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.

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.

High Temperature Storage and HAST Reliability of Copper-Aluminum Wirebond Interconnects

2014 ◽  
Author(s):  
Pradeep Lall ◽  
Shantanu Deshpande ◽  
Luu Nguyen
Keyword(s):  
High Temperature ◽  
Copper Wire ◽  
Gold Wire ◽  
Wire Bonding ◽  
Remaining Useful Life ◽  
Thermal Resistivity ◽  
Wire Bond ◽  
Trade Offs ◽  
Marquardt Algorithm ◽  
Temperature And Humidity

Gold wire bonding has been widely used as first-level interconnect in semiconductor packaging. The increase in the gold price has motivated the industry search for alternative to the gold wire used in wire bonding and the transition to copper wire bonding technology. Potential advantages of transition to Cu-Al wire bond system includes low cost of copper wire, lower thermal resistivity, lower electrical resistivity, higher deformation strength, damage during ultrasonic squeeze, and stability compared to gold wire. However, the transition to the copper wire brings along some trade-offs including poor corrosion resistance, narrow process window, higher hardness, and potential for cratering. Formation of excessive Cu-Al intermetallics may increase electrical resistance and reduce the mechanical bonding strength. Current state-of-art for studying the Cu-Al system focuses on accumulation of statistically significant number of failures under accelerated testing. In this paper, a new approach has been developed to identify the occurrence of impending apparently-random defect fall-outs and pre-mature failures observed in the Cu-Al wirebond system. The use of intermetallic thickness, composition and corrosion as a leading indicator of failure for assessment of remaining useful life for Cu-al wirebond interconnects has been studied under exposure to high temperature and temperature-humidity. Damage in wire bonds has been studied using x-ray Micro-CT. Microstructure evolution was studied under isothermal aging conditions of 150°C, 175°C, and 200°C till failure. Activation energy was calculated using growth rate of intermetallic at different temperatures. Effect of temperature and humidity on Cu-Al wirebond system was studied using Parr Bomb technique at different elevated temperature and humidity conditions (110°C/ 100%RH, 120°C/ 100%RH, 130°C/ 100%RH) and failure mechanism was developed. The present methodology uses evolution of the IMC thickness, composition in conjunction with the Levenberg-Marquardt algorithm to identify accrued damage in wire bond subjected to thermal aging. The proposed method can be used for quick assessment of Cu-Al parts to ensure manufactured part consistency through sampling.

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.

Wire Bond Shear Test Simulation on Sharp Groove Surface Bond Pad

2012 ◽  
Vol 622-623 ◽  
pp. 647-651 ◽  
Author(s):  
Z. Sauli ◽  
V. Retnasamy ◽  
S. Taniselass ◽  
A.H.M. Shapri ◽  
R. Vairavan
Keyword(s):  
Stress Response ◽  
Shear Test ◽  
Copper Wire ◽  
Gold Wire ◽  
Shear Tests ◽  
Groove Surface ◽  
Wire Bond ◽  
Packaging Industry ◽  
Semiconductor Packaging ◽  
Surface Bond

Wire bonding process is first level interconnection technology used in the semiconductor packaging industry. The wire bond shear tests are used in the industry to examine the bond strength and reliability of the bonded wires. Hence, in this study thesimulation on wire bond shear test is performed on a sharp groove surface bond pad. ANSYS ver 11 was used to perform the simulation. The stress response of the bonded wires are investigated.The effects of three wire materials gold(Au), aluminum(Al) and copper(Cu) on the stress response during shear test were examined. The simulation results showed that copper wire bond induces highest stress and gold wire exhibits the least stress response.

Resistance Spectroscopy Based Assessment of Degradation in Cu-Al Wire Bond Interconnects

2013 ◽  
Author(s):  
Pradeep Lall ◽  
Yihua Luo
Keyword(s):  
Health Management ◽  
Copper Wire ◽  
Wheatstone Bridge ◽  
Gold Wire ◽  
Remaining Useful Life ◽  
Thermal Cycles ◽  
Leading Indicator ◽  
Wire Bond ◽  
Useful Life ◽  
The Wire

Escalation of the expense of gold has resulted in industry interest in use of copper as alternative wire bonds interconnect material. Copper wire has the advantage of lower price and comparable electrical resistance to gold wire. In this paper, 32-pin copper-aluminum wire bond chip scale packages are aged at three types of environment conditions separately. Environmental conditions included: 200°C for 10 days, 85°C and 85% RH for 8 weeks and −40°C to 125°C for 500 thermal cycles. The resistances of the wire bond are obtained every 24 hours for 200°C environment, every 7 days for 85C/85RH environment and every 5 days (50 thermal cycles) for the thermal cycling environment. A leading indicator has been developed in order to monitor the progression effect of the different thermal aging condition on the package and prognosticate remaining useful life based on the resistance spectroscopy. The Cu-Al wire bond resistance has been measured using a modified Wheatstone bridge. It has been shown previously that precise resistance spectroscopy is able to offer the failure of a leading indicator prior to the traditional definition of failure. The prognostic health management is qualified to be an efficient and accuracy tool for assessment of the remaining life of the wire bond. The ability to predict the remaining useful life of Cu-Al wire bond provides several advantages, including increasing safety by providing warning ahead of time before the failure.

To Study the High Temperature Effects on Ball Bonds Using Low K Material in Wire Bond Devices

2007 ◽  
Author(s):  
S. A. Kudtarkar ◽  
R. Murcko ◽  
K. Srihari ◽  
S. Saiyed
Keyword(s):  
High Temperature ◽  
Mechanical Stability ◽  
Semiconductor Industry ◽  
Gold Wire ◽  
Wire Bonding ◽  
Mechanical Stresses ◽  
Wire Bond ◽  
Ball Bonds ◽  
Bond Pads ◽  
Low K

Wire bonding is widely used as one of the main interconnect alternatives. This technique applies significant mechanical stresses on the bond pads along with heat and ultrasonic energy to form a bond. An interconnection of copper plus low k material has been a focus of the semiconductor industry with the goal of reducing interconnection delays. The material is below the wire bond pads and complicates the mechanical stability of the device during wire bonding. The low k materials that are suggested are very sensitive to these mechanical stresses. This generates a significant reliability concern for the underlying metal structures. In addition, the integrity of the bond formed may be negatively impacted from a reliability perspective because of the softer material properties of the dielectric. This research explores the ball bond integrity for die with SiO2 and low k dielectric underlying material respectively, using 0.8 mil thick (20 microns) gold wire. Accelerated tests, such as high temperature storage at 150°C and 175°C, were conducted to assess the reliability of these bonds. The results of this investigation reveal that the ball bond’s strength degrades after high temperature tests due to the occurrence of Kirkendall voids between the gold wire and the aluminum bond pad. The degradation recorded was more severe for regular die than its low k counterpart.

Wire Bond Shear Test Simulation on Hemispherical Surface Bond Pad

2012 ◽  
Vol 622-623 ◽  
pp. 643-646 ◽  
Author(s):  
Z. Sauli ◽  
V. Retnasamy ◽  
W.M.W. Norhaimi ◽  
J. Adnan ◽  
M. Palianysamy
Keyword(s):  
Stress Response ◽  
Shear Test ◽  
Copper Wire ◽  
Gold Wire ◽  
Bonding Process ◽  
Wire Bond ◽  
Hemispherical Surface ◽  
Simulation Results ◽  
Semiconductor Packaging ◽  
Surface Bond

Wire bonding process is an interconnection method adopted in the semiconductor packaging manufactory. One of the method used to assess the reliability and bond strength of the bonded wires are wire bond shear test .In this study, simulation on wire bond shear test is done to evaluate the stress response of the bonded wire when sheared on a hemispherical surface bond pad. The contrast between three types of wire material:gold(Au), aluminum(Al) and copper(Cu) were carry out to examine the effects of wire material on the stress response of bonded wire during wire bond shear test. The simulation results showed that copper wire bond induces highest stress and gold wire exhibits the least stress response.

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