Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie, 2014
This study proposed to evaluate the surface morphology of different types of orthodontic brackets... more This study proposed to evaluate the surface morphology of different types of orthodontic brackets and the characteristics of their adhesion to the tooth enamel. There have been taken into study six metallic, five ceramic and one polymeric bracket from different brands (Ormco, Lancer, Leone, Damon, 3M, Ultradent, American Orthodontics, Rocky Mountain). The surface base of the each bracket it have been ESEM analyzed using scanning electron microscope Phillips XL-30 ESEM. There have been investigated several parameters that have a potential influence of the bracket-bonding agent interface joint: chemical composition, roughness, surface morphology and wideness. After ESEM analysis, the same metallic and ceramic brackets have been afterwards collated on extracted teeth and subjected to mechanical tests. After the mechanical testing, the samples were once again ESEM investigated. All fractures occurred in the area of the adhesive system, recording adhesive fractures of the tooth-composite...
2012 35th International Spring Seminar on Electronics Technology, 2012
ABSTRACT The continuous trend towards high density and miniaturization of electronic devices invo... more ABSTRACT The continuous trend towards high density and miniaturization of electronic devices involves the use of multiple reflow processes in assembling technologies for second level of interconnections in electronic packaging hierarchy. According to the “4P” Soldering Model concept (4PSMC), considering the Pad-Paste-Pin-Process elements as Key Process Input Variables (KPIV), the solder joints are the result of KPIV synergistically interactions and correlations with consequences over their microstructure. In the paper, taking into consideration the cooling rate influence over intermetallic compounds (IMC) formation and microstructure, there was described the investigations over electrical and mechanical properties of solder joints resulted from multiple reflow Vapor Phase Soldering (VPS) process, in terms of 4PSMC. Maintaining the pad, pin and paste of KPIV as references measurements of solder joints resistances and shear forces were perform as function of VPS process's number for two values of cooling rate, respectively IMC microstructures and stereofractography studies. The results of the studies performed and presented in the paper will be use for improving process control in order to assure the solder joints reliability, to minimize losses on VPS lines, to reduce defects number and rework time.
2008 31st International Spring Seminar on Electronics Technology, 2008
Recording every aspect of the manufacturing process, from materials to production processes, whet... more Recording every aspect of the manufacturing process, from materials to production processes, whether at the board level or the entire system build, thus providing full product and process traceability, helps manufacturers to limit the scope of product recalls and reduces associated recall costs, while providing for compliance to a variety of environmental and safety regulations across all segments of the
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT The paper shows the results of a second approach of the Surface Insulation Resistance (S... more ABSTRACT The paper shows the results of a second approach of the Surface Insulation Resistance (SIR) test performed in order to test the quality of solder pastes. The aim of the SIR test was to establish the influence of the reflow method used and of a protective coating on the SIR. At the end of this test, a comparison between the obtained results was done. Both tests were done in the conditions of environment heat and high humidity. The boards used in both experiments are special designed test pattern boards (IPC-B-24) and the no-clean solder pastes are the following: SAC305, SN100C, SN100C-XF3 OM338PT, OM5300 [1]. The measurements of the SIR values showed better results keeping in mind that this was the second experiment and that we gained experience during the first experiment.
2008 31st International Spring Seminar on Electronics Technology, 2008
In the last decade new materials were launched on the market. This is the case of PCB substrates,... more In the last decade new materials were launched on the market. This is the case of PCB substrates, also. Requirements for improved heat transfer between power components and the solid metal base led to a new PCB technology, on copper and aluminum substrates. Typical applications are those where high level of heat has to be dissipated from the circuit (in
2007 30th International Spring Seminar on Electronics Technology (ISSE), 2007
... Under work are activities regarding electrical, rheological, climatic, and mechanical testing... more ... Under work are activities regarding electrical, rheological, climatic, and mechanical testing ofexperimental ecological modules ... Starting from the experience obtained after these trials, theresearch team has verified ... An experimental squeezing device is shown in the next figure. ...
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
As known, there are three parameters for controlling the thermal profile in vapour phase solderin... more As known, there are three parameters for controlling the thermal profile in vapour phase soldering machine; the paper refers to one of them - the electric energy from the AC mains introduced in the system in order to bring the thermal agent to the boiling point and to obtain the appropriate vapours density. The idea was to control the power
Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie, 2014
This study proposed to evaluate the surface morphology of different types of orthodontic brackets... more This study proposed to evaluate the surface morphology of different types of orthodontic brackets and the characteristics of their adhesion to the tooth enamel. There have been taken into study six metallic, five ceramic and one polymeric bracket from different brands (Ormco, Lancer, Leone, Damon, 3M, Ultradent, American Orthodontics, Rocky Mountain). The surface base of the each bracket it have been ESEM analyzed using scanning electron microscope Phillips XL-30 ESEM. There have been investigated several parameters that have a potential influence of the bracket-bonding agent interface joint: chemical composition, roughness, surface morphology and wideness. After ESEM analysis, the same metallic and ceramic brackets have been afterwards collated on extracted teeth and subjected to mechanical tests. After the mechanical testing, the samples were once again ESEM investigated. All fractures occurred in the area of the adhesive system, recording adhesive fractures of the tooth-composite...
2012 35th International Spring Seminar on Electronics Technology, 2012
ABSTRACT The continuous trend towards high density and miniaturization of electronic devices invo... more ABSTRACT The continuous trend towards high density and miniaturization of electronic devices involves the use of multiple reflow processes in assembling technologies for second level of interconnections in electronic packaging hierarchy. According to the “4P” Soldering Model concept (4PSMC), considering the Pad-Paste-Pin-Process elements as Key Process Input Variables (KPIV), the solder joints are the result of KPIV synergistically interactions and correlations with consequences over their microstructure. In the paper, taking into consideration the cooling rate influence over intermetallic compounds (IMC) formation and microstructure, there was described the investigations over electrical and mechanical properties of solder joints resulted from multiple reflow Vapor Phase Soldering (VPS) process, in terms of 4PSMC. Maintaining the pad, pin and paste of KPIV as references measurements of solder joints resistances and shear forces were perform as function of VPS process's number for two values of cooling rate, respectively IMC microstructures and stereofractography studies. The results of the studies performed and presented in the paper will be use for improving process control in order to assure the solder joints reliability, to minimize losses on VPS lines, to reduce defects number and rework time.
2008 31st International Spring Seminar on Electronics Technology, 2008
Recording every aspect of the manufacturing process, from materials to production processes, whet... more Recording every aspect of the manufacturing process, from materials to production processes, whether at the board level or the entire system build, thus providing full product and process traceability, helps manufacturers to limit the scope of product recalls and reduces associated recall costs, while providing for compliance to a variety of environmental and safety regulations across all segments of the
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT The paper shows the results of a second approach of the Surface Insulation Resistance (S... more ABSTRACT The paper shows the results of a second approach of the Surface Insulation Resistance (SIR) test performed in order to test the quality of solder pastes. The aim of the SIR test was to establish the influence of the reflow method used and of a protective coating on the SIR. At the end of this test, a comparison between the obtained results was done. Both tests were done in the conditions of environment heat and high humidity. The boards used in both experiments are special designed test pattern boards (IPC-B-24) and the no-clean solder pastes are the following: SAC305, SN100C, SN100C-XF3 OM338PT, OM5300 [1]. The measurements of the SIR values showed better results keeping in mind that this was the second experiment and that we gained experience during the first experiment.
2008 31st International Spring Seminar on Electronics Technology, 2008
In the last decade new materials were launched on the market. This is the case of PCB substrates,... more In the last decade new materials were launched on the market. This is the case of PCB substrates, also. Requirements for improved heat transfer between power components and the solid metal base led to a new PCB technology, on copper and aluminum substrates. Typical applications are those where high level of heat has to be dissipated from the circuit (in
2007 30th International Spring Seminar on Electronics Technology (ISSE), 2007
... Under work are activities regarding electrical, rheological, climatic, and mechanical testing... more ... Under work are activities regarding electrical, rheological, climatic, and mechanical testing ofexperimental ecological modules ... Starting from the experience obtained after these trials, theresearch team has verified ... An experimental squeezing device is shown in the next figure. ...
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
As known, there are three parameters for controlling the thermal profile in vapour phase solderin... more As known, there are three parameters for controlling the thermal profile in vapour phase soldering machine; the paper refers to one of them - the electric energy from the AC mains introduced in the system in order to bring the thermal agent to the boiling point and to obtain the appropriate vapours density. The idea was to control the power
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Papers by G. Varzaru