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Nowadays, hydroponic cultivation represents a widely used agricultural methodology. The purpose of this paper is to study comparatively on hydroponic substrates. This study is highlighting the best substrate to be involved in hydroponic systems, considering its costs and its sustainability.

Seven substrates were evaluated: rock wool, perlite, vermiculite, peat, coconut fibres, bark and sand. Life cycle assessment (life cycle inventory, life cycle impact assessment (LCIA) and life cycle costing (LCC)) was applied to evaluate the environmental and economic impact. Through the results of the impacts, the carbon footprint of each substrate was calculated.

Perlite is the most impacting substrate, as highlighted by LCIA, followed by rock wool and vermiculite. The most sustainable ones, instead, are sand and bark. Sand has the lower carbon footprint (0.0121 kg CO₂ eq.); instead, bark carbon footprint results in one of the highest (1.1197 kg CO₂ eq.), while in the total impact analysis this substrate seems to be highly sustainable. Also for perlite the two results are in disagreement: it has a high total impact but very low carbon footprint (0.0209 kg CO₂ eq.) compared to the other substrates. From the LCC analysis it appears that peat is the most expensive substrate (€6.67/1,000 cm³), while sand is the cheaper one (€0.26/1,000 cm³).

The LCA and carbon footprint methodologies were applied to a growing agriculture practice. This study has highlighted the economic and environmental sustainability of seven substrates examined. This analysis has shown that sand can be the best substrate to be involved in hydroponic systems by considering its costs and its sustainability.

The purpose of this paper is to attempt to study the failure mechanism of BGA (ball grid array) Cu wire bond ball lift and specifically focused on substrate outgassing’s impact on Cu wire bonding quality and reliability.

The Galvanic corrosion theory has been widely adopted in explaining the failure mechanism of Cu ball bond lift issue during reliability test or field application in the presence of moisture. In this study, ion chromatography was performed on BGA substrate halogen analysis. EDX (energy-dispersive X-ray spectroscopy) was also used to detect the contaminant’s element at the bottom surface of a window clamp. Further FTIR (Fourier transform infrared spectroscopy) analysis verified that the contamination is from substrate outgassing during wire bonding. A new window clamp design proved effective in reducing the negative impact from substrate outgassing during wire bonding.

The solder mask in a fresh substrate contains a chlorine element. The chlorine can be detected in the BGA substrate outgassing during wire bonding by FTIR and EDX analyses, which have a negative impact on the Cu wire bonding. The window clamp with a larger opening can reduce the negative impact of the Cu wire bonding from the BGA substrate outgassing.

Because of the limitation of time and resources, bonding pad surface contamination from substrate outgassing and its correlation with Cu bonding ball lift failure after reliability test will be studied in depth later.

The BGA substrate outgassing has negative impacts on Cu wire bondability. A window clamp with a larger opening can reduce the negative impact from substrate outgassing.

Compared with the traditional printed circuit board (PCB) drilling process, the technology of drilling IC substrate is facing more problems, such as much smaller hole diameter, more intensive hole space, thinner sheet and more complicated materials are drilled in process. Moreover, the base material of IC substrate is different from traditional PCB, more kinds of fillers added in IC substrate which make the drill worn seriously during drilling process. Micro-drills wear and micro holes quality are the most important questions when drilling IC substrate so far. Wear morphology of micro-drill, holes wall roughness and hole location accuracy are researched in this paper. The influence factors of micro-drills wear and micro holes quality are also studied in this drilling process. The paper aims to discuss these issues.

Two drills with same structure and different diameter are used to drill different stacks of IC substrate and drill different holes in this paper. There are four experiments made and the drilling parameters including spindle speed (n), feed rate (v_f) and retraction speed (v_r) are recommended by drill manufacturing company. Wear morphologies of drill are observed, holes wall roughness (R_max) and holes location accuracy (C_pk) are measured in this paper. Analyzing the main factors influence on drill wear, holes wall roughness and holes location accuracy through these experiments.

The micro-drills of IC substrate wear more severely compared with other material of PCB through the experimental results in this paper. Drill diameter has influence on micro-drill wear when drilling IC substrate, the smaller of drill is, the more severely of micro-drill wears. Drill diameter affect the holes wall roughness too, the holes wall roughness of larger holes is better than smaller one in a certain range. The drilled holes number also has influence on micro-drills wear, holes wall roughness and holes location accuracy. The more drilled holes, the seriously of micro-drills wear, and the worn drill would destroy the hole quality. Therefore, the more drilled holes lead the bad holes wall roughness and holes location accuracy in this paper. In addition, stacks of IC substrate affect much on the holes location accuracy, the more stacks, the worse holes location accuracy.

Chinese Mainland is obviously lagging behind in technology and manufacturer of IC substrate which is incompatible with the nation circumstances. There is few research of drilling IC substrate in China and research data are lacking so far. It is most necessary to improve the technology level of drilling IC substrate in China. In order to reduce the wear of micro-drills and improve the quality of micro-holes, many experimental tests about drilling IC substrate are researched in this paper.

Selective laser melting (SLM) is a promising additive manufacturing technology in the field of complex parts’ fabrication. High temperature gradient and residual stress are vital problems for the development of SLM technology. The purpose of this paper is to investigate the influence of substrate characteristics on the residual stress of SLMed Inconel 718 (IN718).

The SLMed IN718 samples were fabricated on the substrates with different characteristics, including pre-compression stress, materials and pre-heating. The residual stress at the center of the top surface was measured and compared through Vickers micro-indentation.

The results indicate that the residual stress reduces when the substrate contains pre-compression stress before the SLM process starts. Both substrate thermal expansion coefficient and thermal conductivity affect the residual stress. In addition to reducing the difference of thermal expansion coefficient between the substrate and the deposited material, the substrate with low thermal conductivity can also decrease the residual stress. Substrate pre-heating at 150°C reduces nearly 42.6 per cent residual stress because of the reduction of the temperature gradient.

The influence of substrate characteristics on the residual stress has been studied. The investigation results can help to control the residual stress generated in SLM processing.

This paper aims to find an optimal surface treatment of commonly used polymeric substrates for achieve the high adhesion of printed structures. For this reason, the investigation of substrates surfaces from different perspectives is presented in this paper.

The contact angle measurements as well as the roughness measurements were realised for the analysis of surface properties of investigated substrates. The impact of applied chemical agents for surface treatment onto the wettability is analysed for polyimide, polyethylene terephthalate and polyethylene naphthalene substrates.

The results prove the correlation among wettability, surface energy and work of adhesion with respect to the theoretical background. The surface treatment of polymeric substrates by chemical agents, such as acetone, toluene, ethanol, isopropyl and fluor silane polymer, has a significant impact onto the wettability of substrates which affects the final deposition process of nanoinks.

The main benefit of the surfaces’ investigation presented in this paper lays in surface modification by readily available chemical agents for optimising the deposition process nanoinks used in inkjet printing technology.

In various publications noble steel is mentioned as a possibility for use as a substrate in thick film technology processing. The possibility to cut, stencil and drill steel sheets to desired shapes and the attractive price difference compared with alumina as well as PC board materials justified an investigation. A variety of steel sheets in various formulations from various vendors is offered on the market as well as ceramic pastes for thick film applications. This investigation aims to find out the most suitable ceramic paste for coating steel substrates in a common thick film process.

The purpose of this study is to form fabrication and electrical characteristics of passive device embedded substrate that is embedded chip bead inductor and chip capacitor inside substrate for the application of radio frequency (RF) modules.

Passive device embedded substrate was fabricated using embedding process that consists of lamination process, laser drilling at the electrode Cu pads of passive components, electro-less Cu plating formation process such as photolithography, electrolytic Cu plating and etching. Impedance and capacitance characteristics of the fabricated passive device embedded substrate were evaluated.

By checking what embedded components are placed in the appropriate place using failure analysis via connection performance between copper plane and embedded components was verified. For measuring electrical characteristics of the fabricated passive device embedded substrate, the evaluation was done using test methods like continuity test for checking interconnections which are not connected to any embedded components and in-circuit test for checking interconnections which are connected to any embedded component. From in-circuit testing for embedding passive components with series and parallel circuits, the authors verified how to test passive device embedded substrate by using capacitance and impedance measurement with the comparison of measured results between good samples and bad samples.

Ultra miniaturized and low-profile mobile products are driving the need for embedded passive component integration technologies using a novel manufacturing-compatible organic substrate and interconnect technologies. Fabrication and test methods for passive device embedded substrate described in this paper are expected to lead to be developed to make quality measurable for the application of RF modules.

The purpose of this paper is to study the phenomenology of Al₂O₃-DBC substrate thermal-cracking under different high temperature cyclic loadings. The extremely low cycle fatigue (ELCF) life prediction model for ductile materials was used to describe the thermal fatigue life of Al₂O₃-DBC substrates.

Four groups of thermal cycling tests using Al₂O₃-DBC substrates with 0.65 mm thick copper were conducted using different peak temperatures. The failure samples were observed by optical microscope. The thermal plastic strain distribution in the Al₂O₃-DBC substrates was analyzed using a finite element method with the Chaboche model for describing plastic deformation of copper. The ELCF life prediction model was used to predict the life of Al₂O₃-DBC substrates under high temperature cyclic loadings.

Interface cracking was observed to initiate at the short edge of the bonded copper and deviated into the ceramic layer when the crack grew beyond the critical length of 0.1-0.8 mm. The interface crack deviated into the ceramic layer at different thickness and grew parallel to the interface layer between the ceramic layer and copper layer. The crack propagation stopped after certain cycles. The copper layer with 10-20 μm thick alumina inside was not split away totally from the ceramic layer. The ELCF life prediction model could predict the life of Al₂O₃-DBC substrates well under high temperature cyclic loading. The material constants in the extremely low fatigue life prediction model were obtained using thermal fatigue tests results.

The influence of copper layer thickness and ceramic layer thickness on thermal cracking characteristics of DBC substrate should be studied in the future. Failure models should also be further investigated.

The failure model of Al₂O₃-DBC substrates under high temperature cyclic loading was studied. A method for predicting the life of the substrate samples under high temperature cyclic loading was proposed.

The compatibility of available AIN substrate materials with thin film metallisation processes is briefly discussed. The AIN material is shown to be covered with a very thin oxide layer. NiCr and NiCr‐Ni‐Au layers have been deposited onto the substrates; the adhesion between these layers and the ceramic is tested. In the substrate, via‐holes have been made by laser drilling, and the influences of the ambient gas atmosphere on the creation of such via‐holes have been observed. Advantages and limitations of the different methods of producing via‐holes that can be metallised are discussed. A high density hybrid circuit module on AIN is demonstrated.

The purpose of this paper is to study Bi‐11Ag solder for higher application temperatures. The aim of the research work was to determine the soldering, thermal and mechanical properties of Bi‐11Ag solder.

To determine the melting point interval of experimental Bi‐11Ag solder, DSC analysis was performed. The contact angles were studied on a copper, nickel and silver substrate by use of a sessile drop method. Wettability tests were realised at a temperature of 380°C in a shielding atmosphere (90% N₂+10% H₂). Based on experience achieved with wetting angle measurements, the specimens for measurement of shear strength of Cu, Ni and Ag/Bi‐11Ag joints were fabricated. EDX analysis was used for the study of the solder interaction with the surface of the three metallic substrates.

The best wettability at soldering in a shielding atmosphere was achieved with silver. The wetting angle at 30 min attained the value of 23°. The worst wettability was observed on copper, where at 30 min the wetting angle was 55°. Average shear strength varied from 31 to 45 MPa. The highest strength was obtained with the Cu substrate whereas the lowest was with the Ni substrate. The lowest strength achieved with the Ni substrate was caused by formation of brittle intermetallic phase NiBi₃. Joint formation is realised by eutectic reaction at the contact of Bi with the surface of the copper substrate. Similar joint formation by eutectic reaction occurs also at Bi interaction with the surface of the Ag substrate. At Bi interaction with the nickel substrate a new intermetallic phase (NiBi₃) is formed.

Wettability of Bi‐11Ag solder on Cu, Ag and Ni substrates was determined at application of a shielding atmosphere (90% N₂+10% H₂). Wettability was determined also at application of ZnCl₂‐NH₄Cl flux. The shear strength of Bi‐11Ag on different substrates was determined. The mechanism of joint formation was analysed.