Inside the Integrated Circuit

CSC-114 · Semester I · Introduction to Information Technology

beginner20 minAvailable

Integrated circuitSN7400 · 1970s TTL, DIP-14

Anatomy of the chip

1Silicon die. The real circuit — thousands of transistors built on a single crystal.
2Metal traces. Tiny wires that connect the transistors into logic gates and memories.
3Bond wires. Fine gold threads that carry signals from the die out to the lead frame.
4Lead frame. A stamped metal skeleton inside the package linking wires to the pins.
5Pins. The only part you touch — plugging into a socket or soldered to a board.

This is a DIP-14 — a dual in-line package with two rows of pins. The notch and pin-1 dot mark orientation so the chip is never inserted backwards. The black epoxy body is just a protective shell; all the electronics live on the tiny die inside.

Pins

Package

DIP

Die

Sisilicon

Connections

wiresgold

Rotate the model to inspect every side. Switch to "Inside" to lift the lid and see the die, bond wires and lead frame that make the chip work.

Drag to rotate · scroll to zoom

Lab brief

Objective

Open a dual in-line package (DIP) and trace the signal path from the pins, through the lead frame and bond wires, to the silicon die where millions of transistors form a complete circuit.

Theory & concepts

An integrated circuit packs millions of transistors and the wires between them onto a single chip of silicon. Fabrication builds the circuit layer by layer: doping regions, growing insulating oxides, and patterning metal traces with photolithography.

Rendering diagram…

Signal path inside a packaged integrated circuit

The fragile die cannot be handled or soldered directly, so it is glued to a metal paddle, its pads are joined to a stamped lead frame by fine gold bond wires, and the whole assembly is sealed in an epoxy package. Only the pins stick out, and the notch plus pin-1 dot tell you which way round to insert the chip.

Because a single IC replaced entire circuit boards of discrete transistors, computers shrank from room-sized machines to pocket devices - the driving force behind the third generation of computers.

Prerequisites

Lesson: Evolution of Computers: The Generations
The Transistor lab: what a transistor is

Instructions

1Rotate the model to inspect the DIP package, the two rows of pins, the notch and the pin-1 dot.
2Identify each labelled part: package, lead frame, die and bond wires.
3Switch to Inside view to lift the lid and follow the signal path from a pin to the die.
4Count the pins and check the silicon die, the metal traces and the logic-cell blocks.
5Summarise why the die cannot be used without a package.

Tasks

Trace a signal path
Follow one pin inward: pin -> lead frame -> bond wire -> die pad.
Spot the die
Describe what sits in the middle of the package and what it contains.
Why a package?
Give two reasons the bare silicon chip needs the epoxy package.

Self-check

The student can name the parts of a packaged IC in order.
The student can explain the role of bond wires and the lead frame.
The student can describe how the IC made computers smaller and faster.

Environment

interactive 3D DIP-14exploded package viewpart labelssignal path panel