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.

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.

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.

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.

Silver-Indium Transient Liquid Phase Sintering for High Temperature Die Attachment

2009 ◽  
Vol 6 (1) ◽  
pp. 66-74 ◽  
Author(s):  
Pedro O. Quintero ◽  
F. Patrick McCluskey
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Wide Band ◽  
Liquid Phase Sintering ◽  
Processing Temperature ◽  
Solder Paste ◽  
Scanning Calorimetry ◽  
Die Attach ◽  
Transient Liquid Phase Sintering

The demand for electronics capable of operating at temperatures above the traditional 125°C limit continues to increase. Devices based on wide band gap semiconductors have been demonstrated to operate at temperatures up to 500°C, but packaging remains a major hurdle to product development. Recent regulations, such as RoHS and WEEE, increase the complexity of the packaging task as they prohibit the use of certain materials in electronic products such as lead (Pb), which has traditionally been used in high temperature solder die attach. In this investigation, an Ag-In solder paste is presented as a die attach alternative for high temperature applications. The proposed material has been processed by a transient liquid phase sintering method resulting in an in situ alloying of its main constituents. A shift of the melting point of the system, confirmed by differential scanning calorimetry, provided the basis for a breakthrough in the typical processing temperature rule. The mechanical integrity and reliability of this novel attachment material is discussed.

High Temperature Shear Strength of Cu-Sn Transient Liquid Phase Sintered Interconnects

2015 ◽  
Author(s):  
Hannes Greve ◽  
S. Ali Moeini ◽  
Patrick McCluskey ◽  
Shailesh Joshi
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Time To Failure ◽  
Creep Tests ◽  
Cu Substrates ◽  
Transient Liquid Phase Sintering ◽  
Temperature Shear

In this paper, we assess the high temperature shear strength of interconnects formed by sinter pastes via a Transient Liquid Phase Sintering (TLPS) process. The joints assessed in this study were formed by the transient liquid phase sintering of Sn and Cu. The shear strength of Cu dies sintered to Cu substrates with Cu-Sn sinter pastes was assessed at temperatures of 200°C and compared to that of specimens attached with Sn3.5Ag solder. In contrast to the shear strength of the sintered specimens, the shear strength of the soldered specimens drops below 10MPa under these conditions. High temperature creep tests were performed at the same temperature level for the soldered and sintered specimens. It was found that the Sn3.5Ag interconnects show extensive creep with short time-to-failure. The joints of sintered specimens did not undergo considerable deformation due to creep. Microstructural analyses have been performed on interconnects formed between Cu dies and Cu substrates and Si diodes on Direct Bond Copper (DBC) substrates. The joint microstructure consists of a matrix of Cu-Sn intermetallic compounds (IMCs) either with or without additional Cu particles dispersed in the matrix. It is demonstrated that the paste-based TLPS interconnects assessed combine short durations for process completion with both high shear strength and high resistance to creep under elevated temperature conditions. This, in combination with high thermal conductivity, shows that transient liquid phase sinter pastes have the potential to be an excellent high temperature and high power interconnect technology.

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