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Written by Mike Buetow   
Wednesday, 02 February 2011 15:37

Component Solderability

“An Investigation into the Development of Lead-Free Solder Paste for Package-on-Package (PoP) Component Manufacturing Applications”
Authors: Jasbir Bath, et al; This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Abstract: In the conventional PoP manufacturing process, solder bumps of the top package are immersed into a layer of tacky flux. Once the flux immersion is completed, the top package is placed onto the bottom package and soldered together. One of the challenges of PoP manufacturing is component warpage during the reflow process, which led to the incomplete merger of the solder bump from the top package with the solder land on the bottom package. Once the solder bumps of the top PoP component separate from the land of the bottom component, even if they come into contact again, the tacky flux activity is reduced, leading to incomplete merger.

The work focused on the development of solder paste rather than tacky flux for PoP manufacturing to reduce the incomplete merger occurring during soldering. The solder paste would have the benefit of reducing the gap between the land and solder bumps caused by component warpage, and would hold the two together more when molten to prevent incomplete merger. Tests were conducted on Pb-free PoP solder pastes with adjustments in the flux thixotropic agents, activators and solvents, in addition to the actual flux content used in the solder paste. The results of the investigations are presented. (SMTA International, October 2010)

Nano Materials

“Highly Flexible Silver Nanowire Electrodes for Shape-Memory Polymer Light-Emitting Diodes”
Authors: Zhibin Yu, et al;  This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Indium-doped tin oxide (ITO) is used for electrodes in LCD displays, solar cells, iPad and smartphone touch screens, and organic light-emitting diode (OLED) displays for televisions and computer monitors. But ITO can be fragile and toxic, and is becoming more expensive to produce. A new transparent electrode based on silver nanowires (AgNW) could replace ITO. The new electrode uses low-cost, non-toxic and stable materials and is easy to fabricate. It is produced on a cross-linked, transparent polyacylate substrate, which is cheaper than glass and can be stiff and rigid or flexible and stretchable. The resulting AgNW/polymer electrodes have high transparency, low sheet resistance comparable to ITO, and low surface roughness. They are substantially more compliant than ITO and would be suitable for the fabrication of high-performance and stretchable OLEDs and solar cells. The shape-memory property of the polymer substrate could lead to electronic devices that can be deformed to various stable shapes. The deformation is reversible, causes minimal damage to the devices, and can be repeated for many cycles. (Advanced Materials, Dec. 6, 2010)

Printed Electronics

“Printed Electronics for Flexible Solid State Lighting”
Author: Marc Chason; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Printed electronics technologies are being introduced as competitors to crystalline semiconductor technologies in several applications, including logic circuits, photovoltaic cells and light-emitting diodes. Near-term, solid state lighting products based on LED technologies are entering the general illumination market. These SSL products use conventional SMT processes in a four-level assembly hierarchy to fabricate light engines for incorporation into luminaires. In parallel with LED device development, printed electronics technologies are also moving forward using ink-based systems to fabricate organic-LEDs (OLED). However, the OLED assembly hierarchy used to fabricate light-emitting structures is significantly different from that for LED-based devices. LED and printed OLED assembly technologies are compared, including printing technologies and ink systems for OLED structures and OLED fabrication and assembly issues. (SMTA International, October 2010)

Product Management

“Overcoming Complex Manufacturing Issues with RF MMIC Products: A Case Study”
Authors: Steve Greathouse, et al; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Any high-speed, high-performance RF communications product will need a lot of engineering and expertise involved from inception through full production and field support. This paper reviews the startup to production ramp to volume of a highly complex RF product, where the authors found that with every process and component, a new issue or problem will likely come up that has not been previously encountered. A proactive approach to reviewing the design, processes and material properties of a product before it goes into production will pay itself back many times over in eliminating or reducing many of the issues encountered in production. Time spent doing material characterization will eliminate the need to replicate or change materials or processes after the product is in qualification or production. Having access to advanced failure analysis tools and skilled professionals who know how to obtain the results desired aids a new development program immeasurably. These resources will be utilized extensively for understanding the process issues and resolving problems. The paper describes areas to watch and how to apply adequate safeguards. (SMTA International, October 2010)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.

Last Updated on Wednesday, 02 February 2011 17:23
 

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