Optimization of gold wire bonding on electroless nickel immersion gold for high temperature applications

Author(s):  
Beng Ng ◽  
V.P. Ganesh ◽  
Charles Lee
2010 ◽  
Vol 2010 (1) ◽  
pp. 000675-000681 ◽  
Author(s):  
Mustafa Oezkoek ◽  
Hugh Roberts ◽  
Joe McGurran

As a surface finish, electroless nickel / electroless palladium / immersion gold (ENEPIG) has received increased attention for both packaging/IC-substrate and PWB applications. With a lower gold thickness compared to conventional electroless nickel / immersion gold (ENIG) the ENEPIG finish offers the potential for higher reliability, better performance and reduced cost.[1,2] This paper shows the benefits of using a pure palladium layer in ENEPIG and ENEP (Electroless Nickel / Electroless Palladium) surface finishes in terms of physical properties and in terms of gold wire bonding and solder joint integrity.


2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000334-000338
Author(s):  
Jens Müller ◽  
Thomas Mache ◽  
Torsten Thelemann

Electroless plating on silver is a low cost alternative to printing of mixed metals or pure gold paste systems on LTCC. It overcomes the necessity to have material transitions from inner to outer layers or from conductor lines to wire bonding- or solder-pads. Since no commercial process and material set for silver thick film conductors has been available on the market a proprietary Ni/Pd/Au coating technology was developed for the use on silver inks for LTCC and Al2O3-ceramic as a base for both soldering and wire bonding. The work included the screening of different chemicals as well as several silver paste systems from two commercial vendors. Conductor adhesion, plating layer thicknesses, plating accuracy, (lead free) solderability and gold wire-bondability were assessed to optimize the process. Layers of about 5 microns Ni, (0.1 to 0.3) microns Pd and (0.05 to 0.15) microns Au were electrolessly deposited. The developed Ni-Pd-Au finish is an economical alternative with only about a quarter of the cost compared to the conventional use of silver, silver / palladium and gold compounds for ceramic substrates. This technology allows coating of the structures down to a fine pad size of 200×200 microns and a minimum line width of 100 microns, without reducing the adhesion mechanism between thick-film metallization and ceramic substrate. By covering of pure conductors with high temperature glass or dielectrics, further material saving is possible. Besides, the process offers also very good coating of structures in cavities.


2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000123-000128
Author(s):  
Erick M. Spory

There is an ever-increasing demand for electronics in higher temperature applications, both in variety and volume. In many cases, the actual integrated circuit within the plastic packaging can support operation at higher temperatures, although the packaging and connectivity is unable to do so. Ultimately, there still remains a significant gap in the volume demand required for high temperature integrated circuit lines to justify support of more expensive ceramic solutions by the original component manufacturer vs. the cheaper, high-volume PEM flows. Global Circuit Innovations, Inc. has developed a manufacturable, cost-effective solution to extract the integrated circuit from any plastic encapsulated device and subsequently re-package that device into an identical ceramic footprint, with the ability to maintain high-integrity connectivity to the device and enabling functionality for 1000's of hours at temperatures at 250C and beyond. This process represents a high-value added solution to provide high-temperature integrated circuits for a large spectrum of requirements: low-volume, quick-turn evaluation of integrated circuit prototyping, as well as medium to high-volume production needs for ongoing production needs. Although both die extraction and integrated circuit pad electroless nickel/gold plating have both been performed successfully for many years in the semiconductor industry, Global Circuit Innovations, Inc. has been able to combine the two in a reliable, volume manufacturing flow to satisfy many of the stringent requirements for high-temperature applications.


Author(s):  
Pradeep Lall ◽  
Shantanu Deshpande ◽  
Luu Nguyen

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.


2016 ◽  
Vol 857 ◽  
pp. 31-35
Author(s):  
Wan Yusmawati Wan Yusoff ◽  
Azman Jalar ◽  
Norinsan Kamil Othman ◽  
Irman Abdul Rahman

The effect of high temperature storage of gold ball bonds towards micromechanical properties has been investigated. Gold wire from thermosonic wire bonding exposed to high temperature storage at 150 °C for 10, 100 and 1000 hours. The nanoindentation test was used in order to evaluate the high temperature storage effect on wire bonding in more details and localized. Prior to nanoindentation test, the specimens were cross-sectioned diagonally. The constant load nanoindentation was performed at the center of gold ball bond to investigate the hardness and reduced modulus. The load-depth curve of nanoindentation for the high temperature storage gold wire has apparent the discontinuity during loading compared to as-received gold wire. The hardness value increased after subjected to high temperature storage. However, the hardness decreased when the storage period is extended. The decreasing in the hardness value may due to the grain size of Au metal which recrystallized after subjected to high temperature storage. The results obtained from nanoindentation is important in assessing the high temperature storage of wire bonding.


Author(s):  
S. A. Kudtarkar ◽  
R. Murcko ◽  
K. Srihari ◽  
S. Saiyed

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.


2010 ◽  
Vol 645-648 ◽  
pp. 745-748 ◽  
Author(s):  
M. Guziewicz ◽  
Ryszard Kisiel ◽  
Krystyna Gołaszewska ◽  
Marek Wzorek ◽  
Anna Stonert ◽  
...  

The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts with top Au or Pt layers has been investigated. Long-term tests of the connections are performed in air at 400oC. Evaluation of electrical parameters, morphology and structure of the metallization as well as the strength of Au joint show stable Au wire bonds to the metallization with Ti-ohmic contacts.


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