Electronics Manufacturing Technical Articles

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.