Alloy Joints for High Temperature Electronic Packaging

1998 ◽  
Vol 515 ◽  
Author(s):  
William W. So ◽  
Chin C. Lee
Keyword(s):  
High Temperature ◽  
Melting Temperature ◽  
Cross Sections ◽  
High Vacuum ◽  
Process Temperature ◽  
Development Effort ◽  
Material System ◽  
Constituent Element ◽  
State Diffusion ◽  
Bonding Method

ABSTRACTHigh temperature joints are required for packaging and assembling the emerging high temperature semiconductor devices. A technique of producing high temperature joints at relatively low process temperature is presented. The technique uses liquid-solid interdiffusion to formulate the joint and subsequent solid-state diffusion and interaction to convert the joint material into high temperature alloy. Processes have been developed using the indium-silver binary material system. Joint melting temperature higher than 700°C has been achieved while the process temperature stays below 210°C. In this development effort, the constituent element materials are deposited in multilayer structure in high vacuum to prevent oxidation. As a result, no flux is used and no scrubbing action is applied. The joints produced are examined with a scanning acoustic microscope (SAM) to evaluate the bonding quality. The joint cross-sections are studied using SEM and EDX to find the microstructure and composition. In conventional processes, the process temperature needs to exceed the alloy melting temperature in order to produce a joint. High stresses can develop due to thermal expansion mismatch among materials involved. In the present technique, the relatively low process temperature can significantly reduce the stresses. The multilayer bonding method also facilitates control of the alloy composition and the joint thickness.

A New Gold-Indium Eutectic Bonding Method

1992 ◽  
Vol 264 ◽  
Author(s):  
Chin C. Lee ◽  
Chen Y. Wang ◽  
Goran Matijasevic ◽  
Steve S. Chan
Keyword(s):  
High Temperature ◽  
Diffusion Process ◽  
Thermal Shock ◽  
Melting Temperature ◽  
Acoustic Microscope ◽  
Bonding Quality ◽  
Eutectic Bonding ◽  
Before And After ◽  
Bonding Method ◽  
Scanning Acoustic Microscope

AbstractAu-In eutectic bonding method which needs only a low process temperature (˜200°C) but produces high temperature (450°C) bonds is reported. In this study, multiple layers of Au and In are deposited directly on semiconductor wafers in one vacuum cycle to prevent indium oxidation and then bonded to substrates coated with Au. At 200°C the indium layer melts and dissolves the gold layers to form a mixture of liquid and solid. The diffusion process continues until the bond solidifies. Upon solidification, the bond has a melting temperature of 456.5°C. Scanning Acoustic Microscope was used to determine the excellent bonding quality before and after thermal shock tests and SEM with EDX capability is employed to determine the composition of the resulting bonds.

Effect of Vapor-Deposited Parylene Coating on Reliability of Sintered Silver Joints for Extreme Temperature Applications

2016 ◽  
Vol 2016 (1) ◽  
pp. 000338-000344 ◽  
Author(s):  
Zhenzhen Shen ◽  
Aleksey Reiderman
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Mechanical Strength ◽  
Cross Sections ◽  
Mechanical Performance ◽  
Extreme Temperature ◽  
High Humidity ◽  
Test Analysis ◽  
Bonding Method ◽  
Sintered Silver

Abstract Silver nano-particle (AgNP) sintering has been extensively shown to be an excellent bonding method for use in the assembly of high-temperature multi-chip modules (MCM) rated above 200° C. Among the proven advantages of using this material in the assembly are the high mechanical strength of the attachment joints, resilience to thermal cycles, low resistivity, and high thermal conductivity. One of the concerns related to the reliability of sintered silver joints is silver migration. Another concern is the change in the joint's microstructure under thermal stress. Vapor-deposited high-temperature fluorinated parylene coating (Paralyne HT) may have the potential to mitigate those concerns because of its superior conformal and crevice-penetration properties. In this work, impact of Parylene HT on sintered silver joints has been evaluated from the perspective of mechanical strength. Test vehicles were subjected to thermal cycling and high-temperature aging. To understand the sintered silver joint's failure mechanisms, shear test analysis of the cross sections and fracture surfaces was performed. In addition, the effectiveness of Parylene HT as a coating to inhibit silver migration at high humidity was evaluated. Coated and uncoated sintered silver test patterns were stressed with an electrical field inside a high-humidity chamber. The silver migration progression was monitored and compared between coated and uncoated samples during the test. One of the findings was that the coating material penetrates the pores of the sintered silver joints, altering their mechanical performance under thermal stress. Analysis of the performance differences between coated and uncoated test vehicles is presented in the paper.

scholarly journals High Temperature Behavior of RuAl Thin Films on Piezoelectric CTGS and LGS Substrates

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1605 ◽  
Author(s):  
Marietta Seifert
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Cross Sections ◽  
Barrier Layer ◽  
High Vacuum ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Si Substrates ◽  
20 Nm

This paper reports on a significant further improvement of the high temperature stability of RuAl thin films (110 nm) on the piezoelectric Ca 3 TaGa 3 Si 2 O 14 (CTGS) and La 3 Ga 5 SiO 14 (LGS) substrates. RuAl thin films with AlN or SiO 2 cover layers and barriers to the substrate (each 20 nm), as well as a combination of both were prepared on thermally oxidized Si substrates, which serve as a reference for fundamental studies, and the piezoelectric CTGS, as well as LGS substrates. In some films, additional Al layers were added. To study their high temperature stability, the samples were annealed in air and in high vacuum up to 900 °C, and subsequently their cross-sections, phase formation, film chemistry, and electrical resistivity were analyzed. It was shown that on thermally oxidized Si substrates, all films were stable after annealing in air up to 800 °C and in high vacuum up to 900 °C. The high temperature stability of RuAl thin films on CTGS substrates was improved up to 900 °C in high vacuum by the application of a combined AlN/SiO 2 barrier layer and up to 800 °C in air using a SiO 2 barrier. On LGS, the films were only stable up to 600 °C in air; however, a single SiO 2 barrier layer was sufficient to prevent oxidation during annealing at 900 °C in high vacuum.

scholarly journals A Ceramic Diffusion Bonding Method for Passive LC High-Temperature Pressure Sensor

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2676
Author(s):  
Chen Li ◽  
Boshan Sun ◽  
Yanan Xue ◽  
Jijun Xiong
Keyword(s):  
High Temperature ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Alumina Ceramic ◽  
Harsh Environments ◽  
Ceramic Substrates ◽  
Integrated Technology ◽  
All Ceramic ◽  
Test Platform ◽  
Bonding Method

Alumina ceramic is a highly promising material for fabricating high-temperature pressure sensors. In this paper, a direct bonding method for fabricating a sensitive cavity with alumina ceramic is presented. Alumina ceramic substrates were bonded together to form a sensitive cavity for high-temperature pressure environments. The device can sense pressure parameters at high temperatures. To verify the sensitivity performance of the fabrication method in high-temperature environments, an inductor and capacitor were integrated on the ceramic substrate with the fabricated sensitive cavity to form a wireless passive LC pressure sensor with thick-film integrated technology. Finally, the fabricated sensor was tested using a system test platform. The experimental results show that the sensor can realize pressure measurements above 900 °C, confirming that the fabricated sensitive cavity has excellent sealing properties. Therefore, the direct bonding method can potentially be used for developing all-ceramic high-temperature pressure sensors for application in harsh environments.

Upgrade and Shakedown Test of a High Temperature Fluoride Salt Test Loop

2018 ◽  
Author(s):  
Xiangbo Kong ◽  
Yuan Fu ◽  
Jianyu Zhang ◽  
Huiju Lu ◽  
Naxiu Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Storage Tank ◽  
Base Alloy ◽  
High Vacuum ◽  
Electric Heater ◽  
Batch Mode ◽  
Test Loop

A FLiNaK high temperature test loop, which was designed to support the Thorium Molten Salt Reactor (TMSR) program, was constructed in 2012 and is the largest engineering-scale fluoride loop in the world. The loop is built of Hastelloy C276 and is capable of operating at the flow rate up to 25m3/h and at the temperature up to 650°C. It consists of an overhung impeller sump-type centrifugal pump, an electric heater, a heat exchanger, a freeze valve and a mechanical one, a storage tank, etc. Salt purification was conducted in batch mode before it was transferred to and then stored in the storage tank. The facility was upgraded in three ways last year, with aims of testing a 30kW electric heater and supporting the heat transfer experiment in heat exchanger. Firstly, an original 100kW electric heater was replaced with a 335kW one to compensate the overlarge heat loss in the radiator. A pressure transmitter was subsequently installed in the inlet pipe of this updated heater. Finally, a new 30kW electric heater was installed between the pump and radiator, the purpose of which was to verify the core’s convective heat transfer behavior of a simulator design of TMSR. Immediately after these above works, shakedown test of the loop was carried out step by step. At first the storage tank was gradually preheated to 500°C so as to melt the frozen salt. Afterwards, in order to make the operation of transferring salt from storage tank to loop achievable, the loop system was also preheated to a relatively higher temperature 530°C. Since the nickel-base alloy can be severely corroded by the FLiNaK salt once the moisture and oxygen concentration is high, vacuum pumping and argon purging of the entire system were alternatively performed throughout the preheating process, with the effect of controlling them to be lower than 100ppm. Once the salt was transferred into the loop, the pump was immediately put into service. At the very beginning of operation process, it was found that flow rate in the main piping could not be precisely measured by the ultrasonic flow meter. Ten days later, the pump’s dry running gas seal was out of order. As a result, the loop had to be closed down to resolve these issues.

scholarly journals High temperature infrared absorption cross sections of methane near 3.4 µm in Ar and CO2 mixtures

2018 ◽  
Vol 206 ◽  
pp. 36-45 ◽  
Author(s):  
Batikan Koroglu ◽  
Sneha Neupane ◽  
Owen Pryor ◽  
Robert E. Peale ◽  
Subith S. Vasu
Keyword(s):  
High Temperature ◽  
Cross Sections ◽  
Infrared Absorption ◽  
Absorption Cross

Mobile Packaging and Interconnect Trends

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 1-21
Author(s):  
Brandon Prior
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Thick Film ◽  
Cross Sections ◽  
Shear Test ◽  
Short Review ◽  
Test Machine ◽  
Die Attach ◽  
Shear Failures ◽  
Film Substrate

This paper will focus on emerging and fast growth package solutions to meet mobile products' density and cost requirements. A short review of where package miniaturization and modularization has taken us so far, and where it will lead in the next 5 years. Teardowns of high density systems and packages will be used to illustrate key points. Low temperature Ag sintering technology provides a lead-free die attachment compatible with high temperature (300°C) applications. Previous work with Ag sintering has required some pressure during the sintering process or been limited to small area die. In this paper, a pressureless sintering of micro-scale silver paste procedure is presented for large (8mm x 8mm) area die. Experimental combinations included: Ag metallized Si die, Au metallized Si die, Ag thick film substrate metallization, Au thick film substrate metallization, PdAg thick film metallization and sintering temperature. For Au metallization (die and/or substrate), the initial shear strength results were good with 8mm x 8mm die sintered at lower temperatures (200°C). The shear strength was out range of our shear test machine (100 kg), corresponding to >15.3 MPa. However, after aging for 24 hours at 300°C, the shear strength dropped significantly to 40.38 Kg (6.183 MPa). An SEM was used to characterize cross sections of as-built and aged sample. The decrease in die shear strength with high temperature sintering (250°C and 300°C) or high temperature aging is attributed to surface diffusion of Ag along the Au surface resulting in a dense Ag layer adjacent to the Au surface and a depletion layer within the die attach on the opposite side of the the dense Ag layer. Shear failures occurred through the depleted region. For Ag metallization, no decrease in shear strength was observed with 300°C aging. Shear strength of 8x8cm2 dies was out range of our shear test machine (>100 kg, >15.3 MPa) as-built. The shear strength remained out of range (>15.3MPa) after more than 2000 hours of 300C aging.

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