Side Of Chip Research Articles

21513 旋削加工に於ける工具摩耗抑止に対する切削油剤の効果(生産加工)

The purpose of this research is to make clear a possibility of eco-machining process for turning of carbon steel S45C. Cutting experiment was carried out both dry and wet cutting using carbide tool in cutting speed 150m/min. Observing the process of chip formed, high-speed camera was used. As a result, flank wear and crater wear are not much difference between dry and wet cutting, but boundary wear of dry cutting is about 4 times larger than that of wet cutting. A cause of boundary wear occurred is to cut ruggedness which occurs by intermittently metal flow to free surface in the side of shear type chip. It seems that the reason why an effect of cutting fluid is remarkably shown for boundary wear is that cutting fluid enters easily into interface of tool and work because of cutting in this part done intermittently.

Effect of surface condition on boiling heat transfer from silicon chip with submicron-scale roughness

Boiling heat transfer on treated silicon surfaces was studied. Experiments were conducted to investigate the effects of submicron-scale roughness on the boiling heat transfer at a subcooled condition in FC-72 at the ambient pressure. Two-type of treated silicon surfaces were prepared for boiling surfaces using anodisation with HF (hydrofluoric acid) based electrolyte and DMF (dimethylforamide) based one. The back side of the treated surface was glued to the back side of the other silicon chip on which thin film heaters and thin film temperature sensors were fabricated using conventional MUPs processes with doped polysilicon. The treated chips with submicron-scale roughness which provide many possible nucleation sites showed considerable enhancement in the nucleate boiling heat transfer coefficients compared to the untreated silicon surface. Further, the critical heat flux (CHF) of the treated surfaces increase linearly to the increase in the effective area for boiling.

Widely tunable diffraction limited 1000 mW external cavity diode laser in Littman/Metcalf configuration for cavity ring-down spectroscopy

We report on recent progress on external cavity diode lasers (ECDL) using a new concept of a Littman/Metcalf configuration. Within this concept one facet of the diode laser chip is used for coupling to a high quality Littman/Metcalf resonator whereas the other side of the diode laser chip emits the output beam. The alignment of the external resonator is independent from the alignment of the output beam and there is no need for any compromise in the alignment. This results in an improved behavior of the external resonator with the benefit of a drastic increase in power and single mode tuning.

Multi-Stacked Flip Chips with Copper Plated Through Silicon Vias and Re-distribution for 3D System-in-Package Integration

ABSTRACTThe study is a prototype design and fabrication of multi-stacked flip chip three dimensional packaging (3DP) with TSVs for interconnection. Three chips are stacked together to make a 3DP with solder bumped flip chips. TSVs are fabricated and distributed along the periphery of the middle chip. The TSVs are formed by dry etching, deep reactive ions etching (DRIE), with dimensions of 150 × 100 microns. The TSVs are plugged by copper plating. The filled TSVs are connected to the solder pads by extended pad patterns surrounding the top and the bottom of TSVs on both sides of the wafer for the middle chip. After pad patterning passivation and solder bumping, the wafer is sawed into chips for subsequent 3D stacked die assembly. Because the TSVs are located at the periphery of the middle chips and stretch across the saw street between adjacent chips, they will be sawed through their center to form two open TSVs (with half of the original size) for electrical interconnection between the front side and the back side of the middle chip. The top chip is made by the conventional solder bumped flip chip processes and the bottom chip is a carrier with some routing patterns. The three middle chips and top chip are stacked by a flip chip bonder and the solder balls are reflowed to form the 3DP structure. Lead-free soldering and wafer thinning are also implemented in this prototype. In addition to the conceptual design, all wafer level fabrication processes are described and the subsequent die stacking assembly is also presented.

Coenzyme Binding during Catalysis Is Beneficial for the Stability of 4-Hydroxyacetophenone Monooxygenase

The NADPH-dependent dimeric flavoenzyme 4-hydroxyacetophenone monooxygenase (HAPMO) catalyzes Baeyer-Villiger oxidations of a wide range of ketones, thereby generating esters or lactones. In the current work, we probed HAPMO-coenzyme complexes present during the enzyme catalytic cycle with the aim to gain mechanistic insight. Moreover, we investigated the structural role of the nicotinamide coenzyme. For these studies, we used (i) wild type HAPMO, (ii) the R339A variant, which is active but has a low affinity toward NADPH, and (iii) the R440A variant, which is inactive but has a high affinity toward NADPH. Electrospray ionization mass spectrometry was used as the primary tool to directly observe noncovalent protein-coenzyme complexes in real time. These analyzes showed for the first time that the nicotinamide coenzyme remains bound to HAPMO during the entire catalytic cycle of the NADPH oxidase reaction. This may also have implications for other homologous Baeyer-Villiger monooxygenases. Together with the observations that NADP(+) only weakly interacts with oxidized enzyme and that HAPMO is mainly in the reduced form during catalysis, we concluded that NADP(+) interacts tightly with the reduced form of HAPMO. We also demonstrated that the association with the coenzyme is crucial for enzyme stability. The interaction with the coenzyme analog 3-aminopyridine adenine dinucleotide phosphate (AADP(+)) strongly enhanced the thermal stability of wild type HAPMO. This coenzyme-induced stabilization may also be important for related enzymes.

The reliability assessment of flip chip components

Flip chip technology involves the attachment of active side of the silicon chip onto printed circuit board or substrate. The interconnections are provided by solder bumps, which are arranged in the area under the chip. Encapsulation helps reduce the impact of the thermal stress that results from the mismatch in the coefficient of thermal expansion between the silicon chip and the substrate. The adhesion of the encapsulant to the chip and the board coating are essential to the reliability of the package. This paper studies the adhesion characteristics of an encapsulant to a flip chip package. The quality of the encapsulation was inspected using a scanning acoustic microscope. The electrical continuity of the assemblies was tested during the liquid‐to‐liquid thermal shock testing. The various delamination mechanisms were then studied. Delamination was found predominantly at the interface between the passivation layer and the encapsulant material. Comparisons were made between samples assembled by different materials used, such as chip passivation layer, encapsulant materials, and fluxes. Finally, the best material combination was determined.

Fabrication of the PDMS microchip for serially diluting sample with buffer

We developed a polymer polydimethylsiloxane (PDMS) based microfluidic device that dilutes biological samples with buffer solutions with serially increasing diluted sample concentrations. The device showed the relatively high accuracy in terms of dilution ratios along with the fact that it was faster and easier to operate. With two simple disposable plastic syringes, the plastic microfluidic chip completes ordinary sample dilution sequences faster and more precisely than the conventional manual pipette process in biological or chemical laboratory. The serially diluting mechanism of the microchip is simply that the number of microchannels with the same flow rate determines the total amount of flow into the wells. The soft lithography fabricated the microchannels of tetragonal section length of 50 μm of each side of the microfluidic chip.

Microsensor for the measurement of water content in the human skin

We have developed a thin film microsensor based on interdigital electrodes deposited on a glass substrate. If the film side of the sensor chip is pressed onto human skin, the change of capacitance can be used as a measure for the water content of the skin. As the front side of the sensor must remain flat, the interconnection wires have been fixed at the backside of the chip. In this paper we report on measurements with a frequency of 100 kHz to 2 MHz and a voltage of 100 mV. We compare measuring results on normal skin, atopic (dry) skin and skin moisturized by a humectant.

Thermo-Mechanical Deformation Analysis of Flip-Chip Packages(Electronic Devices)

Moire interferometry technique was applied to the thermo-mechanical analysis of flip-chip packages. Thermal deformations of two kinds of flip-chip structures, no-underfill and underfill flip-chip packages, were studied. The differences of the thermal deformations between the two packages were measured to clarify the effect of underfill. The experimental results showed that the underfill plays an important role to give similar curvatures at the lower side of the silicon chip and the upper side of the substrate. The shear deformation of the solder ball decreased due to the underfill, while the tensile deformation increased.

Single-frequency external-cavity tapered diode laser in a double-ended cavity configuration

We achieved stable single-frequency oscillation in an external-cavity tapered diode laser. The external cavity was constructed from a diffraction grating and an output mirror, which were placed, respectively, in the narrow-area side and the broad-area side of the tapered-stripe chip, with collimator lenses on both sides. The best position for the output mirror was a focal point of the output beam along the axis parallel to the diode junction plane, while the beam along the axis perpendicular to the junction plane was collimated by the collimator lens. Continuous frequency tuning of 900 MHz and a linewidth below 1 MHz were obtained. A bistability was observed in the output power around the threshold current after the output mirror was installed.

Solderable film for bottom side of semiconductor chips

For montage of semiconductor chips there is for many applications a need for solderable film for the bottom side of the chips. This letter contains a description of a new preparation method of thin film with very low soldering velocity, perfect surface coverage with solder, high firmness of connection, and good ohmic contact on both types of the semiconductors.

An integrated-optical silicon microphone with a Fabry–Pérot cavity as modulator

A new construction principle for an integrated-optical microphone is presented. It uses a Fabry–Pérot cavity as modulator. This combines the very sensitive interferometric multiple reflection scheme with a direct intensity modulation. The microphone consists of two chips, the carrier chip and the membrane chip. Both are fabricated in silicon using standard semiconductor technology. The membrane chip is mounted on top of the carrier chip, so that both chips together form the Fabry–Pérot cavity. Unmodulated primary light is generated by a laser diode and partially transmitted to the microphone via a 3-dB coupler. A single fiber, which is attached to the bottom side of the carrier chip, connects the coupler and the microphone. The incoming light is modulated in the Fabry–Pérot cavity by the membrane deflection and is reflected back into the fiber. It passes the coupler in reverse direction and is thereby partially transmitted to a receiver device, e.g., a photo diode. The main advantage of this kind of microphone is that a very low inherent noise level (<30 dB/A) can be achieved with a relatively simple design.

X-Ray Stress Measurement of Mounted Silicon Chips

Stresses in semiconductor silicon chips were measured by an X-ray stress measurement method that is applicable to microareas (60 µ m dia.) of single crystals. The measurement was conducted before and after silicon chip mounting on a substrate. Also measured were residual stresses in areas around bumps. As a result, about +30 to +40 MPa tensile stresses were determined at the corners of the rear side of a test piece silicon chip, which was fixed with resin, and about +70 to +80 MPa tensile stresses were found near the solder-bump formed surface of another test piece silicon chip.

Chemical microsensor systems for medical applications in catheters

Abstract For the synthesis of chemical parameters in human blood, miniaturised sensors have been developed and implemented in common catheter systems. Based on the principle of amperometric sensors, enzyme chips for lactate and glucose determination have been constructed by depositing a thin-film noble metal electrode and a reference electrode at one side of the silicon chips. The enzymes are entrapped into poly-urethane films which are directly attached to the chip surface and optimised by chemical surface modification. The potentiometric sensors have silicon micromachined grooves containing ion-selective ionophores in modified poly(vinyl chloride) (PVC) and electrodes located on both sides of the silicon chip. By means of an intelligent analyte management system the exposure time of the sensors to serum or blood was reduced to about one min/hour. The sensors are conditioned and calibrated immediately before each blood measurement. The analyte and calibrant handling and the signal treatment are controlled by a microprocessor. The sensors assembled in the catheter tip respond reproducibly and accurately to the respective analytes in human serum for more than 70 h.

Liquid cooling performance for a 3-D multichip module and miniature heat sink

Measured thermal performance is presented for a single phase liquid-cooled module. Tape automated bonded (TAB) thermal test chips and their associated substrates are stacked in a compact, 3-D liquid-tight module. A dielectric liquid, polyalphaolefin (PAO), is forced to flow past the active and inactive sides of TAB chips. At a volumetric flowrate of 0.05 gallons per minute (gpm) and an estimated pressure loss less than 0.5 psi, the measured junction-to-liquid thermal resistance is 2.0 C/W for a 0.50 in./spl times/0.50 in./spl times/0.015 in. thermal test chip. The thermal resistance was also measured for an indirect liquid-cooling approach. PAO was used to cool a miniature sink mounted directly to a 0.50 in./spl times/0.50 in. heat source. The heat source was used to simulate the thermal characteristics of a chip carrier package. The overall dimension of the liquid heat sink is 1.0 in./spl times/1.0 in./spl times/0.28 in. The measured junction-to-liquid thermal resistance is 0.52 C/W for a flowrate of 0.05 gpm, and for an estimated pressure loss less than 1.0 psi. Numerical computational techniques yielded results which were comparable to the measured thermal resistances for both the 3-D module and the miniature heat sink. Enhanced thermal performance gained by introducing micro-encapsulated phase change material (microPCM) to the PAO is estimated for both the 3-D module and the miniature heat sink.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

難削材のプラズマ加熱切削 ＩＩ 高Ｍｎ鋼切削機構のシミュレーション解析

In this paper, changes of cutting mechanism in the plasma hot machining of 18% Mn steel are analyzed by means of a two-dimensional cutting simulator incorporated with the flow stress characteristics measured. Firstly, the outline of the simulator is presented, and then the material properties and simulation models used in the analysis are described. Experimental observations, such as the decreases in cutting forces and shear angle, the increases in chip curl radius and chip contact length in the hot machining are successfully simulated. These changing phenomena can closely be related to the changes of strain rate, strain, temperature and flow stress distributions within the primary deformation zone. Especially, the drop of flow stress at the free-surface sides of workpiece and chip by the heating is a main cause of the changing mechanism. Under an ideal heating condition, in which the heat penetrates up to the undeformed chip thickness, the temperatures on the rake face and finished surface are almost independent of the heating. Relating this fact to a wear equation proposed elesewhere, less cratering in the hot machining can analytically be predicted, which is due to the decrease in normal stress on the rake face.

An FET-driven power thyristor

An experimental power thyristor structure is presented, featuring a bipolar gate as well as an FET-driven gate (n-channel MOSFET) on orthogonal sides of a quadratic chip. Thus, the two turn-on modes can be studied independently of each other on the identical thyristor. In addition, the influence of a switchable cathode-emitter short resistance (p-channel MOSFET), integrated on the same chip, is investigated for both types of gate. A simplified analytical model is proposed, assuming that transport effects, represented by a fictitious time dependence of the transport factors in the n- and p-base on one hand and current dependence of the injection coefficient of the cathode emitter on the other hand, are the only variables dominating during turn-on. A quantitative evaluation of the time-dependent thyristor current yields a theoretical description that is in good agreement with the experiment, both for the bipolar as well as for the FET-driven gate. In either case, measurements with and without the shorted emitter are presented. The FET-drive, inducing anode current without delay, leads to a higher dissipation during turn-on. In addition, the current threshold for turn-on is higher since the FET feeds the n-base rather than the p-base. An FET-driven thyristor thus has the advantage of being voltage controlled while the limit of high di/dt capability is more critical than in the conventional case. An additional feature of the structure presented is its potential to serve as a gate turn-off device.

Intermittent loss of light output and switching behavior in AlGaAs lasers modulated at 90 mbit/s

An intermittent loss of light output in AlGaAs lasers modulated at 90 Mbit/s is investigated and is attributed to a parallel intermittent shunt that switches between a resistive and conducting state. The shunt is associated with the presence of In contamination on the sidewalls of the laser chip. A calculation of the switching time based on conducting filaments through In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> is consistent with the pulsed operation of the laser in testing. This shunt is avoided if bonding techniques that eliminate In from sides of the laser chips are employed.

高速度鋼工具の摩耗機構に関する研究(第1報)

It gives an important suggestion in making clear the mechanism of wear of high-speed steel tools to investigate into the mechanism of white layer to be formed on the interface between the built-up edge and the tool when cutting carbon steel. In this paper, a report is given on the results of the observations and experiments obtained from the comparison between (1) the white layer formed during the real cutting and (2) the white layer artificially formed under the condition of almost quick heating and cooling under high pressure and shear stress through the cutting and diffusional simulation of the type of the tapered pin pressing on tool. The results are as follows:(1) The white layer, having Fe as a principal component and C, Cr, Si, Mn, W, V, Co, etc. as minors, was a low-grade high-speed steel having an intermediate component produced by the pipe diffusion from both the tool and workpiece.(2) The white layer consisted basically of a high alloy martensite as matrix and had a mixed structure from which ultra fine complex carbide (Fe, Cr, Mn)3C was precipitated while being cooled.(3) The carbon cohesion on the interface was accelerated from the side of chips to the interface, through the dislocation, vacancy or microcrack in the built-up edge.

The cutting of polymers

The variation in the cutting behaviour of two polymers (Kematal and Perspex) as conditions are varied is described. Subject to the proviso that the Merchant shear plane angle is not greater than 45°, cutting force component data are shown to obey theoretical relations derived to account for the cutting behaviour of metals. The transition from brittle to ductile chip formation can be assessed (a) visually (b) in terms of the cutting force variation and (c) in terms of the change in the proportion of the shear zone which is subject to tensile stress; results obtained by each of these assessments are shown to be substantially in agreement. Utilizing the observations, made inter alia, by Banerjee and Palmer, that during discontinuous chip formation, chip material moves up the rake face by a series of “sticks” and “slips”, a hypothesis is proposed wherein it is suggested that such a motion of chip material occurs not solely during discontinuous chip formation but that it occurs during all forms of chip formation and, in particular, during continuous chip formation. In this way the existence of rugosities on the upper side of continuous chips is explained and deductions from this hypothesis are verified using experimental data.