Cold Gas Spray of Copper on Aluminum Nitride as Substrate for Power Electronics

2021 ◽  
Author(s):  
Margie Guerrero ◽  
Pedro Quintero ◽  
Ozan Ozdemir ◽  
Tricia Schwartz
Keyword(s):  
Aluminum Nitride ◽  
Coefficient Of Thermal Expansion ◽  
Travel Speed ◽  
Manufacturing Method ◽  
Thermal Requirements ◽  
Power Cycling ◽  
Factorial Design Of Experiments ◽  
Substrate Surfaces ◽  
Mechanical Bonding ◽  
Cold Gas

Abstract Ceramic substrates for electronic packaging of high-power applications are growing in demand due to their robustness as power and thermal requirements increase. Aluminum nitride (AlN) has excellent thermal and electrical properties with copper currently being bonded to AlN via a direct bond copper (DBC) technique. However, substrates fabricated by DBC are subjected to thermo-mechanical fatigue during fabrication processes and power cycling. DBC substrate’s reliability is negatively affected by the large mismatch in coefficient of thermal expansion that hinders the possibility of thicker substrates, therefore limiting its use for applications above 20 kV. This work employed cold gas spraying (CGS) to mechanically bond Cu on AlN. CGS is a low-temperature additive manufacturing method that accelerates powder particles at near-supersonic velocities to impact a surface causing plastic deformation and mechanical bonding. On ceramic-metal systems CGS has not been widely studied owing to ceramics’ inability to deform plastically, therefore, surface functionalization was performed to enhance the mechanical interlocking mechanism. A factorial design of experiments (DOE) was used to assess the effect of factors: temperature, pressure, stand-off distance, angle of deposition, and travel speed on various substrate surfaces in the CGS fabrication process. These experiments resulted in a successful deposition of copper on AlN.

Microstructure of Aluminum Bronze Coating Sprayed by Cold Gas Dynamic Spraying (CGDS)

2011 ◽  
Vol 704-705 ◽  
pp. 1112-1116
Author(s):  
Yu Liang Liu ◽  
Tian Ying Xiong ◽  
Jie Wu
Keyword(s):  
316L Stainless Steel ◽  
Cold Gas Dynamic Spraying ◽  
Aluminum Bronze ◽  
Β Phase ◽  
Gas Dynamic ◽  
Α Phase ◽  
Metallurgical Bonding ◽  
A New Technique ◽  
Mechanical Bonding ◽  
Cold Gas

Cold Gas Dynamic Spraying (CGDS) has been developed to fabricate surface coating as a new technique in recent years. In this paper, aluminum bronze particles were sprayed on 45 steel and 316L stainless steel by CGDS, and the coating was sucessfully fabricated on the surface of the steels. The microstructure of the coating and the interface between the coating and the substrate were investigated by scanning electron microscope (SEM), energy dispersive (EDX) and XRD. It was found that the coating was dense and its porosity was low, while the microhardness of the coating was lower than that of the bulk one; Mechanical bonding was the main formation mechanism of the coating, and there was metallurgical bonding too; Diffusion occured at the interface between the coating and substrate; α phase in aluminum bronze particles transformed to β phase after the spray and the transformation was induced by the plastic strain during spraying.

Discussion on the Reliability Issues of Solder-Bump and Direct-Solder Bonded Power Device Packages Having Double-Sided Cooling Capability

2005 ◽  
Vol 128 (3) ◽  
pp. 208-214 ◽  
Author(s):  
John G. Bai ◽  
Jesus N. Calata ◽  
Guo-Quan Lu
Keyword(s):  
Thermal Cycling ◽  
Solder Bump ◽  
Coefficient Of Thermal Expansion ◽  
Operating Temperature ◽  
Power Device ◽  
Element Analysis ◽  
Temperature Changes ◽  
Power Cycling ◽  
Thermomechanical Reliability ◽  
Cycling Experiment

Power device packages with solder-bump (SB) and direct-solder (DS) interconnections were fabricated and some of their thermomechanical reliability issues were discussed based on both thermal cycling experiment and finite element analysis (FEA). The SB interconnection shows superior reliability over the DS interconnection in the thermal cycling experiment because the mismatched coefficient of thermal expansion leads to smaller stresses at the SB interconnection under the same temperature changes. On the other hand, FEA results show that the DS package has significantly lower operating temperatures under the same double-sided cooling condition. After considering the operating temperature difference, the DS package was shown to be superior over the SB package in the power cycling analysis.

scholarly journals High Temperature Microelectromechanical Systems Using Piezoelectric Aluminum Nitride

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000040-000046
Author(s):  
Benjamin A. Griffin ◽  
Scott D. Habermehl ◽  
Peggy J. Clews
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Mechanical Strength ◽  
Gas Turbines ◽  
Power Plants ◽  
Microelectromechanical Systems ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Temperature Limit

We report on the efforts at Sandia National Laboratories to develop high temperature capable microelectromechanical systems (MEMS). MEMS transducers are pervasive in today's culture, with examples found in cell phones, automobiles, gaming consoles, and televisions. There is currently a need for MEMS transducers that can operate in more harsh environments, such as automobile engines, gas turbines, nuclear and coal power plants, and petroleum and geothermal well drilling. Our development focuses on the coupling of silicon carbide (SiC) and aluminum nitride (AlN) thin films on SiC wafers to form a MEMS material set capable of temperatures beyond 1000°C. SiC is recognized as a promising material for high temperature capable MEMS transducers and electronics because it has the highest mechanical strength of semiconductors with the exception of diamond and its upper temperature limit exceeds 2500°C, where it sublimates rather than melts. Most transduction schemes in SiC are focused on measuring changes in capacitance or resistance, which require biasing or modulation schemes that can withstand elevated temperatures. Instead, we are coupling temperature hardened, micro-scale SiC mechanical components with piezoelectric AlN thin films. AlN is a non-ferroelectric piezoelectric material, enabling piezoelectric transduction at temperatures exceeding 1000°C. AlN is a favorable MEMS material due to its high thermal, electrical, and mechanical strength. It is also closely matched to SiC for coefficient of thermal expansion.

Shorter Field Life in Power Cycling for Organic Packages

2006 ◽  
Vol 129 (1) ◽  
pp. 28-34 ◽  
Author(s):  
S. B. Park ◽  
Izhar Z. Ahmed
Keyword(s):  
Fatigue Life ◽  
Temperature Distribution ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Uniform Temperature ◽  
Transfer Coefficients ◽  
Solder Interconnects ◽  
Power Cycling ◽  
Plastic Ball ◽  
Accelerated Thermal Cycling

The importance of power cycling as a mean of reliability assessment was revisited for flip chip plastic ball grid array (FC-PBGA) packages. Conventionally, reliability was addressed empirically through accelerated thermal cycling (ATC) because of its simplicity and conservative nature of life prediction. It was well accepted and served its role effectively for ceramic packages. In reality, an assembly is subjected to a power cycling, i.e., nonuniform temperature distribution with a chip as the only heat source and other components as heat dissipaters. This non-uniform temperature distribution and different coefficient of thermal expansion (CTE) of each component make the package deform differently than the case of uniform temperature in ATC. Higher substrate CTE in a plastic package generates double curvature in the package deformation and transfers higher stresses to the solder interconnects at the end of die. This mechanism makes the solder interconnects near the end of die edge fail earlier than those of the highest distance to neutral point. This phenomenon makes the interconnect fail earlier in power cycling than ATC. Apparently, we do not see this effect (the die shadow effect) in ceramic packages. In this work, a proper power cycling analysis procedure was proposed and conducted to predict solder fatigue life. An effort was made for FC-PBGA to show the possibility of shorter fatigue life in power cycling than the one of ATC. The procedure involves computational fluid dynamics (CFD) and finite element analyses (FEA). CFD analysis was used to extract transient heat transfer coefficients while subsequent FEA–thermal and FEA–structural analyses were used to calculate temperature distribution and strain energy density, respectively.

Analysis of Thermal Displacements Due to CTE Mismatches Using FEA Simulation and Experimental Validation With a Differential Variable Reluctance Transducer

2007 ◽  
Author(s):  
Tony A. Asghari ◽  
Joseph Janas
Keyword(s):  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Relative Displacement ◽  
Linear Displacement ◽  
System Level ◽  
Element Analysis ◽  
Variable Reluctance ◽  
Power Cycling ◽  
Thermal Displacements ◽  
Fea Simulation

Deformation induced by thermal loading in a severe automotive environment, between an electronic ceramic substrate — bonded to an aluminum heatsink — and an adjacent nylon material, was investigated by numerical and experimental methods. The goal of this paper is to quantify the relative displacement of certain points of interest, where an aluminum wire bond exists. This displacement is caused by 1) coefficient of thermal expansion (CTE) mismatches of various parts of the assembly when temperature distribution is uniform, and 2) when temperature gradients exist in either steady-state or transient conditions due to thermal cycling (between +150°C and −40°C) as well as power cycling. ANSYS Workbench™ finite element analysis (FEA) software was used to model the system level deformation under various conditions. A unique, quick, and repeatable method of experimentally measuring displacement using a Differential Variable Reluctance Transducer (DVRT®) was utilized. The DVRT® and its signal conditioner provide an analog DC voltage output, which is proportional to linear displacement (resolution as fine as 1.5 micrometer). Error inherent to the DVRT® was adjusted by further testing using a modified sample of Invar. The numerical and experimental results showed good overall correlation.

Numerical Approach to Cold Gas Spray on Ceramic Substrates for Power Electronics Packaging

2018 ◽  
Author(s):  
Marco J. Echeverría ◽  
Pedro O. Quintero ◽  
Dimeji Ibitayo ◽  
Lauren Boteler
Keyword(s):  
Copper Deposit ◽  
Dielectric Strength ◽  
Numerical Approach ◽  
Solid Particles ◽  
Processing Parameter ◽  
Ceramic Substrates ◽  
Manufacturing Method ◽  
Spray Process ◽  
Thermal Expansion Coefficients ◽  
Cold Gas

In power electronic, ceramic substrates are used owing to their high thermal conductivity and dielectric strength. These substrates cannot withstand high voltages in the range of 20kV because thickness limitations inherit from the direct bond copper manufacturing method. This manufacturing process uses high temperature in order to bond the material layers. This negatively affects the material’s reliability due to the differing materials thermal expansion coefficients and the resulting residual stress. All this results in hindering the ceramic substrate in obtaining a higher dielectric strength. In contrast, cold gas spray has the potential to provide higher reliability due to its bonding mechanism, which relies on plastic deformation of solid particles at very high strain rates during impact to create a mechanical bond, forming a thick deposit. However, cold gas spray on ceramics has not been widely studied due to their brittleness and their inability to form a metallic bond. This work is aimed at providing an effective processing parameter map of the cold gas spray process to achieve a thick copper deposit on aluminum nitride on the basis of the comparison of experimental results with a numerical model and finite element simulation formulated in Mathematica and ABAQUS, respectively.

scholarly journals A Study on Cross-Shaped Structure of Invar Material Using Cold Wire Laser Fillet Welding (PART I: Feasibility Study for Weldability)

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1385 ◽  
Author(s):  
Du-Song Kim ◽  
Changmin Pyo ◽  
Jaewoong Kim ◽  
Jisun Kim ◽  
Hee-Keun Lee
Keyword(s):  
Natural Gas ◽  
Fiber Laser ◽  
Feasibility Study ◽  
Coefficient Of Thermal Expansion ◽  
Welding Distortion ◽  
Fillet Welding ◽  
Manufacturing Method ◽  
Welding Part ◽  
Increasing Demand ◽  
Trial And Error Method

With the need for eco-friendly energy increasing rapidly due to global environmental issues, there is a rapidly increasing demand for liquefied natural gas (LNG). LNG is liquefied at minus 163 degrees Celsius, and its volume decreases to 1/600, giving it a relatively higher storage and transport efficiency than gaseous natural gas (NG). The material for the tanks that store cryogenic LNG must be a material with high impact toughness at cryogenic temperatures. Invar, which contains 36% nickel and has a very low coefficient of thermal expansion, is used for the membranes and corner structures of LNG cargo holds. The cross-shaped Invar structure used in an LNG cargo hold is manufactured through manual tungsten inert gas (TIG) fillet welding, which causes welding distortion and weldability problems. This study is a feasibility study that aims to reduce welding distortion, increase weldability with welding speed, and reduce the steps in an existing process by half by replacing the existing manufacturing method with automatic fiber laser fillet welding. Laser welding using fiber laser parameters are controlled for 1.5 and 3.0 mm thick Invar materials and weldability is secured through cross-section observation. Then, the optimal welding conditions with top and back beads secured are derived through a trial and error method.

scholarly journals Cold Gas Spraying of Nickel-Titanium Coatings for Protection Against Cavitation

2020 ◽  
Author(s):  
Georg Mauer ◽  
Karl-Heinz Rauwald ◽  
Yoo Jung Sohn ◽  
Thomas E. Weirich
Keyword(s):  
Shape Memory ◽  
Deposition Efficiency ◽  
Travel Speed ◽  
Nickel Titanium ◽  
Surface Zone ◽  
Hydraulic Systems ◽  
Near Surface ◽  
Cold Gas Spraying ◽  
Substrate Temperatures ◽  
Cold Gas

AbstractCavitation erosion is a sever wear mechanism that takes place in hydrodynamic systems. Examples are turbine vanes of hydropower plants or components of valves and pumps in hydraulic systems. Nickel-titanium shape memory alloys (NiTi) are attractive materials for cavitation-resistant coatings because of their pronounced intrinsic damping mitigating cavitation-induced erosion. In this work, NiTi coatings were produced by cold gas spraying. The phase transformation behaviors of the powder feedstock and the as-sprayed coatings were investigated. Regarding the obtained transformation temperatures, the measured substrate temperatures during spraying rule out that either the shape memory effect or the pseudoelasticity of NiTi could affect the deposition efficiency under the applied conditions of cold gas spraying. Another potential effect is stress-induced amorphization which could occur at the particle–substrate interfaces and impair particle bonding by stress relaxation. Moreover, also oxide formation can be significant. Thus, the presence of amorphous phases and oxides in the near-surface zone of particles bounced off after impact was investigated. Oxidation could be confirmed, but no indication of amorphous phase was found. Besides, also the evolution of local microstrains implies that the substrate temperatures affect the deposition efficiency. These temperatures were significantly influenced by the spray gun travel speed.

scholarly journals Magnetron Sputtered AlN Layers on LTCC Multilayer and Silicon Substrates

Coatings ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 289 ◽  
Author(s):  
Heike Bartsch ◽  
Rolf Grieseler ◽  
Jose Mánuel ◽  
Jörg Pezoldt ◽  
Jens Müller
Keyword(s):  
Aluminum Nitride ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Conditions ◽  
Substrate Material ◽  
Fractional Factorial ◽  
Silicon Substrates ◽  
Axis Orientation ◽  
Ceramic Substrates ◽  
Wide Range ◽  
Fractional Factorial Experimental Design

This work compares the deposition of aluminum nitride by magnetron sputtering on silicon to multilayer ceramic substrates. The variation of sputter parameters in a wide range following a fractional factorial experimental design generates diverse crystallographic properties of the layers. Crystal growth, composition, and stress are distinguished because of substrate morphology and thermal conditions. The best c-axis orientation of aluminum nitride emerges on ceramic substrates at a heater temperature of 150 °C and sputter power of 400 W. Layers deposited on ceramic show stronger c-axis texture than those deposited on silicon due to higher surface temperature. The nucleation differs significantly dependent on the substrate. It is demonstrated that a ceramic substrate material with an adapted coefficient of thermal expansion to aluminum nitride allows reducing the layer stress considerably, independent on process temperature. Layers sputtered on silicon partly peeled off, while they adhere well on ceramic without crack formation. Direct deposition on ceramic enables thus the development of optimized layers, avoiding restrictions by stress compensating needs affecting functional properties.

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