Technical Library | 2011-12-22 16:45:49.0
This paper reports the feasibility of using surface mount adhesives to produce low temperature microchannel arrays in a wide variety of metals. Sheet metal embossing and chemical etching processes have been used to produce sealing bosses that eliminate ch
OSU School of Mechanical, Industrial, and Manufacturing Engineering (MIME)
Technical Library | 2014-12-04 18:27:40.0
A review on applications of metal-based inkjet inks for printed electronics with a particular focus on inks containing metal nanoparticles, complexes and metallo-organic compounds. The review describes the preparation of such inks and obtaining conductive patterns by using various sintering methods: thermal, photonic, microwave, plasma, electrical, and chemically triggered. Various applications of metal-based inkjet inks (metallization of solar cell, RFID antennas, OLEDs, thin film transistors, electroluminescence devices) are reviewed.
Technical Library | 2013-10-03 16:05:39.0
Printed Circuit Board (PCB) is an essential component of almost all electrical and electronic equipments. The rapid growth of the use of such equipments has contributed enormously to the generation of large quantity of waste PCBs. The WPCBs not only contain valuable metals but also a large variety of hazardous materials. Conventional treatments of such WPCBs have their own limitations. By pyrolysis of WPCBs, it is not only possible to obtain the organic part of it as a fuel or useful chemical but can make further processing to recover metals much easier and efficient. In the present work, a kinetic study on the low temperature pyrolysis of WPCBs using a thermogravimetric analyser has been attempted...
Technical Library | 2016-12-29 15:37:51.0
The reliabilities of the flux residue of electronic assemblies and semiconductor packages are attracting more and more attention with the adoption of no-clean fluxes by majority of the industry. In recent years, the concern of "partially activated" flux residue and their influence on reliability have been significantly raised due to the miniaturization along with high density design trend, selective soldering process adoption, and the expanded use of pallets in wave soldering process. When flux residue becomes trapped under low stand-off devices, pallets or unsoldered areas (e.g. selective process), it may contain unevaporated solvent, "live" activators and metal complex intermediates with different chemical composition and concentration levels depending on the thermal profiles. These partially-activated residues can directly impact the corrosion, surface insulation and electrochemical migration of the final assembly. In this study, a few application tests were developed internally to understand this issue. Two traditional liquid flux and two newly developed fluxes were selected to build up the basic models. The preliminary results also provide a scientific approach to design highly reliable products with the goal to minimize the reliability risk for the complex PCB designs and assembly processes. This paper was originally published by SMTA in the Proceedings of SMTA International
Technical Library | 2020-09-02 22:02:13.0
With the adoption of Wafer Level Packages (WLP) in the latest generation mobile handsets, the Printed Circuit Board (PCB) industry has also seen the initial steps of High Density Interconnect (HDI) products migrating away from the current subtractive processes towards a more technically adept technique, based on an advanced modified Semi Additive Process (amSAP). This pattern plate process enables line and space features in the region of 20um to be produced, in combination with fully filled, laser formed microvias. However, in order to achieve these process demands, a step change in the performance of the chemical processes used for metallization of the microvia is essential. In the electroless Copper process, the critical activator step often risks cross contamination by the preceding chemistries. Such events can lead to uncontrolled buildup of Palladium rich residues on the panel surface, which can subsequently inhibit etching and lead to short circuits between the final traces. In addition, with more demands being placed on the microvia, the need for a high uniformity Copper layer has become paramount, unfortunately, as microvia shape is often far from ideal, the deposition or "throw" characteristics of the Copper bath itself are also of critical importance. This "high throwing power" is influential elsewhere in the amSAP technique, as it leads to a thinner surface Copper layer, which aids the etching process and enables the ultra-fine features being demanded by today's high end PCB applications. This paper discusses the performance of an electroless Copper plating process that has been developed to satisfy the needs of challenging amSAP applications. Through the use of a radical predip chemistry, the formation, build up and deposition of uncontrolled Pd residues arising from activator contamination has been virtually eradicated. With the adoption of a high throwing power Copper bath, sub 30um features are enabled and microvia coverage is shown to be greatly improved, even in complex via shapes which would otherwise suffer from uneven coverage and risk premature failure in service. Through a mixture of development and production data, this paper aims to highlight the benefits and robust performance of the new electroless Copper process for amSAP applications
Technical Library | 2023-03-27 19:18:38.0
Electronic waste (e-waste) is currently the fastest growing hazardous waste stream that continues to be a challenging concern for the global environment and public health. The average useful life of electronic products has continued to decline, and obsolete products are being stored or discarded with increasing frequency. E-waste is hazardous, complex and expensive to treat in an environmentally sound manner. As a result, new challenges related to the management of e-waste have become apparent. Most electronic products contain a combination of hazardous materials, toxic materials, and valuable elements such as precious metals and rare earth elements. There are risks to human health associated with the disposal of E-waste in landfills, or treatment by incineration. Americans discard 400+ million electronic items per year recycling less than 20 percent in safe and sustainable manner. E-waste is exported from developed countries and processed informally using unsafe conditions in many regions of developing countries. A mixture of pollutants is released from these informal rudimentary operations. Exposure to e-waste recycling includes the dismantling of used electronics and the use of hydrometallurgical and pyrometallurgical processes, which emit toxic chemicals, to retrieve valuable components. Thermal analysis integrated with chromatographic and spectroscopic techniques are used to determine dangerous chemicals emitted during the burning of e-waste. The information is used to assess the risk of exposure of workers at these semi-formal recycling centers.
Technical Library | 2018-05-09 22:15:29.0
Creep corrosion on printed circuit boards (PCBs) is the corrosion of copper metallization and the spreading of the copper corrosion products across the PCB surfaces to the extent that they may electrically short circuit neighboring features on the PCB. The iNEMI technical subcommittee on creep corrosion has developed a flowers-of-sulfur (FOS) based test that is sufficiently well developed for consideration as an industry standard qualification test for creep corrosion. This paper will address the important question of how relative humidity affects creep corrosion. A creep corrosion tendency that is inversely proportional to relative humidity may allow data center administrators to eliminate creep corrosion simply by controlling the relative humidity in the data center,thus, avoiding the high cost of gas-phase filtration of gaseous contamination. The creep corrosion relative humidity dependence will be studied using a modified version of the iNEMI FOS test chamber. The design modification allows the achievement of relative humidity as low as 15% in the presence of the chlorine-releasing bleach aqueous solution. The paper will report on the dependence of creep corrosion on humidity in the 15 to 80% relative humidity range by testing ENIG (gold on electroless nickel), ImAg (immersion silver) and OSP (organic surface preservative) finished PCBs, soldered with organic acid flux.
Technical Library | 2019-11-15 02:20:26.0
Material Aging Test-UV Weathering Test Chamber 1.What is UV aging? UV aging chambers use fluorescent ultraviolet lamp as light source to simulate UV radiation and condensation in natural sunlight, and to carry out accelerated weather resistance test in order to obtain the result of weather resistance of the material. UV aging detection is widely used in non-metallic materials, organic materials (such as coatings, paints, rubber, plastics and their products) under the change of sunlight, humidity, temperature, condensation and other climatic conditions to test the aging degree and situation of related products and materials. 2.Why we should do UV aging test? When the product is placed in the ambient environment, there will be different problems taken place, such as appearance changes, including cracking, speckle, powdering or color change, and even performance degradation,which may be due to the loss of components in the resin resulting in chemical bonds changes inside the molecular structure, this is mainly caused by sunlight, industrial exclusion of waste gas, bacteria and so on. The aging performance of the product directly affects the lifespan of the product, so aging test become significant,non-metallic materials, organic materials (such as paints, paints, rubber, plastics and their products) are subject to changes in sunlight, humidity, temperature, condensation and other climatic conditions to test the degree and condition of aging of related products and materials. The natural aging test is to put the plastic specimen under the sun exposure, and it is directly under the natural climate environment,to test the material performance under various factors such as light, heat energy, atmospheric humidity, oxygen and ozone, industrial pollution and the like, the most harsh climate condition should be selected,or near the actual application area of the material, the test site shall be open and flat, no obstacle to affect the test results,the specimen holder shall be facing the equator and at an angle of 45 ° from the ground. When the main performance index of the specimen has been reduced, the test s/b terminated when it achieve the minimum allowable use value . in most case,the test is terminated when the product primary performance index falls to 50% of the initial value. The natural aging process is a very slow process, and there is a great difference in different geographical conditions, which brings difficulties to evaluate the aging resistance of the product. It is an attempt to make an evaluation of the aging performance of the plastic in a shorter time,that is accelerated aging test. The accelerated aging test can be used to simulate the human light source of the fluorescent lamp, including the carbon arc lamp, the xenon arc lamp and the fluorescent ultraviolet lamp, and the artificial light sources can generate more light than the natural sunlight on the ground. When these artificial light sources are used, it is also common to use the combination of the condenser to simulate the rain drop, the dew and the like to conduct the aging test on the product.
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