Low temperature liquid bonding using Cu@Sn preform for high temperature die attach

2017 ◽  
Author(s):  
Hongyan Xu ◽  
Qilong Wu ◽  
Puqi Ning ◽  
Ju Xu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Die Attach ◽  
Temperature Liquid

LT-TLPS Die Attach for High Temperature Electronic Packaging

2014 ◽  
Vol 11 (1) ◽  
pp. 7-15
Author(s):  
Hannes Greve ◽  
F. Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Melting Point ◽  
Low Temperature ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Die Attach ◽  
Metallic Interfaces ◽  
Dsc Analyses ◽  
Transient Liquid Phase Sintering

Low temperature transient liquid phase sintering (LT-TLPS) can be used to form high-temperature joints between metallic interfaces at low process temperatures. In this paper, process analyses and shear strength studies of paste-based approaches to LT-TLPS are presented. The process progression studies include DSC analyses and observations of intermetallic compound (IMC) formation by cross-sectioning. It was found that the sintering process reaches completion after sintering times of 15 min for process temperatures approximately 50°C above the melting point of the low temperature constituent. For the shear studies, test samples consisting of copper dice and copper substrates joined by sintering with a variety of sinter pastes with different ratios of copper and tin have been assessed. A fixture was designed for high temperature enabled shear tests at 25°C, 125°C, 250°C, 400°C, and 600°C. The influence of the ratio of the amount of high melting-point constituent to the amount of low melting-point constituent on the maximum application temperature of the sinter paste was analyzed. Ag20Sn and Cu50Sn pastes showed no reduction in shear strength up to 400°C, and Cu40Sn pastes showed high shear strengths up to 600°C. It was shown that LT-TLPS can be used to form high temperature stable joints at low temperatures without the need to apply pressure during processing.

scholarly journals Deep melting reveals liquid structural memory and anomalous ferromagnetism in bismuth

2017 ◽  
Vol 114 (13) ◽  
pp. 3375-3380 ◽  
Author(s):  
Yu Shu ◽  
Dongli Yu ◽  
Wentao Hu ◽  
Yanbin Wang ◽  
Guoyin Shen ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Electrical Resistance ◽  
Structural Characteristics ◽  
Critical Role ◽  
Melting Curve ◽  
Molten State ◽  
Pressure Independent ◽  
Temperature Liquid ◽  
Structural Memory

As an archetypal semimetal with complex and anisotropic Fermi surface and unusual electric properties (e.g., high electrical resistance, large magnetoresistance, and giant Hall effect), bismuth (Bi) has played a critical role in metal physics. In general, Bi displays diamagnetism with a high volumetric susceptibility (∼10−4). Here, we report unusual ferromagnetism in bulk Bi samples recovered from a molten state at pressures of 1.4–2.5 GPa and temperatures above ∼1,250 K. The ferromagnetism is associated with a surprising structural memory effect in the molten state. On heating, low-temperature Bi liquid (L) transforms to a more randomly disordered high-temperature liquid (L′) around 1,250 K. By cooling from above 1,250 K, certain structural characteristics of liquid L′ are preserved in L. Bi clusters with characteristics of the liquid L′ motifs are further preserved through solidification into the Bi-II phase across the pressure-independent melting curve, which may be responsible for the observed ferromagnetism.

Low Temperature, Fast Sintering of Micro-Scale Silver Paste for Die Attach for 300°C Applications

2015 ◽  
Vol 2015 (1) ◽  
pp. 000654-000660 ◽  
Author(s):  
Fang Yu ◽  
R. Wayne Johnson ◽  
Michael C. Hamilton
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Performance ◽  
High Reliability ◽  
Sintering Process ◽  
Power Devices ◽  
C Storage ◽  
Die Attach ◽  
Increasing Demand ◽  
High Lead

With an increasing demand for SiC and GaN high power devices that operate at high temperature, traditional solder materials are reaching their limitations in performance. In addition, there is a strong desire to eliminate high lead containing solders in Si power device packaging for use over conventional temperature range. Low temperature Ag sintering technology is a promising method for high performance lead-free die attachment. In a previous study, a pressureless sintering process and suitable metallization were demonstrated to provide high reliability die attach by using micro-size Ag sintering. The resulting die attach layer had approximately 30% porosity. In this work, a low temperature pressure-assisted fast sintering process was examined. The porosity was decreased from 30% to 15% with application of a low pressure (7.6MPa) during a one minute sintering process. The shear strength for a 3 mm × 3 mm die was 70 MPa and the 8 mm × 8 mm die could not be sheared off due to a 100 kg shear module force limit. Both the Ag and Au metallization (die and substrate) were studied. Furthermore, a new substrate metallization combination was found that allows the use of Au thick film metallized substrates. High temperature (300 °C) storage tests for up to 2000 hours aging were conducted and results are presented.

Packaging technologies for high temperature control electronics

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000184-000192 ◽  
Author(s):  
Conor Slater ◽  
Radisav Cojbasic ◽  
Thomas Maeder ◽  
Yusuf Leblebici ◽  
Peter Ryser
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Temperatures ◽  
Temperature Control ◽  
Critical Issue ◽  
Temperature Cycling ◽  
Strength Change ◽  
Die Attach ◽  
Number Of Cycles ◽  
Control Modules

Current low temperature electronics (<175°C) with logical functions (CPUs, MCUs) have exceptional levels of reliability in terms of packaging, stemming from decades of research. However, electronics that operate at higher temperatures (>175°C) for prolonged periods of time require packaging technologies that have to tackle many new problems. At high temperatures traditionally used materials such as organic circuit boards, adhesives and standard solders degrade rapidly or undergo changes in structure and properties. An even more critical issue than high-temperature survivability is resistance to temperature cycling. Thermal mismatch between organic boards and semiconductor dies leads to high thermomechanical strains during swings from high to low temperature extremes, which can make an otherwise high temperature resistant assembly fail after a relatively low number of cycles. This work focuses on the packaging technologies for high temperature control modules, those with logical and signal conditioning applications. Although control modules share many similarities with power modules, they present their own unique design challenges, such as significantly higher complexity and a limitation of compatible materials. Here, recent research on substrates, die attach technologies and wirebond interconnects suited for high temperature ICs are presented along with packaging technologies for discrete components (capacitors and resistors) with the aim of identifying the current best solutions. Test vehicles for the various technologies were constructed and were subjected to high temperature storage at temperatures higher than 200°C. They were analysed in terms of degradation (i.e. loss in shear strength, pull strength, change in resistance, etc.). In parallel, a separate set of samples were subjected to temperature cycles from −20°C to 180°C and then analysed using the same tests as before for comparison. The combined data allow a recommendation to be made on how to assemble a viable control module such as one based on an SOI microcontroller designed at EPFL to operate at high temperatures.

Low temperature nanojoining of silver–copper nanopaste as die attach material for high temperature packaging

2016 ◽  
Vol 28 (7) ◽  
pp. 5446-5451 ◽  
Author(s):  
Xiaojian Liu ◽  
Chunqing Wang ◽  
Wei Liu ◽  
Zhen Zheng ◽  
Mingyu Li
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Silver Copper ◽  
Die Attach
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