High performance polymer/AlN composites for electronic substrate application

An ideal high performance poly(etheretherketone) (PEEK)/AlN composite that has unique combination of anisotropic linear coefficient of thermal expansion (CTE) and dielectric properties was developed for the use in electronic packaging substrate as an alternative of conventionally used epoxy/E-glass substrate. The out-of-plane and in-plane CTEs of the composites were very close to that of copper and silicon chip, respectively. The dielectric constants of the composites are almost independent with increasing frequency. The dissipation factor decreased approximately 50% compared to the pure PEEK. These results reveal that the composite may be the futuristic candidate for high performance electronic packaging substrate.     

AlN/玻璃复合材料的低温烧结和性能

用热压方法在850～1000℃制备出低温烧结AlN/硼硅酸盐玻璃复合材料。研究了玻璃的高温行为及其对AlN的润湿能力,分析了颗粒配比对复合材料烧结致密化的影响,探讨了影响复合材料热导率的因素。结果表明:引入对AlN润湿良好的硼硅酸盐玻璃,可将烧结温度降低到1000℃以下;采用适当的AlN和玻璃粉体的粒径比有利于提高复合材料的烧结致密化程度。具有均匀显微结构的低温烧结AlN/玻璃复合材料具有良好的导热性能,其热导率高于10W/(m·K)。     

Tape casting of nickel manganite NTC ceramics for chip thermistors

Tape casting is a reliable route for mass production of precise miniature NTC chip sensors. The present paper describes the development work in tape casting of nickel manganite based NTC formulations. The most suitable dispersion condition of the powder in MEK–ethanol solvent system was determined by rheological and sedimentation studies. The optimized slurry composition for obtaining defect-free tapes was achieved by controlling the amounts of organic additives. The sintered chip samples exhibited 98% theoretical density with an over all shrinkage of 17%.     

Tape casting and dielectric properties of SiO2-filled glass composite ceramic with an ultra-low sintering temperature

The tape casting and the dielectric properties of the suitability of dielectric ceramics made of silicon dioxide-filled zinc borate glass with an ultra-low sintering temperature (650 °C) were investigated. The effects of the dispersion, the binder and the plasticizer amounts on the slurry were found to obtain an optimum composition for tape casting. The sintering temperature dependence on dielectric properties of the tape was reported. In addition, electrodes on a multilayer module made on laminated tapes were prepared using Ag paste and post-firing, followed by scanning electronic microscope to verify the chemical compatibility under the co-firing process. The results show that the composition is well suitable for the tape process for low temperature co-fired ceramic technology.     

Preparation of forsterite-based glass ceramics for LTCC from potassium feldspar

A forsterite-based glass ceramic material has been developed from potassium feldspar for low temperature co-fired ceramics (LTCC). The crystalline phases and microstructure of forsterite-based glass ceramics were investigated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The results show only forsterite was formed in temperature range 900–1,050 °C, and sapphirine was formed in temperature range 1,080–1,100 °C. The glass compact could be well densified at 950 °C, and full densification samples were obtained in temperature range 1,000–1,050 °C. The physical properties including dielectric properties, bending strength and thermal expansion of the specimens were also evaluated. The dielectric constants are in the range 7.00–8.25 and dielectric loss is below 0.01 in the frequency range 1–10 MHz. The specimens obtained in temperature range 950–1,100 °C are of high bending strength (69–106 MPa). The linear coefficient of thermal expansion of the specimen sintered at 1,080 °C is 9.76 × 10^?6 K^?1. All of these qualify the forsterite-based glass ceramic for further investigation as a candidate suitable for applications in LTCC field.     

Low permittivity SrCuSi4O10-LMZBS glass composite for LTCC applications

The tetragonal gillespite type SrCuSi₄O₁₀ (SCS) was prepared by the conventional solid-state ceramic route. The SCS sintered at 1100 °C/6 h showed ε_r = 4.0 and tan δ = 1.1 × 10⁻³ at 5 GHz. The SCS has poor sinterability and the addition of lithium magnesium zinc borosilicate glass (20: Li₂O, 20: MgO, 20: ZnO, 20: B₂O₃, 20: SiO₂) lowered the sintering temperature and improved densification. The SCS ceramic with 5 wt.% LMZBS glass sintered at 900 °C has ε_r = 5.0 and tan δ = 1.9 × 10⁻³ at 5 GHz. The composite is chemically compatible with the common electrode material silver.     

Fabrication of Al/AlN composites by in situ reaction

The tensile properties and microstructures of various Al alloys fabricated by the pressureless infiltration method under a nitrogen atmosphere were examined. The spontaneous infiltration of molten metal into the powder bed occurred at 800 °C for 1 h under a nitrogen atmosphere. As a result, it was possible to fabricate Al alloys reinforced with AlN particles formed by in situ reaction. A significant strengthening even in the control alloy occurred due to the formation of in situ AlN particle even without an addition of artificial reinforcement. Strength values of the control alloy were increased with decreasing Al powders in bottom powders bed. In addition, tensile strength in Al–Mg alloys was increased with Mg content.     

Dielectric cure monitoring for glass/polyester prepreg composites

The on-line cure monitoring of fiber reinforced thermosetting resin matrix composite material has been performed for improving quality and productivity during manufacturing. Since the dissipation factor measured by dielectrometry method is dependent on the degree of cure and temperature of resin, in this study, a new method to obtain the degree of cure during on-line cure monitoring for S-glass/polyester composites without temperature effect was developed by employing a combination function of the temperature and the dissipation factor. The temperature signal was measured with a K-type thermocouple and the dissipation factor signal was measured with an interdigital dielectric sensor during curing process. Then the calculated degree of cure using the measured data from dielectrometry was compared to the measured value from differential scanning calorimetry. The developed on-line cure monitoring method was applied to a 2-step cure cycle for the verification of the developed procedure.     

玻璃纤维/聚丙烯复合材料界面研究

采用γ射线预辐照固相接枝和偶联剂分别对聚丙稀粉粒 (PP)和玻璃纤维 (GF)进行表面改性 .研究接枝PP在基体中的含量、玻璃纤维经偶联剂处理对复合材料层间剪切强度 (ILSS)、拉伸强度的影响 .通过SEM对复合材料的拉伸断口进行了分析 .     

Environmental rupture of PPS/glass composites

Journal of Materials Science Letters -     

原位TiB/Ti复合材料的熔铸制备及其显微组织

结合Ti-B-Al体系的热力学及Ti-B相图,提出了可制备薄壁、复杂形状原位自生钛基复合材料构件的SMIF工艺.采用XRD、SEM和TEM等手段研究用该工艺制备的复合材料的相组成和显微组织.结果表明,钛基复合材料中生成了TiB增强相,且在基体中分布均匀,呈短纤维状;并且Al的加入使得TiB相具有较高的长径比,最高可达110.TiB增强相/基体界面清洁、无污染.受熔模精铸陶瓷型壳的激冷作用,钛基复合材料铸锭表层中TiB相垂直于铸锭的表面分布.与基体合金相比较,钛基复合材料的力学性能有了很大程度的提高.     

Alumina-coated hollow glass spheres/alumina composites

Coating of alumina onto the surface of hollow glass spheres was accomplished by controlled heterogeneous precipitation from aqueous solutions. The processing conditions were optimized to yield thin and uniform precursor coatings. After calcination, converting the precursor to alumina, the alumina-coated hollow glass spheres formed free-flowing powders that were used to produce glass/alumina composites with up to 35 vol% of controlled and well dispersed closed porosity. The dielectric constants and the flexural strengths of such porous composites were determined as a function of porosity. This revised version was published online in November 2006 with corrections to the Cover Date.     

Aligned short glass fibre/epoxy composites

An orientation system based on the principles of the ERDE glycerine process was built and used to prepare short glass fibre mats of known orientation distributions. The mats were subsequently impregnated with epoxy, B staged to yield partially cured prepregs and finally compression moulded. Mechanical characterization and comparison with theoretical formulations were performed on longitudinal, transverse and off-axis specimens. The mechanical characteristics of specimens with different orientation patterns were compared with analytical predicitions based on ‘Laminate analogy’ methods. Fracture surfaces were studied by optical and scanning electron microscopy techniques.     

Shrinkage stresses in glass/resin composites

A simple model has been used to calculate the residual stresses in polyester-resin/glass fibre composites that arise when the material is cooled from the post-curing temperature. An elementary elasticity solution for shrink-fit stresses gives a value of the order of 24 MNm^–2 for interfacial pressures in a single fibre model, and it appears that this stress is between 10 and 20% lower if the matrix is a hypothetical material having the properties of a composite. The pull-out stress for a glass fibre in polyester resin is estimated to be 7.6 MNm^–2, in good agreement with earlier experimental results.     

Molecular characterization of glass fiber surface coatings for thermosetting polymer matrix/glass fiber composites

Model multi-component glass fiber sizings, with formulations based upon current patent disclosures, were prepared to model the full coating packages used in commercial glass fiber manufacture. The sizings consisted of silane coupling agent, film former, and emulsifying surfactant in water and were applied to glass fibers prepared directly from molten glass. Fibers were analyzed before and after acetone extraction. The analyses of the extract solutions, with the fiber analysis, were used to determine the quantity and quality of the physically and chemically adsorbed layers. It was found that all three species remain on the fiber after extraction and that both coupling agent and surfactant concentrations in the coatings are higher than in the applied sizing. The impact of these species on the polymer composite/glass fiber interphase is discussed.