Circuits Assembly - November 2007 - (Page 64)

Ad Index ADVERTISER INFO: To learn about the advertisers in this issue, go to circuitsassembly.com and select “Advertiser Index” in the gray horizontal menu bar at the top of the page. This will provide you with direct links to the home or product pages of each advertiser in this index. Company Page No. Technical Abstracts In Case You Missed It Soldering “Studies on the Removal of Copper During Minipot Rework with Different Lead-Free Alloys” Authors: Kantesh Doss, Alan Donaldson, Andrew Tong, and Raiyo Aspandiar; kantesh. doss@intel.com. Abstract: Copper thickness at PTH knees in thick (>0.062") PCBs decreases substantially during wave soldering and minipot rework processes. Subsequently, thinner copper at PTH knees leaves a PCB more susceptible to thermomechanical stress failure under ambient field conditions over the PCB’s useful lifetime. Hence, it becomes important to understand the copper removal mechanism and mitigate the loss of copper at the PTH knees. This study examines copper loss at PTH knees under two different rework process conditions: stationary molten solder (static dip process), and turbulent solder flow in a minipot (the dynamic rework process). The study also considers alternative alloys as a possible means to mitigate copper loss in the minipot rework process: Four different alternative alloys are compared to SAC 305 in their respective rates of loss of copper as a result of reworking through-hole-mount connectors on three 0.093" thick PCBs. To further aid understanding of copper loss, a separate study also quantified the variability of initial copper thickness in PTHs by PCB supplier and by lots within each PCB supplier. Results showed that incoming copper thicknesses at the barrel knees vary considerably between different suppliers. None of the four alternative alloys exhibited any technically significant performance improvement in the mitigation of copper removal over SAC 305 during minipot rework. Dynamic rework conditions led to greater spread in the final copper thickness compared to static dip test conditions. Dynamic conditions also removed more copper at the middle section of the connector arrays employed in this study than at the end locations. Two distinctly different mechanisms are proposed for the removal of copper at the middle section and end sections of the connector arrays. (SMTAI, October 2007) “Wetting and Spreading Studies for Lead-Free Solder and Flux Materials in Flip Chip Packages” Author: Jinlin Wang; jinlin.wang@intel.com Abstract: This paper presents some wetting angle calculation methods. These methods can be used in a materials development environment where a short turnaround for experimental results is needed. Because the wetting test methods are lower cost and faster than performing an actual assembly, it reduces the overall time-to-data, materials development time and cost for lead-free process. Three solder wetting analysis methods are discussed. The solder wetting balance test is a common method used for wettability evaluation. A solder spreading test was used for solder wetting analysis under different reflow conditions. Wetting angles of solder spheres after reflow were calculated by using analytical equations from the solder spreading diameter. The calculated wetting angles were compared with measured values. Values of contact angles calculated using analytical equations were consistent with measurements. For very low contact angles, it is challenging to measure it accurately. The wetting angle calculated from solder spreading provides a good estimate for low contact angles. The wetting properties for different solders, fluxes and different surface finishes were also studied. A dynamic solder spreading test was also used to obtain the spreading diameter and dynamic contact angle. Our results showed that wetting force and wetting angle measurements can provide useful information about the performance of the solder and flux materials. (SMTAI, October 2007) Reliability Failure Mechanisms in High Voltage Printed Circuit Boards Authors: Craig Hillman, Ph.D., Robert Esser, Ph.D., and Jim McLeish; chillman@dfrsolutions.com. Abstract: High voltage designs often adhere to IPC, UL or MIL requirements. However, blindly following these specifications can cause heartburn when dealing with space constraints or insulation degradation experienced in severe environments. The minimum electrical conductor spacing defined in IPC-2221 is not based on metal migration failure mechanisms. However, research has shown that metal migration can be a critical failure mechanism in high voltage, high-density PCBs. For this reason, issues affecting metal migration should be addressed. This white paper explains industry specifications, the mechanisms that induce failure in high voltage designs and how to avoid them. (circuitsassembly.com/cms/content/view/5343/139/) 2007 Directory of EMS Companies circuitsassembly.com/cms/dems . . . . . . . . . . . . . . . . . . . . . 5, 53 Aim Solder, www.aimsolder.com . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Asymtek, www.asymtek.com. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Balver Zinn, www.balverzinn.com . . . . . . . . . . . . . . . . . . . . . .16-17 Bare Board Group, www.bareboard.com. . . . . . . . . . . . . . . . . . . . 62 BEST, Inc., www.solder.net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 BOW Electronic Solders, www.canfieldmetals.com . . . . . . . . . . . 9 BPM Microsystems, www.bpmicro.com . . . . . . . . . . . . . . . . . . . . 21 Circuitaid+, www.circuitaid.com . . . . . . . . . . . . . . . . . . . . . . . . . 63 CIRCUITS ASSEMBLY Electronic Reprints . . . . . . . . . . . . . . . . . . . . . . 53 CyberOptics, www.cyberoptics.com . . . . . . . . . . . . . . . . . . . . . . . 27 DEK USA, www.dek.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C4 Digi-Key, www.digikey.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Dynatech Technology, Inc., www.dynatechsmt.com . . . . . . . . . . 11 eFabPCB, www.efabpcb.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Electronics Group of Henkel, www.henkel.com/electronics . . . . 23 ERSA, www.ersa.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Essemtec USA, www.essemtec.com . . . . . . . . . . . . . . . . . . . . . . . 43 Fancort Industries, Inc., www.fancort.com . . . . . . . . . . . . . . . . . . 63 FCT Assembly, www.fctassembly.com . . . . . . . . . . . . . . . . . . . . . . 4 Grid-Lok, www.grid-lok.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Imagineering, Inc., www.pcbnet.com . . . . . . . . . . . . . . . . . . . . . . 1 Indium Corporation of America, www.indium.com . . . . . . . . . . . C2 Juki Automation Systems, www.jas-smt.com . . . . . . . . . . . . . . . 19 Madell Technology, www.madelltech.com. . . . . . . . . . . . . . . . . . . 62 Mydata Automation, www.mydata.com . . . . . . . . . . . . . . . . . . . . C3 Nihon Superior, www.nihonsuperior.com . . . . . . . . . . . . . . . . . . . . 4 NITON Analyzers, www.niton.com . . . . . . . . . . . . . . . . . . . . . . . . 34 OK International, www.okinternational.com . . . . . . . . . . . . . . . . . 15 Papros Inc., www.papros.com . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 PCB Shows, www.pcbshows.com . . . . . . . . . . . . . . . . . . . . . . . . . 60 Precision Placement Machines, Inc., www.goppm.com . . . . . . . . 63 RMD Instruments, www.rmd-leadtracer.com . . . . . . . . . . . . . . . . 29 RVSI, www.rvsi.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 SEHO Systems GmbH, www.seho.de . . . . . . . . . . . . . . . . . . . . . . . 47 Service Excellence Awards, circuitsassembly.com/sea. . . . . . . . . 49 Speedline Technology, www.speedlinetech.com . . . . . . . . . . . . . . 7 Transition Automation, Inc., www.transitionautomation.com . . . . 26 Valor Computerized Systems, www.valor.com. . . . . . . . . . . . . . . . 35 Virtual PCB, www.virtual-pcb.com . . . . . . . . . . . . . . . . . . . . . . . . 51 Vitronics Soltec, www.vitronics-soltec.com . . . . . . . . . . . . . . . . 13 VJ Electronix, www.vjelectronix.com . . . . . . . . . . . . . . . . . . . . . . . 39 Webinars by UP Media Group, www.pcbshows.com/webinars . . . . 5 ZESTRON America, www.zestron.com . . . . . . . . . . . . . . . . . . . . . 55 Advertising Sales North UP Media Group, Inc. America: 2400 Lake Park Drive, Suite 440 Smyrna, GA 30080 Susan Jones Group Sales Director, (404) 822-8900 email: sjones@upmediagroup.com Kamden Robb Sales Associate, (678) 589-8843 email: krobb@upmediagroup.com Asia: Korea: Young Media, 82 2 756 4819 email: ymedia@ymedia.co.kr Circuits Assembly NOVEMBER 2007 circuitsassembly.com http://circuitsassembly.com http://circuitsassembly.com/cms/dems http://www.aimsolder.com http://www.asymtek.com http://www.balverzinn.com http://www.bareboard.com http://www.solder.net http://www.canfieldmetals.com http://www.bpmicro.com http://www.circuitaid.com http://www.cyberoptics.com http://www.dek.com http://www.digikey.com http://www.dynatechsmt.com http://www.efabpcb.com http://www.henkel.com/electronics http://www.ersa.com http://www.essemtec.com http://www.fancort.com http://www.fctassembly.com http://www.grid-lok.com http://www.pcbnet.com http://www.indium.com http://www.jas-smt.com http://www.madelltech.com http://www.mydata.com http://www.nihonsuperior.com http://www.niton.com http://www.okinternational.com http://www.papros.com http://www.pcbshows.com http://www.goppm.com http://www.rmd-leadtracer.com http://www.rvsi.com http://www.seho.de http://circuitsassembly.com/sea http://www.speedlinetech.com http://www.transitionautomation.com http://www.valor.com http://www.virtual-pcb.com http://www.vitronics-soltec.com http://www.vjelectronix.com http://www.pcbshows.com/webinars http://www.zestron.com http://circuitsassembly.com/cms/content/view/5343/139/ http://circuitsassembly.com/cms/content/view/5343/139/ http://circuitsassembly.com

Table of Contents Feed for the Digital Edition of Circuits Assembly - November 2007

Circuits Assembly - November 2007 Contents Caveat Lector Industry News Market Watch Talking Heads Focus on Business Global Sourcing On the Forefront Screen Printing Better Manufacturing Pb-Free Manufacturing from a Tier III EMS Perspective ‘Living Documents, Subject to Change’ Creating Ideal Solder Joints An Alternative Drying Process for MSDs ‘Customer Satisfaction is More than a Score’ Optoelectronic Substrates: Will They Happen? Tech Tips Wave Soldering Process Doctor Test and Inspection Getting Lean Materials World Equipment Advances Product Spotlight Assembly Insider Technical Abstracts Ad Index

Circuits Assembly - November 2007

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