SPRAAV1C May   2009  – March 2020 AM3703 , AM3715 , OMAP3503 , OMAP3515 , OMAP3525 , OMAP3530

 

  1.   PCB Design Guidelines for 0.4mm Package-On-Package (PoP) Packages, Part I
    1.     Trademarks
    2. 1  Using This Guide
    3. 2  A Word of Caution
    4. 3  A Team Sport
    5. 4  Be Wary of Quotes
    6. 5  Don’t Forget Your CAD Tools
    7. 6  Metric Vs English
    8. 7  PCB Fab Limits
    9. 8  Routing and Layer Stackup
    10. 9  OMAP35x 0.4mm Pitch
    11. 10 Pad Type
    12. 11 PCB Pad Dimensions for 0.4mm BGA Package
    13. 12 Multiple BGA Packages
    14. 13 Etch Traps and Heat Sinks
    15. 14 Vias and VIP
    16. 15 Laser Blind Vias
    17. 16 Filled Vias
    18. 17 Know Your Tools
    19. 18 BeagleBoard
    20. 19 BeagleBoard Views
      1. 19.1 Top Layer – Signal - Area Underneath the OMAP35x
      2. 19.2 Layer 2 – Ground
      3. 19.3 Layer 3 – Signal
      4. 19.4 Layer 4 – Signal
      5. 19.5 Layer 5 – Power (VDD2)
      6. 19.6 Layer 6 – Signal – Bottom Copper – Bottom Component Outlines
    21. 20 OMAP35x Decoupling
    22. 21 PCB Finishes for High Density Interconnect (HDI)
    23. 22 Real World Second Opinion
    24. 23 Acknowledgments
    25. 24 References
  2.   Revision History

13 Etch Traps and Heat Sinks

The challenge with fine pitch board design is to insure that traces and vias do not pull heat away from the solder ball pad. This means that common sense routing circuit board guidelines are still useable. Also beware of etch traps.

ball_con_praav1.gifFigure 11. Common Sense Routing Circuit Board Guidelines

Small BGA pads do not have much solder and depend on uniform heating for a good joint. Here are some additional tips to insure that traces and vias do not serve as heatsinks:

  • Keep the trace smaller than the pad or via.
  • Do not gang up pads with a copper pour such as around a ground plane.
  • Use individual traces to interconnect the pads.

The OMAP35x processors are relatively low power devices so the smaller traces are appropriate.

ball_con2_praav1.gifFigure 12. Common Sense Routing Circuit Board Guidelines