• Journal of Technologic Dentistry
• /
• v.36 no.4
• /
• pp.239-246
• /
• 2014

Purpose: The purpose of this study was to compare the tensile strength and mechanical properties of orthodontic wire joints made by gas soldering and laser welding, with and without filling material, to identify the effectiveness and potential clinical application of laser welded orthodontic wires. Methods: Three joint configurations of orthodontic wire were used: diameter 0.9 to 0.9 mm wire, diameter 0.9 to 0.5 wire and diameter 0.9 mm wire to band. The joints were made using three different methods: gas soldering, laser welding with and without filling material. For each kind of joint configuration or connecting method 7 specimens were carefully produced. The tensile strengths were measured with a universal testing machine (Zwick/Roell, Instron, USA). The hardness measurements were carried out with a hardness tester(Future-Tech Co. Tokyo, Japan). Data were analyzed by AVOVA(p= .05) and Turkey HD test(p= .05). Results: In all cases, gas soldering joints were ruptured on a low level on tensile bonding strength. Significant differences between laser welding and gas soldering(p< .05) were found in each joint configuration. The highest tensile strength means were observed for laser welding, with filling material, of 0.9 to 0.9 mm wire joint. Conclusion: In conclusion, the elastic modulus and tensile strength means of laser soldering with filling material were the highest, and the tensile strength means of laser soldering were higher than those of gas soldering.

• Journal of Technologic Dentistry
• /
• v.6 no.1
• /
• pp.11-14
• /
• 1984

The auther performed this experimental study on cervical margin distortion in preheating method during soldering. 1. In soldering methods, the method using the furnace has less distortion than the method using open-flame and longer the bridge spon, the larger the distortions. 2. Table Ⅰ Showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.01mm, 0.02mm, 0.03mm, 0.03mm closer adaptation in 3 unit bridge than in 5 unit bridges. 3. Table II showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.06mm, 0.07mm, 0.11mm, 0.05mm closer adaptation in 3 unit bridge than in 5 unit bridges.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.303-306
• /
• 2011

Although PV module manufacturing and its structure are simple, the semi-permanent products can be used out doors for more than twenty years. Therefore it is need to choose proper materials and optimize manufacturing process. This paper suggest that factors of degradation need to be studied to achieve a more understanding of PV module Degradation rates and material failure. Nowadays durability of the PV Module is very important to sustain output safety for obtaining reliability. This paper is about the experiment that soldering uniformity of soldering process and to make least void from soldering process. From This study soldering flux residue and soldering method is main factor to form void blocked soldering uniformity and by using this.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.6
• /
• pp.951-960
• /
• 1997

Package crack caused by the soldering process in the surface mounting plastic package is evaluated by applying the maximum energy release rate criterion. It could be shown that the crack propagation from the lower edge of the ie pad is easily occurred at the maximum temperature during the soldering process, where the pressure acting on the crack surface is assumed by the saturated vapor pressure at maximum temperature. The package crack formation depends on various parameters such as chip size, relative thickness, material properties, the moisture content and soldering temperature etc. The quantitative measure of the effects of the parameters could be easily obtained by using the taguchi's method which requires only a few kinds of combinations with such parameters. From the results, it could be obtained that the more significant parameters to effect the package reliability are the orders of Young's modulus, die pad size, down set, chip thickness and maximum soldering temperature.

• Clean Technology
• /
• v.14 no.2
• /
• pp.103-109
• /
• 2008

In this study, in order to develop evaluation method of the cleaning efficiency of residual flux which remains on the surface after soldering with solder paste, a specially designed metal tool is used to reduce spread uncertainty of flux while soldering. Using this tool, the measurement of cleaning efficiency of flux after soldering for some typical alternative semi-aqueous cleaners and 1,1,1-TCE by weighing method was conducted. As the test result of cleaning efficiency for each cleaner at several different cleaning times, the precision of the data is confirmed to within about 4% relative standard deviation (RSD) range. So, it is considered that this would be a good evaluation method for evaluating the cleaning efficiency of the residual flux which remains after solder paste soldering in the alternative cleaning. The results of this test method shows that the cleaning efficiency of ST 100SX and Neozal 750H in the cleaning of residual flux was better than other semi-aqueous cleaners, but its cleaning efficiency was clearly inferior to 1,1,1-TCE.

• Journal of Welding and Joining
• /
• v.15 no.6
• /
• pp.105-115
• /
• 1997

A numerical study is performed to predict the thermal response of a detailed card assembly during infrared reflow soldering. The card assembly is exposed to discontinuous infrared panel heater temperature distributions and high radiative/convective heating and cooling rates at the inlet and exit of the oven. The convective, radiative and conduction heat transfer within the reflow oven as well as within the card assembly are simulated and the predictions illustrate the detailed thermal responses. The predictions show that mixed convection plays an important role with relatively high frequency effects attributed to buoyancy forces, however the thermal response of the card assembly is dominated by radiation. The predictions of the detailed card assembly thermal response can be used to select the oven operating conditions to ensure proper solder melting and minimization of thermally induced card assembly tresses and warpage.

• Journal of Technologic Dentistry
• /
• v.21 no.1
• /
• pp.55-65
• /
• 1999

So far, I Conducted an examination with focus on the type, characteristic, and test methods of impact test. which is a type of mechanical that evaluate materials. As mentioned previously, in testing soldering strength of soldering is the load when the object under experiment is broken down with the result of flexibility test or peel test. In this method, a hevay load is necessary until alloy of parent metal is bended, if the alloy of the parent metal has a large mechanical quality(peel strength or resisting power). Once the alloy of the parent metal is bended, however, it tends to come into pieces abruply form the part where soldered. Therefore, a metal has a high breakdown value if the degree of strength of its parent metal is high even if the result of measurement indicates otherwise. Thus, the result of the test did not correspond to the clinical result. Therefore, this study concludes as the following from a test of strength of soldering by mean of conducting an impact test, which is a type of mechanical evaluation methods : 1. Among various impact tests, a charpy thpe is more appropriate than the izod type in testing strength of soldering. 2. As far as test piece is concerned, to use subsized impact test piece is appropriate in the impact test in that it does not have notch. 3. In the matter of analysis, it is appropriate to measure absorbing energy which results from rupture of test piece.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.402-407
• /
• 2002

Laminate tooling process is a fast and simple method to make metal tools directly for various molding processes such as injection molding in rapid prototyping field. Metal sheets are usually cut, stacked, aligned and joined with brazing or soldering. Through the joining process, all of the metal sheet layers should be rigidly joined. When joining process parameters are not appropriate, there would be defects in the layers. Among various types of defects, non-bonded gaps of the tool surface are of great importance, because they directly affect the surface quality and dimensional accuracy of the final products. If a laminate tool with defects has to be abandoned, it could lead to great loss of time and cost. Therefore a repair method for non-bonded gaps of the surface is essential and has important meaning for rapid prototyping. In this study, a rapid laminate tooling system composed of a CO2 laser, a furnace, and a milling machine was developed. Metal sheets were joined by furnace brazing, dip soldering and adhesive bonding. Joined laminate tools were machined by a high-speed milling machine to improve surface quality. Also, repair brazing and soldering methods of the laminates using the $CO_2$ laser system have been investigated. ill laser repair process, the beam duration, beam power and beam profile were of great importance, and their effects were simulated by [mite element methods. The simulation results were compared with the experimental ones, and optimal parameters for laser repair process were investigated.

• Proceedings of the KIPE Conference
• /
• 1997.07a
• /
• pp.318-321
• /
• 1997

This paper is about improving characteristic of plant by using micro-step driver method in 5 phase step motor for satisfying the condition of low oscillation and high accuracy in soldering machine. We choose open loop control method for minimizing hardware system and use one chip microprocessor, power MOSFET nd some device to realize accurate micro-step driver system.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.58.1-58.1
• /
• 2010

In solar cell module manufacturing, single solar cells has to be joined electrically to strings. Copper stripes coated with tin-silver-copper alloy are joined on screen printed silver of solar cells which is called busbar. The bus bar collects the electrons generated in solar cell and it is connected to the next cell in the conventional module manufacturing by a metal stringer using conventional hot air or infrared lamp soldering systems. For thin solar cells, both soldering methods have disadvantages, which heats up the whole cell to high temperatures. Because of the different thermal expansion coefficient, mechanical stresses are induced in the solar cell. Recently, the trend of solar cell is toward thinner thickness below 180um and thus the risk of breakage of solar cells is increasing. This has led to the demand for new joining processes with high productivity and reduced error rates. In our project, we have developed a new method to solder solar cells with a laser heating source. The soldering process using diode laser with wavelength of 980nm was examined. The diode laser used has a maximum power of 60W and a scanner system is used to solder dimension of 6" solar cell and the beam travel speed is optimized. For clamping copper stripe to solar cell, zirconia(ZrO)coated iron pin-spring system is used to clamp both joining parts during a scanner system is traveled. The hot plate temperature that solar cell is positioned during lasersoldering process is optimized. Also, conventional solder joints after $180^{\circ}C$ peel tests are compared to the laser soldering methods. Microstructures in welded zone shows that the diffusion zone between solar cell and metal stripes is better formed than inIR soldering method. It is analyzed that the laser solder joints show no damages to the silicon wafer and no cracks beneath the contact. Peel strength between 4N and 5N are measured, with much shorter joining time than IR solder joints and it is shown that the use of laser soldering reduced the degree of bending of solar cell much less than IR soldering.