Metal Stud Bumps Reduce Package-on-Package Thickness

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Solution Overview

Problem

The semiconductor industry faces limitations in reducing the total thickness of package-on-package (PoP) technology due to the height of solder ball joints between top and bottom packages, which hinders further integration density and miniaturization of electronic components.

Innovation Solution

The implementation of metal stud bumps with a flattened ball shape and a tail region, attached to the substrate using a wire-bonding method, allows for a lower profile connection between packaged dies, reducing the overall thickness of PoP devices by embedding these bumps within solder joints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solder ball joints are used to connect top and bottom packages in PoP technology, then reliable electrical connections are achieved, but the total thickness of the PoP device increases due to the height of the solder ball joints

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidPoP device thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The solder joint is segmented into two functional parts: a solder ball that provides the electrical connection and a flattened metal stud bump that provides the mechanical support and positioning. This segmentation allows the solder ball to be smaller and embedded within the flattened bump structure, reducing the overall standoff height and device thickness while maintaining connection reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solder ball is nested within or against the flattened metal stud bump structure. The metal stud bump serves as a base or platform for the solder ball, allowing the solder joint to have a reduced profile while maintaining structural integrity and electrical connectivity between packages

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If traditional solder ball joints are used in PoP devices, then electrical connections are established, but the standoff height between packages is large, limiting further miniaturization

Engineering Contradiction:

Improveelectrical connectionVSAvoidstandoff height

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of using a traditional spherical solder ball that stands alone, the invention inverts the approach by creating a flattened metal stud bump with a tail region that extends into the solder joint. This inverted structure allows the solder to flow around and embed the metal stud, creating a lower profile connection that reduces standoff height while maintaining electrical connectivity

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach decreases the thickness of PoP devices by up to 10% and reduces the standoff height by 40%, enabling more compact and densely integrated semiconductor packages while maintaining reliable electrical connections.

Implementation Method 1

attached to the substrate using a wire-bonding method

Methodology Applied

Scientific EffectWire-bonding: Welding

Data Source

PatentUSRE49045E1Package on package devices and methods of packaging semiconductor dies

Publication Date: 2022.04.19 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Package on package (PoP) devices and methods of packaging semiconductor dies are disclosed. A PoP device includes a first packaged die and a second packaged die coupled to the first packaged die. Metal stud bumps are disposed between the first packaged die and the second packaged die. The metal stud bumps include a bump region and a tail region coupled to the bump region. The metal stud bumps are embedded in solder joints.