Transient Liquid Phase Sintered Joints for Power Electronic Modules

2013 ◽  
Author(s):  
Hannes Greve ◽  
F. Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
Melting Point ◽  
Liquid Phase ◽  
Intermetallic Phase ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Process Time ◽  
Power Electronic ◽  
High Melting ◽  
High Melting Point

Pastes consisting of micron-sized particles of a low melting point metal (i.e. Sn) and a high melting point metal (e.g. Ag, Cu) embedded in organic binder have been developed to attach silicon or wideband gap semiconductor devices to metallic or ceramic substrates for power electronic applications requiring operation at high temperatures. The attachment is made by a pressure-less, low temperature transient liquid phase sintering (LT-TLPS) process in air. Process time and temperature, along with binder type and amount are adjusted to minimize the formation of voids in the joints. Test samples consisting of copper dice on copper substrates joined by these LT-TLPS sinter pastes have been manufactured for shear testing. A shear fixture for high-temperature testing has been designed, and shear tests have been performed at temperatures of 25°C, 125°C, 250°C, 400°C, and 600°C. The influence of process time, process temperature, and the ratio of low-melting point metal (Sn) to high-melting point metal (Ag, Cu) on the shear strength at each temperature has been assessed. It has been shown that the shear strength of TLPS sinter joints remains high up to the melting point of the dominant intermetallic phase of the joint. The joints show no softening below the melting point of these phases. AgSn sinter joints show only limited change in shear strength up to 400°C. CuSn joints exhibit high shear strength up to 600°C for high copper ratios. While process times of 5–15 minutes are sufficient to drive the sintering reaction to near completion, extended curing improves the strength of the sinter joints even more. Failure analyses for joints of different compositions have been conducted along with cross-sectioning of sintered but non-sheared specimens to correlate reliability to microstructure.

Next Generation Solder-Systems for Thermal Interface and Interconnect Applications via Liquid Phase Sintering

2009 ◽  
Author(s):  
J. Liu ◽  
P. Kumar ◽  
I. Dutta ◽  
R. Raj ◽  
M. Renavikar
Keyword(s):  
Thermal Conductivity ◽  
Melting Point ◽  
Liquid Phase ◽  
Liquid Phase Sintering ◽  
Thermal Interface Material ◽  
High Melting ◽  
New Paradigm ◽  
High Melting Point ◽  
Thermal Interface ◽  
Mechanical Compliance

This paper reports on a new paradigm for highly flexible solder design, proffering high electrical and thermal conductivity, in conjunction with good mechanical compliance, via a novel Liquid Phase Sintering (LPS) approach. The new LPS solders comprise a high melting point phase HMP (e.g., Cu or Sn) with a small amount of a low melting-point phase LMP (e.g., In) at grain boundaries, such that different properties can be controlled by different constituents. In general, conductivity is dominated by the majority HMP constituent, while deformation is controlled by the minority, LMP grain boundary constituent. The LPS solders are suitable for both thermal interface material (TIM) and interconnect applications. As the application space for solders shifts in the future, and requirements for new property-sets emerge, the flexibility of the LPS solder approach will allow integration of different materials into new LPS solder-systems.

scholarly journals Development of Self-Densification and High Melting-Point Liquid Phase Sintering Process for Pisolitic Limonite Ores.

Materia Japan ◽  
1995 ◽  
Vol 34 (5) ◽  
pp. 647-649 ◽  
Author(s):  
Yukihiro Hida ◽  
Jun Okazaki ◽  
Mitsunobu Migita ◽  
Tadashi Deno
Keyword(s):  
Melting Point ◽  
Liquid Phase ◽  
Liquid Phase Sintering ◽  
High Melting ◽  
Sintering Process ◽  
High Melting Point

Microstructure of Transient Liquid Phase Sintering Joint by Sn-Coated Cu Particles for High Temperature Packaging

2015 ◽  
Vol 2015 (1) ◽  
pp. 000449-000452 ◽  
Author(s):  
Xiangdong Liu ◽  
Hiroshi Nishikawa
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Liquid Phase ◽  
Applied Pressure ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Thermally Stable ◽  
Bonding System ◽  
Cu Substrates ◽  
Transient Liquid Phase Sintering

We develop a transient liquid phase sinter (TLPS) bonding using Sn-coated Cu micro-sized particles. With this bonding process, a thermally stable joint comprising Cu3Sn phase and a dispersion of ductile Cu particles can be obtained. The particle paste, which contained Cu particles with a thin Sn coating and terpineol, was used to join Cu substrates. The setup was bonded at 300 °C for 30s under an applied pressure of 10 MPa using a thermo-compression bonding system under a formic acid gas atmosphere for reducing the oxide layer on the Sn coating and the Cu substrate. After bonding, the TLPS joint showed a thermally stable microstructure with a good shear strength, which was fully consisted of Cu3Sn intermetallic compounds matrix and embedded ductile Cu particles. The kinetics of the microstructure transformation and high temperature reliability of the TLPS joint were investigated. After 300 °C isothermal aging for 200h, the shear strength and microstructure of the TLPS joints showed almost unchanged. The results demonstrate that joint with high-melting-point obtained by the TLPS bonding using Sn-coated Cu particle paste has the potential to fulfill the requirement of high temperature electronic packaging.

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.

High Temperature Sintered Interconnects Formed by Transient Liquid Phase Sintering

2013 ◽  
Vol 2013 (1) ◽  
pp. 000951-000956 ◽  
Author(s):  
Hannes Greve ◽  
F. Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Liquid Phase ◽  
Low Temperature ◽  
Melting Temperature ◽  
Extreme Temperature ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Temperature Conditions ◽  
Transient Liquid Phase Sintering

Low Temperature Transient Liquid Phase Sintering (LT-TLPS) enables the formation of joints robust to high temperatures at low process temperatures. TLPS systems consist of one or more low temperature constituents (i.e. Sn) and one or more high temperature constituents (i.e. Cu). The sinter joints are formed by intermetallic compound formation between these constituents. In this paper a paste based LT-TLPS approach is demonstrated. The organic binders and fluxes used to mix the pastes prevent the metal particles from oxidation and facilitate a vacuum-free process in air without the need of a reducing atmosphere. Pastes based on the Cu-Sn system have been developed enabling a completely pressure-less process. Furthermore sinter pastes for LT-TLPS at low pressure (<0.5MPa) applied during the initial stage of the sintering process have been developed which form almost void free joints. To assess the strength of the sintered joints a high-temperature shear fixture has been designed. Shear tests have been performed at 25°C, 400°C, and 600°C to characterize the influence of high temperature conditions on the joint performance. The shear strength of the joints formed without pressure has been assessed for different Cu-to-Sn ratios at all temperature levels. It is shown that the maximum application temperature and shear strength depends on the ratio of low melting temperature and high melting temperature constituents. The pastes introduced here can be used to form joints resilient to application temperatures of up to 600°C. They show the potential to form joints for reliable operation under extreme temperature conditions.

Reliable Additive Manufacturing Using Transient Liquid Phase Sintering

2021 ◽  
Author(s):  
Gilad Nave ◽  
Clifton Buxbaum ◽  
F. Patrick McCluskey
Keyword(s):  
Electrical Conductivity ◽  
Additive Manufacturing ◽  
Melting Point ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Laser Sintering ◽  
Liquid Phase Sintering ◽  
Metal Powders ◽  
Sintering Process ◽  
Transient Liquid Phase Sintering

Abstract Additive manufacturing is rapidly revolutionizing the way products are designed and built. Its advantages in terms of mobile manufacturing, mass customization, part reduction, waste reduction, and just-in-time sparing are causing it to be considered for many electronics applications. Many of these applications require high thermal and electrical conductivity and high strength in harsh environments. Such applications would benefit greatly from additive manufacturing of metals. However, the number of metal systems that can be successfully manufactured this way is small, with some of the highest conductivity metals (e.g. Cu, Ag) being particularly difficult. Two ways of depositing metals dominate the market. The first is direct ink writing (DIW). The other common technique is laser sintering, including direct metal laser sintering (DMLS). While the DIW process is fine in principle, the inks typically used are not optimized for harsh applications, and produce a voided and porous layer that limits the thermal and electrical conductivity. Laser sintering must be done in vacuum and requires that the laser raise the temperature of the powder to around 500°C which can result in damage to the substrate. Furthermore, this process is expensive, lacks mobility, and consumes significant energy. This paper will discuss a new form of metal additive manufacturing that addresses the shortcomings of current direct writing and laser sintering approaches by making use of the transient liquid phase sintering process. During the TLPS process, low melting point semimetal powder of Indium will be melted at a temperature of 300°C. This liquid will then surround and diffuse with high melting temperature metal powders forming intermetallic compounds at the solid-liquid interface. These intermetallics possess a higher melting point than the low temperature semimetal. The paper will demonstrate the use of this technique to make reliable 2D lines and 3D structures. It will also discuss the deposition and sintering process and its effect on the adhesion strength, thermal conductivity, and electrical resistivity of the resulting structures.

scholarly journals Microstructure Evolution and Shear Property of Cu-In Transient Liquid Phase Sintering Joints

2021 ◽  
Vol 8 ◽  
Author(s):  
Bang Jiang ◽  
Qiaoxin Zhang ◽  
Lin Shi ◽  
Chundong Zhu ◽  
Zhiwen Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
Shear Strength ◽  
Liquid Phase ◽  
Solder Joints ◽  
Bonding Temperature ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Holding Time ◽  
Bonding Pressure ◽  
Transient Liquid Phase Sintering

Transient liquid phase sintering (TLPS) is a promising joining technology that can achieve high temperature resistant solder joints at low temperature, showing excellent potential in power electronics. In this work, Cu/Cu-In/Cu solder joints were successfully prepared by TLPS process. The effects of bonding pressure and holding time on the microstructure and shear strength of Cu-In TLPS joints at 260 and 320°C were studied. The results showed that as bonding pressure increased from 0.1–0.6 MPa, the porosity decreased and shear strength increased significantly. No obvious change was found as bonding pressure continued to increase to 1 MPa. As holding time increased at 260°C, Cu11In9 was formed and gradually transformed to Cu2In that can withstand elevated temperature. Meanwhile, the porosity decreased while shear strength increased. It was calculated that volume expansion (12.74%) occurred during the phase transition from Cu11In9 to Cu2In. When bonding temperature increased to 320°C, only Cu2In was detected and then gradually transformed to Cu7In3 with the growing holding time. As holding time reached 120 min, their porosity increased and lead to weak shear strength due to volume shrinkage (15.43%) during the phase transition from Cu2In to Cu7In3.

LT-TLPS Die Attach for High Temperature Electronic Packaging

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000246-000253 ◽  
Author(s):  
Hannes Greve ◽  
F. Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Melting Point ◽  
Low Temperature ◽  
Process Analysis ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Die Attach ◽  
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 analysis 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 minutes for process temperatures around 50°C above the melting point of the low temperature constituent. For the shear strength studies, test samples consisting of copper dice and copper substrates joined by sintering with a variety of pastes having different ratios of copper and tin have been assessed. A fixture was designed for high temperatures 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, Cu40Sn pastes showed high shear strengths up to 600°C, and extended curing further increased the joint strength. It was shown that LT-TLPS can be used to form high temperature stable joints at low temperatures without the need of applying pressure during processing.

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