A STUDY OF SURFACE FINISHES FOR IC SUBSTRATES AND WIRE BOND APPLICATIONS

2011 ◽  
Vol 2011 (1) ◽  
pp. 000516-000520 ◽  
Author(s):  
John Ganjei ◽  
Ernest Long ◽  
Lenora Toscano
Keyword(s):  
Surface Finish ◽  
Printed Circuit Boards ◽  
Performance Enhancement ◽  
High Reliability ◽  
Cost Effective ◽  
Electroless Nickel ◽  
Gold Wire ◽  
Electronics Industry ◽  
Surface Finishes ◽  
And Performance

The continuing drive for ever increasing performance enhancement in the electronics industry, in combination with the recent, very significant increase in precious metal costs have left fabricators and OEMs questioning what the best, most cost effective, surface finish is for high reliability applications. Currently, the IC substrate market relies heavily on electrolytic nickel and gold as a solderable and superior wire bondable surface. The use of this finish has allowed manufacturers to avoid the reliability concerns However, this choice also results in significant design restraints being imposed. Many in the industry are now investigating the use of electroless nickel/electroless palladium/immersion gold (ENEPIG) to achieve both high reliability and performance, without the negative design restraints imparted by the use of electrolytic processes. However, over the last year alone, the industry has watched the price of gold increase by 50% and that of palladium double [1]. With this in mind, and considering the historic precedent set in the mid 1990’s when ENEPIG was also evaluated as a surface finish for printed circuit boards, when coincidentally, the cost of palladium also reached an all time high, it should be remembered that the electronics industry quickly moved to evaluate alternate, more cost sustainable, surface finishes. This paper details the use of lower cost, alternate surface finishes for IC substrate applications, with particular experimental focus on gold wire bonding capabilities and BGA solderability of the finishes described. The paper also discusses related process cycle advantages and the significantly reduced operating costs associated with these new finishes.

Increased High-Temperature IC Packaging Reliability Using Die Extraction and Additive Manufacturing Assembly

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000018-000022
Author(s):  
Erick M. Spory
Keyword(s):  
Additive Manufacturing ◽  
Oil And Gas ◽  
Functional Performance ◽  
Operating Temperature ◽  
High Reliability ◽  
Electroless Nickel ◽  
Gold Wire ◽  
Silver Deposition ◽  
Oil And Gas Exploration ◽  
Temperature Range

Abstract Semiconductor parts are most often specified for use in the “commercial” 0 to 70°C and, to a lesser extent, in the “industrial” −40 to 85°C operating temperature range. These operating temperature ratings generally satisfy the demands of the dominant semiconductor customers in the computer, telecommunications, and consumer electronic industries. There is also a demand for parts rated beyond the “industrial” temperature range, primarily from the aerospace, military, oil and gas exploration, and automotive industries (−55 to +125C, and even higher). However, the demand has not been large enough to attract or retain the interest of major semiconductor part manufacturers to make these parts. In fact, wide temperature range parts are becoming obsolete and functionally equivalent parts are not replacing them. Today, for some applications, it is difficult to procure parts that meet engineering, economic, logistical, and technical integration requirements of product manufacturers, and that are rated for an extended temperature range (typically beyond 0 to 70°C). In some applications, the product is available only in the “commercial” temperature range, with commercial packaging. If the product application environment is outside the commercial range, steps must be taken to address this apparent incompatibility. For example, oil exploration and drilling applications require small, advanced communication electronics to work underground at high temperatures where cooling is not possible. This is where uprating comes into play. Despite the fact that a part can be uprated relative to functional performance at higher than specified temperatures, the original packaging and connectivity may not be reliable with long term exposure to greater than 150C due to Kirkendall voiding and general plastic degradation. However, if the original die with gold wire and aluminum pad bond is extracted from the original plastic commercial package and reassembled into a new ceramic package body, excellent reliability at temperatures exceeding 200C can be achieved. The original gold/aluminum bond interface can be removed and replaced with an electroless nickel, electroless palladium, immersion gold (ENEPIG) process, or a much more economical, automated process can be used. This process is discussed in the accompanying paper and utilizes additive manufacturing to place an aerosol jet silver deposition over the existing gold ball, interfacing with the remaining exposed aluminum. In this manner, a high-reliability connection system can be achieved which is immune to Kirkendall voiding for the temperature range of interest.

Electroplating and Electroless Plating Process Development for DuPont™ GreenTape™ 9K7 LTCC

2013 ◽  
Vol 2013 (CICMT) ◽  
pp. 000283-000287
Author(s):  
Allan Beikmohamadi ◽  
Steve Stewart ◽  
Jim Parisi ◽  
Mark McCombs ◽  
Michael Smith ◽  
...  
Keyword(s):  
Thick Film ◽  
Surface Finish ◽  
Electroless Plating ◽  
Process Development ◽  
Cost Effective ◽  
Electroless Nickel ◽  
Free Atmosphere ◽  
Gold Plating ◽  
Cost Effective Approach ◽  
Easy Integration

Low Temperature Co-fired Ceramic (LTCC) technology provides an attractive packaging platform for microwave and millimeter wave circuits and systems due to its unique properties. Generally, thick film gold or silver conductors are used as metallizations on LTCC substrates along with occasional use of copper thick films. This paper reports methods and results of extensive process development experiments DuPont Microcircuit Materials has undertaken to establish a commercially viable plating process for the market leading DuPont™ GreenTape™ 9K7 LTCC system. Both Electroplating and Electroless plating processes are investigated in this work. These techniques provide certain advantages when used in isolation or in combination with standard thick film metallizations, helping to extend their applicability. Electroplating of copper on LTCC provides a means of using copper as the external conductor without having to use complicated firing processes in oxygen-free atmosphere as required for copper thick film. This approach leads to a much more cost effective approach if copper is required as the external metal. Electroless Nickel/Gold plating (ENIG) of both silver and copper (electroplated and/or thick film) provides an industry standard, highly reliable, robust surface finish. Such surface finish enables easy integration of both soldering and wire bonding processes.

FAILURE ANALYSIS OF DISCOLORED ENIG PADS IN THE MANUFACTURING ENVIRONMENT

2014 ◽  
Vol 2014 (1) ◽  
pp. 000653-000661
Author(s):  
Monika Marciniak ◽  
Michael Meagher ◽  
Jon Davis ◽  
Jack Josefowicz
Keyword(s):  
Failure Analysis ◽  
Printed Circuit Boards ◽  
Electroless Nickel ◽  
Manufacturing Environment ◽  
Electron Microscopic ◽  
Verification Method ◽  
Surface Finishes ◽  
Line Process ◽  
Cleaning Methods ◽  
Surface Examination

Manufacturing of electronic assemblies using printed circuit boards (PCBs) with electroless nickel/immersion gold (ENIG) surface finishes requires front-end PCB evaluation that will guarantee that good quality product enters the assembly line. The most common is an IPC-4552 mandated plating thicknesses verification of 3-6μm and a minimum of 0.05μm for nickel and gold, respectively. Coupled with visual examination, this verification method suffices for general PCB acceptance but may not be robust enough in cases where ENIG plating in PCBs is compromised. That poses challenges in the manufacturing environment, where resulting latent defects are detected in downstream processes but not at upfront incoming inspection. Manifestation of such latent anomaly was observed in the form of ENIG pad discoloration with variations from yellow, red or grey discolored surfaces to a more pronounced plating degradation, such as corrosive pitting. The launched failure analysis involved evaluation of manufacturing processes suspected to contribute to the cause of the condition. Effects of thermal processes, cleaning methods, soldering, parylene deposition and factory cleanliness were examined thoroughly. Concurrently, metallurgical analysis of ENIG pads was performed, where samples were subjected to scanning electron microscopic/energy dispersive x-ray spectroscopic (SEM/EDX) cross section analysis, Auger electron spectroscopy (AES) and gold (Au) and electroless nickel (Ni) surface examination. The resulting analysis revealed a highly porous electroless nickel coating with deep crevasses and fissures penetrating down to the base copper (Cu) layer. These open nickel boundaries were attributed to the corrosive environment within ENIG plating, which resulted in the pad surface discoloration. The root cause of ENIG pad discoloration and pitting was traced back to poor ENIG line process controls. Subsequent introduction of a nickel controller into the ENIG line were the implemented countermeasures. To mitigate the effects of discoloration at the electronic assembly level, a tinning process was implemented to prevent nickel plating oxidation and to ensure that good wettability for reliable solder joints was maintained.

Mechanical and Thermal Board Level Reliability Comparison Between Electroless Ni Im. Au and Solder on Pad Surface Finishes for Large Flip Chip BGA Packages

2006 ◽  
Author(s):  
Gnyaneshwar Ramakrishna ◽  
Donghyun Kim ◽  
Mudasir Ahamad ◽  
Lavanya Gopalakrishnan ◽  
Mason Hu ◽  
...  
Keyword(s):  
Surface Finish ◽  
Flip Chip ◽  
High Reliability ◽  
Electroless Nickel ◽  
Temperature Cycling ◽  
Design Parameters ◽  
Temperature Cycle ◽  
Bga Packages ◽  
Reliability And Robustness ◽  
Board Level

Large Flip Chip BGA (FCBGA) packages are needed in high pin out applications (>1800), e.g., ASIC's and are typically used in high reliability and robustness applications. Hence understanding the package reliability and robustness becomes one of paramount importance for efficient product design. There are various aspects to the package that need to be understood, to ensure an effective design. The focus of this paper is to understand the BGA reliability of the package with particular reference to comparison of the surface finish, vis-a`-vis, between Electroless Nickel Immersion Gold (ENIG) and Solder On Pad (SOP) on the substrate side of the package, which are the typical solutions for large plastic FC-BGA packages. Tests, which include board level temperature cycling, monotonic bend and shock testing have been conducted to compare the two surface finish options. The results of these tests demonstrate that the mechanical strength of the interface exceeds by a factor of two for the SOP surface finish, while BGA design parameters play a key role in ensuring comparative temperature cycle reliability in comparison with ENIG packages.

The formation of intermetallic layer structure of SAC405/Cu and SAC405/ENImAg solder joint interfaces

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rabiatul Adawiyah Mohamed Anuar ◽  
Saliza Azlina Osman
Keyword(s):  
Shear Strength ◽  
Surface Finish ◽  
Printed Circuit Boards ◽  
Solder Joints ◽  
Layer Structure ◽  
Ageing Time ◽  
Intermetallic Layer ◽  
Electroless Nickel ◽  
Optical Microscope ◽  
Content Type

Purpose The surface finish is an essential step in printed circuit boards design because it provides a solderable surface for electronic components. The purpose of this study to investigate the effects of different surface finishes during the soldering and ageing process. Design/methodology/approach The solder joints of Sn-4.0Ag-0.5Cu/Cu and Sn-4.0Ag-0.5Cu/electroless nickel/immersion silver (ENImAg) were investigated in terms of intermetallic (IMC) thickness, morphology and shear strength. The microstructure and compositions of solder joints are observed, and analyzed by using scanning electron microscopy (SEM-EDX) and optical microscope (OM). Findings Compounds of Cu6Sn5 and (Cu, Ni)6Sn5 IMC were formed in SAC405/Cu and SAC405/ENImAg, respectively, as-reflowed. When the sample was exposed to ageing, new layers of Cu3Sn and (Ni, Cu)3Sn5 were observed at the interface. Analogous growth in the thickness of the IMC layer and increased grains size commensurate with ageing time. The results equally revealed an increase in shear strength of SAC405/ENImAg because of the thin layer of IMC and surface finish used compared to SAC405/Cu. Hence, a ductile fracture was observed at the bulk solder. Overall, the ENImAg surface finish showed excellent performance of solder joints than that of bare Cu. Originality/value The novel surface finish (ENImAg) has been developed and optimized. This alternative lead-free surface finish solved the challenges in electroless nickel/immersion gold and reduced cost without affecting the performance.

Reliability Analysis of Lead-Free Solder Joints with Solder Doping on Harsh Environment

2016 ◽  
Vol 2016 (1) ◽  
pp. 000117-000122 ◽  
Author(s):  
Cong Zhao ◽  
Thomas Sanders ◽  
Zhou Hai ◽  
Chaobo Shen ◽  
John L. Evans
Keyword(s):  
Surface Finish ◽  
Isothermal Aging ◽  
Electroless Nickel ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Surface Mount ◽  
Surface Finishes ◽  
Free Solder ◽  
Immersion Silver

Abstract This paper investigates the effect of long term isothermal aging and thermal cycling on the reliability of lead-free solder mixes with different solder compositions, PCB surface finishes, and isothermal aging conditions. A variety of surface mount components are considered, including ball grid arrays (BGAs), quad flat no-lead packages (QFNs) and 2512 Surface Mount Resistors (SMRs). 12 lead-free solder pastes are tested; for BGA packages these are reflowed with lead-free solder spheres of SAC105, SAC305 and matched doped solder spheres (“matched” solder paste and sphere composition). Three surface finishes are tested: Organic Solderability Preservative (OSP), Immersion Silver (ImAg), and Electroless Nickel Immersion Gold (ENIG). All test components are subjected to isothermal aging at 125°C for 0 or 12 months, followed by accelerated thermal cycle testing from −40°C to 125°C. Data from the first 1500 cycles is presented here, with a focus on the effect of surface finish on package reliability. Current results demonstrate that the choice of surface finish has a strong effect on reliability. However, different solder materials appear to show different reliability trends with respect to the surface finishes, and the reliability trends of BGA and SMR packages also diverge.

Surface Finish Effects on High-Speed Interconnects

2003 ◽  
Author(s):  
Xin Wu ◽  
Omar M. Ramahi ◽  
Gary A. Brist ◽  
Donald P. Cullen
Keyword(s):  
Surface Finish ◽  
High Speed ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Signal Loss ◽  
Differential Mode ◽  
Hot Air ◽  
Full Wave ◽  
Surface Finishes ◽  
High Speed Interconnects

In printed circuit boards (PCB), the selection of surface finish is a balance of cost, performance and material compatibility consideration. When the operating frequency is in gigahertz range, the signal loss in interconnects has stronger dependence on the material composition of traces, surface finishes, substrates, and geometry of the traces. Skin effects, frequency dependent dielectric properties and the electrical functioning mechanism are important factors that affect signal integrity. In this work, both measurements and finite element method (FEM) based full wave simulation are used to investigate the effects of hot air solder leveling (HASL) and its alternatives on signal degradation of high-speed interconnect structures. For the microstrip line structure, the loss due to surface finishes is negligible. For the differential mode coupled microstrip lines, the loss increment resulted from surface finish can be up to 50%∼200% at 10 GHz. Surface finish caused signal loss must be carefully considered for differential mode interconnects.

Influence of Second Reflow on the Intermetallic Compound Growth with Different Surface Finish

2016 ◽  
Vol 701 ◽  
pp. 127-131
Author(s):  
Hardinnawirda Kahar ◽  
Zetty Akhtar Abd Malek ◽  
Siti Rabiatull Aisha Idris ◽  
Mahadzir Ishak
Keyword(s):  
Intermetallic Compound ◽  
Surface Finish ◽  
Electroless Nickel ◽  
Optical Microscope ◽  
Compound Formation ◽  
Intermetallic Compound Growth ◽  
Surface Finishes ◽  
Intermetallic Compound Formation ◽  
Free Solder ◽  
Immersion Tin

The formation and growth of the intermetallic were frequently discussed since lead free solder took place replacing the lead solder. However, the effect of multiple reflow process on the intermetallic morphology that was subjected to aging still needs further investigation. Thus, this study aimed to investigate the effect of second reflow towards the intermetallic compound formation and growth. Two types of surface finishes were used such as Immersion Tin (ImSn) and Electroless Nickel Immersion Gold (ENIG). Both test boards were reflowed once with Sn-3Ag-0.5Cu at the temperature of 225 °C and soaking for 8 seconds. Then, they were reflowed again at the same temperature for 25 minutes prior to an isothermal aging process for 250, 500, 1000 and 2000 hours at the temperature of 150 °C. The ProgRes C3 IM7200 Optical Microscope and ImageJ were used for the microstructural study, which includes morphology and thickness. Results indicated that IMC thickness formed between solder and ImSn surface finish increased significantly with 1.28 µm incremental when exposed to the second reflow. Whereas the IMC thickness of ENIG surface finish was increased for up to 0.15 µm. In addition, ENIG showed higher activation energy as compared to ImSn.

scholarly journals Modification and the Performance Enhancement of Solar Biomass Dryer

2021 ◽  
pp. 31-38
Author(s):  
Tanvir Ahmed ◽  
Tanjid Zaman
Keyword(s):  
Rural Areas ◽  
Performance Enhancement ◽  
Performance Testing ◽  
Cost Effective ◽  
Ambient Air ◽  
Agricultural Products ◽  
Small Scale ◽  
Turbulent Air Flow ◽  
And Performance ◽  
Improved Design

Drying is an important agricultural process, particularly for crops, and shriveled products are used all over the world. The performance of drying green chili was also tested in this article, which created an alternate way of drying agricultural products. The goal of this study is to provide a solar biomass hybrid dryer with improved design, construction, and performance testing. During most hours of the trial, the temperature within the solar collector and dryer was sufficiently higher than the ambient temperature, according to the results obtained during the test period. The temperature of the ambient air at the collector intake ranged from 30 to 35 degrees Celsius. The temperature of the air at the collector's outlet ranged from 54 to 64 degrees Celsius, while the temperature of the drying chamber ranged from 51 to 60 degrees Celsius, making it suitable for drying green chili and a variety of other agricultural products. The collector was found to be 46.54 percent efficient. The findings revealed that the alteration of the collector, which produces turbulent air flow and improves chamber wall insulation, affects drying. Based on the results of this study, the created solar biomass hybrid drier is cost-effective for small-scale crop growers in rural areas of developing countries.

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