氧化铝陶瓷基板过孔的新型激光打孔工艺

陶瓷基板激光打孔一固有缺点即孔周围会形成大量不规则堆溅物。提出一种直接在凝胶注模成型陶瓷素坯上激光打孔的新工艺。Nd:YAG激光在氧化铝上打孔的研究表明,该方法能大大减少堆溅物的形成,从而得到分布致密、形状规则的微孔。     

Footprint study of ultrasonic wedge-bonding with aluminum wire on copper substrate

The effects of the process parameters of ultrasonic power and normal bonding force on bond formation at ambient temperatures have been investigated with scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis. A model was developed based on classical microslip theory¹ to explain the general phenomena observed in the evolution of bond footprints left on the substrate. Modifications to the model are made due to the inherent differences in geometry between ball-bonding and wedge-bonding. Classical microslip theory describes circular contacts undergoing elastic deformation. It is shown in this work that a similar microslip phenomenon occurs for elliptical wire-to-flat contacts with plastically deformed wire. It is shown that relative motion exists at the bonding interface as peripheral microslip at lower powers, transitioning into gross sliding at higher powers. With increased normal bonding forces, the transition point into gross sliding occurs at higher ultrasonic bonding powers. These results indicate that the bonding mechanisms in aluminum wire wedge-bonding are very similar to those of gold ball-bonding, both on copper substrate. In ultrasonic wedge-bonding onto copper substrates, the ultrasonic energy is essential in forming bonding by creating relative interfacial motion, which removes the surface oxides.     

Annealing effects of a high-quality ZnTe substrate

The sharp photoluminescence (PL) and optical-reflection spectra in the bandedge region of the high-quality nondoped ZnTe substrate (100) were observed at 4.2 K. Free exciton, associated with lower and upper polaritons (EX^L and EX^U) at 2.382 eV and 2.381 eV, respectively, were clearly observed. This meant that this substrate was high quality. The intensity of a bound exciton peak (2.375 eV), which is caused by a Zn vacancy, of a neutral acceptor decreased with an increase of the Zn vapor pressures.     

Molecular beam epitaxy growth of high-quality HgCdTe LWIR layers on polished and repolished CdZnTe substrates

We report here molecular beam epitaxy (MBE) mercury cadmium telluride (HgCdTe) layers grown on polished and repolished substrates that showed state-of-the-art optical, structural, and electrical characteristics. Many polishing machines currently available do not take into account the soft semiconductor materials, CdZnTe (CZT) being one. Therefore, a polishing jig was custom designed and engineered to take in account certain physical parameters (pressure, substrate rotational frequency, drip rate of solution onto the polishing pad, and polishing pad rotational velocity). The control over these parameters increased the quality, uniformity, and the reproducibility of each polish. EPIR also investigated several bromine containing solutions used for polishing CZT. The concentration of bromine, as well as the mechanical parameters, was varied in order to determine the optimal conditions for polishing CZT.     

Dual-band infrared detectors made on high-quality HgCdTe epilayers grown by molecular beam epitaxy on CdZnTe or CdTe/Ge substrates

In this paper, we present all the successive steps for realizing dual-band infrared detectors operating in the mid-wavelength infrared (MWIR) band. High crystalline quality HgCdTe multilayer stacks have been grown by molecular beam epitaxy (MBE) on CdZnTe and CdTe/Ge substrates. Material characterization in the light of high-resolution x-ray diffraction (HRXRD) results and dislocation density measurements are exposed in detail. These characterizations show some striking differences between structures grown on the two kinds of substrates. Device processing and readout circuit for 128×128 focal-plane array (FPA) fabrication are described. The electro-optical characteristics of the devices show that devices grown on Ge match those grown on CdZnTe substrates in terms of responsivity, noise measurements, and operability.     

Processing, microstructure, properties and wear behavior of in situ synthesized TiB2 and TiC thick films on steel substrates

TiB₂ and TiC reinforced Fe matrix thick films (2 mm thickness) were produced through the synthesis reaction from Ti, C and FeB powders with varying porosity on the steel substrates. Powder technology was used as a processing method. The films and the substrates were sintered in a single step. TiB₂, TiC and Fe were detected in the films by X-ray diffraction analysis. The fact that no other reaction product was detected revealed the thermal stability of TiB₂ and TiC. The formation of secondary reaction products was inhibited during the reactive sintering. The films showed maximum strength of 163-466 MPa when sintered separately at 1350 °C. The strength of the films varied with their porosity. The films showed considerable bonding strength with the steel substrates. The delamination of the films from the steel substrates was observed at stress values from 454-781 MPa. The microstructure, fracture and delaminated surface morphologies were studied. The wear resistance against hardened high speed steel was studied in reciprocating sliding tests. The wear mechanisms were discussed by means of microscopical observation on the worn surfaces.     

Reliability of transparent conducting substrates for rollable displays: A cyclic loading investigation

Abstract— Failure mechanisms for flexible conducting substrates are investigated herein in the context of rollable/flexible display applications. Cyclic loading experiments (substrates subjected to multiple cycles of tensile strain) were carried out on both ITO‐coated PET and PEDOT:PSS‐coated PET substrates. The resistance was measured after each bending cycle. The resistance increased with the number of cycles and was not reversible. Even when the tensile strain on the ITO/PET was below the virgin cracking threshold (～2%) previously reported [Appl Phys Lett ⁷⁶, 1425 (2000)], slight increases in resistance were measurable after just a few cycles.     

Fed-batch digestion of insoluble solid-state substrates

Performance equations for the fed-batch digestion of insoluble solid-state substrates were developed based on a verified interfacial kinetic model for microbial uptake of these substrates. Fed-batch anaerobic digestions of a suspension of stearic acid with a mean particle size of 2 μm were conducted to verify the derived equations. Agreement between the experimental and calculated results indicated the validity of these equations. The performance equations should be useful for describing the time courses of cell growth, substrate consumption and product accumulation in a fed-batch digestion system with insoluble solid-state organics as substrate.     

Substrate issues for the growth of mercury cadmium telluride

Close lattice matching and lattice compatibility with mercury cadmium telluride (MCT) make CdTe and related alloys ideal substrate materials for growth of MCT layers for the purpose of making high-performance second-generation infrared detectors. However, the limitations in the properties of CdTe and the difficulties in its bulk growth have prompted extensive research in the area of alternative substrates. Some basic relevant characteristics of substrates such as sapphire, GaAs, and silicon are compared and the possibilities and problems associated with each material are analyzed in the light of the most recent results in the field.