A package substrate is an intermediate substrate that connects a semiconductor chip to a printed circuit board.

Roles:

・Signal wiring

・Power delivery

・Securing the chip

・Heat dispersion

Inside electronic equipment, it bridges the chip and the motherboard.

Semiconductor products have a three-layer structure of

・Chip

・Package substrate

・Printed circuit board

Flow:

Chip → Package substrate → System board

This structure is the foundation of electronic equipment.

Substrates used for high-performance chips.

ABF stands for Ajinomoto Build-up Film, an insulating material.

Features:

・Fine wiring

・High-layer-count structure

・High reliability

It is the standard substrate for high-performance processors such as CPUs and GPUs.

Leading-edge chips have an enormous number of wires.

For this reason, multilayer substrates with

・10 layers

・20 layers

・30 or more layers

are used.

The more layers there are, the better the

・Signal wiring

・Power stability

become.

Scaling is also progressing in package substrates.

Typical indicators:

・Line width

・Space

In recent years, wiring of 10µm or less has also come into use.

This is for high-density chip connections.

RDL stands for Redistribution Layer.

It is a layer that relocates the chip’s connection points to external wiring.

Roles:

・Expanding chip connections

・Fan-out packages

・High-density connections

It is an important technology in advanced packaging.

In AI chips,

・High currents

・High signal speeds

・Huge chips

become problems.

For this reason, substrates are required to provide

・Low noise

・Low latency

・High-current capability.

AI chips use HBM (High Bandwidth Memory).

With HBM,

・The GPU

・The memory

are connected with a silicon interposer.

This is 2.5D packaging technology.

Representative companies:

・Ibiden (Japan)

・Shinko (Japan)

・Unimicron (Taiwan)

・Nan Ya PCB (Taiwan)

Japanese companies are strong in high-performance substrates.

Package substrates have fallen into short supply due to the AI boom.

Causes:

・Demand for HBM

・Demand for GPUs

・Shortage of manufacturing equipment

For this reason, substrates can become a bottleneck in semiconductor supply.

Next-generation technologies:

・Glass substrates

・High-frequency substrates

・Optical interposers

・Liquid-cooled packages

We are entering an era in which semiconductor performance is determined by packages and substrates.

・Package substrates bridge the chip and the system

・ABF substrates are the standard for high-performance chips

・Fine wiring and higher layer counts are advancing

・Substrate performance is important for AI chips

・Japanese companies are strong in high-performance substrates

1.What is the role of a package substrate?

2.Why are ABF substrates used?

3.Why does substrate technology become important for AI chips?

 

Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.