scholarly journals A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope

2015 ◽  
Vol 259 (1) ◽  
pp. 66-73 ◽  
Author(s):  
J. TRÄGÅRDH ◽  
K. MACRAE ◽  
C. TRAVIS ◽  
R. AMOR ◽  
G. NORRIS ◽  
...  
Keyword(s):  
Quantitative Measurement ◽  
Optical Microscope ◽  
Precise Method ◽  
Laser Focus

EVALUATION OF TRIBOTECHNICAL PROPERTIES OF THE COATING OBTAINED BY ELECTRIC SPARK HARDENING

2020 ◽  
Vol 4 (141) ◽  
pp. 157-163
Author(s):  
IL’YA ROMANOV ◽  
◽  
ROMAN ZADOROZHNIY
Keyword(s):  
Wear Resistance ◽  
Reference Sample ◽  
Optical Microscope ◽  
Research Purpose ◽  
Tribotechnical Properties ◽  
Uncoated Surface ◽  
Before And After ◽  
Materials Used ◽  
Friction Track

When applying coatings using various methods on the surfaces of moving parts that work in joints, it is important to make sure that the coatings are strong and wear-resistant in order to return them to their original resource. All existing hardening technologies and materials used to perform coatings have their own characteristics, therefore, the quality of the resulting coatings can be judged only after specific tests. (Research purpose) The research purpose is in evaluating the properties of the coating obtained by the method of electric spark hardening, and its ability to resist friction and mechanical wear. (Materials and methods) Authors conducted tests on the basis of the "Nano-Center" center for collective use. A coating was applied on the BIG-4M unit with a VK-8 hard alloy electrode, tribological properties were evaluated on a CSM Instruments TRB-S-DE-0000 tribometer, the width of the friction track was measured after the test using an inverted OLYMPUS gx51 optical microscope, and samples were weighed before and after the test on a VLR-200 analytical balance. Conducted research in accordance with GOST 23.224-86 and RD 50-662-88 guidelines. (Results and discussion) The article presents performed tests on the run-in and wear resistance of the coating. The samples were worked on with a step-by-step increase in the load. During the tests, the friction force was drawed on the diagram. Authors compared the results with the reference sample, an uncoated surface. (Conclusions) The resulting coating has better run-in and wear resistance compared to the standard, and the increase in wear resistance in dry friction conditions is very significant.

Die Bonding Issues on Silicon Carbide Diodes

2006 ◽  
Vol 527-529 ◽  
pp. 875-878 ◽  
Author(s):  
Seung Yong Lee ◽  
Jang Sub Lee ◽  
Tae Hong Kim ◽  
Sung Yong Choi ◽  
Hak Jong Kim ◽  
...  
Keyword(s):  
Shear Test ◽  
Vertical Structure ◽  
Optical Microscope ◽  
Device Fabrication ◽  
Cleaning Process ◽  
X Ray ◽  
The Third ◽  
Bottom Side ◽  
Die Bonding

We report on the die bonding processes and how the surface roughness and metallization schemes affect the processes of die bonding in 4H-SiC device fabrication using a soldering test and die shear test (DST) with differently prepared 4H-SiC samples. The first set of samples (FZ#1 and FZ#2) was capped with sequentially evaporated Ti and Au on an annealed Ni layer. The second set of samples (FZ#3 and FZ#4) and the third set of samples (FZ#5 and FZ#6) were prepared by 4μm-thick Au electroplating on an annealed Ni layer and an un-annealed Ni layer, respectively. The quality of the soldering, such as the solder coverage, void, and adhesion, was characterized by optical microscope, X-ray microprobe, and DST. We found that the samples (FZ#4 and FZ#6) deposited by Au electroplating on C-face (bottom-side) 4H-SiC provided a satisfactory result for the tests of solder coverage, void, and DST and also realized the cleaning process prior to the electroplating and soldering was the most crucial in the die packaging processes of vertical structure devices. The void fraction measured by X-ray microprobe for the samples, FZ#4 and FZ#6 was 2.2% (average for 5 samples) and 0.8% (average for 3 samples), respectively.

Mechanical Interlocking on Leadframe Surface for Bondability of Au Wedge Bond

2016 ◽  
Vol 857 ◽  
pp. 79-82
Author(s):  
Roslina Ismail ◽  
Fuaida Harun ◽  
Azman Jalar ◽  
Shahrum Abdullah
Keyword(s):  
Optical Microscope ◽  
Bonding Process ◽  
Mechanical Interlocking ◽  
Average Roughness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies ◽  
Scanning Electron ◽  
Effect Of Surface

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

scholarly journals HISTOLOGICAL ANALYSIS AND PERFORMANCE OF SOUR PASSION FRUIT POPULATIONS UNDER DIFFERENT ROOTSTOCKS RESISTANT TO Fusarium spp

2018 ◽  
Vol 40 (1) ◽  
Author(s):  
Moisés Ambrósio ◽  
Willian Krause ◽  
Celice Alexandre Silva ◽  
Laís Alves Lage ◽  
Natan Ramos Cavalcante ◽  
...  
Keyword(s):  
Histological Analysis ◽  
Block Design ◽  
Welding Process ◽  
Anatomical Study ◽  
Optical Microscope ◽  
Passion Fruit ◽  
Randomized Block Design ◽  
Physical And Chemical ◽  
Sour Passion Fruit

ABSTRACT The present study aimed to describe histological traits of the graft welding process and evaluate the effect of rootstocks on the physical and chemical traits and the productivity of sour passion fruit populations. The experiment was arranged in a randomized block design, in a 4x2 + 4 factorial scheme (cultivars / canopy x rootstocks), three replicates and nine plants per plot. Commercial cultivars and populations and Passiflora alata and P. nitida rootstocks, in addition to ungrafted plants were used as canopy. Cleft grafting was the grafting type adopted. Traits analyzed such as productivity and physical and chemical quality of fruits were submitted to analysis of variance and compared by the Tukey test. The canopy morphology was evaluated according to descriptors of the Ministry of Agriculture, Livestock and Supply. Grafting was carried out for each graft/rootstock combination for histological analysis. Sections were obtained by freehand cuts, stained and mounted on semi-permanent slides, examined under optical microscope and photomicrographed. Rootstocks affected the early cultivation and reduced productivity and number of fruits of passion fruit populations. Grafting did not affect the quality of fruits or the canopy morphology. Considering the complete culture cycle, P. alata species is able to be used as rootstock. The anatomical study demonstrates the occurrence of better compatibility in the connection of P. edulis tissues on P. alata, compared to grafting on P. nitida.

Fabrication and surface treatment of fine copper lines for HDI printed circuit board with modified full-additive method

Circuit World ◽  
2017 ◽  
Vol 43 (3) ◽  
pp. 131-138 ◽  
Author(s):  
Huirong He ◽  
Jida Chen ◽  
Shengtao Zhang ◽  
Minhui Liao ◽  
Lingxing Li ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
High Efficiency ◽  
Oxidation Process ◽  
Optical Microscope ◽  
Circuit Board ◽  
Content Type ◽  
Printed Circuit ◽  
Additive Method ◽  
Fine Copper

Purpose This paper aims to propose a modified full-additive method (MFAM) to fabricate fine copper lines for high density interconnection (HDI) printed circuit boards (PCBs). In addition, the surface of the fine copper lines is treated with a brown oxidation process to obtain good adhesion between the copper and the dielectric resin. Design/methodology/approach Fine copper lines fabricated by MFAM were observed to evaluate the undercut quality, in comparison to undercut quality of copper lines fabricated by the semi-additive method and the subtractive method. The effect of the thickness of the dry film on the quality of the copper plating was investigated to obtain the regular shape of fine lines. The fine copper lines treated with the brown oxidation process were also examined to generate a coarse surface microstructure to improve the adhesion between the copper and the dielectric resin. The cross section and surface of as-fabricated fine copper lines were characterized using an optical microscope, a scanning electron microscope and an atomic force microscope. Findings MFAM has the potential to fabricate high-performance fine copper lines for HDI PCBs. Undercut of as-fabricated fine copper lines could be prevented to meet the design requirement of impedance. In addition, fine copper lines exhibit enough adhesive force to laminate with dielectric resin after the brown oxidation process. Originality/value MFAM, with the advantages of high efficiency and being a facile process, is developed to fabricate high-quality fine copper lines for industrial HDI PCB manufacture.

Micromachining of Metals, Alloys and Ceramics by Picosecond Laser Ablation

2008 ◽  
Author(s):  
Wenqian Hu ◽  
Galen B. King ◽  
Yung C. Shin
Keyword(s):  
Electron Microscope ◽  
Laser Ablation ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Optical Microscope ◽  
Recast Layer ◽  
Laser Machining ◽  
Percussion Drilling ◽  
Scanning Electron

Microhole drilling and microstructure machining with a picosecond (ps) Nd:YVO4 laser (pulse duration of 10 ps) in metals, alloys and ceramics are reported. Blind and through microholes were drilled by percussion drilling as well as trepanning drilling. The diameters of the holes were in the range from 20 μm to 1000 μm. Microfeatures were machined and the flexibility of ps laser machining was demonstrated. The quality of drilled holes, e.g., recast layer, microcrack and conicity, and that of the microstructures, were investigated by optical microscope, surface profilometer, or scanning electron microscope (SEM). Ps laser ablation rate was investigated by experiments as well as a simplified laser ablation model.

Quantitative Measurement of Pantograph Loss of Contact Dynamics

2013 ◽  
Author(s):  
Bih-Yuan Ku ◽  
Jen-Sen Liu ◽  
Ming-Jan Ko
Keyword(s):  
Quantitative Measurement ◽  
Photovoltaic Cells ◽  
Quantitative Measure ◽  
Contact Dynamics ◽  
Term Operation ◽  
Current Collection ◽  
Voltage Signal ◽  
Loss Of Contact

In this paper we present our work on the development of a quantitative measurement advice to capture the dynamics of pantograph arcing during loss of contact. Despite the difficulties involved, it is very important for the railroad operators to accurately measure the pantograph loss-of-contact dynamics in order to assess the current collection quality of the pantograph with the overhead contact system during the commissioning phase and long-term operation. We use photovoltaic cells to construct a simple but effective sensor that can produce a voltage signal proportional to arc strength and duration, which can then be used as a precise quantitative measure of the loss of contact dynamics of the pantograph.

Green Laser Drilling Assisted with Neutral Salt Solution

2010 ◽  
Vol 26-28 ◽  
pp. 698-701
Author(s):  
Hua Zhang ◽  
Jia Wen Xu ◽  
Jian She Zhao ◽  
Guo Ran Hua
Keyword(s):  
Salt Solution ◽  
Second Harmonic ◽  
Optical Microscope ◽  
Green Laser ◽  
Laser Drilling ◽  
Recast Layer ◽  
Ambient Atmosphere ◽  
Neutral Salt ◽  
New Processing

Recast layer is an inherent defect commonly associated with holes produced with laser drilling. The defect is likely to limit the extent of aero industrial application. In order to solve the problem, a new processing of laser drilling assisted with neutral salt solution (SALD) has been developed to improve the overall quality of laser-drilled holes. The process bases on the application of a fluid neutral salt solution, which is being on the workpiece surface with the focused laser beam at the same time. The effects of the neutral salt solution during the process mostly consist of thermal chemical reaction and continuing cooling effect of materials. Because of green laser being weakly absorbed underwater, the experiments of SALD have been performed on 0.5mm thickness 321 stainless steel with pulsed Nd:YAG laser at second harmonic wavelength. The optical microscope is used to detect the experimental results. It is found that the recast layer has been effectively removed during the SALD compared with laser drilling in ambient atmosphere conditions. It is confirmed that the principle of SALD is right and the new process can obtain good hole quality without recast layer.

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