Embedded Components

“Integration of Electronic Components in PCB for Electromobility Application”

Authors: Thomas Hofmann, Stefan Gottschling, Richard Randoll and Wolfgang Wondrak; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: This work presents new concepts for control units and power modules with innovative materials, packaging technologies and cooling concepts. For high-power applications in electric cars with high-power densities, there is a volume increase in conductor structures, chips and wirebonds with an increasing amount of heat generation during driving operation. New thermal management concepts are needed to dissipate the heat. One possible solution is the embedding of different electrical components from the surface of the substrates into special PCBs optimized for high electrical and thermal conductivity. Several PCB embedding technologies exist now and have to show their potential. The presentation shows concepts for embedding fine-pitch components for logic applications and the integration of high-current components for power modules. In addition, the passive cooling of the whole system has to be optimized or replaced by active cooling. Furthermore, special attention must be paid to the dramatic increase in the overall operating time of the control units for electric vehicles. (SMTAI, October 2012)

PCB Substrates

“Package Substrate Advancements through Improved Adhesion of Electroless Copper to Dielectrics”

Author: Robin Taylor, Lutz Brandt, Ph.D, Zhiming Liu, Ph.D. and Tafadzwa Magaya; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Fabrication of advanced package substrates is a relatively complex process, requiring numerous pretreatment, cleaning, surface preparation, deposition and rinsing steps. In most cases, metalizing a dielectric surface includes some form of activation or “seeding” process, followed by the autocatalytic (electroless) deposition of copper. It is essential to achieve sufficient adhesion of this initial copper layer to the dielectric surface to maintain reliability. Specifically, this metallization must withstand normal mechanical stresses imposed by the subsequent electrolytic copper deposit, thermal stresses encountered in downstream substrate processing steps (i.e., soldering) and thermal and mechanical stresses encountered through the normal operation of the final system. This paper explains a novel approach for treating and preparing the dielectric surface for the subsequent deposition of electroless copper. Data presented demonstrate improved copper-to-dielectric adhesion resulting from such treatment. Measurable improvements in the overall reliability of the substrate, attributable to use of this adhesion promotion process, are established. (SMTAI, October 2012)

Solder Reliability

“Mechanical Reliability: Updated Results from a Spherical Bend Test Program”

Authors: John McMahon and Brian Standing; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Celestica has been conducting an ongoing testing program to assess Pb-free compatible materials and area array packages against the currently accepted levels of process strain. The latest phases of this work have been designed to extend our understanding of component construction dependencies, to begin investigations into some other package types and to compare more materials. This paper outlines the theory and practice of the test vehicle design, the assembly and test method used to generate data, and then discusses selected test results and failure modes determined by physical failure analysis. (SMTAI, October 2012)

“Solder Alloy Creep Constants for Use in Thermal Stress Analysis”

Authors: Robert Darveaux, Ph.D., Corey Reichman; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Creep constants were determined by conducting mechanical tests on solder joint array specimens. Either double lap shear or tensile loading was employed. Thirty combinations of alloy, pad metallization, and joint size were characterized. The test temperature range was from -55˚ to 134˚C. The strain rate range was from 10-8/sec. to 10/sec. The stress range was from 0.1MPa to 100Mpa. All data sets were fit to the same basic constitutive relation. (SMTAI, October 2012)