scholarly journals Rapid and Localized Soldering Using Reactive Films for Electronic Applications

2019 ◽  
Vol 16 (4) ◽  
pp. 182-187
Author(s):  
Rabih Khazaka ◽  
Donatien Martineau ◽  
Toni Youssef ◽  
Thanh Long Le ◽  
Stéphane Azzopardi
Keyword(s):  
Phase Distribution ◽  
Coefficient Of Thermal Expansion ◽  
Applied Pressure ◽  
Temperature Sensitive ◽  
Soldering Process ◽  
External Power Source ◽  
Solder Reflow ◽  
External Power ◽  
The One ◽  
Joint Quality

Abstract The rapid and localized heating techniques allow the joining of temperature-sensitive materials and components without thermal induced damage commonly encountered when high-temperature solder reflow processes are used. This is also advantageous for making assemblies with materials having a large difference in the coefficient of thermal expansion without induced bowing or cracking. The use of exothermic reactive foil sandwiched between solder preforms is a promising local and rapid soldering process because it does not require any external heat source. The reactive foil is formed from alternatively stacked nanolayers of Ni and Al until it reaches the total film thickness. Once the film is activated by using an external power source, a reaction takes place and releases such an amount of energy that is transferred to the solder preforms. If this amount of energy is high enough, solder preforms melt and insure the adhesion between the materials of the assembly. The influences of the applied pressure, the reactive film (RF) thickness as well as the solder, and the attached materials chemical composition and thickness were investigated. It was shown that the applied pressure during the process has a strong effect on the joint initial quality with voids ratio decreases from 64% to 26% for pressure values between .5 and 100 kPa, respectively. This can be explained by the improvement of the solder flow under higher pressure leading to a better surface wettability and voids elimination. Otherwise, the joint quality was found to be improved once the solder melting duration is increased. This relationship was observed when the thickness of the reactive foil is increased (additional induced energy) or the thickness of solders, Cu, and/or Si is decreased (less energy consumption). The microstructure of the AuSn joint achieved using the RFs shows very fine phase distribution compared with the one obtained using conventional solder reflow process in the oven because of high cooling rate. The mechanical properties of the joint were evaluated using shear tests performed on 350-μm-thick silicon diodes assembled on active metal brazed substrates under a pressure of 100 kPa. The RFs were 60 μm thick and sandwiched between two 25-μm-thick 96.5Sn3Ag.5Cu (SAC) preforms. The voids ratio was about 37% for the tested samples and shear strength values above 9.5 MPa were achieved which remains largely higher than MIL-STD-883H requirements. Finally, the process impact on the electrical properties of the assembled diodes was compared with a commonly used solder reflow assembly and the results show a negligible variation.

Parametric study of electronics components joining using reactive films for high temperature applications

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000016-000021
Author(s):  
Rabih Khazaka ◽  
Donatien Martineau ◽  
Toni Youssef ◽  
Thanh Long Le ◽  
Stéphane Azzopardi
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Film Thickness ◽  
Void Ratio ◽  
Phase Distribution ◽  
Applied Pressure ◽  
Acoustic Microscopy ◽  
External Power Source ◽  
Solder Reflow ◽  
Joint Quality

Abstract In this paper, in order to assemble electronic components onto substrates, a local rapid soldering process using an exothermic reactive foil sandwiched between solder preforms was evaluated. Among others, the main interest of this technique is that it can allow the use of high temperature melting solders, without the need to heat the whole assembly above this melting temperature. The reactive foil is commercially available and is formed from alternatively stacked nanolayers of Ni and Al until it reaches the total film thickness. Once the film is activated by using an external power source, a reaction takes place and releases such an amount of energy that is transferred to the solder preforms. If this amount of energy is high enough, solder preforms melt and insure the adhesion between the materials of the assembly. The process was evaluated using a standard SAC305 and a high temperature Au80Sn20 preforms. The influences of the applied pressure, the reactive film thickness as well as the solder and the attached materials nature and thicknesses were investigated. The initial joint quality was evaluated using scanning acoustic microscopy, scanning electron microscopy, and shear strength measurements. It was shown that the applied pressure during the process has a strong effect on the joint initial quality. The voids ratio between metallized diode dice and an Active Metal Braze (AMB) substrate decreases from 64% to 26% for pressure values between 0.5kPa and 100kPa respectively. Otherwise, under a constant low pressure of 13kPa, reducing the substrate metal thickness on a low thermal conductivity insulator allows the improvement of the initial joint quality and a voids ratio of about 15% was reached when using 35μm of copper on FR4 substrate. The use of aluminum instead of copper as a metal for the ceramic metallized substrate (with the same gold finishing layer) led to a reduction in the void ratio in the joint. The microstructure of the AuSn joint achieved using the reactive films shows very fine phase distribution compared to the one obtained using conventional solder reflow process in the oven. The mechanical properties of the joint were evaluated using shear tests performed on 350μm thick silicon diodes assembled on AMB substrates under a pressure of 100kPa. The reactive films were 60μm thick and were sandwiched between two 25μm thick SAC preforms. The void ratio was about 37% for the tested samples and shear strength values above 9.5MPa were achieved which remains largely higher than MIL-STD-883H requirements. Finally, the process impact on the electrical properties of the assembled diodes was compared with a commonly used solder reflow assembly and results show a negligible variation.

scholarly journals Automatic Solar Panel Tracking System

2019 ◽  
Vol 9 (1) ◽  
pp. 264-269
Keyword(s):  
Solar Energy ◽  
Alternative Energy ◽  
Tracking System ◽  
Solar Panel ◽  
Controlled System ◽  
Solar Tracking ◽  
External Power Source ◽  
External Power ◽  
R 134A ◽  
The One

Solar Energy is the one of best renewable source of alternative energy. The efficiency of the solar panel can be improved more by tracking it in such way that it always faces perpendicular to the sun-rays throughout the day rather than it is kept fixed at an angle. At present, there are three methods for solar tracking, out of which refrigerant method is found to be more efficient as it is of a passive type and requires no external power source for its operation. In this project we have used R-134a [Tetrafluoroethene (CF3CH2F)] as the refrigerant medium for tracking the panel. To store the refrigerant, we have made use of two canisters and a copper conduit for connecting the canisters. The tracking system works on the principle of Differential Pressure Controlled system where high-pressure refrigerant from one canister to other flows and due to imbalance in the weight of canisters, the panel will tilt in the direction of the side where the weight is high due to gravity. Thus, our main objective is to harvest more solar energy at a much lower cost than the available trackers.

scholarly journals Design of a Purely Mechanical Sensor-Controller Integrated System for Walking Assistance on an Ankle-Foot Exoskeleton

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3196 ◽  
Author(s):  
Xiangyang Wang ◽  
Sheng Guo ◽  
Haibo Qu ◽  
Majun Song
Keyword(s):  
Human Body ◽  
Proper Time ◽  
Metabolic Cost ◽  
Human Locomotion ◽  
Essential Elements ◽  
Integrated System ◽  
External Power Source ◽  
Key Factor ◽  
External Power ◽  
The One

Propulsion during push-off (PO) is a key factor to realize human locomotion. Through the detection of real-time gait stage, assistance could be provided to the human body at the proper time. In most cases, ankle-foot exoskeletons consist of electronic sensors, microprocessors, and actuators. Although these three essential elements contribute to fulfilling the function of the detection, control, and energy injection, they result in a huge system that reduces the wearing comfort. To simplify the sensor-controller system and reduce the mass of the exoskeleton, we designed a smart clutch in this paper, which is a sensor-controller integrated system that comprises a sensing part and an executing part. With a spring functioning as an actuator, the whole exoskeleton system is completely made up of mechanical parts and has no external power source. By controlling the engagement of the actuator based on the signal acquired from the sensing part, the proposed clutch enables the ankle-foot exoskeleton (AFE) to provide additional ankle torque during PO, and allows free rotation of the ankle joint during swing phase, thus reducing the metabolic cost of the human body. There are two striking advantages of the designed clutch. On the one hand, the clutch is lightweight and reliable—it resists the possible shock during walking since there is no circuit connection or power in the system. On the other hand, the detection of gait relies on the contact states between human feet and the ground, so the clutch is universal and does not need to be customized for individuals.

Improving the accuracy of the synthesis of the amplitude-phase distribution in an antenna array with an arbitrary geometry

2021 ◽  
Author(s):  
D.D. Gabrielyan ◽  
Dan.S. Fedorov ◽  
Den.S. Fedorov
Keyword(s):  
Antenna Arrays ◽  
Phase Distribution ◽  
Problem Statement ◽  
Arbitrary Geometry ◽  
Radiating Element ◽  
Path Measurement ◽  
The One ◽  
The Given ◽  
Single Approach

Problem statement. One of the constructing antenna arrays (AA) topic is related to the determination of complex amplitudes at the input of the antenna-feeder path, which, taking into account the distortions introduced by the its, ensure the formation of an amplitude-phase distribution (APD), in which the formed DP differed minimally from the set one. The statement of the problem assumes the known number and coordinates of the location of the emitters, the DP of the radiating element in the composition of the radiating opening, a given radiation pattern. It is required to form an APD in a given opening of the AA, which ensures the formation of a DP that has a minimum deviation from the specified one. To solve the problem, the following algorithm is proposed: determination of the APD at the input of the antenna-feeder path, which ensures the formation of a given DP in the absence of distortions introduced by the antenna-feeder path; measurement for the selected directions of the generated DP with the selected APD in the presence of APD distortions introduced by the antenna-feeder path; formation of a refined APD that ensures the fulfillment of required condition in the presence of distortions introduced by the antenna-feeder path of the AA. Objective. Minimize the root-mean-square deviation of the generated PD from the one specified for the AP with the opening of an arbitrary geometry. Results. The results obtained showed: The formulation of the problem of synthesis of the APD allows us to consider, within the framework of a single approach, AA with different geometries, including AA with a non-planar radiating opening, no restrictions are imposed on the shape of the boundary, and linear (quasi-ring) AA, the emitters of which are located along an arbitrary mane. Using the proposed algorithm for the synthesis of APD, which includes three main stages: the formation of APD for a given DP; measurement of complex values of the generated DP; refinement of the APD by determining the corrections while minimizing the standard deviation (SD) between the specified and formed at the first stage of the DP, allows us to form an APD that provides a minimum SD between the specified and formed DP. The performed studies have shown that when choosing the number of angular directions in each plane, comparable to the number of emitters in this plane, there is a large difference between the given and formed DP. When the number of angular directions for measuring the DP is approximately three times greater than the number of emitters in a given plane, the SD between the specified and formed DP is close to the minimum value and practically does not change with further increase.

NanoBond® Assembly – A Rapid, Room Temperature Soldering Process

2011 ◽  
Vol 2011 (1) ◽  
pp. 000521-000526
Author(s):  
Jacques Matteau
Keyword(s):  
Room Temperature ◽  
New Technology ◽  
Local Heat ◽  
Temperature Sensitive ◽  
Ignition Process ◽  
Light Emitting ◽  
Exothermic Reactions ◽  
Soldering Process ◽  
Order Of Magnitude ◽  
Reactive Foils

Indium Corporation of America has commercialized a new technology that will revolutionize how manufacturers join components using solder materials. (See Figure 1) The joining process is based on the use of reactive multilayer foils as local heat sources. The foils are a new class of nano-engineered materials, in which self-propagating exothermic reactions can be ignited at room temperature through an ignition process. By inserting a multilayer foil between two solder layers and two components, heat generated by the reaction in the foil melts the solder and consequently bonds are completed at room temperature in air, argon or vacuum in approximately one second. The resulting metallic joints exhibit thermal conductivities two orders of magnitude higher, and thermal resistivity’s an order of magnitude lower, than current commercial TIMs. The use of reactive foils as a local heat source eliminates the need for torches, furnaces, or lasers, speeds the soldering processes, and dramatically reduces the total heat that is needed. Thus, temperature-sensitive or small components can be joined without thermal damage or excessive heating. In addition, mismatches in thermal contraction on cooling can be avoided because components see very small increases in temperature. This is particularly beneficial for joining metals to ceramics. The fabrication and characterization of the reactive foils is described, and the value proposition for NanoBonding is presented. This presentation also shows the applicability of this platform technology to many areas of packaging including Thermal Interface Materials, microelectronics, optoelectronics, and Light Emitting Diodes (LEDs)

scholarly journals Performance Study of Split Ferrite Cores Designed for EMI Suppression on Cables

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1992
Author(s):  
Adrian Suarez ◽  
Jorge Victoria ◽  
Jose Torres ◽  
Pedro A. Martinez ◽  
Antonio Alcarria ◽  
...  
Keyword(s):  
Electromagnetic Compatibility ◽  
Electronic Device ◽  
Fem Simulation ◽  
Power Cables ◽  
Performance Study ◽  
External Power Source ◽  
External Power ◽  
Cable Assembly ◽  
Wired Communication

The ideal procedure to start designing an electronic device is to consider the electromagnetic compatibility (EMC) from the beginning. Even so, EMC problems can appear afterward, especially when the designed system is interconnected with external devices. Thereby, electromagnetic interferences (EMIs) could be transmitted to our device from power cables that interconnect it with an external power source or are connected to another system to establish wired communication. The application of an EMI suppressor such as a sleeve core that encircles the cables is a widely used technique to attenuate EM disturbances. This contribution is focused on the characterization of a variation of this cable filtering solution based on openable core clamp or snap ferrites. This component is manufactured by two split parts pressed together by a snap-on mechanism which turns this into a quick, easy to install solution for reducing post-cable assembly EMI problems. The performance of three different materials, including two polycrystalline (MnZn and NiZn) materials and nanocrystalline (NC) solution, are analyzed in terms of effectiveness when the solid sleeve cores are split. The possibility of splitting an NC core implies an innovative technique due to the brittleness of this material. Thus, the results obtained from this research make it possible to evaluate this sample’s effectiveness compared to the polycrystalline ones. This characterization is carried out by the introduction of different gaps between the different split-cores and analyzing their behavior in terms of relative permeability and impedance. The results obtained experimentally are corroborated with the results obtained by a finite element method (FEM) simulation model with the aim of determining the performance of each material when it is used as an openable core clamp.

Precise quantitative addition of multiple reagents into droplets in sequence using glass fiber-induced droplet coalescence

The Analyst ◽  
2015 ◽  
Vol 140 (3) ◽  
pp. 701-705
Author(s):  
Chunyu Li ◽  
Jian Xu ◽  
Bo Ma
Keyword(s):  
Glass Fiber ◽  
Power Source ◽  
Droplet Coalescence ◽  
External Power Source ◽  
External Power ◽  
Serial Addition

Serial addition of reagents with controlled volumes is performed using a glass fiber-induced droplet coalescence method without the requirement for an external power source.

scholarly journals Noiseless intensity amplification of repetitive signals by coherent addition using the temporal Talbot effect

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Reza Maram ◽  
James Van Howe ◽  
Ming Li ◽  
José Azaña
Keyword(s):  
Optical Pulse ◽  
Wave Train ◽  
Extinction Ratio ◽  
Power Source ◽  
Wave System ◽  
Talbot Effect ◽  
Physical Processes ◽  
External Power Source ◽  
External Power ◽  
Time Average

Abstract Amplification of signal intensity is essential for initiating physical processes, diagnostics, sensing, communications and measurement. During traditional amplification, the signal is amplified by multiplying the signal carriers through an active gain process, requiring the use of an external power source. In addition, the signal is degraded by noise and distortions that typically accompany active gain processes. We show noiseless intensity amplification of repetitive optical pulse waveforms with gain from 2 to ~20 without using active gain. The proposed method uses a dispersion-induced temporal self-imaging (Talbot) effect to redistribute and coherently accumulate energy of the original repetitive waveforms into fewer replica waveforms. In addition, we show how our passive amplifier performs a real-time average of the wave-train to reduce its original noise fluctuation, as well as enhances the extinction ratio of pulses to stand above the noise floor. Our technique is applicable to repetitive waveforms in any spectral region or wave system.

Sign in / Sign up

Export Citation Format

Share Document