IC Fabrication : Assembly and Packaging

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⚙️ Big Picture: Where Does Assembly & Packaging Fit in IC Fabrication?

IC Fabrication has 3 major phases:

1. Front-End (Wafer fabrication) – Transistors and circuits are formed on the silicon wafer.

2. Back-End (Wafer test and dicing) – Chips are tested and cut from the wafer.

3. Assembly & Packaging – Each chip is enclosed in a protective package and connected to the outside world.

You're here ➡️ 🟨 Phase 3: Assembly and Packaging

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🔩 What Happens in Assembly & Packaging?

Let’s walk through it step-by-step:

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🧱 1. Wafer Dicing

• The wafer is diced into individual dies (aka chips).

• Done using a diamond saw or laser.

📌 Think of slicing a pizza into square micro-slices 🍕➡️🔲🔲🔲

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🖇️ 2. Die Attach

• Each chip (die) is attached to a substrate or lead frame using epoxy or solder.

There are two types:

• Epoxy die attach

• Solder die attach

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⚡ 3. Wire Bonding / Flip-Chip

This is how the tiny die connects to the package pins or pads:

🧵 Wire Bonding:

• Fine gold or aluminum wires connect chip pads to package leads.

• Used in traditional packages.

🧲 Flip-Chip:

• Die is flipped upside down.

• Bumps (usually solder) directly connect to the substrate.

• Shorter path = better performance.

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🛡️ 4. Encapsulation / Molding

• The die and wires are covered with plastic or ceramic to protect from:

  • Moisture

  • Heat

  • Physical damage

➡️ This is when your tiny naked silicon chip becomes a neat IC package (like the black rectangle you see on PCBs).

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📦 5. Packaging

Common package types:

• DIP (Dual In-line Package)

• QFP (Quad Flat Package)

• BGA (Ball Grid Array)

• CSP (Chip Scale Package)

Each has trade-offs in size, cost, thermal, and electrical performance.

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✅ 6. Final Testing & Burn-in

• Packages are tested for functionality, speed, and reliability.

• Sometimes they go through burn-in ovens (stress testing under high heat/voltage).

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📚 Want to Learn More?

If you want to deepen your knowledge, here are areas to explore:

Topic	What to Learn
📐 Package Design	Thermal management, signal integrity
💡 Materials	Underfill, solder bumps, molding compounds
🛠️ Processes	Wire bonding, flip-chip, encapsulation
🔬 Reliability Testing	Burn-in, thermal cycling, HAST
🧪 Standards	JEDEC, IPC standards for packaging

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🧭 Motivation Plan for You (If You’re on Bench or Exploring)

🎯 Goal: Get familiar and project-ready in IC Packaging

✅ Week 1-2: Learn the basics

• Watch short videos (Intel, TSMC, Amkor have great ones on YouTube).

• Read intro PDFs from universities (MIT, IIT, or companies like ASE or TI).

✅ Week 3: Pick a topic to dive deeper

• Example: Flip-chip bonding

• Read a whitepaper, maybe build a mini presentation for yourself or LinkedIn post.

✅ Week 4: Project idea!

• Make a presentation, blog, or simple visual guide explaining the flow.

• If you're into CAD: Try basic IC package modeling in Fusion 360 or Altium (even for fun).