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Written by Mike Buetow and Chelsey Drysdale   
Tuesday, 04 September 2012 23:16

Component Placement
“Two Worlds Converging: Chipshooting and Flip-chip Bonding”
Authors: Eric Klaver and Patrick Huberts
Abstract: Pick-and-place equipment has over the years mostly evolved in four key areas: It is faster, more reliable, more accurate and more user friendly. Most pick-and-place vendors have aimed at the mass production market, while others have moved toward more dedicated markets – mostly where production flexibility is needed, as with high-mix, prototyping or evaluation. But in the end, we’re all doing the same thing: picking and placing components on bare substrates. (Company white paper; circuitsassembly.com/cms/white-papers)

PCB Assembly
“New Product Introduction”
Authors: ASM Siplace
Abstract: This new publication presents solutions for everyday challenges, lots of tips and tricks, and a convenient checklist for the NPI process. It is directed toward manufacturers that want to implement robust NPI processes in their high-mix electronics production environments with consistent tool chains in order to raise the efficiency and quality of their new product introductions. Readers will learn how even the first yield can be produced efficiently and error-free despite faulty Gerber data, incomplete bills of material, and missing or late component descriptions. (Company white paper; circuitsassembly.com/cms/white-papers)

Plating
“Electrochemical Cell Geometry for Uniform Processing of Printed Circuit Boards”
Authors: S.T. Snyder, H.M. Garich, B.S. Kagajwala and E. J. Taylor;  This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: An electrochemical cell geometry based on a novel flow mechanism for uniform processing (metallization or electroetching) of PCBs is described. This unique flow scheme utilizes eductors, coupled with dampening elements and flow channels to enable a non-impinging flow scheme that results in uniform boundary layer thickness and consequent uniform current and thickness distribution over a full-size printed circuit board panel (18×24 in.). This tank has been extensively characterized for thickness distribution under direct current plating conditions and compared with commercial plating cell geometries that utilize both eductor flow and/or air sparging agitation. Uniformity data, along with plating results of varying printed circuit board feature sizes, are also presented. (Products Finishing, August 2012)

“Immersion Gold: Why More is Not Better”
Authors: Hank Lajoie and Trainor; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: The nature of immersion gold is to attack the electroless nickel, remove it and replace it for the benefits that gold can offer. This activity of gold can defeat the intent for its use and supports the approach, starting with gold is good, so more must be better. The ENIG process has been challenged with this “more is better” concept. The ENEPIG process attempts improvement with protecting the EN from the gold. The dynamic chemistries involved within the process require close control and proper balances of ingredients. The effects of some of these contaminations and process imbalances can be exacerbated through ignorance and neglect of process control and pursuing the “more is better” approach. Experience with these dynamics of the electroless nickel, electroless palladium and immersion gold have offered improved and robust chemistries that fit with practiced process controls and can realize the value of gold without the “more is better.” Effects of commonly encountered bath contaminations from materials, process environment and process controls are presented to illustrate the immersion gold impact on the electroless nickel that can lead to defects. (SMTA International, October 2012)

Soldering
“Overcoming Head-in-Pillow Defects in Hybrid LGA Socket Assembly”
Authors: Marie Cole, et al; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: The processor card of a new midrange server system has a unique large mass SMT connector system that requires use of a vapor phase reflow. In addition, the board contains four ball grid array connectors, known as hybrid LGA sockets, to accommodate plugging of LGA processors. Due to the large size of these BGA sockets, which makes them vulnerable to dynamic warpage and other physical changes during Pb-free processing, solder joints in the connector array may be more susceptible to the formation of HiP defects. This paper discusses optimization of the assembly process for this complex PCBA. Several design of experiments were evaluated, including solder paste chemistry, stencil parameters, vapor phase reflow profile settings, reflow SMT pallet and fixture designs. Additionally, characterization of the contribution of incoming connector tolerances and thermal dynamic warpage was considered, along with various reliability evaluations related to this type of head-in-pillow defect. (SMTA International, October 2012)

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, 05 September 2012 18:36
 

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