“Fine Pitch Reliability Comparisons between Components Assembled on Motherboards with Filled and Unfilled Microvia-in-Pad”
Abstract: Fine-pitch surface-mount WLCSP and CSP devices often require printed circuit boards containing microvia-in-pad for complete route-out. Often the microvias are left open, or “unfilled.” The resulting solder voiding and routing design can presumably alter the reliability of the assembly when compared to a plated shut, or “filled” via. This study was designed to compare the reliability of fine-pitch (i.e., 0.5mm and below) components assembled on filled and unfilled microvia-in-pads using thermal cycling and drop testing. (SMTA International, October 2013)
“Trends and Considerations in Automotive Electronic Packaging”
Abstract: Semiconductor growth is accelerating with a rapid transition from mechanical to electronic systems. An important part of winning automotive business is in having package platforms that pass demanding automotive requirements. Automotive manufacturers strive for a “zero defect” policy on all components found in a car. A package may look like a standard product, but it may actually utilize special materials, processes or construction. Includes a list of the discussion points that make automotive packaging different. (Meptec Report, vol. 17, no. 3, Fall 2013)
“Additive Manufacturing Technologies for a Direct Integration of Microelectronic Components and Contact Structures”
Authors: David Ifland, Frank Ansorge, Christian Baar and Klaus-Dieter Lang.
Abstract: System-in-package (SiP) modules were manufactured using an additive manufacturing process. In this case, electrical components are integrated in the manufacturing process of the support substrate. An electrically conductive adhesive was then applied. This feasibility study demonstrates a novel three-dimensional construction and connection technology for microsystems.
(Leuze Verlag, August 2013; http://leuze-verlag.de/en/fachzeitschriften/galvanotechnik/aktuelles-heft/mikrosystemtechnik)
“Process and Material Envelope for Allowable Package-on-Package Warpage”
Abstract: Package-on-package (PoP) assemblies may experience warpage during package fabrication and later during surface mount assembly. Excessive warpage may result in loss-of-coplanarity, open connections, misshaped joints, and reduction in package board-level reliability (BLR) under environmental stresses of thermal cycling, shock and vibration. Previous researchers have shown that warpage may be influenced by a number of design and process factors, including underfill properties, mold properties, package geometry, package architecture, board configuration, underfill and mold dispense and cure parameters, and package location in the molding panel. A comprehensive inverse model incorporating a full set of design and process parameters and their effect on PoP package and PoP assembly warpage is presently beyond the state of art. In this paper, data have been gathered on multiple package-on-package assemblies under a variety of assembly parameters. The packages have been speckle-coated. The warpage of the PoP assemblies has been measured using a glass-top reflow oven using multiple cameras. Warpage measurements have been taken at various temperatures of the reflow profile between room temperature and the peak reflow temperature. Finite
element models have been created, and the package-on-package warpage predictions have been correlated with the experimental data. The experimental data-set has been augmented with the simulation data to evaluate configurations and parameter-variations that were not available in the experimental dataset. Statistical models have been developed to capture the effect of single and multiple parameter variations using principal components regression and ridge regression. Best subset variables obtained from stepwise methods have been used for model development. The developed models have been validated with experimental data using a single factor design of experiment study and are found to accurately capture material and geometry effects on part warpage. The results show that the proposed approach has the potential of predicting both single and coupled factor effects on warpage. (SMTA International, October 2013)
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.