Beam lead technology

Beam lead technology for microcircuit interconnections with applications to metallization, passivation, and bondin

NASA Contributions to Development of Special-Purpose Thermocouples. A Survey

The thermocouple has been used for measuring temperatures for more than a century, but new materials, probe designs, and techniques are continually being developed. Numerous contributions have been made by the National Aeronautics and Space Administration and its contractors in the aerospace program. These contributions have been collected by Midwest Research Institute and reported in this publication to enable American industrial engineers to study them and adapt them to their own problem areas. Potential applications are suggested to stimulate ideas on how these contributions can be used

Electrical termination techniques

A technical review of high reliability electrical terminations for electronic equipment was made. Seven techniques were selected from this review for further investigation, experimental work, and preliminary testing. From the preliminary test results, four techniques were selected for final testing and evaluation. These four were: (1) induction soldering, (2) wire wrap, (3) percussive arc welding, and (4) resistance welding. Of these four, induction soldering was selected as the best technique in terms of minimizing operator errors, controlling temperature and time, minimizing joint contamination, and ultimately producing a reliable, uniform, and reusable electrical termination

Research and development program on magnetic electrical conductor, electrical insulation, and bore seal materials - Electrical conductor and electrical insulation materials topical report

Electrical, mechanical, and thermo-physical properties of conductor and insulation materials for application to advanced space electric power system

Synthesis and Application of Ceramic Paste for High-Temperature Electronic Packaging

This dissertation research focused on the synthesis and application of ceramic paste for high-temperature applications. An alumina paste material comprising aluminum dihydric phosphate and alumina powder was developed for high-temperature electronic packaging. Nano aluminum nitride and nano-silica powders were embedded to promote the paste curing process, limit the grain growth, and increase its bond shear strength. The chip-to-substrate bond strength was enhanced and met the MIL-STD requirements for die-attach assembly. Its encapsulation property was improved with fewer cracks compared to similar commercial ceramic encapsulants. The die-attach material and encapsulation properties tested at 500°C showed no defect or additional cracks. Thermal aging and thermal cycling were carried out on the synthesized paste. XPS analysis revealed a higher oxygen bonding percentage for the 10% nanosilica ceramic sample than other samples. XRD peak broadening is largest for the 10% nano-silica ceramic which indicated smaller crystallite sizes. The smaller crystallite size for the 10% nanosilica sample introduces a larger microstrain to the alumina crystal structure. FTIR revealed the presence of alumina-silicate bonds on these samples with the largest amount present in the 10% nanosilica samples. SEM and EDX results showed a uniform bond line for the 10% sample and uniform material distribution. An electronic packaging technology that survives the Venusian condition was developed. Alumina ceramic substrates and gold conductors on alumina were evaluated for electrical and mechanical performance. The most promising die-attach materials were found to be thick-film gold and alumina-based ceramic pastes. Alumina, sapphire, silicon, and silicon carbide dice were attached to the alumina substrates using these die-attach materials and exposed to the Venusian condition for 244 hours. The devices on the packaging substrates were encapsulated by a ceramic encapsulant with no significant increase in cracks and voids after the Venusian simulator test. Wire pull strength tests were conducted on the gold bond wire to evaluate mechanical durability before and after the Venusian simulator exposure test with about 30.8% decrease which satisfied the minimum requirement for the MIL-STD-885 method. The overall wire-bond daisy-chain resistance change was 0.47% after the Venus simulator test, indicating a promising wire bond integrity. A titanium package was fabricated to house the ceramic packaging substrate and a two-level metalized feedthrough was fabricated to provide electrical interfaces to the package. A double-layer ceramic electronic packaging technology that survives the Venusian surface condition was developed using a ceramic interlayer dielectric with gold conductors. A 60-µm ceramic interlayer dielectric served as the insulator between the top and bottom gold conductors on high-purity ceramic substrates. Test devices with AuPtPd metallization were attached to the top gold pads using a thick-film gold paste. Thermal aging for 115 hours at 500°C and thermal cycling from room temperature to 450°C were performed. Dielectric leakage tests of the interlayer ceramic layer between the top and bottom gold conductors revealed a leakage current density of less than 50 10-7 A/cm2 at 600V after thermal cycling. The die shear test showed a 33% decrease in die shear strength after thermal tests but still satisfies the MIL-STD method

Cabling and connectors for use on a nuclear stage Final report

Cabling and connectors for use on nuclear stage, environmental and related test

Electrical and thermal stability of Al-Cu welds: Performance benchmarking of the hybrid metal extrusion and bonding process

Advances in joining processes for aluminum and copper are sought after to facilitate the greater adoption of aluminum in electrical applications. Aluminum's chemical affinity to copper causes the joining and lifetime of Al-Cu welds to be vulnerable to the formation of various intermetallic compounds. Intermetallic compounds and the resulting weld structure are known to reduce the structural integrity and increase the electrical resistance of Al-Cu welds. In this study we evaluate the novel joining process, Hybrid Metal Extrusion and Bonding, for butt welding aluminum and copper. The weld structure was examined using scanning and transmission electron microscopy, and the weld resistance was measured using four-point measurements forecast to the weld interface. Energy dispersive spectroscopy and electron diffraction zone axis patterns were analysed to identify intermetallic compounds. Weld samples were examined pre and post heat treatment at 200 °C, 250 °C and 350 °C for total durations of over 1000 h. The results are compared to existing Al-Cu joining processes, and a new metric, weld interface resistivity, is proposed to compare the electrical properties of bimetallic welds. The Hybrid Metal Extrusion and Bonding process was found to form a thin, consistent and straight intermetallic layer with negligible impact on electrical resistance in the as-welded condition. Artificial ageing of samples by heat treatment established the overall growth rate of intermetallic compounds. The growth rate was used to evaluate the weld's operational lifetime versus temperature. The intermetallic growth rate of Hybrid Metal Extrusion and Bonding was quantified at 200 °C and compared to alternative processes. The Hybrid Metal Extrusion and Bonding process showed a significant performance advantage requiring the longest time to reach 2 μm thickness. Furthermore, the growth of intermetallic compounds did not increase the electrical resistance of the weld interface. The negligible impact on electrical resistance and slow intermetallic growth are promising results of the potential functional performance. This study is the first characterisation of the Hybrid Metal Extrusion and Bonding process for electrical applications showcasing its exciting potential for the joining of aluminum and copper.publishedVersio

Design and develop a MOS magnetic memory Final report, 11 Mar. - 11 Sep. 1966

Interface problems between plated wire magnetic memory and MO

Design guidelines for use of adhesives and organic coatings in hybrid microcircuits

A study was conducted to investigate the reliability of organic adhesives in hybrid microcircuits. The objectives were twofold: (1) to identify and investigate problem areas that could result from the use of organic adhesives and (2) to develop evaluation tests to quantify the extent to which these problems occur for commercially available adhesives. Efforts were focused on electrically conductive adhesives. Also, a study was made to evaluate selected organic coatings for contamination protection for hybrid microcircuits

Prediction of properties for the production and application of graphene reinforced metal matrix composites

This paper presents the development of finite element analysis (FEA) modelling for the prediction of the properties of the metal matrix composites (MMCs) reinforced with graphene. Process parameters taken into consideration were matrix metal (such as Al, Mg Ti, Ni, Cu and Fe) and volume fractions (1%, 5%, 10%, 15%, and 20%) of graphene. The FEA model was developed using ANSYS 14 based on the assumptions that it is free of voids and irregularities, and that the graphene sheets are perfectly aligned. Modelling results were discussed in relation to experimental data from the literature and also verified with theoretical methods; Rule of Mixtures (ROM) and Bettie’s reciprocal theorem. The comparative study of results obtained from the analysis of composite has shown that the properties such as Young's moduli and Poisson's ratio and electrical conductivity of the material are significantly enhanced by the reinforcing graphene in the metal matrix. In particular, it was found that there is a significant increase of longitudinal Young's modulus with increasing volume fraction of graphene reinforcement. Graphene reinforced MMCs has the capability as an advanced composite material of being applied in many highly demanding advanced engineering applications in aero, auto and energy industries. In this paper, the case for application of aluminium-graphene metal matrix composite as the material of choice for power transmission lines is elaborated