Reliability Evaluation of Cu-Al WB in High Temperature and High Current Applications

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Sungmo Jung
Keyword(s):  
High Temperature ◽  
High Reliability ◽  
Copper Wire ◽  
Planck Equation ◽  
Operating Conditions ◽  
Polarization Curves ◽  
Automotive Electronics ◽  
Wire Bonds ◽  
Chlorine Ions ◽  
Copper Aluminum

Abstract High reliability harsh environment applications necessitate a better understanding of the acceleration factors under operating stresses. Automotive electronics has transitioned to the use of copper wire for first level interconnects. A number of copper wire formulations have emerged including palladium coated copper and gold-flash palladium coated copper. The corrosion reliability of copper wire bonds in high temperature conditions is not yet fully understood. The EMC used to encapsulate chips and interconnects can vary widely in formulation, including pH, porosity, diffusion rate, composition of contaminants and contaminant concentration. To realistically represent the expected wirebond reliability, there is need for a predictive model that can account for environmental conditions, operating conditions, and exposure to EMCs. In this paper, different EMCs were studied in a high-temperature-current environment with temperature range of 60°C–100°C under current of 0.2A–1A. The diffusion kinetics based on the Nernst-Planck Equation for migration of the chlorine ions has been coupled with the Butler-Volmer equation for corrosion kinetics to create a Multiphysics model. Polarization curves have been measured for copper, aluminum and intermetallics under a number of pH values, and chlorine-ion concentrations. Tafel parameters have been extracted through measurements of the polarization curves.

Critical Barriers Associated with Copper Wire

2015 ◽  
Vol 2015 (1) ◽  
pp. 000394-000398
Author(s):  
William G. Crockett
Keyword(s):  
High Reliability ◽  
Copper Wire ◽  
Automotive Electronics ◽  
Bonding Wire ◽  
Cu Alloy ◽  
Bonding Wires ◽  
Reducing Costs ◽  
Cu Bonding ◽  
Bonding Characteristics ◽  
Bare Copper

Since around 2008, the shift from Gold (Au) bonding wire to Copper (Cu) bonding wire has been taking place, full scale, with the aim of reducing costs. When compared with Au, Cu wire presents challenges in reliability and repeatable bonding characteristics in terms of chemical stability, which is required in high reliability applications. Therefore Cu wire adoption in automotive and industrial semiconductors has been limited. Conventionally the market for Cu bonding wires has been divided into two types: bare Cu wires (high purity) and Palladium coated copper (PCC) bonding wires. These wires have yet to satisfy the required characteristics for high reliability products such as industrial and automotive electronics. A new breed of alternative bonding wires has been developed to offer performance advantages for high reliability applications compared to bare copper wire and PCC wire. Cu alloy wire and Ag alloy wires continue their market introduction for advanced bonding applications, where bare Cu and PCC wires have known limitations.

Reliability Assessment of Cu-Al WB Under High Temperature and High Voltage Bias Application

2020 ◽  
Author(s):  
Pradeep Lall ◽  
Sungmo Jung
Keyword(s):  
High Temperature ◽  
High Voltage ◽  
Galvanic Corrosion ◽  
Copper Wire ◽  
Ionic Transport ◽  
Gold Wire ◽  
Process Window ◽  
Voltage Bias ◽  
Wire Bond ◽  
Wire Bonds

Abstract Electronics in automotive underhood environments may be subjected to high temperature in the range of 125–200°C. Transition to electric vehicles has resulted in need for electronics capable of operation under high voltage bias. Automotive electronics has simultaneously transitioned to copper wire-bond from gold wire-bond for first-level interconnections. Copper has a smaller process window and a higher propensity for corrosion in comparison with gold wire bonds. There is scarce information on the reliability of copper wire bonds in presence of high voltage bias under operation at high temperature. In this paper, a multiphysics model for micro galvanic corrosion in the presence of chlorine is introduced. The diffusion cell is used to measure the diffusivity of chlorine in different pH values and different temperatures. Diffusivity measurements are incorporated into the 3D ionic transport model to study the effect of different environmental factors on the transport rate of chlorine. The tafel parameters for copper, aluminum and intermetallics have been extracted through measurements of the polarization curves. The multiple physics of ionic transport in presence of concentration gradient, potential gradient is coupled with the galvanic corrosion.

Reliability Performance of Palladium Coated Copper Wire in High Temperature Bake at Extreme Durations

2015 ◽  
Vol 2015 (1) ◽  
pp. 000292-000297 ◽  
Author(s):  
Tu Anh Tran ◽  
Chu-Chung (Stephen) Lee ◽  
Varughese Mathew
Keyword(s):  
High Temperature ◽  
High Reliability ◽  
Copper Wire ◽  
Plastic Packages ◽  
Low Profile ◽  
Need To Evaluate ◽  
Interconnect Reliability ◽  
The Wire ◽  
Reliability Performance ◽  
Pull Testing

New automotive requirements expect plastic packages to survive higher operating temperatures with extended thermal duration. Further module integration and more stringent environmental requirements push modules and thus plastic packages closer to the heat source. As such, new mission profiles include more than 3500 total hours at 150°C, or 1000 total hours at 175°C. To satisfy new automotive requirements, plastic packages must meet AEC Grade 0 or higher. Therefore, there is a need to evaluate the wire bond interconnect reliability to 2X AEC Grade 0 to assess the interconnect robustness. Palladium coated copper wire (Pd-Cu) was selected to be the wire of choice on aluminum bond pad for high reliability. Low Profile Quad Flat Pack with Exposed Pad (LQFP-EP) packages wire bonded with 20 micron Pd-Cu wire were submitted to high temperature baking (HTB) at 150°C and 175°C for 4032 and 2016 hours, respectively. This paper will discuss the results of electrical test, package deprocessing and wire pull testing, and cross-sectioning through the ball bonds to examine the welding region. Cu voiding within the bulk of the Cu ball bond, specifically close to the capillary chamfer squeezed region on top of the squashed ball, and at the ball edge interfacing with the intermetallic compound was found predominantly at 175°C bake. A trace of Sulfur was found inside the Cu corroding region. Sulfur compounds in mold compounds were examined. EFO current settings were evaluated in order to reduce the propensity to Sulfur corrosion in the Pd-Cu bond balls. Cu voiding is considered as cosmetic defect as it did not lead to electrical failures even at 2X AEC Grade 0 durations. Pd-Cu wire on aluminum bond pad forms very robust and reliable interconnect in extended thermal aging condition, including 4032 hour HTB-150°C and 2016 hour HTB-175°C, making it suitable for more demanding automotive mission profiles.

Measurement of Ion-Mobility in Copper-Aluminum Wirebond Electronics Under Operation at High Voltage and High Temperature

2017 ◽  
Author(s):  
Pradeep Lall ◽  
Yihua Luo ◽  
Shantanu Deshpande ◽  
Luu Nguyen
Keyword(s):  
High Temperature ◽  
High Voltage ◽  
Copper Wire ◽  
Extended Period ◽  
Ionic Mobility ◽  
Gold Wire ◽  
Voltage Bias ◽  
Wire Bond ◽  
Mobility Of Ions ◽  
Copper Aluminum

Transition of ground vehicles to HEV and FEV has necessitated the operation of electronics in automotive underhood at high voltage bias and high temperature for extended period-of-time. Examples include gate drivers and IGBT modules. A typical automotive benchmark is operation for 10 years and 100,000 miles. Simultaneously, the first-level interconnects are migrating to use copper-wire interconnects in place of the previously used gold wire. Copper wire has higher propensity for corrosion and a narrower process-bonding window in comparison with gold wire based systems. Exposure to high temperature, humidity and bias influences the mobility of ions in the EMC and thus the contaminant transport to the WB interfaces. Measurements of diffusion behavior of EMCs at high temperature and high voltage bias are not available for readily being used in models. Prior studies have focused on biased humidity tests on wire bonds with the amplitude of the bias being limited up to 3.5Volts. In this paper, a PWM-controlled-gate drive-based test setup is established to study the effect of high voltage (up to 20Volts) on Cu-Al wire bond interconnects. A migration-diffusion cell experiment is designed to quantify the effect of voltage bias on transport of chlorine in EMCs. Diffusion coefficient and ionic mobility of chlorine at different temperatures are obtained. Resistance spectroscopy measurements show the progression of corrosion induced by voltage bias. A corrosion simulation is used to quantify the effect of voltage bias on corrosion rate of Cu-Al wire bond.

High Temperature Reliability of the SiC-MOSFET with Copper Metallization

2014 ◽  
Vol 778-780 ◽  
pp. 955-958
Author(s):  
Hiroaki Okabe ◽  
Motoru Yoshida ◽  
Takaaki Tominaga ◽  
Jun Fujita ◽  
Kazuyo Endo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
High Reliability ◽  
Gate Oxide ◽  
Copper Metallization ◽  
Cu Metallization ◽  
Gate Electrodes ◽  
Wire Bonds ◽  
Power Modules ◽  
Al Metallization

We investigated the SiC-MOSFET with Cu metallization instead of conventional Al metallization to apply to high reliability power modules. As Cu has higher electrical and thermal conductivity, yield strength, and tolerance of its migration than those of Al, applying Cu to metallization and wire bonds will lead to longer lifetime for power modules. One of the major difficulties with Cu metallization is its high diffusivity into SiO2 and poly-Si which are used as gate oxide, interlayer oxide, and gate electrodes in SiC-MOSFETs, resulting in degradation of devices. We fabricated the SiC-MOSFET with Cu metallization and a diffusion barrier. We have successfully obtained good characteristics same as conventional Al metallization and demonstrated its high temperature reliability.

Temperature Field in Electric Control Unit of Diesel Engine and its Optimization Design

2011 ◽  
Vol 340 ◽  
pp. 76-80
Author(s):  
Zhen Jie Liu ◽  
Yu Long Lei ◽  
Yong Jun Li
Keyword(s):  
Thermal Analysis ◽  
Temperature Field ◽  
High Temperature ◽  
Diesel Engine ◽  
Structural Optimization ◽  
Optimization Design ◽  
High Reliability ◽  
Control Unit ◽  
Operating Conditions ◽  
Electric Control

In order to satisfy the requirements of the high reliability of electric control unit (ECU) of the Diesel Engine, the thermal analysis of ECU was performed by using the software FLOTHERM based on the finite volume method. The temperature field of ECU was obtained under different operating conditions. The structural optimization of ECU was completed to solve the problem of local high temperature. As a result, the operational temperature of ECU is reduced under the allowable limit, and its reliability is improved. The physical experiment shows that the thermal analysis and structural optimization are valid. The local high temperature could be reduced effectively and the operational reliability is improved.

Effects of Bond Pad Thickness on Shear Strength of Copper Wire Bonds

2017 ◽  
Vol 2017 (HiTEN) ◽  
pp. 000068-000073 ◽  
Author(s):  
Subramani Manoharan ◽  
Chandradip Patel ◽  
Stevan Hunter ◽  
Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Failure Modes ◽  
High Reliability ◽  
Copper Wire ◽  
Test Method ◽  
Ball Bond ◽  
Wire Bond ◽  
Industry Standards ◽  
Wire Bonds

Abstract Copper (Cu) wire bonding is now widely accepted as a replacement for gold (Au), however, its use in high reliability applications is limited due to early failures in high temperature and humid conditions. The Au to Cu wire transition is mainly driven by cost savings though there are other advantages to Cu such as better electrical and thermal conductivity, slower intermetallic compound (IMC) formation and reduced wire sweep during transfer molding. Some automotive, industrial and aerospace industries are still reluctant to adopt Cu wire bonded products due to perceived risks of wire and bond pad cracks, the potential for corrosion, and some lack of understanding about its reliability in harsh conditions. A wire bond is considered good if destructive sampling qualification tests and periodic monitors pass for the batch. Tests include wire pull strength, wire bond shear, IMC coverage, and thickness of bond pad aluminum (Al) remaining beneath the bond. Nondestructive inspections also verify acceptable ball diameter and Al “splash”. This paper focuses on the bond shear test and its contribution to Cu ball bond reliability assessment, especially when changing Al bond pad thickness. A new revision of the JEDEC Wire Bond Shear Test Method, JESD22-B116B, has just been released, to include Cu wirebonds for the first time. It helps to clarify shear test failure modes for Cu ball bonds. However, there are still questions to be answered through research and experimentation, especially to learn the extent to which one may predict Cu ball bond reliability based on shear test results. Pad Al thickness is not considered in the current industry standards for shear test. Yet bond pad Al thickness varies widely among semiconductor products. This research is intended to contribute toward improved industry standards. In this study, power and time bonding parameters along with bond pad thickness are studied for bond strength. Several wire bonds are created at different conditions, evaluated by optical microscope and SEM, IMC% coverage and bond shear strength. Similar bonding conditions are repeated for bond pads of 4um, 1um and 0.5um thickness.

Effects of alloying elements in high reliability copper wire bond material for high temperature applications

2020 ◽  
Vol 114 ◽  
pp. 113819
Author(s):  
M. Eto ◽  
N. Araki ◽  
T. Yamada ◽  
R. Klengel ◽  
S. Klengel ◽  
...  
Keyword(s):  
High Temperature ◽  
High Reliability ◽  
Copper Wire ◽  
Alloying Elements ◽  
Wire Bond ◽  
Temperature Applications

Ensuring Suitability of Cu Wire Bonded ICs for Automotive Applications

2015 ◽  
Vol 2015 (1) ◽  
pp. 000751-000756
Author(s):  
James McLeish ◽  
Randy Schueller
Keyword(s):  
High Reliability ◽  
Gold Wire ◽  
Consumer Products ◽  
Harsh Environment ◽  
Automotive Electronics ◽  
Package Design ◽  
Automotive Market ◽  
Wire Bonds ◽  
Bond Wires ◽  
Validation Tests

The transition to replace gold with copper bond wires in semiconductor components, primarily driven by the ever increasing price of gold wire, has been under way for several years. Cu wire bonds (Cu-WBs) are technically more challenging than gold to produce, requiring improved designs, processes and equipment. After introduction in consumer products, their use is now migrating to automotive electronics where product integrity for quality, reliability and durability (QRD) and safety over 10–15 years in a demanding harsh environment is paramount, in addition to managing cost in the highly competitive global automotive market. Reliability issues with some Cu wire bonded components detected during the rigorous product validation durability–reliability tests of automotive electronics, however, are starting to appear. The indications are that only optimized package design with well-controlled assembly processes are suitable for high reliability (hi-rel) harsh environment applications such as automotive, military and aerospace. A concern is that non-optimized Cu-WBs and package materials issues are being detected in module-level durability validation tests in parts that were qualified as automotive grade per AEC Q-100 or AEC-Q101. This article will explore the issues and discuss potential solutions as the Automotive Electronics Council (AEC) – the organization that defines requirements for automotive grade electronic components – works to update qualification procedures for evolving Cu-wire bond technology.

Reliability of Cu Wirebonded ICs for Automotive Applications

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001721-001752
Author(s):  
Jim McLeish ◽  
Greg Caswell ◽  
Randy Schueller
Keyword(s):  
High Reliability ◽  
Gold Wire ◽  
Consumer Products ◽  
Harsh Environment ◽  
Automotive Electronics ◽  
Package Design ◽  
Automotive Market ◽  
Wire Bonds ◽  
Bond Wires ◽  
Validation Tests

The transition to replace gold with copper bond wires in semiconductor components, primarily driven by the ever increasing price of gold wire, has been under way for several years. Cu wire bonds (Cu-WBs) are technically more challenging than gold to produce, requiring improved designs, processes and equipment. After introduction in consumer products, their use is now migrating to automotive electronics where product integrity for quality, reliability and durability (QRD) and safety over 10–15 years in a demanding harsh environment is paramount, in addition to managing cost in the highly competitive global automotive market. Reliability issues with some Cu wire bonded components detected during the rigorous product validation durability–reliability tests of automotive electronics, however, are starting to appear. The indications are that only optimized package design with well-controlled assembly processes are suitable for high reliability (hi-rel) harsh environment applications such as automotive, military and aerospace. A concern is that non-optimized Cu-WBs and package materials issues are being detected in module-level durability validation tests in parts that were qualified as automotive grade per AEC Q-100 or AEC-Q101. This paper will explore the issues and discuss potential solutions as the Automotive Electronics Council (AEC) – the organization that defines requirements for automotive grade electronic components – works to update qualification procedures for evolving Cu-wire bond technology.

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