Reliability of paste based transient liquid phase sintered interconnects

Greve, Hannes; Moeini, S. Ali; McCluskey, F. Patrick

doi:10.1109/ectc.2014.6897462

Cited by 14 publications

(6 citation statements)

References 5 publications

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“…The nominal shear strength was measured to be at least 40 MPa according to the normal shear testing procedure. Greve et al have demonstrated a shear strength capacity above 10 MPa at 600°C [31]. Fractography revealed that the strength was limited by a poor adhesion layer.…”

Section: Resultsmentioning

confidence: 99%

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Intermetallic Bonding for High-Temperature Microelectronics and Microsystems: Solid-Liquid Interdiffusion Bonding

Aasmundtveit¹,

Luu²,

Nguyen³

et al. 2018

Intermetallic Compounds - Formation and Applications

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Solid-liquid interdiffusion (SLID) bonding for microelectronics and microsystems is a bonding technique relying on intermetallics. The high-melting temperature of intermetallics allows for system operation at far higher temperatures than what solder-bonded systems can do, while still using similar process temperatures as in common solder processes. Additional benefits of SLID bonding are possibilities of fine-pitch bonding, as well as thin-layer metallurgical bonding. Our group has worked on a number of SLID metal systems. We have optimized wafer-level Cu-Sn SLID bonding to become an industrially feasible process, and we have verified the reliability of Au-Sn SLID bonding in a thermally mismatched system, as well as determined the actual phases present in an Au-Sn SLID bond. We have demonstrated SLID bonding for very high temperatures (Ni-Sn, having intermetallics with melting points up to 1280°C), as well as SLID with low process temperatures (Au-In, processed at 180°C, and Au-In-Bi, processed at 90-115°C). We have verified experimentally the high-temperature stability for our systems, with quantified strength at temperatures up to 300°C for three of the systems: Cu-Sn, Au-Sn and Au-In.Keywords: microelectronics/microsystem assembly, bonding technology, harsh environments, wafer processing, reliability, transient liquid phase © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Motivation for SLID The challenge of die attach and interconnectionFor all electronic systems, the attachment of components to substrates and their electrical connection is a crucial part of the system. Traditionally, the processes for attachment and interconnection have been considered more a craft than a science. The historical focus of electronics and microtechnology has been on the design, manufacturing and testing of components, circuits and devices, rather than on the system integration and the processes needed for actually building the system. The 'electronic revolution' has given ever-increasing performance of devices at ever-decreasing prices for more than half a century. Initial milestones were the invention of the transistor (1947) and the integrated circuit (IC) (1958). The driving factor has been a continuous decrease in size (of components and on features of components) and cost, made possible through batch processing of silicon wafers. Single-crystal silicon is a very well-defined material with extremely well-characterized properties, allowing process technology that yields extremely small features (10 nm by 2017, with a further decrease expected). Miniaturization of components and the use of large Si wafers give a huge number of components manufactured in every batch, lowering the cost. Furthermore, miniaturization allows an increase in operating frequency (or a decrease...

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Section: Resultsmentioning

confidence: 99%

“…One way to overcome the problem of forming the large idiomorphic crystals restricting the joint compliancy would be to fabricate joints with an Ni-Sn paste. This would also significantly reduce the necessary process time to homogenize the bond [31]. Unfortunately, such pastes are per now not commercially available.…”

Section: Resultsmentioning

confidence: 99%

Intermetallic Bonding for High-Temperature Microelectronics and Microsystems: Solid-Liquid Interdiffusion Bonding

Aasmundtveit¹,

Luu²,

Nguyen³

et al. 2018

Intermetallic Compounds - Formation and Applications

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“…Furthermore, we predicted that the thermal conductivity of TLPS joints formed from these pastes is high [18]. Additionally, we demonstrated that they have good reliability under cyclic drop loads [25] but are susceptible to crack formation in the brittle IMC regions under power cycling conditions [19].…”

Section: Introductionmentioning

confidence: 82%

“…No such cracks have appeared in Cu-Sn TLPS joints between Cu-substrates [18,19,21,22] or Ni-Sn joints between Ni-substrates [25][26][27] under identical process conditions. This indicates that thermomechanical loads induced by CTE mismatch between the TLPS joint, the diode, and the substrate, in combination with temperature gradients between sintering and ambient, are the source of the crack formation.…”

Section: Sample Preparation and Failure Analysismentioning

confidence: 99%

“…This decouples the process completion time from the joint thickness, because the required IMC thickness is equal to the short distance between high-melting temperature particles. Because of these advantages, considerable research has been pursued on the Cu-Sn [14][15][16][17][18][19][20][21][22] and Ni-Sn [18,[23][24][25][26][27] material systems in the last years.…”

Section: Introductionmentioning

confidence: 99%

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Prediction and Mitigation of Vertical Cracking in High-Temperature Transient Liquid Phase Sintered Joints by Thermomechanical Simulation

Greve

Moeini

McCluskey

et al. 2018

Journal of Electronic Packaging

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Transient liquid phase sintering (TLPS) is a novel high-temperature attach technology. It is of particular interest for application as die attach in power electronic systems because of its high-melting temperature and high thermal conductivity. TLPS joints formed from sinter pastes consist of metallic particles embedded in matrices of intermetallic compounds (IMCs). Compared to conventional solder attach, TLPS joints consist to a considerably higher percentage of brittle IMCs. This raises the concern that TLPS joints are susceptible to brittle failure. In this paper, we describe and analyze the cooling-induced formation of vertical cracks as a newly detected failure mechanism unique to TLPS joints. In a power module structure with a TLPS joint as interconnect between a power device and a direct bond copper (DBC) substrate, cracks can form between the interface of the DBC and the TLPS joint when large voids are located in the proximity of the DBC. These cracks do not appear in regions with smaller voids. A method has been developed for the three-dimensional (3D) modeling of paste-based TLPS sinter joints, which possess complex microstructures with heterogeneous distributions of metal particles and voids in IMC matrices. Thermomechanical simulations of the postsintering cooling process have been performed and the influence of microstructure on the stress-response within the joint and at the joint interfaces have been characterized for three different material systems (Cu þ Cu 6 Sn 5 , Cu þ Cu 3 Sn, Ni þ Ni 3 Sn 4 ). The maximum principal stress within the assembly was found to be a poor indicator for prediction of vertical crack formation. In contrast, stress levels at the interface between the TLPS joint and the power substrate metallization are good indicators for this failure mechanism. Small voids lead to higher joint maximum principal stresses, but large voids induce higher interfacial stresses, which explain why the vertical cracking failure was only observed in joints with large voids.

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Transient Liquid Phase Bonding

Holaday

Handwerker

2019

Die-Attach Materials for High Temperature Applications in Microelectronics Packaging

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Reliability of paste based transient liquid phase sintered interconnects

Cited by 14 publications

References 5 publications

Intermetallic Bonding for High-Temperature Microelectronics and Microsystems: Solid-Liquid Interdiffusion Bonding

Intermetallic Bonding for High-Temperature Microelectronics and Microsystems: Solid-Liquid Interdiffusion Bonding

Prediction and Mitigation of Vertical Cracking in High-Temperature Transient Liquid Phase Sintered Joints by Thermomechanical Simulation

Transient Liquid Phase Bonding

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