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Monday, 04 May 2009 13:30

Technical AbstractsPrinting

“Next-Level Requirements For Ultra Fine-Pitch Printing”
Authors: Richard Brooks, John Carr and Marty Carr; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: New assembly technologies are being considered for production to reduce size and/or increase functionality. These new technologies include 0201 and 01005 chip components and 0.4 and 0.3 mm pitch CSP devices. To implement these new technologies, major changes in the manufacturing process may have to be addressed. First, the solder paste must provide the ability to print very small apertures, such as 0.008" (0.2 mm) and below, and with consistent paste release from the stencil.
Therefore, one of the possible solutions may be to change the standard solder powder size, which is Type 3 powder. Also, printing very small aperture openings means considering changes in stencil technology. Some of those changes are the stencil type (laser versus electroformed) and the stencil thickness. Additionally, because we are attempting to print very small apertures, the printing process must be in control and characterized. This paper reviews new technology requirements and how they affect solder paste and stencil performance in the manufacturing and printing processes. (SMTA Pan Pac Symposium, February 2009)

Reliability

“Planning and Implementing a Successful Box-Build: A Process FMEA Implementation”
Authors: Haans Petruschke and Roy Starks; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: The main subject of this paper is the Process Failure Mode Effect Analysis (PFMEA), and how this methodology was used to identify risk, priority rank potential problems, and create actions to minimize or eliminate risk, resulting in a highly reliable and successful box-build assembly process. PFMEA is the methodology for analyzing potential reliability problems early in the manufacturing and assembly cycle, when it is easier to take actions to overcome these issues, thereby enhancing reliability. This paper includes a description of the product, assembly challenges, initial process, resulting process and benefits. (SMTA Pan Pac Symposium, February 2009)

“Studies On Solder Electromigration in Lead-Free Flip Chip Joint System”
Authors: Kimihiro Yamanaka, Takafumi Ooyoshi, Takayuki Nejime and Yutaka Tsukada; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Electromigration phenomena in SnAg3.0CuIn0.5 solders in flip chip joint systems were investigated. Electromigration life was longer when underfill was used, and significant solder joint deformation toward the cathode occurred when underfill was not. An underfill stress was introduced as an additional factor to a conventional back stress in order to explain the phenomena. It was an internal stress induced by the underfill and relieved by solder deformation. Thus, a greater Young’s modulus of the underfill created a greater underfill stress, resulting in longer electromigration life. However, the underfill loses effectiveness on the electromigration life under high current density. In addition, a unique method employing a resistance change in the junction line between the two solder joints was introduced to determine the solder joint temperature. The method successfully measured the temperature increase caused by electromigration void growth. (SMTA Pan Pac Symposium, February 2009)

Wave Soldering

“Heavy Thermal Load Pb-Free Wave Soldering – Getting Top Hole Fillets with +3 Oz. Copper Planes”
Authors: Corey Peterson and Jeff Kennedy; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: High copper weight boards with internal ground plane structures act like heatsinks. This usually has a detrimental effect on hole fill. While much work and experimentation has investigated many parameters of the wave soldering process, one item seems missing: a thorough review and understanding of fluxer operation, fluxer setup methodology and performance capability analysis. The ability to fill flux to the top of the PTH barrel with the component lead in the hole could be the single most important contributor to hole fill. Results of this work show how improvements in understanding and setup of wave solder, fluxing and wave configuration can help meet IPC-A-610 Class 3 hole fill requirements for heavy thermal loaded products. The evaluations took place on several different wave machine configurations and final results meeting the product requirements have been achieved – up to 100% fill for 0.125"-thick boards with 26 oz. of copper (4 to 5 oz. innerlayer, 2 to 3 oz. outerlayers) at process speeds exceeding 2.5'/min. (SMTA Pan Pac Symposium, February 2009)

 

Columns

Eastern-US: China’s New Competitor?

Parity emerges among EMS Factories from Asia, Mexico and the US.

For the first time in years we see parity in the Eastern US among EMS factories from Asia, Mexico and the US. This EMS market condition will permit American OEMs (the EMS industry refers to OEMs as customers) to have more EMS pathways to choose from. Now more than ever, such EMS assignments will require deeper investigation relating to the OEMs’ evaluation of manufacturing strategies.

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The Human Touch

For those who count on the electronics industry for big feats, it’s been a remarkable couple of years.

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Features

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Circuits Disassembly: Materials Characterization and Failure Analysis

A systematic approach to nonconventional methods of encapsulant removal.

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