Local Heating Method Research Articles

Wheatstone bridge sensor composed of linear MgO magnetic tunnel junctions

A full Wheatstone bridge sensor composed of linear MgO based magnetic tunnel junctions (MTJ) was designed and achieved. The magnetization direction of reference layers in the required bridge arms was successfully switched by using local current heating method, also demonstrating a viable method of manipulation of pinning direction for exchange bias system on a chip level. The final bridge output shows approximately full signal of individual MTJ but almost null output in the absence of any applied sensing field and small offset of voltage and field.

Localized mold heating with the aid of selective induction for injection molding of high aspect ratio micro-features

High-frequency induction is an efficient, non-contact means of heating the surface of an injection mold through electromagnetic induction. Because the procedure allows for the rapid heating and cooling of mold surfaces, it has been recently applied to the injection molding of thin-walled parts or micro/nano-structures. The present study proposes a localized heating method involving the selective use of mold materials to enhance the heating efficiency of high-frequency induction heating. For localized induction heating, a composite injection mold of ferromagnetic material and paramagnetic material is used. The feasibility of the proposed heating method is investigated through numerical analyses in terms of its heating efficiency for localized mold surfaces and in terms of the structural safety of the composite mold. The moldability of high aspect ratio micro-features is then experimentally compared under a variety of induction heating conditions.

Local Inductive Heating Method Using Novel High-Temperature Implant for Thermal Treatment of Luminal Organs

The authors have previously proposed both a regional heating system, which introduced auxiliary electrodes, and a local inductive heating system, which introduced high-temperature-rise implants. In this paper, we present two novel types of high-temperaturerise implants aiming at luminal organ treatments, namely, a coaxial needle and a stent. Since hot-spot generation may degrade the accuracy of temperature measurements when developing these inductive heating implants, a simple method using a high-conductivity eddy-current absorber such as an aluminum foil is proposed. This is suggested based on theoretical investigations using the 3-D finite-element method and experiments. The heating tests of the novel folding-type implants suggested by medical doctors were conducted at a frequency of 4.0 MHz and an output power of 500 W using the proposed EC A. It was found that in the case of the coaxial-needle-type implant, a high temperature rise of more than 60 omicronC can be achieved.

Low Temperature Growth of High-Quality Carbon Nanotubes by Local Surface Joule Heating without Heating Damage to Substrate

In this study, a low temperature growth of high-quality carbon nanotubes on glass substrate using a local surface heating without heating damage to substrate was tried and characterized. The local joule heating was induced to only Ni/Ti metal film on glass substrate by applying voltage to the film. It was estimated that local surface joule heating method could heat the metal surface locally up to around <TEX>$1200^{\circ}C$</TEX> by voltage control. We could successfully obtain high-quality carbon nanotubes grown at <TEX>$300^{\circ}C$</TEX> by applying 125 V for joule heating as same as carbon nanotubes grown at <TEX>$900^{\circ}C$</TEX>.

Local heating method for growth of aligned carbon nanotubes at low ambient temperature

We use a highly localized resistive heating technique to grow vertically aligned multiwalled nanotube films and aligned single-walled nanotubes on substrates with an average temperature of less than 100°C. The temperature at the catalyst can easily be as high as 1000°C but an extremely high temperature gradient ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the local heater. We demonstrate the influence of temperature on the height of multiwalled nanotube films, illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters and also show that nanotubes can be grown over temperature-sensitive materials such as resist polymer.

박판재 변형의 가열교정에서 가열면적의 영향

Use of sheet metal structure is increased in various fields such as automobile, aerospace and communication equipment industry. When this structure is welded, welding distortion is generated due to the non-uniformity of temperature distribution. Recently welding distortion becomes a matter of great importance in the structure manufacture industry because it deteriorates the product's quality by bringing about shape error. Accordingly many studies for solving the problems by controlling the welding distortion are being performed. However, it is difficult to remove all kinds of distortion by welding process, though various kinds of methods for reducing distortion are applied to production. Consequently, straightening process is operated if the high precision quality is requested after welding. The local heating method induces compression plastic deformation by thermal expansion in the heating stage and then leaves constriction of length direction in the cooling stage. Accordingly, in the case of sheet metal structure, straightening effect is expected by heating for the part of distortion. This study includes numerical analysis of straightening effect by the local heating method in distortion comes from production of welded sheet metal structure. Particularly straightening effect followed by dimensions of heating area is analyzed according to the numerical analysis. The numerical analysis is performed by constructing 3-dimensional finite element model for 0.4mm stainless steel-sheet metal. Results of this study confirm that straightening effect changes as heating area increases and the optimum value of heating area that proves the maximum straightening effect exists.

Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method

A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method.

Investigation of multilayer structural changes in phase and amplitude-defects correction process

Controlling defects on the extreme ultraviolet lithography (EUVL) mask has become a critical issue among many EUVL element technologies. We have conducted experiments to investigate the correctability of two kinds of major defect types, phase and amplitude defects. Phase defects correctability was addressed by using the electron-beam local heating method and amplitude defects correctability were done by using the focused ion-beam (FIB). Additionally, two kinds of multilayers, Mo∕Si and Mo∕Ru∕Si, were used as substrates to inspect the behavior in a comparative way. As a result, the sink brought by electron-beam (e-beam) localized heating on a planar multilayer surface was about 8 and 13.6 nm in Mo∕Si and Mo∕Ru∕Si multilayers, respectively, under the e-beam dose of 250μC∕cm2. However, the heating effect was limited to within a few layers from the surface. FIB etching was also conducted on a planar surface of a multilayer. There are two types of FIB correction methods, image mode and spot mode. The etched area was relatively large (∼3μm×3μm) in image mode. But in the spot mode, the etched area could be confined to a few tens of nanometers in diameter. This FIB method also caused some damage on the multilayer surface.

Identifying and Mapping Surface Amorphous Domains

Undesirable amorphous material generation during formulation is implicated in a growing number of pharmaceutical problems. Due to the importance of interfacial properties in many drug delivery systems, it seems that surface amorphous material is particularly significant. Consequently, this study investigates a range of methods capable of detecting and mapping surface amorphous material. A micron-sized localized surface domain of amorphous sorbitol is generated using a novel localized heating method. The domain is subsequently investigated using atomic force microscopy (AFM) imaging, nanomechanical measurements, and Raman microscopy 3-D profiling. AFM phase and height images reveal nanoscale-order variations within both crystalline and amorphous sorbitol domains. Nanomechanical measurements are able to quantitatively distinguish the amorphous and crystalline domains through local Young's modulus measurements. Raman microscopy also distinguishes the amorphous and crystalline sorbitol through variations in peak width. This is shown to allow mapping of the 3-D distribution of the amorphous phase and is hence complementary to the more surface sensitive AFM measurements. AFM and Raman microscopy map the distribution of amorphous material at the surface of a sorbitol crystal with submicron spatial resolution, demonstrating surface analysis methods for characterizing semicrystalline solids generated during pharmaceutical processing.

局所加熱法による純銅の結晶粒組織制御

The present work deals with a preferential grain growth process in a localized region utilizing local heating method in order to fabricate some unique microstructures different from those fabricated in the homogeneous way of microstructure evolution. A Monte Carlo simulation of grain growth under a heterogeneous temperature gradient, i.e. spot heating, was performed. Steep temperature gradient brought about a preferential grain growth in the higher temperature region, showing that the local heating was effective for the control of grain structure of polycrystalline materials. Such type of preferential grain growth became less significant under the mild temperature gradient. Local heating of pure copper foil with 0.2mm in thickness utilizing laser beam was performed by changing the irradiation conditions. In the case of 200W for laser power and 18mm/s for sweep velocity, some grains were observed to have larger grain sizes than their surrounding grains, suggesting a possibility of preferential grain growth in the localized region.

사각고리형상의 AuSn 합금박막을 이용한 MEMS 밀봉 패키징 및 특성 시험

This paper presents a hermetic MEMS on-chip package bonded by a closed-loop AuSn solder-line. We design three different package specimens, including a substrate heated specimen without interconnection-line (SHX), a substrate heated specimen with interconnection-line (SHI) and a locally heated specimen with interconnection-line (LHI). Pressurized helium leak test has been carried out for hermetic seal evaluation in addition to the critical pressure test for bonding strength measurement. Substrate heating method (SHX, SHI) requires the bonding time of 40min. at 400℃, while local heating method (LHI) requires 4 min. at the heating power of 6.76W. In the hermetic seal test, SHX, SHI and LHI show the leak rates of 8.4??6.7x^10mbar-????s 13.5??9.8x 10^10mbar-????s and 18.8??9.9x10_10mbar-????s, respectively, for an identical package chamber volume of 6.89??0.2x ^6??. In<br/> the critical pressure test, no fracture is found in the bonded specimens up to the applied pressure of<br/> 1??0.1MPa, resulting in the minimum bonding strength of 3.53??0.07MPa. We find that the present on-chip packaging using a closed AuSn solder-line shows strong potential for hermetic MEMS packaging with interconnection-line due to the hermetic seal performance and the shorter bonding time for mass production.

Protein charge transport in gas phase

We propose a local heating method via molecular dynamic simulation to investigate the charge transport efficiency along a polypeptide chain in the gas phase. In the protein charge transfer process, the carbonyl groups next to a C α -hinge collide with each other. Within a critical contact distance between OO atoms, charge starts to transfer otherwise the charge being at rest. This is termed a bifunctional model. In the gas phase and in the low temperature limit, the rotational energy can be transferred with very high efficiency and hence one obtains high charge transport efficiency.

P‐40: New Vacuum Packaging Using Wire‐Heater and Optical Fiber Spacer for FED

AbstractWe suggested a new FED packaging technology using the localized heating method of glass frit and a high aspect ratio spacer formation technology using the optical fibers. A nickel wire heater of 300 μm diameter was used to melt the glass frit and to activate a getter. The FED panel was vacuum packaged in 230 °C by applying current to wire. The optical fiber spacer of 100 μm diameter was built to 300 μm as mesh type. Through the leakage test, we confirmed that the panel was hermetic sealed. As a result, the electron emission was successfully obtained in 1.25‐inch packaged FED panel.

The retardation of fatigue crack growth rate caused by local heating at the crack tip

The present, paper proposes a method to retard the fatigue crack growth rate by a local heating procedure.Steady fatigue crack growth under constant amplitude loading can be disturbed by sudden change in plastic zone size resulting from a single overload. However, mechanical properties of metal, such as yield stress, Young's modulus, etc may vary with increasing temperature. Therefore, the fatigue crack tip plastic zone size can be altered by locally changing the mechanical properties of this areaIn order to identify the thermal effect on the retardation of fatigue crack, fatigue propagation tests using A5083P-O aluminum alloy specimens under various heating conditions were carried out. Further-more, to compare with the degree of retardation caused by a single overload, overload propagation tests under five overload ratios were carried out as well. By using CTOD (crack tip opening displacement) as the evaluating parameter, the configuration of crack tip were recorded through CCD camera, and its effect to the degree of retardation were discussed.The results show that when the heat input was increased to a level that exceeded the threshold, the larger the heat input was the obvious retardation become. Local heating method proposed in this study is effective in retarding fatigue crack rate.

Electric current passage and interface heating

Features of contact spots heating are considered when electric current passes through the metallic interface. Relationships are presented for contact temperature evaluation at different mechanisms of current passage. Emphasis is put on the contact with thin (nanometer scale) boundary films. The analysis indicates that the method of local heating of the contact zone by electric current can be used in modelling thermal conditions when either surface films are absent or homogeneous conductive films are present. Current densities for a required temperature regime creation are determined based on Kohlraush-relation in the former case and on modified Block and Jaegear's formulas in the latter case. Experimental data are presented on regularities of current passage and heat liberation in static contacts with thin tunnel-conductive surface films. The results have been analysed from the viewpoint of heat conditions simulation in the contact zone. It is shown that current passage through the contact is accompanied by formation of a channel (bridge) with elevated conductivity even in extremely thin films. This leads to localisation of the Joule heat predominantly in the vicinity of the formed bridge thus excluding regular heating of the contact area.

Removal of Copper and Tin in Molten Iron with Combination of Plasma Heating and Powder Blowing Decarburization under Reduced Pressure.

The combination of plasma heating and the powder blowing decarburization method was applied to remove copper and tin, which are tramp elements in relation to recycling, from molten iron in a large scale experiment. Plasma heating was adopted as the local heating method and combined with a weak oxidizing powder blowing method under a commonly used reduced pressure of about 0.13-0.65 kPa for their removal. The results demonstrated that the method could accelerate the efficient removal of copper and tin from iron melted from scrap under a reduced pressure compared with only the powder blowing method. The apparent removal rates of copper and tin increased as 2-3 times and 4 times much as that without plasma heating. The plasma heating is thought to compensate for the heat loss at the reaction site by this method.

The thermal shock resistance of a joining material of C/C composite and copper

Plasma facing materials for the next fusion reactor devices will have severe problems such as thermal shock fracture, surface erosion and injection of sputtering particles to plasma caused by charged particle fluxes and very high heat shocks. A joining material, in which a carbon fiber reinforced carbon composite was joined to oxygen-free copper by inserting a molybdenum plate and some metallic films in the joining layers, was developed for a solution of those problems. The thermal shock resistance and the thermal shock fracture toughness were evaluated by an eccentric local heating method of arc discharge. The joining material did not fracture during severe thermal shock tests such as plasma disruption, however, thermal and delamination cracks were observed at the joining parts by scanning electron microscope (SEM). These results can be useful in contributing to the development and the safety design of plasma facing components for fusion reactor devices.

95/05121 Performance evaluation of pin-fin heat sinks utilizing a local heating method

95/05121 Performance evaluation of pin-fin heat sinks utilizing a local heating method

Local heating method by a Nd:YAG laser beam for the measurements of the optical properties of Si wafers.

Local heating method by a Nd:YAG laser beam for the measurements of the optical properties of Si wafers.

A New, Thermally Controlled, Non-Contact Rotor Balancing Method

Available alternative rotor balancing techniques applied to rotors manufactured in high volumes often have productivity limitations. A new method has been devised that allows a rotor to be balanced as it rotates, without physical contact. The method accomplishes balance correction by means of deformable torsion elements that permanently relocate discrete masses through local heating under the action of centrifugal forces. The method exploits the elevated temperature, time-dependent deformation behavior of metallic materials under stress to produce controlled incremental deformation through radiative pulse heating. The important aspects of the new method: the physical configuration of the deformable elements, the non-contact, local heating method, and the method of producing controlled incremental deformation of the mass relocation element have been modeled analytically and demonstrated experimentally.