Semiconductor Package Measurement Pad Corrosion Protection
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Solution Overview
Problem
Conventional semiconductor packages with wire bonding techniques face reliability issues due to corrosion of measurement pads during electrical testing, which can damage interconnections and reduce package reliability.
Innovation Solution
The semiconductor package design includes a measurement pad with a bump that prevents corrosion by having a lower ionization tendency material, such as tin, and applying a voltage to the pad to reduce corrosion risk, while the connection pad is connected to the substrate pad for external electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a measurement pad is used for electrical testing, then testing functionality is enabled, but corrosion occurs during testing which damages interconnections and reduces reliability
Solution Approach 1:
A bump structure is introduced as an intermediary between the measurement pad and the test probe. The bump serves as a sacrificial element that undergoes corrosion instead of the measurement pad and interconnections, protecting the critical components while enabling testing functionality.
Solution Approach 2:
The bump is designed as a disposable, sacrificial element with lower ionization tendency than the measurement pad material. It is intentionally made to corrode first during electrical testing, serving as a short-living protective barrier that sacrifices itself to preserve the measurement pad and interconnections.
2Measurement precision
If voltage is applied to the measurement pad during testing, then electrical characteristics can be measured, but corrosion risk increases
Solution Approach 1:
The bump acts as an intermediary that bears the corrosive effects of voltage application during electrical testing. It provides a controlled interface between the test probe and the measurement pad, allowing measurements to be taken while the bump protects against voltage-induced corrosion.
Solution Approach 2:
The ionization tendency parameter is strategically manipulated by selecting materials with different corrosion resistances. The bump material is chosen to have lower ionization tendency (higher corrosion resistance) than the measurement pad material, creating a controlled corrosion hierarchy that protects critical components during voltage application.
3Reliability
If the measurement pad is made of highly conductive material, then electrical testing is improved, but corrosion resistance decreases
Solution Approach 1:
Different regions of the pad structure are assigned different material properties. The measurement pad uses highly conductive material for optimal electrical testing, while the bump uses corrosion-resistant material. This local differentiation allows each component to optimize its function without compromising the other.
Solution Approach 2:
The pad structure employs a composite configuration with two distinct materials: a highly conductive material for the measurement pad and a corrosion-resistant material for the bump. This composite approach combines the advantages of both materials, achieving both electrical performance and corrosion protection.
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 design enhances the reliability of semiconductor packages by preventing corrosion of the measurement pad and maintaining the integrity of interconnections during electrical testing and operation.
Implementation Method 1
the measurement pad may have greater ionization tendency than the connection pillar and the solder, and the solder may have greater ionization tendency than the connection pillar
Data Source
AI summary
A semiconductor package includes a package substrate; a semiconductor chip mounted on a top surface of the package substrate; a chip pad disposed on a bottom surface of the semiconductor chip to face the top surface of the package substrate, the chip pad including a connection pad and a measurement pad; and a chip bump including a first bump provided between the package substrate and the connection pad and a second bump provided between the package substrate and the measurement pad. An interconnection disposed within the package substrate is not connected to the second bump to be electrically isolated from the second bump.