Electronics Manufacturing Technical Articles

Board Design and Assembly Process Evaluation for 0201 Components on PCBs

May 02, 2023 | Mei Wang, Dr. Dongkai Shangguan, David Geiger, Kazu Nakajima, CC. Ho, and Sammy Yi

As 0402 has become a common package for printed circuit board (PCB) assembly, research and development on mounting 0201 components is emerging as an important topic in the field of surface mount technology for PWB miniaturization. In this study, a test vehicle for 0201 packages was designed to investigate board design and assembly issues. Design of Experiment (DOE) was utilized, using the test vehicle, to explore the influence of key parameters in pad design, printing, pick-andplace, and reflow on the assembly process. These key parameters include printing parameters, mounting height or placement pressure, reflow ramping rate, soak time and peak temperature. The pad designs consist of rectangular pad shape, round pad shape and home-based pad shape. For each pad design, several different aperture openings on the stencil were included. The performance parameters from this experiment include solder paste height, solder paste volume and the number of post-reflow defects. By analyzing the DOE results, optimized pad designs and assembly process parameters were determined....

Publisher: Flextronics International

PCB Design Optimization of 0201 Packages for Assembly Processes

May 02, 2023 | Mei Wang, Dr. Dongkai Shangguan, David Geiger, Fredrik Mattsson and Sammy Yi

The demand for 0201 components in consumer products will increase sharply over the next few years due to the need for miniaturization. It is predicted that over 20 billion 0201 components will be used in more than one billion cell phones worldwide by the year 2003. Therefore, research and development on 0201 assembly is becoming a very hot topic. The first step to achieve a successful assembly process is to obtain a good PCB design for 0201 packages. This paper presents the data and criteria of PCB design for 0201 packages, including the pad design for 0201 components, and the minimum pad spacing or component clearance between 0201 components or between 0201 and other components. A systematic study on pad design and pad spacing was undertaken, using two test vehicles and three Design of Experiments (DOEs). In the first DOE, 2 out of 18 types of 0201 pad designs were selected based on process yield. The second DOE was focused on pad spacing, including 10mil, 8mil, 6mil and 4mil. The third experiment was final optimization, using two types of optimized pad designs with 10mil, 8mil and 6mil pad spacing. Through the above experiments, the design guideline for PCB layout for 0201 packages and the assembly process capability are identified....

Publisher: Flextronics International

RULES FOR WORKING WITH 0201s AND OTHER SMALL PARTS

May 02, 2023 | Advanced Assembly, LLC

Surface-mount PCB components are smaller than their lead-based counterparts and provide a radically higher component density. They are available in a variety of shapes and sizes designated by a series of standardized codes curated by the electronics industry. Of these PCB components, the 0201-sized are the smallest, measuring 0.024 x 0.012 in. (0.6 x 0.3 mm) – that's 70% smaller than the previous 0402 level! The 0201 components are designed to improve reliability in space-constrained applications such as portable electronics like smartphones, tablets, robotics and digital cameras, but require delicate handling during the assembly process....

Publisher: Advanced Assembly, LLC.

RULES FOR WORKING WITH 0201s AND OTHER SMALL PARTS

May 02, 2023 | Advanced Assembly, LLC

Surface-mount PCB components are smaller than their lead-based counterparts and provide a radically higher component density. They are available in a variety of shapes and sizes designated by a series of standardized codes curated by the electronics industry. Of these PCB components, the 0201-sized are the smallest, measuring 0.024 x 0.012 in. (0.6 x 0.3 mm) – that's 70% smaller than the previous 0402 level! The 0201 components are designed to improve reliability in space-constrained applications such as portable electronics like smartphones, tablets, robotics and digital cameras, but require delicate handling during the assembly process. Given the miniaturized dimensions of an 0201 package, it is crucial that the mounting process abide by a series of guidelines regarding the design of the PCB mounting pads and solderable metallization, PCB circuit trace width, solder paste selection, package placement and overages, solder paste reflow, solder stencil screening, and final inspection. It's advisable that one review this information when procuring the services of a PCB assembler....

Publisher: Advanced Assembly, LLC.

Neo Station: Revolutionize PCB assembly

Apr 29, 2023 | Neotel Technology

The world of electronics is continuously evolving, and the need for faster, more efficient, and more precise assembly of printed circuit boards (PCBs) has become paramount. Neotel Technology's latest innovation, the Neo Station, offers a comprehensive solution for PCB assembly that combines state-of-the-art features with unparalleled ease of use. This document outlines the key features and benefits of the Neo Station, a groundbreaking tool that is set to revolutionize the electronics industry....

Publisher: Neotel Technology Co., Ltd

PWB Contamination & Reliability DOE

Apr 25, 2023 | Michael R. Weekes

This report hopes to achieve several goals: 1. Determine the link between bare PWB contamination, soldered assembly contamination and long-term product reliability. 2. Establish measurable limits for bare PWB cleanliness as well as process control limits for both an aqueous as well as a water-soluble soldering process. 3. Determine whether there is any correlation between common, industry-accepted rose/modified rose (omegameter/ionograph type) testing and long term product reliability. 4. Determine the effect PWB plating finish (HASL, Immersion Silver and Cu OSP) has on both bare PWB contamination as well as soldered assembly in a no clean and water soluble process. 5. Determine whether there is a link between percentage of saponifier used to wash soldered assemblies and long-term reliability. 6. Establish a more cost-effective test for manufacturers to use as a process-monitoring tool.

Publisher: John Deere Electronic Solutions

WHY test for Ionic Contamination?

Apr 17, 2023 | Specialty Coating Systems

Ionic contamination is a leading cause in the degradation and corrosion of electronic assemblies, leading to lifetime limitation and field failure (Fig. 1). Ionic residue comes from a variety of sources shown in Fig. 2 opposite: Examples of ionic contaminants: * Anions * Cations * Weak Organic Acid...

Publisher: Specialty Coating Systems

The Relationship Between Cleanliness and Reliability/Durability

Apr 17, 2023 | Debbie Carboni

Outline/Agenda * Introduction of Ionics and ROSE * Evolution in technology * Rev H in the IPC-J-STD-001 * Real World Case Study * Conclusions...

Publisher: KYZEN Corporation

Comparison of ROSE, C3/IC, and SIR as an effective cleanliness verification test for post soldered PCBA

Apr 17, 2023 | Kong Hui Lee, Rob Jukna, Jim Altpeter, Kantesh Doss

The purpose of this paper is to evaluate and compare the effectiveness and sensitivity of different cleanliness verification tests for post soldered printed circuit board assemblies (PCBAs) to provide an understanding of current industry practice for ionic contamination detection limits. Design/methodology/approach – PCBAs were subjected to different flux residue cleaning dwell times and cleanliness levels were verified with resistivity of solvent extract, critical cleanliness control (C3) test, and ion chromatography analyses to provide results capable of differentiating different sensitivity levels for each test. Findings – This study provides an understanding of current industry practice for ionic contamination detection using verification tests with different detection sensitivity levels. Some of the available cleanliness monitoring systems, particularly at critical areas of circuitry that are prone to product failure and residue entrapment, may have been overlooked. Research limitations/implications – Only Sn/Pb, clean type flux residue was evaluated. Thus, the current study was not an all encompassing project that is representative of other chemistry-based flux residues. Practical implications – The paper provides a reference that can be used to determine the most suitable and effective verification test for the detection of ionic contamination on PCBAs. Originality/value – Flux residue-related problems have long existed in the industry. The findings presented in this paper give a basic understanding to PCBA manufacturers when they are trying to choose the most suitable and effective verification test for the detection of ionic contamination on their products. Hence, the negative impact of flux residue on the respective product's long-term reliability and performance can be minimized and monitored effectively....

Publisher: Jabil Circuit, Inc.

Evaluation of No-Clean Flux Residues Remaining After Secondary Process Operations

Apr 17, 2023 | Phil Isaacs, Jennifer Bennett, Terry Munson

In an ideal world, manufacturing devices would work all of the time, however, every company receives customer returns for a variety of reasons. If these returned parts contributed to a fail, most companies will perform failure analysis (FA) on the returned parts to determine the root cause of the failure. Failure can occur for a multitude of reasons, for example: wear out, fatigue, design issues, manufacturing flaw or defect. This information is then used to improve the overall quality of the product and prevent reoccurrence. If no defect is found, it is possible that in fact the product has no defect. On the other hand, the defect could be elusive and the FA techniques insufficient to detect said deficiency. No-clean flux residues can cause intermittent or elusive, hard to find defects. In an attempt to understand the effects of no-clean flux residues from the secondary soldering and cleaning processes, a matrix of varying process and cleaning operation was investigated. Of special interest, traveling flux residues and entrapped residues were examined, as well as localized and batch cleaning processes. Various techniques were employed to test the remaining residues in order to assess their propensity to cause a latent failure. These techniques include Surface Insulation Resistance1 (SIR) testing at 40⁰C/90% RH, 5 VDC bias along with C32 testing and Ion Exchange Chromatography (IC). These techniques facilitate the assessment of the capillary effect the tight spacing these component structures have when flux residues are present. It is expected that dendritic shorting and measurable current leakage will occur, indicating a failing SIR test. However, since the residue resides under the discrete components, there will be no visual evidence of dendritic growth or metal migration....

Publisher: Foresite Inc.

Characterizing of Emissions from Open Burning of Electronic Waste using TG-GC-MS System

Mar 27, 2023 | Jun Wang

Electronic waste (e-waste) is currently the fastest growing hazardous waste stream that continues to be a challenging concern for the global environment and public health. The average useful life of electronic products has continued to decline, and obsolete products are being stored or discarded with increasing frequency. E-waste is hazardous, complex and expensive to treat in an environmentally sound manner. As a result, new challenges related to the management of e-waste have become apparent. Most electronic products contain a combination of hazardous materials, toxic materials, and valuable elements such as precious metals and rare earth elements. There are risks to human health associated with the disposal of E-waste in landfills, or treatment by incineration. Americans discard 400+ million electronic items per year recycling less than 20 percent in safe and sustainable manner. E-waste is exported from developed countries and processed informally using unsafe conditions in many regions of developing countries. A mixture of pollutants is released from these informal rudimentary operations. Exposure to e-waste recycling includes the dismantling of used electronics and the use of hydrometallurgical and pyrometallurgical processes, which emit toxic chemicals, to retrieve valuable components. Thermal analysis integrated with chromatographic and spectroscopic techniques are used to determine dangerous chemicals emitted during the burning of e-waste. The information is used to assess the risk of exposure of workers at these semi-formal recycling centers....

Publisher: PerkinElmer Optoelectronics

Material & Process Influences on Conductive Anodic Filamentation (CAF)

Mar 16, 2023 | Alun Morgan and Doug Trobough

HISTORY: * In the late 1970s an abrupt unpredictable loss of insulation resistance was observed in PCBs, which were subject to hostile climatic conditions of high relative humidity and temperature while having an applied voltage. * The loss of resistance, even leading to a short circuit was observed to be due to the growth of a subsurface filament from the anode to the cathode. * The term "Conductive Anodic Filamentation" (CAF) was coined....

Publisher: Isola Group

Conductive Anodic Filament (CAF) Formation: A Potential Reliability Problem for Fine-Line Circuits

Mar 16, 2023 | Laura J. Turbini, W. Jud Ready & Brian A. Smith

Outline * Introduction & Background * Factors Affecting CAF Formation * CAF Formation ** Catastrophic Field Failure of Military Hardware ** Laboratory Experiments * Conclusion...

Publisher: Georgia Institute of Technology

Conductive Anodic Filament Failure: A Materials Perspective

Mar 16, 2023 | Laura J. Turbini and W. Jud Ready

Conductive anodic filament (CAF) formation was first reported in 1976.1 This electrochemical failure mode of electronic substrates involves the growth of a copper containing filament subsurface along the epoxy-glass interface, from anode to cathode. Despite the projected lifetime reduction due to CAF, field failures were not identified in the 1980s. Recently, however, field failures of critical equipment have been reported.2 A thorough understanding of the nature of CAF is needed in order to prevent this catastrophic failure from affecting electronic assemblies in the future. Such an understanding requires a comprehensive evaluation of the factors that enhance CAF formation. These factors can be grouped into two types: (1) internal variables and (2) external influences. Internal variables include the composition of the circuit board material, and the conductor metallization and configuration (i.e. via to via, via to surface conductor or surface conductors to surface conductors). External influences can be due to (1) production and (2) storage and use. During production, the flux or hot air solder leveling (HASL) fluid choice, number and severity of temperature cycles, and the method of cleaning may influence CAF resistance. During storage and use, the principal concern is moisture uptake resulting from the ambient humidity. This paper will report on the relationship between these various factors and the formation of CAF. Specifically, we will explore the influences of printed wiring board (PWB) substrate choice as well as the influence of the soldering flux and HASL fluid choices. Due to the ever-increasing circuit density of electronic assemblies, CAF field failures are expected to increase unless careful attention is focused on material and processing choices....

Publisher: Georgia Institute of Technology

Paper Substrates and Inks for Printed Electronics

Mar 13, 2023 | Laura K. Wood†, Erika Hrehorova, Thomas W. Joyce†, Paul D. Fleming, Margaret Joyce†, Alexandra Pekarovicova and Valery Bliznyuk

The present work explores the effects of paper properties on conventional silver-based conducting inks. The effects of smoothness, relative humidity, porosity, permeability and wettability on electrical properties of silver inks on different paper substrates were studied. Another objective of this work was to prepare and study polyaniline synthesized in the presence of different lignosulfonates....

Publisher: Western Michigan University

Printed Electronics: Manufacturing Technologies and Applications

Mar 13, 2023 | Chuck Zhang

Translational Research in Additive Manufacturing at GTMI * Additive manufacturing/3D printing process and equipment development (e.g., metal, polymer and composites part manufacturing) * Computational modeling and simulation of additive manufacturing/printed electronics processes * Advanced materials development for additive manufacturing/printed electronics * Application development and demonstration of additive manufacturing/printed electronics...

Publisher: Georgia Institute of Technology

Modeling Resistance Increase In A Composite Ink Under Cyclic Loading

Mar 13, 2023 | Q Li, E Chung, A Antoniou and O Pierron

The electrical performance of stretchable electronic inks degrades as they undergo cyclic deformation during use, posing a major challenge to their reliability. The experimental characterization of ink fatigue behavior can be a time-consuming process, and models allowing accurate resistance evolution and life estimates are needed. Here, a model is proposed for determining the electrical resistance evolution during cyclic loading of a screen-printed composite conductive ink. The model relies on two input specimen-characteristic curves, assumes a constant rate of normalized resistance increase for a given strain amplitude, and incorporates the effects of both mean strain and strain amplitude. The model predicts the normalized resistance evolution of a cyclic test with reasonable accuracy. The mean strain effects are secondary compared to strain amplitude, except for large strain amplitudes (>10%) and mean strains (>30%). A trace width effect is found for the fatigue behavior of 1 mm vs 2 mm wide specimens. The input specimen-characteristic curves are trace-width dependent, and the model predicts a decrease in Nf by a factor of up to 2 for the narrower trace width, in agreement with the experimental results. Two different methods are investigated to generate the rate of normalized resistance increase curves: uninterrupted fatigue tests (requiring ∼6–7 cyclic tests), and a single interrupted cyclic test (requiring only one specimen tested at progressively higher strain amplitude values). The results suggest that the initial decrease in normalized resistance rate only occurs for specimens with no prior loading. The minimum-rate curve is therefore recommended for more accurate fatigue estimates....

Publisher: Georgia Institute of Technology

An Introduction To The Process Of Printed Electronics

Mar 13, 2023 | S.G.R. Avuthu, Ph.D., M. Gill, N Ghalib, M. Sussman, G. Wable, J. Richstein, Ph.D.

Printed electronics (PE) is impacting almost every branch of manufacturing. The printing of electronics on mechanically flexible substrates such as plastic, paper and textile, using traditional printing techniques, provides novel applications for wearable and stretchable electronics. Government sponsored consortiums, universities, contract printers, startups and global manufacturers are developing processes to bring this technology to market faster, more costeffectively and at scale. By increasing the speed of technology adoption while following industrialization best practices, industry researchers aim to create processes that ramp up the scale of production for simple circuits and integrated conductive structures....

Publisher: Jabil Circuit, Inc.

Printable Electronics: Towards Materials Development And Device Fabrication

Mar 13, 2023 | Rabindra N. Das, How T. Lin, John M. Lauffer and Voya R. Markovich

Purpose – There has been increasing interest in the development of printable electronics to meet the growing demand for low-cost, large-area, miniaturized, flexible and lightweight devices. The purpose of this paper is to discuss the electronic application of novel printable materials. Design/methodology/approach – The paper addresses the utilization of polymer nanocomposites as it relates to printable and flexible technology for electronic packaging. Printable technology such as screen-printing, ink-jet printing, and microcontact printing provides a fully additive, non-contacting deposition method that is suitable for flexible production....

Publisher: i3 Electronics

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Mar 04, 2023 | Management representative

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Publisher: Hiflo Solders Private Limited

PCB terminology you must know

Feb 28, 2023 | FS PCBA

With the popularization of electronic products, more and more people know the importance of printed circuit board (PCB), but it is a very complicated and huge knowledge system. In this article, we will discuss some terms about the PCB industry so that you can better understand the circuit board. Printed circuit board professional noun Array: Usually we also refer to it as panelized, stepped or palletized PCB, which refers to the combination of multiple copies of the PCB into a connected matrix of circuit boards. Usually we refer to the PCB as the bare board of the circuit board, that is, the part that does not contain components, it is not working, and the electronics manufacturer needs to find a suitable PCBA processing plant to complete the assembly after completing the PCB manufacturing. Through the above-mentioned assembly method, PCBA company can complete the assembly work faster. https://www.fs-pcba.com/ Board Aspect Ratio: It is the ratio between board thickness and minimum via diameter, which is very important. We know that a circuit board is an electronic product that contains circuit images, and the circuit diagrams are formed during production through methods such as SUV exposure. In order to ensure the accuracy of circuit images and assembly work, designers need to ensure a lower aspect ratio to reduce potential risks that may arise. Cable: It is used for the transmission of electric current just like the wires in our daily life. There are various wires in electronic products, these wires connect different components, and they are electrically connected to each other to operate. https://www.fs-pcba.com/manufacturing-pcb/ Main body: As mentioned above, the PCB board cannot operate alone, but the components are mounted on the surface of the bare board through PCB assembly. These components are very small, but when they are installed, there are many extra parts such as: pins, leads and accessories. In order to accurately express their views, designers usually use the main body of the component to represent the central part of the electronic component. https://www.fs-pcba.com/assembly-pcb/ More Interesting Board Articles The PCB industry involves a lot of content. In order to complete a complete PCBA board, we need to go through multiple links, such as design, manufacturing, assembly, testing, etc., and there are more categories under each link. If you want to know more about this industry, it will be helpful for you to read more about PCB....

Publisher: FS Technology

Printed Circuit Board (PCB) Micro-Sectioning For Quality Control

Feb 27, 2023 | Nanu Vahora

Quality control in Printed Circuit Board (PCB) manufacturing is very important, including but not limited to drilling hole quality, Desmearing of drilled hole, plating thickness of various metals and integrating of the final production board. During the manufacture of printed circuit boards, test coupons are introduced in each production panel. This allows each panel to be tested without wasting actual production board. The coupon is separated from the panel to confirm product specifications have been met.

Publisher: Buehler, a division of Illinois Tool Works Inc.

ALD Atomic Layer Deposition for space applications

Feb 19, 2023 | Marko Pudas

ALD – Atomic Layer Deposition

- Is a batch coating process with surface chemistry
- Wide range of material, e.g. Al2O3, TiO2, M-, M-C,M-N
- Typical; 100 nm up to ~0,5 μm
- True 3D down to nanopores, no pinholes
- Vacuum deposition process
-- Substrates are degassed & heated (degas analyzed)
-- ~40 C – 125C – 400 C
- Mature IC manufacturing process
- Extremely repeatable in thickness & quality over time
- Chemically adhesion; will not peal off/flak
-- Dense,
-- Pinhole- and defect-free films
-- Digitally repeatable process

Publisher: Picosun Oy

Atomic Layer Deposition (ALD) to Mitigate Tin Whisker Growth and Corrosion Issues on Printed Circuit Board Assemblies

Feb 19, 2023 | TERHO KUTILAINEN, MARKO PUDAS, MARK A. ASHWORTH , TERO LEHTO, LIANG WU, GEOFFREY D. WILCOX, JING WANG, PAUL COLLANDER, and JUSSI HOKKA

This paper presents the results of a research program set up to evaluate atomic layer deposition (ALD) conformal coatings as a method of mitigating the growth of tin whiskers from printed circuit board assemblies. The effect of ALD coating process variables on the ability of the coating to mitigate whisker growth were evaluated. Scanning electron microscopy and optical microscopy were used to evaluate both the size and distribution of tin whiskers and the coating/whisker interactions. Results show that the ALD process can achieve significant reductions in whisker growth and thus offers considerable potential as a reworkable whisker mitigation strategy. The effect of ALD layer thickness on whisker formation was also investigated. Studies indicate that thermal exposure during ALD processing may contribute significantly to the observed whisker mitigation....

Publisher: Poltronic Inc

Investigation of the Atomic Layer Deposition of the Titanium Dioxide (TiO2) Film as pH Sensor Using a Switched Capacitor Amplifier

Feb 19, 2023 | Mozhdeh Nematzadeh , Ola Nilsen , Philipp Dominik Häfliger and Veronica Anne-Line Kathrine Killi

The electrical and chemical properties of the titanium dioxide (TiO2) coated spirals grown by the atomic layer deposition (ALD) technique in two different temperatures of 150 °C and 300 °C are studied. The thickness of the TiO2 layers studied are 20, 40, and 80 nm. A switched capacitor amplifier is used to investigate the pH response and the capacitance of the samples. It is found that the performance of the TiO2 samples depends on either the thickness or the deposition temperature due to the differences in the physical properties of the oxide layer such as surface roughness and film density. The high temperature samples are more crystalline, whereas the low temperature samples are more amorphous. Since there is a low pass filter effect in the electrolyte–sample interface, the TiO2 coated samples show the better response to the pH change for the high temperature samples as the sensor surface area for binding the hydrogen ions is larger and the charge transfer resistance is smaller. Furthermore, more roughness on the surface can be obtained by increasing the thickness, which reduces the charge transfer resistance. In this study, the 80 nm sample deposited at 300 °C gives the best pH response of 40 mV/pH.

Publisher: University of Oslo

Atomic Layer Deposition for Encapsulation and Hermetic Sealing of RF and Power Electronics

Feb 19, 2023 | Forge Nano

Radio frequency (RF) and power electronics are vital to an array of industries, from telecom and consumer electronics to transportation and energy distribution. As energy diversification and the prevalence of high-speed electronics continue to grow, RF and power electronics are expected to reach a global market of $36.6 billion by 2027.1 Extreme environments such as high temperatures, ultra-violet radiation, oxygen, salinity and moisture are all threats that degrade and corrode active components causing early failure. Atomic layer deposition (ALD) has created substantial improvements to the reliability and performance of RF and power electronics. Using ALD as an encapsulation layer at the wafer level or as a final hermetic seal at the chip/module/PCB level has been shown to substantially improve electronic performance and lifetime.2,3 ALD layers enable longer lifetimes, higher performance and lower cost without adding the considerable mass gain and high temperature processing associated with conventional hermetic coatings.

Publisher: Forge Nano

Potting-optimized component design

Feb 15, 2023 | Scheugenpflug

With regard to potting, the design of electronic assemblies and components has a significant impact on economical and sustainable production. Key aspects in this respect are pottability, material use, cycle times, quality and the process technology needed. Optimized, bubble-free potting contributes greatly to the function and longevity of products. It is best practice during the design and development phases therefore to follow the potting tips contained in this White Paper....

Publisher: Scheugenpflug Inc.

Generation of Sn Whiskers During Electrodeposition

Feb 13, 2023 | M. Saitou

Sn whiskers generated during electrodeposition on a Cu plate within a range of the deposition temperature from 273 to 303 K were investigated using scanning electron microscopy and X-ray diffraction. The critical film thickness for the formation of Sn whiskers on a Sn thin film was determined (1.9 um). The critical film thickness was found to be independent of the deposition temperature. At the film thicknesses more than 5 um, the (220) dominant crystallographic plane transformed the (112) plane parallel to the Cu plate. This can be attributed to the morphological change (coarse to dense Sn whiskers). This suggests that the Sn whiskers with the (220) plane acted as crystal seeds to generate the Sn whiskers with the (112) plane. The fine string-like Sn whiskers generated at 303 K during the electrodeposition showed an anomalous growth rate of 45 nm s-1 at least.

Publisher: University of the Ryukyus

Effects of Tin Whisker Formation on Nanocrystalline Copper

Feb 13, 2023 | David M. Lee, Lesly A. Piñol

Spontaneously forming tin whiskers, which emerge unpredictably from pure tin surfaces, have regained prevalence as a topic within the electronics research community. This has resulted from the ROHS-driven conversion to "lead-free" solderable finish processes. Intrinsic stresses (and/or gradients) in plated films are considered to be a primary driving force behind the growth of tin whiskers. This paper compares the formation of tin whiskers on nanocrystalline and conventional polycrystalline copper deposits. Nanocrystalline copper under-metal deposits were investigated, in terms of their ability to mitigate whisker formation, because of their fine grain size and reduced film stress. Pure tin films were deposited using matte and bright electroplating, electroless plating, and electron beam evaporation. The samples were then subjected to thermal cycling conditions in order to expedite whisker growth. The resultant surface morphologies and whisker formations were evaluated....

Publisher: Johns Hopkins Applied Physics Laboratory

DoD/EPA/DOE SERDP WP-2213: Novel Whisker Mitigating Composite Conformal Coat Assessment

Feb 13, 2023 | Dr. Stephan Meschter, Dr. Polina Snugovsky, Dr. Abdullah Ekin, Dale Starkey,Dr. Junghyun Cho

Technology Focus: Develop and evaluate nanoparticle filled conformal coatings designed to provide long term whisker penetration resistance and coverage on tin rich metal surfaces prone to whisker growth in commercial lead-free electronics used in modern DoD systems. Research Objectives: Identify the fundamental mechanisms by which conformal coatings provide long-term tin whisker penetration resistance and inhibit nucleation/growth. Correlate mechanical properties and coverage thickness to whisker penetration resistance. Project Progress and Results: Functionalized nanosilica and non-functional nanoalumina enhanced polyurethane conformal coatings have shown improved spray coating coverage characteristics and crack resistance during thermal cycling fatigue testing. Lead-free assembly whisker mitigation validation testing is in process. Technology Transition: Current project partners provide coating materials to industry. SERDP test data will be considered during updates to the DoD adopted IPC standards for coating materials and coverage....

Publisher: BAE SYSTEMS

Strategies To Mitigate The Tin Whisker Phenomenon

Feb 13, 2023 | Patrick Laver

The tin whisker phenomenon is a failure mode associated with all electronic devices that use a number of low melting point elements (e.g., Sn, Cd, In) in operations such as soldering. Recognized many years ago, the problem was minimized by adding lead, now identified as a hazardous substance and banned...

Publisher: Vicor Corporation

Whisker Formation Induced by Component and Assembly Ionic Contamination

Feb 13, 2023 | POLINA SNUGOVSKY, STEPHAN MESCHTER, ZOHREH BAGHERI, EVA KOSIBA, MARIANNE ROMANSKY, and JEFFREY KENNEDY

This paper describes the results of an intensive whisker formation study on Pb-free assemblies with different levels of cleanliness. Thirteen types of as-received surface-mount and pin-through-hole components were cleaned and intentionally contaminated with solutions containing chloride, sulfate, bromide, and nitrate. Then the parts were assembled on double-sided boards that were also cleaned or intentionally contaminated with three fluxes having different halide contents. The assemblies were subjected to high-temperature/high-humidity testing (85_C/85% RH). Periodic examination found that contamination triggered whisker formation on both exposed tin and solder fillets. Whisker occurrence and parameters depending on the type and level of contamination are discussed. Cross-sections were used to assess the metallurgical aspects of whisker formation and the microstructural changes occurring during corrosion....

Publisher: Celestica Corporation

Via Hole Filling Technology for High Density, High Aspect Ratio Printed Wiring Boards Using a High Tg, low CTE Plugging Paste

Feb 06, 2023 | Michael Carano

The continued fast pace towards miniaturization is leading circuit board designers to push the envelope on integration density. This trend is driving fabricators to closely look at methods and processes that will enable the move towards sequential lamination and blind and buried via technology. Circuit board fabricators particularly in North America are adopting techniques such as via filling capability with nonconductive, high Tg, low CTE plugging pastes. This paper describes the implementation of the via filling process in a highly effective and reliable fashion for high density, high aspect ratio printed wiring boards. Close attention is paid to use of these via filling materials under high temperature assembly conditions. In addition, via plugging material requirements, equipment considerations and process limitations will be presented. Further, the pros and cons of different filling techniques are discussed. Finally, desmear and metallization techniques to insure adhesion of the plating to the filled via are presented in the context of “Best Practices.”

Publisher: Omg Electrochemicals / Macdermid Alpha

PCB Quality Metrics that Drive Reliability

Jan 23, 2023 | Bhanu Sood, Ph.D.

PDC Outline Section 0: Intro Section 1: What is reliability and root cause? Section 2: Overview of failure mechanisms Section 3: Failure analysis techniques – Non-destructive analysis techniques – Destructive analysis – Materials characterization Section 4: Summary and closure...

Publisher: NASA Office Of Safety And Mission Assurance

The Inline X-Ray Component Counter: The Next Step in SMT Inventory Automation

Jan 22, 2023 | Neotel Technology

The inline X-ray component counter, Neo Counter X800, can receive materials from an automated guided vehicle (AGV) or manually loaded by a trolley. The materials are picked up by a robotic arm and sent to the counter for counting. After the counting process, the software records the results and automatically prints a label with the correct quantity. This label is then attached to the surface of the reel. A stacker stacks the materials before being unloaded by the AGV or trolley. This process ensures accurate counting, efficient labelling, and streamlined material handling, making it a convenient way of managing electronic component inventory....

Publisher: Neotel Technology Co., Ltd

Introducing Closed-loop Nitrogen Control To Solder Reflow

Jan 17, 2023 | David Heller

To achieve higher levels of consistency in PCB output, process engineers are able to maintain tighter controls and reduce process-related defects by using closed-loop process controls. At every stage of assembly, from screen printing through placement to reflow, closed-loop systems help control the variable factors that can have adverse effects on the process....

Publisher: Heller Industries Inc.

How Challenging Conventional Wisdom Can Optimize Solder Reflow

Jan 17, 2023 | Marc Peo

As a manufacturing technology, SMT has acquired a "heritage" of widely accepted assumptions about its processes. However, yesterday'spractices are continually confronted by the shifting paradigms of today's production line....

Publisher: Heller Industries Inc.

The User Benefits of a Supplier Partnership

Jan 17, 2023 | Bjorn Dahle, Marc Peo

EQUIPMENT SUPPLIERS HAVE BECOME A RESOURCE FOR PROCESS CONTROL EXPERTISE, EVEN IN THE REFLOW OPERATION....

Publisher: Heller Industries Inc.

Vacuum Fluxless Reflow Technology for Fine Pitch First Level Interconnect Bumping Applications

Jan 17, 2023 | Yue Deng, Xike Zhao, Liang He, David Wright, Hossein Madanipour, Bret Halbe, Jung Kyu, Fred Tarazi, Gang Duan, Dror Trifon, Rahul Manepalli, David Heller

Heterogeneous integration has become an important performance enabler as high-performance computing (HPC) demands continue to rise. The focus to enable heterogeneous integration scaling is to push interconnect density limit with increased bandwidth and improved power efficiency. Many different advanced packaging architectures have been deployed to increase I/O wire / area density for higher data bandwidth requirements, and to enable more effective die disaggregation. Embedded Multi-die Interconnect Bridge (EMIB) technology is an advanced, cost-effective approach to in-package high density interconnect of heterogeneous chips, providing high density I/O, and controlled electrical interconnect paths between multiple dice in a package. In emerging architectures, it is required to scale down the EMIB die bump pitch in order to further increase the die-to-die (D2D) communication bandwidth. Aa a result, bump pitch scaling poses significant challenges in the plated solder bump reflow process, e.g., bump height / coplanarity control, solder wicking control, and bump void control. It's crucial to ensure a high-quality solder bump reflow process to meet the final product reliability requirements. In this paper, a combined formic acid based fluxless and vacuum assisted reflow process is developed for fine pitch plated solder bumping application. A high-volume production (HVM) ready tool has been developed for this process....

Publisher: Heller Industries Inc.

Flux Management

Jan 17, 2023 | Heller Industries

This paper describes the new flux management systems that Heller Industries introduced in 1999....

Publisher: Heller Industries Inc.

Function and Operational Theory of Condenser Tube Flux Collection System

Jan 17, 2023 | Heller Industries

Heller's new Condenser Tube Flux Recovery System is designed to provide more efficient flux collection than earlier Heller flux collection systems; while providing minimal down time for inspection and cleaning. The entire system easily fits within the rear of the top shell of an 1800-EXL oven. The system utilizes a different set of top shell caps specially designed to provide the best serviceability of both the flux collection system and maintenance of the heater zone blower motors....

Publisher: Heller Industries Inc.

Repeatability of the Temperature Profile under Load Variation

Jan 17, 2023 | Prepared by: John Poling

Repeatability of the Temperature Profile under Load Variation...

Publisher: Heller Industries Inc.

Are You Ready for Lead Free

Jan 17, 2023 | Marc Peo & Don DeAngelo

Various international market trends drive electronics manufacturers and their mate- rials and equipment suppliers to develop new assembly techniques to reduce the industry's environmental impact. Two pri- mary forces in this drive are the movements to lead-free assembly and ISO 14000 cer- tification. In response to these factors, reflow technology advances are enabling manufacturers to meet or anticipate the new environmental mandates....

Publisher: Heller Industries Inc.

The Greening of the Reflow Process

Jan 17, 2023 | Atsushi Kikuchi

After years of concentration on resolving productivity- related concerns such as increasing speed, consistency and throughput while reducing costs, many of the world's leading electronics manufacturers have added a new mandate to their agendas. They are seeking to minimize the environmental impacts of their assembly processes and final products without sacrificing the high levels of productivity and quality that have been achieved through decades of effort....

Publisher: Heller Industries Inc.

Let's Get the Lead Out

Jan 17, 2023 | Marc Peo

Let's Get the Lead Out...

Publisher: Heller Industries Inc.

A Practical Investigation into the Use of No Lead Solders for SMT Reflow

Jan 17, 2023 | Heller Industries and Soldering Technology David Heller and Jim Raby

A Practical Investigation into the Use of No Lead Solders for SMT Reflow...

Publisher: Heller Industries Inc.

Effect of Reflow Profile on SnPb and SnAgCu Solder Joint Shear Force

Jan 17, 2023 | Jianbiao Pan , Brian J. Toleno , Tzu-Chien Chou , Wesley J. Dee

Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent strength of the solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile on both 63%Sn 37%Pb (SnPb) and 96.5%Sn 3.0%Ag 0.5%Cu (SAC 305) solder joint shear force. Specifically, the effect of the reflow peak temperature and time above solder liquidus temperature are studied. Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb have been developed with three levels of peak temperature (230 o C, 240 o C, and 250 o C for SAC 305; and 195 o C, 205 o C, and 215 o C for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear force of the resistors is measured at time 0 (right after assembly). The fracture surfaces have been studied using a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS)...

Publisher: Heller Industries Inc.

Reflow Techniques for Void Reduction

Jan 17, 2023 | David Heller

BTC Void Reduction For Yield and Performance Enhancement...

Publisher: Heller Industries Inc.

THE LAST WILL AND TESTAMENT OF THE BGA VOID

Jan 17, 2023 | David Hillman, Dave Adams, Tim Pearson, Brad Williams, Brittany Petrick, and Ross Wilcoxon Rockwell Collins. David Bernard, Ph.D., John Travis, Evstatin Krastev, Ph.D., and Vineeth Bastin Nordson DAGE

The impact of voiding on the solder joint integrity of ball grid arrays (BGAs)/chip scale packages (CSPs) can be a topic of lengthy and energetic discussion. Detailed industry investigations have shown that voids have little effect on solder joint integrity unless they fall into specific location/geometry configurations. These investigations have focused on thermal cycle testing at 0°C-100°C, which is typically used to evaluate commercial electronic products. This paper documents an investigation to determine the impact of voids in BGA and CSP components using thermal cycle testing (-55°C to +125°C) in accordance with the IPC- 9701 specification for tin/lead solder alloys. This temperature range is more typical of military and other high performance product use environments. A proposed BGA void requirement revision for the IPC-JSTD-001 specification will be extracted from the results analysis....

Publisher: Heller Industries Inc.

THE EFFECT OF VACUUM REFLOW PROCESSING ON SOLDER JOINT VOIDING AND THERMAL FATIGUE RELIABILITY

Jan 17, 2023 | Richard Coyle, Dave Hillman, Michael Barnes, David Heller, Charmaine Johnson, Richard Popowich, Richard Parker, Keith Howell, Joerg Trodler, Adam Murling

A test program was developed to evaluate the effectiveness of vacuum reflow processing on solder joint voiding and subsequent thermal cycling performance. Area array package test vehicles were assembled using conventional reflow processing and a solder paste that generated substantial void content in the solder joints. Half of the population of test vehicles then were re-processed (reflowed) using vacuum reflow. Transmission x-ray inspection showed a significant reduction in solder voiding after vacuum processing. The solder attachment reliability of the conventional and vacuum reflowed test vehicles was characterized and compared using two different accelerated thermal cycling profiles. The thermal cycling results are discussed in terms of the general impact of voiding on solder thermal fatigue reliability, results from the open literature, and the evolving industry standards for solder voiding. Recommendations are made for further work based on other void reduction methods and additional reliability studies....

Publisher: Heller Industries Inc.