Packaging and assembly

Why does warpage from heating during reflow become a problem for large packages?

  1. ABecause the package changes color
  2. BBecause some solder balls fail to join the board, causing connection failures
  3. CBecause the package becomes lighter
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Answer: B. Because some solder balls fail to join the board, causing connection failures

Packages are made of materials with different coefficients of thermal expansion, such as the chip, substrate and mold resin, so they warp when heated. Large warpage can keep some solder balls from reaching the board or cause neighboring balls to merge, leading to connection failures. It is an important issue as packages grow larger.

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More Packaging and assembly questions

  1. For surface-mount packages, which moisture-related rating specifies, among other things, how long they may be left after opening the moisture-proof packing before reflow?
  2. In high-power processor packages, what is the metal plate placed on top of the chip to spread heat called?
  3. Which organic package substrate, used in flip-chip BGAs and similar packages, is made by stacking insulating layers and fine wiring layers?
  4. Which wire bonding method melts the tip of a gold wire with an electrical discharge to form a ball, then bonds it to the electrode with heat and ultrasonic energy?
  5. Which package, used in applications needing high reliability such as space, seals its interior with ceramic or metal?