Microstructural Evolution and Thermal Stability Characterization of a High Temperature Die Attach Lead-Free System

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 1-11 ◽  
Author(s):  
Rogie I. Rodriguez ◽  
Dimeji Ibitayo ◽  
Pedro Quintero
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Microstructural Evolution ◽  
Diffusion Mechanism ◽  
Processing Temperature ◽  
Mechanical And Thermal Properties ◽  
Promising Alternative ◽  
Free System ◽  
Die Attach

There is a need for electromechanical devices capable of operating in high temperature environments (>200°C) for a wide variety of applications. Today's wide-bandgap (WBG) semiconductor based power electronics have demonstrated a potential of operating above 400°C, however they are still limited by packaging. Among the most promising alternative is the Au-Sn eutectic solder, which have been widely used due to its excellent mechanical and thermal properties. However, the operating temperature of this metallurgical system is still limited to ∼250°C owing to its melting temperature of 280°C. Therefore, a higher temperature resistant system is much needed, but without affecting the current processing temperature of ∼325°C typically exhibited in most high temperature Pb-Free solders. This paper presents the development and characterization of a fluxless die attach soldering process based on gold enriched solid liquid inter-diffusion (SLID). A low melting point material (eutectic Au-Sn) was deposited in the face of a substrate, whereas a high melting point material, gold in this instance, was deposited in its mating substrate. Deposition of all materials was performed using a jet vapor deposition (JVD) equipment where thicknesses were controlled to achieve specific compositions in the mixture. Sandwiched coupons where isothermally processed in a vacuum reflow furnace. SEM and EDS were employed to reveal the microstructural evolution of the samples in order to study the interfacial reactions of this fluxless bonding process. Mechanical characterization of the each individual intermetallic phase was achieved by nanoindentation. Differential scanning calorimetry demonstrated the progression of the SLID process by quantifying the remaining low melting point constituent as a function of time and temperature. Post-processed samples confirmed the inter-diffusion mechanism as evidenced by the formation of sound joints that proved to be thermally stable up to ∼490°C after the completion of the SLID process.

High Temperature Die Attach by Low Temperature Solid-Liquid Interdiffusion

2011 ◽  
Author(s):  
Rogie I. Rodriguez ◽  
Dimeji Ibitayo ◽  
Pedro O. Quintero
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Diffusion Mechanism ◽  
Processing Temperature ◽  
Mechanical And Thermal Properties ◽  
Reflow Time ◽  
Promising Alternative ◽  
Soldering Process ◽  
Die Attach ◽  
Solid Liquid

There is a need for electromechanical devices capable of operating in high temperature environments (>200°C) for a wide variety of applications. Today’s wide-bandgap semiconductor based power electronics have demonstrated a potential of operating above 400°C, however they are still limited by packaging. Our group has been conducting research in novel interconnect technologies to develop reliable electronic packaging for high temperature environments. Among the most promising alternative is the Au-Sn eutectic solder (80 wt.% Au - 20 wt.% Sn), which have been widely used due to its excellent mechanical and thermal properties. However, the operating temperature of this metallurgical system is still limited to ∼250°C owing to its melting temperature of 280°C. Therefore, a higher temperature resistant system is much needed, but without affecting the current processing temperature of ∼325°C typically exhibited in most high temperature Pb-Free solders. This paper presents the development and characterization of a fluxless die attach soldering process based on gold enriched solid liquid inter-diffusion (SLID). A low melting point eutectic Au-Sn was deposited in the faces of two substrates, followed by the deposition of a subsequent layer of high melting point material, gold in this instance, in one of the substrates. Deposition of all materials was performed using Jet Vapor Deposition (JVD) equipment where thicknesses were controlled to achieve specific compositions in the mixture. Sandwiched coupons where isothermally processed in a vacuum reflow furnace. Scanning electron microscopy (SEM) was employed to reveal the microstructural evolution of the samples in order to study the interfacial reactions of this fluxless bonding process. EDS analysis was used to identify the intermetallic formation and to characterize the joint in an attempt to study the kinetics of this diffusion couple. Post-processed samples confirmed the inter-diffusion mechanism evidenced by the formation of sound joints between the two substrates. As expected, it was observed that the Au was dissolved into the eutectic Au-Sn as the reflow time and temperature were increased.

A multi-pronged approach to low-pressure Cu sintering using surface-modified particles, substrate and chip metallization

2019 ◽  
Vol 2019 (1) ◽  
pp. 000387-000392 ◽  
Author(s):  
Sri Krishna Bhogaraju ◽  
Omid Mokhtari ◽  
Jacopo Pascucci ◽  
Fosca Conti ◽  
Hiren R Kotadia ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Cost ◽  
Surface Modifications ◽  
Low Pressure ◽  
Bonding Pressure ◽  
High Tendency ◽  
Promising Alternative ◽  
Die Attach ◽  
Bandgap Semiconductors ◽  
Surface Modified

Abstract High temperature power electronics based on wide-bandgap semiconductors have prominent applications, such as automotive, aircrafts, space exploration, oil/gas extraction, electricity distribution. Die-attach bonding process is an essential process in the realization of high temperature power devices. Here Cu offers to be a promising alternative to Ag, especially because of thermal and mechanical properties on par with Ag and a cost advantage by being a factor 100 cheaper than Ag. With the aim to achieve a low-pressure Cu sintering process, a low cost wet chemical etching process is developed to selectively etch Zn from brass to create nano-porous surface modifications to enhance sinterability, enabling sintering with low bonding pressure of 1MPa and at temperatures below 300°C. However, high tendency of Cu to oxidize poses a major challenge in realizing stable interconnects. For this purpose, in this contribution, we present the use of polyethylene-glycol 600 as reducing binder in the formulation of the Cu sintering paste. Finally, we propose a multi-pronged approach based on three crucial factors: surface-modified substrates, nanostructured surface modifications on micro-scale Cu-alloy particles and use of a reducing binder in the Cu particle paste.

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.

Hot Pressing and Characterization of ZrB2-SiC-MoSi2 Composite

2015 ◽  
Vol 830-831 ◽  
pp. 421-424
Author(s):  
T. Venkateswaran ◽  
M. Agilan ◽  
D. Sivakumar ◽  
Bhanu Pant
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Oxidation Resistance ◽  
Hot Pressing ◽  
Mechanical And Thermal Properties ◽  
High Melting ◽  
Hafnium Diboride ◽  
High Melting Point ◽  
Microstructural Investigation ◽  
Ultra High Temperature

Transition metal diborides, especially zirconium and hafnium diboride are potential ceramic material for ultra high temperature applications above 1800°C. These borides are characterized by high melting point, formation of high melting point oxides, good oxidation resistance and excellent thermo-mechanical properties. In this present exploration, zirconium diboride (ZrB2) has been selected for its moderate density (6.09 gm/cc) and better oxidation resistance compared to high density hafnium diboride (11.2 gm/cc). The developed ZrB2 composite in the present study contains 10 wt. % SiC and 10 wt. % MoSi2 as sintering additives. SiC and MoSi2 were added to improve the thermal shock resistance and sinterability of the ultra high temperature ceramics (UHTCs). Vacuum hot pressing was carried out at 1800°C for a holding period of 30 minutes and applied pressure of 30 MPa. Attractive feature of this ZrB2 composite is good machinability due to better electrical conductivity and complicated shapes can be realized easily through electro discharge machining (EDM) process. Detailed XRD phase analysis and microstructural investigation of the polished and fractured composites was carried out using SEM. Mechanical and thermal properties tests have been carried out for the optimized ZrB2 composite material.

Characterization of Bi–Ag–X Solder for High Temperature SiC Die Attach

2014 ◽  
Vol 4 (11) ◽  
pp. 1778-1784 ◽  
Author(s):  
Zhenzhen Shen ◽  
Kun Fang ◽  
R. Wayne Johnson ◽  
Michael C. Hamilton
Keyword(s):  
High Temperature ◽  
Die Attach

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.

Characterization of AgBiX™ Solder Paste on Thick Film for 200°C Applications

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000340-000346 ◽  
Author(s):  
Zhenzhen Shen ◽  
Wayne Johnson ◽  
Michael C. Hamilton
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Solidus Temperature ◽  
Passive Component ◽  
Solder Paste ◽  
Die Attach ◽  
High Temperature Storage ◽  
Temperature Storage

AgBiX™ (Indium Corporation) solder paste has a solidus temperature of ∼262°C after reflow, which is suitable for passive component, semiconductor and power die attach for 200°C applications. In this work, the paste has been used to assemble SiC die with Ti/Ni/Ag thin film metallization to Ag and PdAg thick film substrates. High temperature storage testing (200°C) was preformed to characterize the reliability of the assemblies. Surface mount chip resistors attached to thick film substrates were also subject to high temperature storage. Comparisons of the performance of die attach and resistor attach on Ag substrates and PdAg substrates are made. EDX and failure analysis was used to understand the role of Pd on the failure mode and lower aged shear strengths with the thick film PdAg conductors.

Perspectives of High-Temperature Pb-Free Bonding Materials

2018 ◽  
Vol 2018 (1) ◽  
pp. 000088-000098
Author(s):  
Hongwen Zhang ◽  
Ning-Cheng Lee
Keyword(s):  
High Temperature ◽  
High Power ◽  
Temperature Cycling ◽  
Processing Temperature ◽  
Potential Candidate ◽  
High Porosity ◽  
Solder Paste ◽  
Material Cost ◽  
Die Attach ◽  
High Lead

Abstract High lead solders have been used as die-attach and interconnect materials in discrete power packages. Due to the demand of SiC devices serving the high-power market and the harmful effects of Pb to human health and the environment, alternative Pb-free solders, novel bonding materials, as well as solutions have been studied extensively in recent years. The exemption of using high-Pb solders has been extended again to 2021, although it could be terminated at any time if a new technology or material were to be accepted by the industry. This paper presents potential materials and technologies for high-temperature Pb-free die-attachment, focusing on alternative solders. Sintering materials and transient liquid phase bonding (TLPB) materials have been briefly covered as well. AuSn, AuSi, and AuGe solders have shown to be exceptionally high in cost, which limited their application. BiAg- and BiCu-based solders—the BiAgX® family including solder paste, solder wire, and solder preform—improved wetting and exhibited remelting temperatures of 262°C and 270°C, respectively. The acceptable reliability performance on temperature cycling and thermal aging, as well as low material cost, has made them the most competitive candidates for low-power discrete die-attach devices. SnSbAgCu, with well-designed compositions in recent studies, offers a remelting temperature above 320°C. SnSbAgCu is targeted in markets for mid-to-high power devices. Reliability testing for other recently designed SnSbAgCu pastes for various die-attach vehicles is being studied. ZnAl has a remelting temperature above 380°C and an extremely low material cost (comparable to or even lower than the high-lead solders). Although the bonding process is stringent, the excellent thermomechanical behavior and the superior thermal/electrical conductivity have allowed ZnAl to be a potential candidate for high-temperature/high-power die-attach that is competitive with AuSi and AuGe solders. Sintering materials form bonds through solid state interdiffusion, while TLPB materials create a joint through solid-liquid interdiffusion, in which the remelting temperature is enhanced by forming massive IMCs. The desired high thermal/electrical/mechanical/melting performances, as well as the relatively low processing temperature (<350°C), are shining the sintering materials (especially Ag-sintering materials). The intrinsic high porosity (>20%) and the evolution of pores from pressureless sintering may overshadow the reliability. In addition, the immaturity of the processing (time/temperature/pressure/atmosphere/equipment availability, etc.) may deter the industrial adoption of sintering materials. So far, none of these materials or technologies is ideal to satisfy all the requirements of the variety of high-temperature, Pb-free die-attach applications in terms of processing, reliability, and cost. However, each material and solution has the potential to be a niche within this broader categorization.

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