An Evaluation of Gold and Copper Wire Bonds on Shear and Pull Testing

2005 ◽  
Vol 128 (3) ◽  
pp. 192-201 ◽  
Author(s):  
S. Murali ◽  
N. Srikanth ◽  
Charles J. Vath
Keyword(s):  
Void Nucleation ◽  
Copper Wire ◽  
Intermetallic Layer ◽  
Bonding Layer ◽  
Ball Bond ◽  
Wire Bonds ◽  
Aluminum Metallization ◽  
Gold Ball ◽  
Ball Bonds ◽  
Pull Testing

In microelectronic packaging technology wire bonding is a common interconnect technique. The quality and reliability of wire bonds are generally evaluated by ball shear and stitch pull testing. From the load versus time and load versus tool tip displacement plots of the shear test, three regions can be observed. Region I primarily exhibits elastic-plastic deformation occur, while crack nucleate in region II which propagates in region III which finally ends in a catastrophic failure. Fractographs reveal in the case of gold ball bonds shows fracture occurs in Al bond pad metallization close to Au-Al intermetallics. In Cu ball bonds of 1, 2, and 4ml wire sizes also Al bond pad metallization cracks but penetrate deeper into the pad which indirectly shows that the bonding layer is stronger than that of gold ball bonds. Optical microscopic observation of the sheared copper bond surfaces reveal sticking of Al which provides qualitative information of the area of the bond between the ball bond and the bond pad. In thermally aged gold ball bonds, the gold above the intermetallic layer fractures. The energy required to fracture a gold or copper ball bond of 1ml wire size is around 370J∕m2, while an aged gold ball bond consumes about 520J∕m2. Void nucleation and coalescence mechanism of ductile fracture takes place in the ball and stitch bonds, however, silicon particles may be the preferential void nucleation sites in bond pad aluminum metallization failures. To understand the second bond strength, a stitch pull test was conducted and the results showed the neck of the stitched wire cracks thus leaving behind a tail bond on the lead finger.

High Temperature Storage Reliability of Bond Resistance of Palladium-Coated Copper Ball Bonds

2017 ◽  
Vol 2017 (1) ◽  
pp. 000432-000437 ◽  
Author(s):  
Michael David Hook ◽  
Michael Mayer ◽  
Stevan Hunter
Keyword(s):  
High Temperature ◽  
Ball Bond ◽  
Wire Bonds ◽  
High Temperature Storage ◽  
Ball Bonding ◽  
Ball Bonds ◽  
Bond Pads ◽  
Wire Resistance ◽  
Temperature Storage

Abstract Reliability of wire bonds made with palladium-coated copper (PCC) wire of 25 μm diameter is studied by measuring the wire bond resistance increase over time in high temperature storage at 225 °C. Ball bonds are made on two bond pad thicknesses and tested with and without mold compound encapsulation. Bond pads are aluminum copper (Al-0.5%Cu), 800 nm and 3000 nm thick. The wirebonding pattern is arranged to facilitate 4-wire resistance measurements of 12 bond pairs in each 28-pin ceramic test package. The ball bonding recipe is optimized to minimize splash on 3000 nm Al-0.5%Cu with shear strength at least 120 MPa. Ball bond diameter is 61 μm and height is 14 μm. Measurements include bond shear test data and in-situ resistance before and during high temperature storage. Bonds on 3000 nm pads are found to be significantly more reliable than bonds on 800 nm pads within 140 h of aging.

Bondability and Strength Evaluation of Gold Ball Bond Using Nanoindentation Approach

2016 ◽  
Vol 700 ◽  
pp. 132-141
Author(s):  
Muhammad Nubli Zulkifli ◽  
Azman Jalar ◽  
Shahrum Abdullah ◽  
Norinsan Kamil Othman
Keyword(s):  
Wire Bonding ◽  
Strength Distribution ◽  
Nanoindentation Test ◽  
Ball Bond ◽  
New Approach ◽  
Bonding Parameter ◽  
Responsible Mechanism ◽  
Reduced Modulus ◽  
Gold Ball ◽  
Ball Bonds

The evaluation of the strength and bondability of gold, Au ball bond requires a new approach to provide a more detail data. Nanoindentation test was used as a new approach to evaluate the strength distribution and bondability of Au ball. Au ball bonds that experienced different value of wire bonding parameter namely bonding force, bonding time, bonding power, and stage temperature were used as samples for the present analysis. The distribution of strength based on hardness and reduced modulus values located at the bonding area of Au ball bonds were found to be related with the values of the wire bonding parameter. Nanoindentation test was found to be a suitable approach to analyze and evaluate the bondability of Au ball bond in a localized and detailed manner. In addition, the responsible mechanism for the thermosonic Au wire bonding can be identified and analyzed by using the results obtained from the nanoindentation test.

A Study of the Copper Wire Ball Bonding Processes

1992 ◽  
Vol 260 ◽  
Author(s):  
Fang Hongyuan ◽  
Qian Yiyu ◽  
Jiang Yihong
Keyword(s):  
Copper Wire ◽  
New Technology ◽  
Gold Wire ◽  
Ultrasonic Power ◽  
Maximal Strength ◽  
Ball Bond ◽  
Gold Ball ◽  
Ball Bonding ◽  
Microelectronic Components ◽  
Improve Reliability

ABSTRACTCopper ball bonding is a new technology which is expected to replace the traditional gold ball bonding and paid attention in woled recently, the technology is very important to reduce cost and improve reliability of microelectronic components. In this paper, the copper wire ball bonding processes have been studied by means of the MW-EFO metal wire ball forming device and the JWYH-2 thermosonic ball bonder. The bond strength of the ball bond under varied ultrasonic power and bonding time have been tested. The tested results show that the maximal strength of copper ball bond can be over 20g, it has advantage over the gold wire ball bonding. In this paper, the deformation process of the copper ball bond has been analyzed and viewed by SME.

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 ball bond diameter on wire bond reliability for automotive application

2016 ◽  
Vol 33 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Hui Yuen Peng ◽  
Mutharasu Devarajan ◽  
Teik Toon Lee ◽  
David Lacey
Keyword(s):  
Isothermal Aging ◽  
Production Costs ◽  
Automotive Application ◽  
Comsol Multiphysics ◽  
Ball Bond ◽  
Content Type ◽  
Wire Bond ◽  
Wire Bonds ◽  
Ball Bonds ◽  
The Wire

Purpose – The purpose of this paper is to investigate the reliability of wire bonds with three varying ball bond diameters, which are ball bonded with three different sizes of gold wires in light-emitting diode (LED) package under high-temperature environment. In automotive applications, “lifted ball bond” issue is a potential critical point for LED device reliability, as the wire bonds are usually stressed under high operating temperature during their lifetime. Moreover, the reliability of wire bonds in recent LED production has fallen under scrutiny due to the practice of reducing wire diameters to cut down production costs. Design/methodology/approach – Three gold wires with sizes of 2, 1.5 and 1 mm were ball bonded on the LED chip bond pad via thermosonic wire bonding method to produce three different ball bond diameters, that is, 140, 120 and 100 μm, respectively. The reliability of these wire bond samples was then studied by performing isothermal aging at 200°C for the time interval of 30, 100 and 500 hours. To validate hypotheses based on the experimental data, COMSOL Multiphysics simulation was also applied to study the thermal stress distribution of wire bond under an elevated temperature. Findings – Experimental results show that the interfacial adhesion of wire bond degrades significantly after aging at 200°C for 500 hours, and the rate of interfacial degradation was found to be more rapid in the wire bond with smaller ball bond diameter. Experimental results also show that ball bonds randomly elongate along an axis and deforms into elliptical shapes after isothermal aging, and ball bonds with smaller diameters develop more obvious elongations. This observation has not been reported in any previous studies. Simulation results show that higher thermal stress is induced in the wire bond with the decrease of ball bond diameter. Practical implications – The reliability study of this paper provides measurements and explanation on the effects of wire diameter downsizing in wire bonds for automotive application. This is applicable as a reliability reference for industries who intend to reduce their production costs. Other than that, the analysis method of thermal stresses using COMSOL Multiphysics simulations can be extended by other COMSOL Multiphysics users in the future. Originality/value – To resolve “lifted ball bond” issue, optimization of the bond pad surface quality and the wire bond parameter has been studied and reported in many studies, but the influence of ball bond diameter on wire bond reliability is rarely focused. Moreover, the observation of ball bonds randomly elongate and deform more into elliptical shape, and ball bond with smaller diameter has the highest elongation after isothermal aging also still has not been reported in any previous studies.

Challenges of Wire Bonding In High Value and High Performance Medical Devices

2010 ◽  
Vol 2010 (1) ◽  
pp. 000470-000473
Author(s):  
James A. Ohneck
Keyword(s):  
Medical Device ◽  
Medical Devices ◽  
High Performance ◽  
Wire Bonding ◽  
Current Status ◽  
Implantable Medical Device ◽  
Wire Bonds ◽  
Gold Ball ◽  
High Yields ◽  
Pull Testing

Wire bonding is a fairly mature technology that has been used in medical implantable products for over twenty years. Today however, its relevance continues to grow as the size of die continues to get smaller. Size, weight and volume are paramount when developing and manufacturing an implantable medical device, which often needs to perform a specific function such as, monitoring or adjusting parameters of the device itself, monitoring patient data or communicating data from the device to the healthcare professional. Wire bonding can be the answer to addressing many of the requirements mentioned above. This paper will review the current status of the use of gold ball wire bonding and its relevance to the medical device industry as well as discuss how advancements in wire bonding processes benefit today's implantable products. Wire bond interconnections can be made using gold, aluminum and copper wires. They each have different bonding characteristics and therefore require different application methods and equipment. The advantages and characteristics of gold ball wire bonding will be reviewed as this process relates to High Value Medical Devices. Achieving high yields can also be a challenge with any wire bonding processes. Today's smaller die and pads require smaller gage wires. Typical production requirements are .8 – 1.2 mil wire and 4X4 pads. The demand to still go smaller requires continual adaptations and ingenuity as wire thicknesses are being pushed to .5 mils and below. Bond pull testing at the beginning, mid and end of production runs becomes important to verify integrity of the wire bonds with such small wire gages. The complexities involved in wire bonding can lead to increased cost as well. To address this, a single process procedure is being adopted by many, which eliminates pattern plating and saves time and money. This new process will also be explained and reviewed.

Failure Analysis on Power Trench MOSFET Devices with Copper Wire Bonds

2011 ◽  
Author(s):  
Huixian Wu ◽  
Arthur Chiang ◽  
David Le ◽  
Win Pratchayakun
Keyword(s):  
Failure Analysis ◽  
Copper Wire ◽  
New Technology ◽  
Analytical Techniques ◽  
Wire Bonding ◽  
Bonding Process ◽  
Wire Bonds ◽  
Copper Wire Bonding ◽  
Wet Chemical ◽  
Microelectronic Components

Abstract With gold prices steadily going up in recent years, copper wire has gained popularity as a means to reduce cost of manufacturing microelectronic components. Performance tradeoff aside, there is an urgent need to thoroughly study the new technology to allay any fear of reliability compromise. Evaluation and optimization of copper wire bonding process is critical. In this paper, novel failure analysis and analytical techniques are applied to the evaluation of copper wire bonding process. Several FA/analytical techniques and FA procedures will be discussed in detail, including novel laser/chemical/plasma decapsulation, FIB, wet chemical etching, reactive ion etching (RIE), cross-section, CSAM, SEM, EDS, and a combination of these techniques. Two case studies will be given to demonstrate the use of these techniques in copper wire bonded devices.

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.

Reliability of Coated and Alloyed Copper/Silver Ball Bonds

2017 ◽  
Vol 2017 (1) ◽  
pp. 000318-000324 ◽  
Author(s):  
Sarangapani Murali ◽  
Bayaras Abito Danila ◽  
Zhang Xi
Keyword(s):  
Electrical Resistance ◽  
Stress Test ◽  
Thermal Ageing ◽  
Epoxy Compound ◽  
Resistance Test ◽  
Ball Size ◽  
Green Mold ◽  
Wire Bonds ◽  
Ball Bonds

Abstract The paper discusses on the reliability of coated and alloyed copper/silver ball bonds on both epoxy molded and unmolded conditions:Moisture resistance test using unmolded device at 130°C 85%RH (humidity chamber) revealed no ball lift failure until 96hours for the ball size of 1.65 times the diameter of wireCorrosion resistance test using unmolded device at room temperature by dripping (or soaking) dilute chlorine (Cl) solution revealed no ball lift failure for gold wires. Copper base wire bonds failed after 6min of storage while silver (Ag) base wire bonds showed a few bond lifts within 2min. This shows that Ag base wires are more sensitive to Cl environment than copper (Cu) base wiresA case study of epoxy molded device using green mold compound and four types of Cu and Ag base ball bonds passed on thermal ageing (HTS) at 175°C for 4000h and on +5V bHAST for 500h. The test response is by measuring electrical resistance in order not to reduce below 10% of contact resistance measured during time zero bonding○ Cross-section analysis of the samples showed intact bonding of Cu and Ag base ball bonds after 4000h of HTS○ The result shows when Cu and Ag base wire bonds molded with a good compatible green mold epoxy compound satisfy the automotive electronic council (AEC – Q006 & Q100 Rev-H, for Cu) requirements of 2X stress test with respect to electrical resistance measurementAnother case study of epoxy molded device revealed Cu and Ag base wire bonds pass 3000cycles of thermal cycling (−55°C to +150°C) without any neck/heel cracks and stitch lifts In addition, fine wires are baked at elevated temperature under vacuum or by purging nitrogen to find the quality of wire surface. As expected, Au, Cu and Ag base wires show clean surface. For palladium (Pd) coated Cu wire, a good Pd adhesion to Cu core surface without blisters is evident.

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