Elevated temperature impact on performance of Low Temperature Co-fired Ceramic dielectrics

The need for electronics to operate at temperatures of 200°C and above continues to grow. These applications include avionics, aerospace, automotive, downhole drilling, mining, and many others. To satisfy this demand, a significant amount of research and development has been conducted. Despite the efforts, the number of new electronic components designed specifically for high-temperature operation is still relatively limited. In Low Temperature Co-fired Ceramic (LTCC) packages, LTCC materials are generally used as the host media for a number of pre-fabricated semiconductor components. As a result, reliability of the entire LTCC package largely depends on the performance of the least robust component. Ferro A6M-E and Ferro L8 are the two well-established and recognized LTCC dielectrics widely used for mid and high frequency LTCC applications, including several high reliability aerospace and defense applications that require demanding Mil-Spec qualifications. This study is our first attempt to characterize and understand basic high-temperature dielectric properties of these two commercial LTCC materials. The secondary objective is to initiate a dialogue in attempt to establish reliability requirements for LTCC packages dedicated for high-temperature operation.     

LTCC水基流延生带材料的制备与叠层性能

利用硼硅酸盐玻璃和氧化铝陶瓷复合制备了相对介电常数为7～9的LTCC材料粉体,利用苯丙乳液作为粘结剂,甘油作为增塑剂,成功制备出了浆料固含量高、稳定性好的水基流延浆料; 该工艺制备的生带材料表面光滑,强度高,且容易在室温下叠层,经过850～900 ℃烧结,其相对体积密度最高可以达到96%以上;以上述LTCC生带为原材料,在室温条件下制备了烧结性能良好的叠层器件,具有很好的应用前景.     

一种基于LTCC 的吸收式低通滤波器的设计

为了阻止阻带反射信号回到信号源,设计了一款LTCC半分布式吸收低通滤波器。该滤波器通过衰减电阻把阻带能量衰减掉,在不增加插入损耗的情况下达到吸收阻带反射信号的效果。仿真结果表明,该款滤波器的3 dB截止频fc=2.5 GHz,带内回波损耗大于20 dB,6fc处对反射信号的吸收大于12 dB,3.7 GHz处的带外抑制大于20 dB,模型尺寸仅为4.8 mm×3.6 mm×1.43 mm。     

一种改进结构的毫米波基片集成波导滤波器

介绍了基片集成波导（SIW）这一新技术,并对其中的主模（TE10）进行了简要分析。为了实现毫米波电路系统小型化,对传统链式SIW滤波器进行改进,提出了一种新型的带倒角的紧缩结构SIW滤波器。利用这2种结构,设计了中心频率为31.15 GHz,3 dB带宽2.4 GHz,相对带宽7.7%,插损小于1.9 dB的带通滤波器。仿真结果表明：带倒角的紧缩结构SIW滤波器不仅布局更紧凑,最大长度缩短了近一半,而且具有更好的滤波性能。     

含钡玻璃陶瓷LTCC粉体的表面修饰及其对玻璃陶瓷性能的影响

为了降低BaO-TiO2-B2O3-SiO2玻璃陶瓷中钡离子的析出,通过化学沉淀法和硫酸处理法对玻璃陶瓷粉体进行了表面修饰,在玻璃陶瓷粉体的表面形成了一层不溶于水的无机膜(氧化铝或BaSO4),不仅阻断了LTCC中钡离子与水的接触途径,使LTCC玻璃陶瓷粉体制备可适用于水基流延工艺的浆料,且操作简便,无毒副作用.研究发现用共沉淀法包覆氧化铝对玻璃陶瓷的性能影响不大,但是硫酸包覆处理后大大提高了玻璃陶瓷的烧结温度,限制了LTCC的应用.     

LTCC专用烧结炉的应用及发展趋势

综述了LTCC烧结的原理、特点与技术要求。举例阐述了两种LTCC专用烧结炉在行业中的应用状况,指出了LTCC专用烧结设备在当前应用中存在的问题,并展望了发展趋势。     

Fabrication and advanced electrical and stability characterization of laser-shaped thick-film and LTCC microresistors for high temperature applications

Thick-film and LTCC (Low Temperature Co-fired Ceramics) technologies are well-established and relatively low-cost fabrication method of passives. This paper presents systematic studies of fabrication and a wide spectrum of geometrical and electrical properties of thick-film and LTCC microresistors with dimensions down to 30 × 200 μm². The geometrical parameters (average length, width and thickness, relations between designed and real dimensions, distribution of planar dimensions) are correlated with basic electrical properties of resistors (sheet resistance, temperature dependence of resistance), long-term stability as well as durability of microresistors to short electrical pulses in the temperature range from 25 °C to 400 °C.     

LTCC层压工艺及设备

层压是LTCC工艺中继切片、冲孔、填充、印刷、叠片之后的工序,层压之后再经过热切、烧结成为LTCC成品。介绍了LTCC层压的原理和工艺及3种加压曲线。根据LTCC层压工艺要求,阐述了层压机的研发。     

高性能LTCC高温压力传感器的制备

研究了通过烧结曲线优化来实现无排气孔结构的高性能低温共烧陶瓷（ LTCC）无源高温压力传感器的制备。通过对比实验,成功摸索出了无排气孔结构的传感器烧结温度曲线。相比于传统LTCC压力传感器,该无排气孔结构的传感器由于无需玻璃浆料封口,避免了由于两种材料高温下热膨胀系数不匹配导致的传感器密封失效问题,确保了传感器在高温下工作的可靠性。测试结果表明：在2.0 bar,400℃以内,所制备的LTCC高温压力传感器具有极好的灵敏度和线性度,最大平均灵敏度为1.96 MHz/bar,最大非线性误差为4.52%,优于之前国内外研究水平。     

X 波段四通道MMCM 基板设计

低温共烧陶瓷（LTCC）是制作微波多芯片组件（MMCM）基板的理想材料。本文介绍了基于LTCC 工艺的微 波传输线、集成腔体、功分器和散热过孔的设计。对于多通道微波组件,采用带状传输线和腔体结构有利于实现通道 间的高隔离度,集成功分器和浆料电阻有利于实现组件的小型化并可获得较好的微波性能,而矩阵散热过孔可以显著 改善基板导热性能,满足小功耗器件的散热要求。