Packaging and assembly

In high-pin-count BGA packages, why are many of the balls assigned to power and ground?

  1. ATo make the package heavier
  2. BTo reduce the number of signals
  3. CTo spread large currents, lowering supply resistance and inductance and suppressing power noise and voltage drop
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Answer: C. To spread large currents, lowering supply resistance and inductance and suppressing power noise and voltage drop

High-performance chips draw large currents, and rapid current changes make the voltage drop or fluctuate because of the resistance and inductance of the supply path. Placing many power and ground balls in parallel spreads the current and lowers path impedance, stabilizing the supply.

  • A. It is not about weight.
  • B. It is not intended to reduce the number of signals.
  • C. Correct. Lowering supply path impedance stabilizes the supply.
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More Packaging and assembly questions

  1. In wire bonding that forms a ball, where is the first bond (ball bond) generally made?
  2. What is the main purpose of heating packages in an oven for some time after molding (post-mold cure)?
  3. What is the defect called in which bonding wires are pushed aside and deformed by the resin flow during molding?
  4. What change occurs when the temperature of a molding compound exceeds its glass transition temperature (Tg)?
  5. Which method makes very thin chips by first cutting grooves partway into the wafer from the front and then grinding the back to separate the chips?