Electronics Manufacturing Technical Articles

Study of the Rheological Behaviors of Solder Pastes

Nov 06, 2018 | Michal KRAVČÍK, Igor VEHEC

Solder paste is a homogeneous, stable suspension of solder powder particles suspended in a flux binder, and is one of the most important process materials today in surface mount technology (SMT). By varying the solder particle size, distribution and shape, as well as the other constituent materials, the rheology and printing performance of solder pastes can be controlled. Paste flow behavior is very important in defining the printing performance of any paste.

The purpose of this paper is to study the rheological behavior of SAC (Sn-Ag-Cu) solder paste used for surface mount applications in the electronic industry. The reason why the rheological tests are presented in this paper are two critical sub-processes: aperture filling and paste withdraw. In this paper, we report on the investigation of the rheological profiles, the serrated cone-to-plate system was found as effective in parameter minimizing the wall-slip effect...

Publisher: Technical University of Košice

High Throw DC Acid Copper Formulation for Vertical Continuous Electroplating Processes

Oct 31, 2018 | Saminda Dharmarathna, PhD, Ivan Li, PhD, Maddux Sy, Eileen Zeng, Bob Wei, William Bowerman, Kesheng Feng, PhD

The electronics industry has grown immensely over the last few decades owing to the rapid growth of consumer electronics in the modern world. New formulations are essential to fit the needs of manufacturing printed circuit boards and semiconductors. Copper electrolytes for high throwing power applications with high thermal reliability and high throughput are becoming extremely important for manufacturing high aspect ratio circuit boards.

Here we discuss innovative DC copper metallization formulations for hoist lines and VCP (Vertical Continues Plating) applications with high thermal reliability and throughput for high aspect ratio PCB manufacturing...

Publisher: MacDermid Inc.

QPlan - NPI Tools included

Oct 29, 2018 | Alexei Shkolnik from Proventus Technologies

We found that NPI process of SMT is mostly similar and sometimes overlapping to tooling process. In addition, in most cases the programmer is part of the team working on the NPI process. So, QPlan was extended with NPI Tools as a part of tooling process. This allows the team to carry out the NPI process at offline. And at the end of it, they can create corrected SMT program at zero time....

Publisher: Proventus Technologies

Rosin Resins Solution for Soldering Industry

Oct 26, 2018 | Jack Su

A product whitepaper of modified resins for soldering industry....

Publisher: Foreverest Resources Ltd.

Durable Conductive Inks and SMD Attachment for Robust Printed Electronics

Oct 24, 2018 | Leonard Allison

Polymer Thick Film (PTF)-based printed electronics (aka Printed Electronics) has improved in durability over the last few decades and is now a proven alternative to copper circuitry in many applications once thought beyond the capability of PTF circuitry. This paper describes peak performance and areas for future improvement.

State-of-the-art PTF circuitry performance includes the ability to withstand sharp crease tests, 85C/85%RH damp heat 5VDC bias aging (silver migration), auto seat durability cycling, SMT mandrel flexing, and others. The IPC/SGIA subcommittee for Standards Tests development has adopted several ASTM test methods for PTF circuitry and is actively developing needed improvements or additions. These standards are described herein. Advantages of PTF circuitry over copper include: varied conductive material compositions, lower cost and lower environmental impact. Necessary improvements include: robust integration of chip and power, higher conductivity, and fine line multi-layer patterning....

Publisher: Engineered Materials Systems, Inc.

SMT Troubleshooting Guide

Oct 20, 2018 | Cookson Electronics

With this easy-to-use Troubleshooting Guide, you can learn to troubleshoot common SMT issues. After using it a few times, it will become an essential companion for you and anyone in your company responsible for operating an SMT line.

This Guide offers troubleshooting advice for common SMT assembly issues by process defect. If your issue is not resolved after following the steps to help identify the possible root cause and solution, please contact your Cookson Electronics representative who will be able to provide you with further assistance....

Publisher: Cookson Electronics

Analysis of the Design Variables of Thermoforming Process on the Performance of Printed Electronic Traces

Oct 18, 2018 | Gill M., Gruner A., Ghalib N., Sussman M., Avuthu S., Wable G, Richstein J.

One specific market space of interest to emerging printed electronics is In Mold Label (IML) technology. IML is used in many consumer products and white good applications. When combined with electronics, the In Mold Electronics (IME) adds compelling new product functionality. Many of these products have multi-dimensional features and therefore require thermoforming processes in order to prepare the labels before they are in-molded. While thermoforming is not a novel technique for IML, the addition of printed electronic functional traces is not well documented. There is little or no published work on printed circuit performance and design interactions in the thermoforming process that could inform improved IME product designs. A general full factorial Design of Experiments (DOE) was used to analyze the electrical performance of the conductive silver ink trace/polycarbonate substrate system. Variables of interest include trace width, height of draw, and radii of both top and bottom curvatures in the draw area. Thermoforming tooling inserts were fabricated for eight treatment combinations of these variables. Each sample has one control and two formed strips. Electrical measurements were taken of the printed traces on the polymer sheets pre- and post- forming with a custom fixture to evaluate the effect on resistance. The design parameters found to be significant were draw height and bottom radius, with increased draw and smaller bottom curvature radii both contributing to the circuits’ resistance degradation. Over the ranges evaluated, the top curvature radii had no effect on circuit resistance. Interactions were present, demonstrating that circuit and thermoforming design parameters need to be studied as a system. While significant insight impacting product development was captured further work will be executed to evaluate different ink and substrate material sets, process variables, and their role in IME....

Publisher: Jabil Circuit, Inc.

3D Printed Electronics for Printed Circuit Structures

Oct 10, 2018 | Samuel LeBlanc, Paul Deffenbaugh, Jacob Denkins, Kenneth Church

Printed electronics is a familiar term that is taking on more meaning as the technology matures. Flexible electronics is sometimes referred to as a subset of this and the printing approach is one of the enabling factors for roll to roll processes. Printed electronics is improving in performance and has many applications that compete directly with printed circuit boards. The advantage of roll to roll is the speed of manufacturing, the large areas possible, and a reduction in costs. As this technology continues to mature, it is also merging with the high profile 3D printing. (...)

This paper will show working demonstrations of printed circuit structures, the obstacles, and the potential future of 3D printed electronics....

Publisher: nScrypt Inc.

Fill the Void II: An Investigation into Methods of Reducing Voiding

Oct 03, 2018 | Tony Lentz - FCT Assembly, Patty Chonis, JB Byers - A-Tek Systems

Voids in solder joints plague many electronics manufacturers. Do you have voids in your life? We have good news for you, there are many excellent ways to "Fill the Void." This paper is a continuation of previous work on voiding in which the following variables were studied: water soluble lead-free solder pastes, a variety of stencil designs, and reflow profiles. Quad Flat No-Lead (QFN) component thermal pads were used as the test vehicle. The voiding results were summarized and recommendations were made for reduction of voiding....

Publisher: FCT ASSEMBLY, INC.

Assessing the Effectiveness of I/O Stencil Aperture Modifications on BTC Void Reduction

Sep 26, 2018 | Carlos Tafoya, Gustavo Ramirez, Timothy O’Neill

Bottom terminated components, or BTCs, have been rapidly incorporated into PCB designs because of their low cost, small footprint and overall reliability. The combination of leadless terminations with underside ground/thermal pads have presented a multitude of challenges to PCB assemblers, including tilting, poor solder fillet formation, difficult inspection and – most notably – center pad voiding. Voids in large SMT solder joints can be difficult to predict and control due to the variety of input variables that can influence their formation. Solder paste chemistries, PCB final finishes, and reflow profiles and atmospheres have all been scrutinized, and their effects well documented. Additionally, many of the published center pad voiding studies have focused on optimizing center pad footprint and stencil aperture designs. This study focuses on I/O pad stencil modifications rather than center pad modifications. It shows a no-cost, easily implemented I/O design guideline that can be deployed to consistently and repeatedly reduce void formation on BTC-style packages....

Publisher: AIM Solder

Moisture Measurements in PCBs and Impact of Design on Desorption Behaviour

Sep 21, 2018 | Chris Hunt, Owen Thomas, Martin Wickham

Moisture accumulates during storage and industry practice recommends specific levels of baking to avoid delamination. This paper will discuss the use of capacitance measurements to follow the absorption and desorption behaviour of moisture. The PCB design used in this work, focused on the issue of baking out moisture trapped between copper planes. The PCB was designed with different densities of plated through holes and drilled holes in external copper planes, with capacitance sensors located on the inner layers. For trapped volumes between copper planes, the distance between holes proved to be critical in affecting the desorption rate. For fully saturated PCBs, the desorption time at elevated temperatures was observed to be in the order of hundreds of hours. Finite difference diffusion modelling was carried out for moisture desorption behaviour for plated through holes and drilled holes in copper planes. A meshed copper plane was also modelled evaluating its effectiveness for assisting moisture removal and decreasing bake times. Results also showed, that in certain circumstances, regions of the PCB under copper planes initially increase in moisture during baking....

Publisher: National Physical Laboratory

Supply Chain Security: DFARS - Detection & Avoidance of Counterfeit Electronic Parts

Sep 19, 2018 | Robert S. Metzger

Coverage

• The threat of counterfeit electronics
• The statute - Section 818 NDAA FY 2012
• The DFARS – Detection & Avoidance of Counterfeit Electronic Parts – Revised August 2016

Publisher: Rogers Joseph O’Donnell, P.C.

Counterfeit Electronic Components Identification: A Case Study

Sep 12, 2018 | Martin Goetz, Ramesh Varma

Counterfeit electronic components are finding their way into today’s defense electronics. The problem gets even more complex when procuring DMS (diminishing manufacturing source) parts. This paper will provide a brief introduction to counterfeit prevention and detection standards, particularly as they relate to the Aerospace and Defense sector. An analysis of industry information on the types and nature of counterfeit components will be discussed in order to illustrate those most likely to be counterfeited, followed a specific case at a major defense contractor....

Publisher: Northrop Grumman Corporation

Moisture and Bubble-Free Material Preparation in Larger Quantities

Sep 10, 2018 | Scheugenpflug

Issue: Moisture and bubbles in your dispensing material with larger quantities Solution: Scheugenpflug’s 55-gal Barrel Agitator Station Barrel agitators for casting resins take their technology from the paint sector. They fall short of meeting the special demands of the auto, medical, aeronautics and electronics industries. They can’t guarantee a solid seal on the barrels – often containing expensive, moisture sensitive resins – allowing the humidity of the surrounding environment to damage the material. Also, conventional barrel agitators, as opposed to smaller units, cannot work in a vacuum to process materials directly....

Publisher: Scheugenpflug Inc.

Improved Flux Reliability of Lead-Free Solder Alloy Solder Paste Formulated with Rosin and Anti-Crack Resin for Automotive and Other High Reliability Applications

Sep 05, 2018 | Shantanu Joshi, Jasbir Bath, Mitsuyasu Furusawa, Junichi Aoki, Roberto Garcia, Manabu Itoh

In recent years, a growing number of electronic devices are being incorporated into automotive and other high reliability end products where the challenge is to make these devices more reliable. The package size of the devices is largely driven by the consumer industry with their sizes getting smaller making it harder to assemble and be reliable at the same time. For automotive and other high reliability electronics product, it is of the utmost priority to secure high reliability because it directly involves human life and safety. Challenges include selecting an appropriate solder alloy and having good reliability of the solder paste flux....

Publisher: Koki Company LTD

Does Thermal Cycling Impact the Electrical Reliability of a No-Clean Solder Paste Flux Residue

Aug 29, 2018 | Eric Bastow

No-clean solder pastes are widely used in a number of applications that are exposed to wide variations in temperature during the life of the assembled electronics device. Some have observed that cracks can and do form in flux residue and have postulated that this is the result of or exacerbated by temperature cycling. Furthermore, the potential exists for the flux residue to soften or liquefy at elevated temperatures, and even flow if orientated parallel to gravity. In situations such as in automotive electronics, where significant temperature cycling is a reality and high reliability is a must, concern sometimes exists that the cracking and possible softening or liquefying of the residue may have a deleterious effect on the electrical reliability of the flux residue. This paper will attempt to address this concern....

Publisher: Indium Corporation

To dispense material under vacuum or dispense degassed material in atmosphere ….that is the question

Aug 23, 2018 | Scheugenpflug

Simply put, the proper system design and use of vacuum in the potting process can make the difference between a mediocre part and a perfect part. Air entrapment is inevitable whether you utilize syringes, cartridges, pails, or drums of material in the process....

Publisher: Scheugenpflug Inc.

Board-Level Thermal Cycling and Drop-Test Reliability of Large, Ultrathin Glass BGA Packages for Smart Mobile Applications

Aug 22, 2018 | Bhupender Singh, Gary Menezes, Scott McCann, Vidya Jayaram, Urmi Ray, Venky Sundaram, Raj Pulugurtha, Vanessa Smet, Rao Tummala

Glass substrates are emerging as a key alternative to silicon and conventional organic substrates for high-density and high-performance systems due to their outstanding dimensional stability, enabling sub-5-µm lithographic design rules, excellent electrical performance, and unique mechanical properties, key in achieving board-level reliability at body sizes larger than 15 × 15 mm2.

This paper describes the first demonstration of the board-level reliability of such large, ultrathin glass ball grid array (BGA) packages directly mounted onto a system board, considering both their thermal cycling and drop-test performances....

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Demystifying Adhesive Dispensing within the High-End Appliance Industry

Aug 16, 2018 | Scheugenpflug Inc.

Appliance designers are constantly evolving to satisfy the ever changing wants and needs of their consumer base. These changes filter down and include not only the materials but also the equipment used to dispense the material in the manufacturing processes. Moreover, the latest evolution of appliances also seeks to add luxury controls and eye-catching applications. This challenge then, of new applications and material dispensing, often means the application and execution of these increasingly complex materials present multiple challenges up and down the appliance supply chain. Successfully meeting the material dispensing challenge has the potential to spur growth significantly in the higher-end appliance industry as the manufacturing adhesion processes evolve to meet market demand....

Publisher: Scheugenpflug Inc.

Reliable Young's Modulus Value of High Flexible, Treated Rolled Copper Foils Measured by Resonance Method

Aug 15, 2018 | Kazuki Kammuri, Atsushi Miki, Hiroki Takeuchi

Smartphones and tablets require very high flexibility and severe bending performance ability of the flexible printed circuits (FPCs) to fit into their thinner and smaller body designs. In these FPCs, the extraordinary highly flexible, treated rolled-annealed (RA) copper foils have recently used instead of regular RA foil and electro deposited foils. It is very important to measure the Young's moduli of these foils predicting the mechanical properties of FPCs such as capabilities of fatigue endurance, folding, and so on. Even though the manufacturers use IPC TM-650 2.4.18.3 test method for measuring Young's modulus of copper foils over many years, where Young's modulus is calculated from the stress–strain (S–S) curve, it is quite difficult to obtain the accurate Young's modulus of metal foils by this test method....

Publisher: JX Nippon Mining & Metals

New Phosphorus-based Curing Agents for PWB

Aug 08, 2018 | A. Piotrowski, M. Zhang, S. Levchik - ICL-IP, Y. Zilberman, Eran Gluz - IMI

As a result of the continuous industrial trend towards high density packaging there is a growing demand for highly thermally-stable laminate materials. Although the epoxy resin defines the thermal stability, often the flame retardant used becomes the limiting factor in achieving a higher stability. Recognizing this industrial need, the company has developed a new flame-retardant curing agent, Material A. This is a phosphorus-based polymer which cures epoxy via a very specific mechanism. Common Novolac epoxy resins cured with Material A and a phenol-formaldehyde resin show a Tg >180 °C and Td >400 °C. In addition to a high thermal stability, Material A also shows a dielectric loss factor lower than commercial phosphorus-based flame retardants....

Publisher: ICL-IP

Best Practices for Improving the PCB Supply Chain: Performing the Process Audit

Aug 03, 2018 | Greg Caswell, Dr. Craig Hillman

In the electronics industry, the quality and reliability of any product is highly dependent upon the capabilities of the manufacturing suppliers. Manufacturing defects are one of the top reasons why companies fail to meet warranty expectations. These problems can result in severe financial pain and eventual loss of market share. What a surprising number of engineers and managers fail to realize is that focusing on processes addresses only part of the issue. Supplier selection also plays a critical role in the success or failure of the final product....

Publisher: DfR Solutions

Early Design Review of Boundary Scan in Enhancing Testability and Optimization of Test Strategy

Aug 01, 2018 | Sivakumar Vijayakumar

With complexities of PCB design scaling and manufacturing processes adopting to environmentally friendly practices raise challenges in ensuring structural quality of PCBs. This makes it essential to have a good 'Design for Test' (DFT) to ensure a robust structural test. (...)

During the course of the DFT review, can we realize a good test strategy for the PCBA. How can the test strategy of the PCBA be partitioned as to what portions of the design can be covered structurally and what is covered functionally, in a way that provides best diagnostics to discover faults...

Publisher: Keysight Technologies

Expanding IEEE Std 1149.1 Boundary-Scan Architecture Beyond Manufacturing Test of Printed Circuit Board Assembly

Jul 25, 2018 | Jun Balangue

This paper will discuss the expanded use of boundary-scan testing beyond the typical manufacturing test to capture structural defects on a component/devices in a printed circuit board assembly (PCBA). The following topics will be discussed to demonstrate the capability of boundary-scan test system on how we can extend beyond typical manufacturing test: Boundary-scan as a complete manufacturing test system, Boundary-scan implementation during PCBA design stage, Implementation of boundary-scan beyond typical structural testing...

Publisher: Keysight Technologies

Improve SMT Assembly Yields Using Root Cause Analysis in Stencil Design

Jul 18, 2018 | Greg Smith

Reduction of first pass defects in the SMT assembly process minimizes cost, assembly time and improves reliability. These three areas, cost, delivery and reliability determine manufacturing yields and are key in maintaining a successful and profitable assembly process. It is commonly accepted that the solder paste printing process causes the highest percentage of yield challenges in the SMT assembly process. As form factor continues to get smaller, the challenge to obtain 100% yield becomes more difficult.

This paper will identify defects affecting SMT yields in the printing process and discuss their Root Cause. Outer layer copper weight and surface treatment will also be addressed as to their effect on printability. Experiments using leadless and emerging components will be studied and root cause analysis will be presented...

Publisher: FCT ASSEMBLY, INC.

Improving Thermal Cycle and Mechanical Drop Impact Resistance of a Lead-free Tin-Silver-Bismuth-Indium Solder Alloy with Minor Doping of Copper Additive

Jul 11, 2018 | Takehiro Wada, Seiji Tsuchiya, Shantanu Joshi, Roberto Garcia, Kimiaki Mori, Takeshi Shirai

For a demanding automotive electronics assembly, a highly thermal fatigue resistant solder alloy is required, which makes the lead-free Sn-Ag-Cu type solder alloy unusable. Sn-Ag-Bi-In solder alloy is considered as a high reliability solder alloy due to significant improvement in thermal fatigue resistance as compared to a standard Sn-Ag-Cu alloy. The alloy has not only good thermal fatigue properties but it also has superior ductility and tensile strength by appropriate addition of In; however, initial results indicated a sub-par performance in joint reliability when it is soldered on a printed circuit board (PCB) with Electroless Nickel Immersion Gold (ENIG) surface finish. Numerous experiments were performed to find out appropriate alloying element which would help improve the performance on ENIG PCBs. Sn-Ag-Bi-In solder alloys with and without Cu additions were prepared and then tests were carried out to see the performance in a thermal fatigue test and a drop resistance test.to investigate the impact of Cu addition towards the improvement of joint reliability on ENIG finish PCB. Also, the mechanism of such improvement is documented....

Publisher: Koki Company LTD

Inkjet-Printed and Paper-Based Electrochemical Sensors

Jul 03, 2018 | Ryan P. Tortorich, Hamed Shamkhalichenar, Jin-Woo Choi

It is becoming increasingly more important to provide a low-cost point-of-care diagnostic device with the ability to detect and monitor various biological and chemical compounds. Traditional laboratories can be time-consuming and very costly. Through the combination of well-established materials and fabrication methods, it is possible to produce devices that meet the needs of many patients, healthcare and medical professionals, and environmental specialists. Existing research has demonstrated that inkjet-printed and paper-based electrochemical sensors are suitable for this application due to advantages provided by the carefully selected materials and fabrication method. Inkjet printing provides a low cost fabrication method with incredible control over the material deposition process, while paper-based substrates enable pump-free microfluidic devices due to their natural wicking ability. Furthermore, electrochemical sensing is incredibly selective and provides accurate and repeatable quantitative results without expensive measurement equipment. By merging each of these favorable techniques and materials and continuing to innovate, the production of low-cost point-of-care sensors is certainly within reach...

Publisher: Louisiana State University

Flexible Hybrid Circuit Fully Inkjet-Printed: Surface Mount Devices Assembled By Silver Nanoparticles-Based Inkjet Ink

Jun 27, 2018 | J. Arrese, G. Vescio, E. Xuriguera, B. Medina-Rodriguez, A. Cornet, and A. Cirera

Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology.

In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology...

Publisher: Universitat de Barcelona

Design for Testability (DFT) to Overcome Functional Board Test Complexities in Manufacturing Test

Jun 20, 2018 | Louis Y. Ungar

Manufacturers test to ensure that the product is built correctly. Shorts, opens, wrong or incorrectly inserted components, even catastrophically faulty components need to be flagged, found and repaired. When all such faults are removed, however, functional faults may still exist at normal operating speed, or even at lower speeds. Functional board test (FBT) is still required, a process that still relies on test engineers’ understanding of circuit functionality and manually developed test procedures. While functional automatic test equipment (ATE) has been reduced considerably in price, FBT test costs have not been arrested. In fact, FBT is a huge undertaking that can take several weeks or months of test engineering development, unacceptably stretching time to market. The alternative, of selling products that have not undergone comprehensive FBT is equally, if not more, intolerable....

Publisher: A.T.E. Solutions, Inc.

1 Liter of Gap Filler in Only 13 Seconds - New Dispensing Solution for the Thermal Management for HV Batteries

Jun 18, 2018 | Scheugenpflug

Thermal influences can significantly compromise the service life, capacity and especially the operational safety of HV batteries. In order to prevent damage due to excessive temperatures, large quantities of heat-conducting potting media are used here. Scheugenpflug has developed a new system solution for fast and reliable application of these materials....

Publisher: Scheugenpflug Inc.

Unlocking The Mystery of Aperture Architecture for Fine Line Printing

Jun 13, 2018 | Clive Ashmore

The art of screen printing solder paste for the surface mount community has been discussed and presented for several decades. However, the impending introduction of passive Metric 0201 devices has reopened the need to re-evaluate the printing process and the influence of stencil architecture. The impact of introducing apertures with architectural dimensions’ sub 150um whilst accommodating the requirements of the standard suite of surface mount connectors, passives and integrated circuits will require a greater knowledge of the solder paste printing process.

The dilemma of including the next generation of surface mount devices into this new heterogeneous environment will create area ratio challenges that fall below todays 0.5 threshold. Within this paper the issues of printing challenging area ratio and their associated aspect ratio will be investigated. The findings will be considered against the next generation of surface mount devices....

Publisher: ASM Assembly Systems GmbH & Co. KG

Potting Under Vacuum or Atmosphere?

Jun 04, 2018 | Scheugenpflug

Potting under vacuum or atmospheric conditions? This question about the correct procedure concerns many users, among others i.e. electronics manufacturers, who pot more and more complex parts and components for a huge variety of products. Against the actual requirements of product and process, a decision on the procedure is often made under the assumption: „Potting under atmosphere = affordable and easy“and „Potting under vacuum = expensive and difficult“. But that’s a thing of the past. The way to the correct method, however, requires the clarification of a number of factors....

Publisher: Scheugenpflug Inc.

Green Supply Chain Management, Economic Growth and Environment: A GMM Based Evidence

May 30, 2018 | Syed Abdul Rehman Khan, Yu Zhang, Muhammad Anees, Heris Golpîra, Arij Lahmar, Dong Qianli

The aim of this research is to examine the relationship between green logistics operations and energy demand, economic growth and environmental sustainability need to make factors for relationship clearer in a panel data of 43 different countries around the globe. The study employed panel Generalized Method of Moments (GMM) estimates for robust inferences. The results have revealed that logistics operations consume energy and fossil fuel, while the amount of fossil fuel and non-green energy sources create significant harmful effect on the environmental sustainability and also have negative effect on economic growth. In addition, poor transport-related infrastructure and logistics service are a major contributor of CO2 and total greenhouse gas emissions. However, carbon emission damages fauna and flora, and reduces economic growth. The findings suggest that renewable energy sources and green practices can mitigate harmful effect of logistics operations on environmental sustainability and spur economic activities with greatly export opportunities in a region....

Publisher: Changan University

Wettable-Flanks: Enabler for the Use of Bottom-Termination Components in Mass Production of High-Reliability Electronic Control Units

May 23, 2018 | Udo Welzel, Marco Braun, Stefan Scheller, Sven Issing, Harald Feufel

Driven by miniaturization, cost reduction and tighter requirements for electrical and thermal performance, the use of lead-frame based bottom-termination components (LF-BTC) as small-outline no-leads (SON), quad-flat no leads (QFN) packages etc., is increasing. However, a major distractor for the use of such packages in high-reliability applications has been the lack of a visible solder (toe) fillet on the edge surface of the pins: because the post-package assembly singulation process typically leaves bare copper leadframe at the singulation edge, which is not protected against oxidation and thus does not easily solder-wet, a solder fillet (toe fillet) does not generally develop....

Publisher: Robert Bosch LLC Automotive Electronics Division

Statistical Aspect on the Measuring of Intermetallic Compound Thickness of Lead Free Solders

May 17, 2018 | Azman Jalar, Maria Abu Bakar, Roslina Ismail, Abdul Razak Daud

Intermetallic compound (IMC) growth is being studied in earnest in this past decade because of its significant effect the solder joint reliability. It appears that from numerous investigations conducted, excessive growth of IMC could lead to solder joint failure. Leading to this, many attempts has been made to determine the actual IMC thickness. However, precise and true representation of the growth in the actual 3D phenomenon from 2D cross-section investigations has remained unclear.

This paper will focus on the measuring the IMC thickness using 3D surface profilometer (Alicona Focus G4). Lead free solder, Sn3.0Ag0.5Cu (SAC305) was soldered onto copper printed circuit board (Cu PCB). The samples were then subjected to thermal cycle (TC) storage process with temperature range from 0 °C to 100 °C for 200 cycles and up to 1000 cycles were completed....

Publisher: Universiti Kebangsaan Malaysia

Relative Humidity Dependence of Creep Corrosion on Organic-Acid Flux Soldered Printed Circuit Boards

May 09, 2018 | Haley Fu - iNEMI, Prabjit Singh - IBM Corporation, Dem Lee, Jeffrey Lee - iST-Integrated Service Technology, KarlosGuo, Julie Liu - Lenovo, Simon Lee, Geoffrey Tong - The Dow Chemical Company, Chen Xu - Nokia

Creep corrosion on printed circuit boards (PCBs) is the corrosion of copper metallization and the spreading of the copper corrosion products across the PCB surfaces to the extent that they may electrically short circuit neighboring features on the PCB. The iNEMI technical subcommittee on creep corrosion has developed a flowers-of-sulfur (FOS) based test that is sufficiently well developed for consideration as an industry standard qualification test for creep corrosion. This paper will address the important question of how relative humidity affects creep corrosion. A creep corrosion tendency that is inversely proportional to relative humidity may allow data center administrators to eliminate creep corrosion simply by controlling the relative humidity in the data center,thus, avoiding the high cost of gas-phase filtration of gaseous contamination. The creep corrosion relative humidity dependence will be studied using a modified version of the iNEMI FOS test chamber. The design modification allows the achievement of relative humidity as low as 15% in the presence of the chlorine-releasing bleach aqueous solution. The paper will report on the dependence of creep corrosion on humidity in the 15 to 80% relative humidity range by testing ENIG (gold on electroless nickel), ImAg (immersion silver) and OSP (organic surface preservative) finished PCBs, soldered with organic acid flux....

Publisher: iNEMI (International Electronics Manufacturing Initiative)

Autonomous Maintenance (AM) increases efficiency and productivity

May 05, 2018 | Don Fitchett

With the growing demand for manufacturing facilities, authorities took many actions to escalate the efficiency of production processes. Many formal methods were implemented for a longer period of time without acquiring significant growth in the field. But with the introduction of Autonomous Maintenance (AM) to the modern manufacturing facilities they achieved an increment in efficiency and productivity in a historical brisk pace. This article is about AM Step Zero too....

Publisher: Business Industrial Network

Understanding the Heat Output of your BGA Rework Station

Apr 27, 2018 | Dennis O'Donnell

When performing BGA component rework, it is important to know the actual heat that is coming out of the top and bottom heaters. This will be critical in setting up accurate heat profiles. Monitoring your heat output will also keep you aware of your heaters performance so that you will know when the heaters need to be replaced....

Publisher: Precision PCB Services, Inc

Hot Air vs. IR BGA Rework Stations

Apr 27, 2018 | Dennis O'Donnell

Hot Air and IR are the two main types of rework stations used by OEMs and PCB contract manufacturers today. Both have advantages and disadvantages and choosing the right one for your application requires a careful consideration of a number of factors, including your budget, your working requirements and the capabilities of your staff. In this article, we outline some of the differences between hot air and IR BGA rework stations....

Publisher: Precision PCB Services, Inc

Modeling And Optimizing Wire Harness Costs For Variation Complexity

Apr 25, 2018 | Sjon Moore

An automotive wire harness rarely has just a single part number that can be ordered and installed in a vehicle. Typically, there are many different versions of the same harness based on the orderable content in the vehicle. These versions (often called harness levels) will have unique part numbers. The quantity of these levels and their content is what is typically called complexity and it has a significant impact on the cost of the harness.

Quantifying these costs is often very difficult especially with manual methods of deriving and costing the complexity solution. Therefore, traditionally, harness costing has focused on the piece cost of each harness level. When these complexity related costs are considered it is typically with overly simplified cost modeling techniques.

This paper will focus on the quantification of these complexity related costs so that they can be modeled allowing automated algorithms to optimize for these costs. A number of real world examples will be provided as well. Since no two businesses are alike, it is the aim of this paper to provide the foundational knowledge and methodology so the reader can assess their own business to model how variation complexity costs affect their business....

Publisher: Mentor Graphics

Semi-Additive Process for Low Loss Build-Up Material in High Frequency Signal Transmission Substrates

Apr 18, 2018 | Fei Peng, Naomi Ando, Roger Bernards, Bill Decesare

Higher functionality, higher performance and higher reliability with smaller real estate are the mantras of any electronic device and the future guarantees more of the same. In order to achieve the requirements of these devices, designs must incorporate fine line and via pitch while maintain good circuitry adhesion at a smooth plating-resin interface to improve signal integrity. The Semi-Additive Process (SAP) is a production-proven method used on low dielectric loss tangent (Df) build-up materials that enables the manufacture of ultra-fine circuitry. (...)

This paper will discuss a new SAP process for low loss build-up materials with low desmear roughness (Ra= 40-100 nm) and excellent adhesion (610-680 gf/cm) at various processing conditions. Along with the process flow, the current work will also present results and a discussion regarding characterization on the morphology and composition of resin and/or metal plating surfaces using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), surface roughness analysis, plating-resin adhesion evaluation from 90o peel tests...

Publisher: MacDermid Inc.

Understanding Circuit Material Performance Concerns for PCBs at Millimeter-Wave Frequencies

Apr 11, 2018 | John Coonrod

Millimeter-wave (mmWave) frequency applications are becoming more common. There are applications utilizing PCB technology at 60 GHz, 77 GHz and many other mmWave frequencies. When designing a PCB for mmWave frequency, the properties of the circuit materials need to be considered since they can be critical to the success of the application. Understanding the properties of circuit materials at these frequencies is very important.

This paper will give an overview of which circuit material properties are important to mmWave frequency applications using PCBs. There will be data supplied which demonstrates why these properties are essential to the circuit material selection for mmWave applications. Some properties discussed will be dielectric constant (Dk) control, dissipation factor, moisture absorption, thickness control and TCDk (Temperature Coefficient of Dk). Measured comparisons will be shown for insertion loss and Dk versus frequency for different types of circuit materials up to 110 GHz. As part of the test data, the impact on circuit performance due to TCDk and moisture absorption will be shown at mmWave frequencies....

Publisher: Rogers Corporation, Advanced Circuit Materials Division

High Reliability and High Throughput Ball Bumping Process Solution – Solder Joint Encapsulant Adhesives

Apr 05, 2018 | Dr. Mary Liu and Dr. Wusheng Yin

The miniaturization of microchips is always driving force for revolution and innovation in the electronic industry. When the pitch of bumps is getting smaller and smaller the ball size has to be gradually reduced. However, the reliability of smaller ball size is getting weaker and weaker, so some traditional methods such as capillary underfilling, corner bonding and edge bonding process have been being implemented in board level assembly process to enhance drop and thermal cycling performance. These traditional processes have been increasingly considered to be bottleneck for further miniaturization because the completion of these processes demands more space. So the interest of eliminating these processes has been increased. To meet this demand, YINCAE has developed solder joint encapsulant adhesives for ball bumping applications to enhance solder joint strength resulting in improving drop and thermal cycling performance to eliminate underfilling, edge bonding or corner bonding process in the board level assembly process. In this paper we will discuss the ball bumping process, the reliability such as strength of solder joints, drop test performance and thermal cycling performance. ...

Publisher: YINCAE Advanced Materials, LLC.

Screen Making for Printed Electronics- Specification and Tolerancing

Mar 28, 2018 | Jesse Greenwood

Six decades of legacy experience makes the specification and production of screens and masks to produce repeatable precision results mostly an exercise in matching engineering needs with known ink and substrate performance to specify screen and stencil characteristics. New types of functional and electronic devices, flex circuits and medical sensors, industrial printing, ever finer circuit pitch, downstream additive manufacturing processes coupled with new substrates and inks that are not optimized for the rheological, mechanical and chemical characteristics for the screen printing process are becoming a customer driven norm. Many of these materials do not work within legacy screen making, curing or press set-up parameters. Many new materials and end uses require new screen specifications.

This case study presents a DOE based method to pre-test new materials to categorize ink and substrate rheology, compatibility and printed feature requirement to allow more accurate screen recipes and on-press setting expectations before the project enters the production environment where time and materials are most costly and on-press adjustment methods may be constrained by locked, documented or regulatory processes, equipment limitations and employee experience....

Publisher: Hazardous Print Consulting Inc

Using Lean Six Sigma to Optimize Critical Inputs on Solder Paste Printing

Mar 21, 2018 | Tom Watson

Solder paste printing is the first step in the surface mount manufacturing process for PCBA assembly. When the solder paste printing process is uncontrolled, defects can be produced, which may not become apparent until the PCBA is downstream. (...)

This paper will discuss how Lean Six Sigma techniques were used to optimize the solder paste printing process. It will highlight how a cross-functional team used the structured Define, Measure, Analyze, Improve and Control (DMAIC) methodology to identify and control the critical inputs. The advantage of the Lean Six Sigma methodology is that it guides the team through the rigorous structured process so that all possible inputs are considered and the critical ones can be identified....

Publisher: Kimball Electronics, Inc.

SMT Stencil, Surface Performance Returning to Basics in the SMT Screen Printing Process to Significantly Improve the Paste Deposition

Mar 15, 2018 | JimVillalvazo

The SMT assembly process is continuously challenged by the factors which enhance circuit board performance and limit productivity. The pick and place and reflow systems reflect these driven issues by adding more and more controls to their systems, but the fact is one of the age old processes continues to operate within the same rules since the dawn of the SMT assembly world: The SMT screen printing. (...)

This paper showcases a new stencil process that was discovered by reverting to the basics:understanding the reason for each stencil material process, focusing on detailed finishes and a disciplined aperture design process, maintaining original designs, and making the correctly designed apertures to control the paste deposition. The test results drove us to focus the efforts on the aperture walls In this paper we will demonstrate with lab tests SMT process results howthe improved paste release results in improved SMT print process performance and its positive impact on SPI yields and EOL performance....

Publisher: InterLatin

PCB Assembly With Obsolete Parts and Hard-To-Find Components

Mar 13, 2018 | Tuan Tran

Many companies take their supply chain for granted until they need an obsolete part or a hard-to-find component. Then the importance of having resourceful contract manufacturing partners becomes an incredibly valuable asset....

Publisher: Power Design Services

Optimization of Stencil Apertures to Compensate for Scooping During Printing

Mar 07, 2018 | Gabriel Briceno, Ph. D., Miguel Sepulveda

This study investigates the scooping effect during solder paste printing as a function of aperture width, aperture length and squeegee pressure. The percent of the theoretical volume deposited depends on the PWB topography. A typical bimodal percent volume distribution is attributed to poor release apertures and large apertures, where scooping takes place, yielding percent volumes <100%, while SMD apertures and apertures near PWB features that raise the stencil yield percent volumes >100%. This printing experiment is done with a concomitant validation of the printing process using standard 3D Solder Paste Inspection (SPI) equipment....

Publisher: Qual-Pro Corporation

Design and Process Development for the Assembly of 01005 Passive Components

Mar 05, 2018 | J. Li, S. Poranki, K. Srihari - Watson Institute for Systems Excellence, R. Gallardo, M. Abtew, R. Kinyanjui - Sanmina-SCI Corporation

Growing demands for smaller electronic assemblies has resulted in reduced sizes of passive components, requiring the introduction of newer components, such as the 01005 devices. Component miniaturization presents significant challenges to the traditional surface mount assembly process. A successful assembly solution for these 01005 devices should be repeatable and reproducible, and should include guidelines for (i) the selection of solder paste and (ii) appropriate stencil and substrate pad design, and should ensure strict process control standards....

Publisher: Sanmina-SCI

Stencil Design for Lead-Free SMT Assembly

Mar 05, 2018 | Chrys Shea

In order to comply with RoHS and WEEE directives, many circuit assemblers are transitioning some or all of their soldering processes from tin-lead to lead-free within the upcoming year. There are no drop-in replacement alloys for tin-lead solder, which is driving a fundamental technology change. This change is forcing manufacturers to take a closer look at everything associated with the assembly process: board and component materials, logistics and materials management, solder alloys and processing chemistries, and even soldering methods.

Do not expect a dramatic change in soldering behavior when moving to lead-free solders. The melting points of the alloys are higher, but at molten temperatures the different alloys show similar behaviors in a number of respects. Expect subtler changes, especially near the edges of a process window that is assumed based on tin-lead experience rather than defined through lead-free experimentation. These small changes, many of them yet to be identified and understood, will manifest themselves with lower assembly yields. The key to keeping yields up during the transition to lead-free is quickly learning what and where the subtle distinctions are, and tuning the process to accommodate them....

Publisher: Cookson Electronics