperspectral camera of 400-1000 nm, with a spectral resolution of 5 nm was employed to acquire hyperspectral images of packaged spinach. Reflectance spectra were obtained from various positions on the sample surface and pretreated using Sawitzky-Golay. Chemometrics including principal component analysis (PCA) and artificial neural network (ANN) were then used to analyze the pre-processed data. The PCA was implemented to remove redundant information of the hyperspectral data. The ANN was trained using Bayesian regularization and was capable of correlating hyperspectral data with number of E. coli. Once trained, the ANN was also used to construct a prediction map of all pixel spectra of an image to display the number of E. coli in the sample. The prediction map allowed a rapid and easy interpretation of the hyperspectral data. The results suggested that incorporation of hyperspectral imaging with chemometrics provided a rapid and innovative approach for the detection of E. coli contamination in packaged fresh spinach.     

RF-LDMOS射频功率器件内匹配电路设计

介绍了一种RF-LDMOS功率器件内匹配电路的设计方法.首先通过ADS/De-Embed提取管芯的S参数,得到其输入阻抗;然后建立LC内匹配电路,确定电容值、电感值以及提升的目标阻抗值;最后在HFSS中建立金丝键合线模型,确定金丝键合线的长度及根数,完成内匹配电路的设计.该内匹配电路设计的目的是将管芯的输入阻抗提升为较大的阻值,使得在PCB上进行外匹配设计更为方便.设计仿真结果表明,通过在管壳内加入合适的内匹配电路,在目标频率1.2GHz时,将管芯的输入阻抗从0.8 Ω提升到12.4Ω,S11小于-46 dB,符合设计要求.为LDMOS功率器件设计者提供了一种有效的内匹配设计方法.     

用于结构损伤诊断的实用型光纤光栅传感器研究

提出了一种适用于建筑结构传感的光纤光栅传感器.用细的不锈钢管匹配叠套方式保护光纤光栅,它能与建筑结构有很好的融合.这样的传感器对应力和温度响应具有良好的线性关系,其线性拟合度达0.9996和0.9985. 分段封装光纤光栅使之具有双反射峰,通过测量两反射峰的漂移能够消除温度交扰效应.     

Determination and Control of Pesticide Residues in Beverages: A Review of Extraction Techniques,Chromatography, and Rapid Detection Methods

Abstract

We present a review concerning the determination and control of pesticide residues and transformation products in beverages. We review preparation methods using microextraction techniques, which are time-consuming, inexpensive, simple, and endeavor to be environment friendly. Mass spectrometry (MS) and tandem mass spectrometry (MS/MS) technologies are able to detect and quantify matrix-induced chromatographic response effects (matrix effects) accurately, even with the low milligram per kilogram levels. Rapid detection technology is an important tool in food product analysis. We review the technology to analyze the persistence of pesticide residues in beverages in order to effectively control their quality and safety.     

建立封装芯片热阻网络模型的方法研究

针对电子设备系统级热分析中封装芯片模型复杂程度与计算精度的矛盾,引入热阻网络法,替代系统级分析中封装芯片的详细物理模型;并以某PBGA封装芯片为例,进行两种建模方法的对比分析,同时介绍一种快速确定网络中热阻值的方法.结果表明,热阻网络等效方法具有模型简单、分析快速、准确度高的优点,在系统级热分析中可完全替代详细的物理模型.     

Analysis of UV ink photoinitiators in packaged food by fast liquid chromatography at sub-ambient temperature coupled to tandem mass spectrometry

A fast method of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed for the analysis of eleven UV ink photoinitiators in packaged food. Chromatographic separation was achieved in a pentafluorophenylpropyl (PFPP) column at 5°C and acetonitrile:25 mM formic acid-ammonium formate (pH 2.7) in gradient elution. To reduce sample treatment, a QuEChERS (quick, easy, cheap, effective, rugged and safe) method for the extraction and clean-up of UV photoinitiators in packaged foods was evaluated. Triple quadrupole working in H-SRM on Q1 mode was used for both quantitation and confirmation purposes and the most intense and selective transitions were chosen. Quality parameters of the developed QuEChERS LC-MS/MS method were established and applied for the analysis of photoinitiators in food packaged at ng kg(-1) levels.     

改善波形并增敏的光纤光栅温度传感技术

选用热膨胀系数较大的聚合物和某种偶联材料,采用特殊工艺用其对裸光纤光栅进行封装,消除了封装过程中所带来的光纤光栅啁啾现象,极大地改善了光纤光栅反射波的波形,提高了封装测试过程的重复性,为波长解调解决了一大难题.在30.6℃~120℃范围内,测量过程中波形很好并几乎不变,温度灵敏度为0.1173 nm/℃,温度分辨率为<0.43℃,比裸光纤光栅增加了11倍;平均灵敏度增敏倍数γ′=10.34,与理论计算灵敏度增敏倍数γ=10.76符合得比较好.聚合物封装光纤光栅的温度响应曲线具有很好的线性.