Packaging and assembly

In dense assemblies such as smartphones, what is the purpose of forming a metal film on the package surface by sputtering or similar?

  1. ATo make soldering unnecessary
  2. BTo shield electromagnetic waves and prevent electromagnetic interference (EMI) with nearby parts
  3. CTo make the package transparent
Show answer and explanation

Answer: B. To shield electromagnetic waves and prevent electromagnetic interference (EMI) with nearby parts

When high-frequency parts are packed closely, their electromagnetic waves interfere and cause malfunctions. A grounded metal film on the package surface acts as an electromagnetic shield, preventing interference while staying thinner and smaller than a traditional metal can.

  • A. Soldering is still needed.
  • B. Correct. It acts as an EMI shield.
  • C. A metal film does not make the package transparent.
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More Packaging and assembly questions

  1. In reflow, what is the defect called in which one end of a small part such as a chip resistor lifts up so the part stands on end?
  2. What is the defect called in which the force or ultrasound of wire bonding cracks the insulator or silicon beneath the bond pad?
  3. Which correctly describes wire bonding?
  4. Which correctly describes flip-chip mounting?
  5. Which correctly describes a feature of BGA (ball grid array) packages?