Electronics Manufacturing Technical Articles

Understanding the Effect of Process Changes and Flux Chemistry on Mid-Chip Solder Balling

Nov 30, 2016 | Katherine Wilkerson, Ian J. Wilding, Michael Carter, Daniel Buckland

Mid-chip solder balling is a defect typically associated with solder paste exhibiting poor hot slump and/or insufficient wetting during the reflow soldering process, resulting in paste flowing under the component or onto the solder resist. Once molten, this solder is compressed and forced to the side of the component, causing mid-chip solder balling.

This paper documents the experimental work performed to further understand the impact on mid-chip solder balling from both the manufacturing process and the flux chemistry....

Publisher: Henkel Electronic Materials

Review of Interconnect Stress Testing Protocols and Their Effectiveness in Screening Microvias

Nov 30, 2016 | Edward Arthur; Raytheon Company, Charles Busa, Wade Goldman P.E., Alisa Grubbs; The Charles Stark Draper Laboratory, Inc.

The use of microvias in Printed Circuit Boards (PCBs) for military hardware is increasing as technology drives us toward smaller pitches and denser circuitry. Along with the changes in technology, the industry has changed and captive manufacturing lines are few and far between. As PCBs get more complicated, the testing we perform to verify the material was manufactured to our requirements before they are used in an assembly needs to be reviewed to ensure that it is sufficient for the technology and meets industry needs to better screen for long-term reliability. The Interconnect Stress Testing (IST) protocol currently used to identify manufacturing issues in plated through holes, blind, or buried vias are not necessarily sufficient to identify problems with microvias. There is a need to review the current IST protocol to determine if it is adequate for finding bad microvias or if there is a more reliable test that will screen out manufacturing inconsistencies.

The objective of this research is to analyze a large population of PCB IST coupons to determine if there is a more effective IST test to find less reliable microvias in electrically passing PCB product and to screen for manufacturing deficiencies. The proposed IST test procedure will be supported with visual inspection of corresponding microvia cross sections and Printed Wiring Assembly (PWA) acceptance test results. The proposed screening will be shown to only slightly affect PCB yield while showing a large benefit to screening before PCBs are used in an assembly....

Publisher: Raytheon

Miniaturizing IoT Designs

Nov 23, 2016 | Tom Nordman, Pasi Rahikkala

As we wirelessly connect more and more devices to the Internet, electronics engineers face several challenges, including how to package a radio transmitter into their existing device real estate and how to make increasingly smaller devices. They’re also striving to meet consumer demand for Internet of Things (IoT) products that are ergonomically easy to use and unobtrusive to the environment.

This whitepaper explores the challenges that come with designing connected devices into increasingly smaller products, specifically antenna integration, and how system-inpackage modules can help....

Publisher: Silicon Labs

How Mitigation Techniques Affect Reliability Results for BGAs

Nov 17, 2016 | Greg Caswell, Melissa Keener

Since 2006 RoHS requirements have required lead free solders to take the place of tin-lead solders in electronics. The problem is that in some environments the lead free solders are less reliable than the older tin-lead solders. One of the ways to solve this problem is to corner stake, edge bond or underfill the components. When considering what mitigation technique and material to use, the operating conditions must be characterized. The temperature range is important when selecting a material to use since the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are important properties. If improperly chosen, the mitigation material can cause more failures than an unmitigated component....

Publisher: DfR Solutions (acquired by ANSYS Inc)

A High Thermal Conductive Solderable Adhesive

Nov 17, 2016 | Dr. Mary Liu and Dr Wusheng Yin

With increasing LED development and production, thermal issues are becoming more and more important for LED devices, particularly true for high power LED and also for other high power devices. In order to dissipate the heat from the device efficiently, Au80Sn20 alloy is being used in the industry now. However there are a few drawbacks for Au80Sn20 process: (1) higher soldering temperature, usually higher than 320°C; (2) low process yield; (3) too expensive. In order to overcome the shortcomings of Au80Sn20 process, YINCAE Advanced Materials, LLC has invented a new solderable adhesive – TM 230. Solderable adhesives are epoxy based silver adhesives. During the die attach reflow process, the solder material on silver can solder silver together, and die with pad together. After soldering, epoxy can encapsulate the soldered interface, so that the thermal conductivity can be as high as 58 W/mk. In comparison to Au80Sn20 reflow process, the solderable adhesive has the following advantages: (1) low process temperature – reflow peak temperature of 230°C; (2) high process yield – mass reflow process instead of thermal compression bonding process; (3) low cost ownership. In this paper we are going to present the die attach process of solderable adhesive and the reliability test. After 1000 h lighting of LED, it has been found that there is almost no decay in the light intensity by using solderable adhesive – TM 230. ...

Publisher: YINCAE Advanced Materials, LLC.

Corrosion Resistant Servers for Free-Air Cooling Data Centers

Nov 10, 2016 | Qiujiang Liu; Baidu, Inc., Prabjit Singh; IBM

The demand for compute capability is growing rapidly fueling the ever rising consumption of power by data centers the worldwide. This growth in power consumption presents a challenge to data center total cost of ownership. Free-air cooling is one of the industrial trends in reducing power consumption, the power usage effectiveness (PUE) ratio, and the total cost of ownership (TCO). Free-air cooling is a viable approach in many parts of the world where the air is reasonably clean. In Eastern China, the poor quality of air, high in particle and gaseous contamination, is a major obstacle to free-air cooling. Servers exposed to outside air blowing in to data centers will corrode and fail at high rate. The poor reliability of hardware increase TCO dramatically.

This paper describes a corrosion resistant server design suitable for reliable operation in a free-air cooling data center located in Eastern China where the indoor air quality can be as poor as ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) severity level G3. An accelerated corrosion test method of verifying hardware reliability in the ASHRAE severity level G3 environment is also described....

Publisher: IBM Corporation

The Impact of LV 214-4 – The German Automotive OEM Connector Test Specification

Nov 10, 2016 | Rob Boyd, Senior Product Manager, Schleuniger, Inc.

It goes without saying that every manufacturer wants to ensure they are producing a quality product. Standards and specifications from various organizations provide a guideline from which manufacturers can measure different areas of quality, while also providing the end user with the reassurance that they are purchasing a trustworthy, long-lasting product. Within the wire processing industry there are many standards that manufacturers may choose or be required to adhere to. These standards and specifications are constantly evolving and increasing in detail, especially as monitoring technology improves. ...

Publisher: Schleuniger, Inc.

Is coating adhesion a problem?

Nov 09, 2016 | Dave Selestak, Alex Berlin, and Carla Loeffler

Nordson MARCH found a solution for a manufacturer of PCBAs used in ruggedized environments. Read how plasma prior to conformal coating reduced defects and virtually eliminated coating-related failures....

Publisher: MARCH Products | Nordson Electronics Solutions

How can you tell the differences between revisions of the same board?

Nov 08, 2016 | Simon Garrison

Over time most PCB designs need to change – a mistake is found, or a part becomes obsolete, etc. Typically once the changes are complete, a new set of manufacturing files (Gerbers, NC Drill files, BOM, Pick and Place, etc) are generated, and the updated design is stored as separate version within a version control system. Using a version control system makes it possible for design teams to go back later and compare differences between design versions. ****** http://www.numericalinnovations.com/blogs/news/gerber-comparisons-between-revisions-of-the-same-board *****...

Publisher: Numerical Innovations

A Novel Method for the Fabrication of a High-Density Carbon Nanotube Microelectrode Array

Nov 03, 2016 | Adam Khalifa, Zhaoli Gao, Amine Bermak, Yi Wang, Leanne Lai Hang Chan

We present a novel method for fabricating a high-density carbon nanotube microelectrode array (MEA) chip. Vertically aligned carbon nanotubes (VACNTs) were synthesized by microwave plasma-enhanced chemical vapor deposition and thermal chemical vapor deposition. The device was characterized using electrochemical experiments such as cyclic voltammetry, impedance spectroscopy and potential transient measurements. Through-silicon vias (TSVs) were fabricated and partially filled with polycrystalline silicon to allow electrical connection from the high-density electrodes to a stimulator microchip.

In response to the demand for higher resolution implants, we have developed a unique process to obtain a high-density electrode array by making the microelectrodes smaller in size and designing new ways of routing the electrodes to current sources....

Publisher: Hong Kong University of Science