Ag Bonding Layer Thickness for Void-Controlled Semiconductor Packaging
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Solution Overview
Problem
Void generation in Ag bonding materials due to thermal shrinkage and solvent volatilization leads to decreased and varied heat dissipation in semiconductor devices.
Innovation Solution
The thickness of the Ag bonding material is set to be larger than the height of the metal burr by 2 μm or more, ensuring a path for void release and reducing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Ag paste is used as bonding material, then environmental compliance is improved, but void generation increases due to thermal shrinkage and solvent volatilization
Solution Approach 1:
The patent applies preliminary action by pre-forming a groove structure in the bonding material before bonding occurs. This groove is designed in advance to serve as a void evacuation path, allowing solvent vapor to escape during the bonding process before voids can form and compromise heat dissipation stability.
Solution Approach 2:
The bonding material is segmented by introducing a groove that divides the bonding interface into distinct regions. This segmentation creates a dedicated channel for void evacuation while maintaining the overall bonding structure, allowing the bonding material to both adhere surfaces and facilitate void escape.
2Ease of manufacture
If solvent content in Ag paste is increased, then ease of application is improved, but void generation increases due to excessive volatilization
Solution Approach 1:
The groove acts as an intermediary structure that mediates between the solvent volatilization process and the bonding interface. It provides a dedicated pathway for solvent vapor to escape, decoupling the ease of paste application (which benefits from solvent) from the harmful effect of excessive volatilization (which creates voids).
3Manufacturing precision
If metal burr height is increased, then dicing precision is improved, but void trapping increases due to blocked solvent exhaust paths
Solution Approach 1:
The groove is strategically positioned and dimensioned to create a local quality difference in the bonding material. The groove depth and width are optimized to allow solvent vapor to pass through while the surrounding bonding material maintains sufficient thickness to accommodate metal burrs without trapping voids.
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 effectively reduces the number of voids in the Ag bonding material, thereby improving heat dissipation and minimizing variations in heat dissipation.
Implementation Method 1
Sinter-bonding using an Ag paste has been applied
Implementation Method 2
voids are easily generated in an Ag bonding material due to thermal shrinkage and solvent volatilization
Implementation Method 3
voids are easily generated in an Ag bonding material due to thermal shrinkage and solvent volatilization
Data Source
AI summary
A semiconductor device includes: a die pad having a conductive property; a semiconductor chip; a back surface electrode formed on a back surface of the semiconductor chip; an Ag bonding material containing 50 to 85% Ag and bonding the back surface electrode and the die pad; a terminal connected to the semiconductor chip; and sealing resin having an insulating property and covering the die pad, the semiconductor chip, the Ag bonding material, and a part of the terminal, wherein a distal end of the terminal protruding from the sealing resin includes a substrate bonding surface, a metal burr protrudes from a peripheral portion on a lower surface of the back surface electrode contacting the Ag bonding material, and a thickness of the Ag bonding material is larger than a height in an up-down direction of the metal burr by 2 μm or more.