Packaging · Topic 7 of 14
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PackagingLesson 7 of 14
Flip chip
Mounting the die face-down on solder bumps for dense, fast connections.
What you’ll learn
- How flip-chip differs from wire bonding
- Why area-array I/O helps
- Where it's used
Why it matters
Flip-chip enables the thousands of fast connections high-performance chips need.
Explanation
In flip-chip, solder bumps are formed across the die's whole face; the die is flipped and bonded directly to the substrate. This gives area-array I/O (connections across the die, not just the edge) with short, low-inductance paths.
It supports far more connections and higher speeds than wire bonding.
Visual explanation
Key terminology
- Solder bump
- A small solder ball on the die face.
- Area-array I/O
- Connections distributed across the die, not just the edge.
- Underfill
- Epoxy that mechanically reinforces the bump joints.
Example
A CPU die is flip-chip bonded to its substrate with thousands of bumps.
Common mistakes
Watch out for:
- Forgetting underfill — it's needed to relieve thermal-mechanical stress on bumps.
Real-world application
Flip-chip is standard for CPUs, GPUs, and other high-I/O chips.
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Flip chip
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Traditional packaging
Packaging
Classic single-die packages that protect and connect a chip.
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