1.BGA Layoutfor ease of usePresenter Mike Galloway Manufacturing Engineer

2. Overview Introduction BGA Capability BGA History DFM Standards Technologies Design Thermal Management Trace Routing and Vias 3. IntroductionMike Galloways Experience: 18 years in electronics manufacturing. Technical Support Team Manager for Screaming Circuits.Screaming Circuits History: Established in 2003. Assemble tens of thousands of boards with BGA components a year. Screaming Circuits and its parent company MEC share 50 years of PCB assembly experience. 4. BGA ExperienceSolder Paste:Package Solder Jet PrintingStandard Stencil Paste Applicationon Package: Two BGAs stacked.Fig. 4www.mydata.com Fig. 3 Hybrid ProcessMicro BGA:Mixed Alloys Less than .5mmwww.laocsmta.org Fig. 5Fig. 6 5. BGA HistoryDeveloped in late 1980s, gained popularity in 1990s, andwide spread use in 2000s.More complicated ICs mean more I/O. Real estate is at a premium, therefore smaller packagetypes are becoming more common. .5mm pitch and smaller is being used more. Package on Package (POP) gaining popularity. Extensiveuse in the mobile device market. 6. StandardsRecommended reads: IPC-7095B Design and Assembly ProcessImplementation for BGAs IPC- 7351A Land pattern standard IPC-A-610E Acceptability of ElectronicAssemblies IPC-J-STD-001E Requirements for SolderedElectrical and Electronic Assemblieshttp://www.ipc.org 7. Technologies Ball Alloy and its effect on assembly. Mixed Technology: Lead free BGA and leaded solder. Some good history in the industry. Alloy seems to be somewhat reliable for commercial applications.www.jovy-sys.com Fig. 10 Leaded BGA and lead free solder. (Not recommended) Voiding. Alloy issues. Part integrity compromised due to heat.Avoid mixing if possible. Stick with what is reliable and easy. 8. DesignsMicro BGAs and the challengesaround them: Larger dense parts nearby. Issues with profiling. Small pads. SMDP (Solder Mask Defined Pad)www.polarinstruments.com Fig. 11 Trace routing: Via in pad. (Fig. 12)Fig. 12 9. DesignsPackage on Package (POP): Limited experience in prototypes. Requires significant process development. Things to consider while designing: Adjacent Components PCB Stack up Process development: Part warping causing defects or long term reliability issues. 10. Surface Finish Choices HASL - Micro BGA not recommended due to coplarinarity variations. (Fig. 14) ENIG - Needs good plating controls. Most vendors watch this very close. (Fig. 15) IMAg - Some concerns with microvoids. (Fig. 16) Fig. 14 Fig. 15 Fig. 16 11. Thermal ManagementGround/thermal pad under package: Effects of inner ball reflow. (Fig. 17) Voiding in pad causing insufficient heat transfer. Vias in ground pad leaching solder away from the die and down the vias. (Fig. 18) Fig. 17Fig. 18 12. Trace Routing and ViasDesigns that try to keep everything on few layers: Routing between pads. (Fig. 19) Connecting a series of pads. (Fig. 20) Using a thick trace, mask defined pads Oversize or undersize pads, or a combination of both on one BGAFig. 19Fig. 20 13. Summary Best guide for DFM standards is IPC-7095B. BGAs are becoming unavoidable and require more knowledgefor manufacturability. Learn more, ask questions: Go to SMTA meetings www.ipc.org http://www.element14.com/community/groups/screaming-circuits mgalloway@screamingcircuits.com 14. Thank you for joining us.Questions?