Semiconductor Package Corner Dummy Bumps for Underfill Stress Relief
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Solution Overview
Problem
Existing semiconductor packages face issues with underfill cracking or delamination at the die edge due to mechanical and thermal stresses, which affects the reliability of the package.
Innovation Solution
A dummy pad structure with dummy bumps is formed near the die corner outside the seal ring structure to anchor the underfill, enhance adhesion, and provide stress relief without significant impacts on manufacturing processes, time, or costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill is applied between the die and circuit carrier to increase reliability, then the reliability of the conductive bumps is improved, but the underfill at the die edge is prone to cracking and delamination due to mechanical and thermal stresses
Solution Approach 1:
The patent applies beforehand cushioning by forming a stress relief structure (dummy pad with dummy bump) near the die corner before the underfill is applied. This pre-positioned structure serves as a cushion that absorbs and redistributes mechanical and thermal stresses, preventing the underfill from cracking or delaminating at the die edge during subsequent thermal cycling and mechanical loading.
Solution Approach 2:
The dummy pad structure acts as an intermediary element between the die and the underfill. It provides a transition zone that mediates the stress transfer, allowing the underfill to be anchored securely while protecting it from the concentrated stresses that would otherwise occur at the die edge. The dummy bump and dummy pad create an intermediate stress distribution pattern.
2Reliability
If dummy pad structure with dummy bumps is formed near die corner to anchor underfill and provide stress relief, then the underfill is protected from cracking and delamination, but the device complexity increases
Solution Approach 1:
The patent applies local quality by placing the stress relief structure only in the specific location where it is most needed - near the die corner where mechanical and thermal stresses are most concentrated. The dummy pad and dummy bump are positioned strategically in the peripheral region outside the seal ring structure, providing localized protection exactly where the underfill is most vulnerable, rather than uniformly across the entire die surface.
Solution Approach 2:
The dummy bump and dummy pad serve as sacrificial or non-functional elements whose primary purpose is to provide mechanical support and stress relief. They do not contribute to the electrical functionality of the device but serve a structural protection role, analogous to disposable or auxiliary components that enhance reliability without adding functional complexity.
3Strength
If dummy bumps are formed in the peripheral region outside the seal ring structure, then stress relief is enhanced and underfill adhesion is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the formation of the dummy bump with the existing bump formation process. The dummy bump is formed using the same bump formation steps (such as electroplating or solder ball placement) that are already used to create the functional conductive bumps on the die. This integration means that the dummy structure is created as part of the standard manufacturing sequence without requiring entirely new process equipment or methods.
Solution Approach 2:
The dummy pad structure serves multiple functions: it anchors the underfill, provides stress relief, and potentially serves as a mechanical reference feature. By designing a single structure that accomplishes multiple objectives, the patent avoids the need for separate components for each function, thereby simplifying the overall manufacturing approach despite the added structural element.
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
The dummy pad structure effectively protects the underfill from cracking or delamination, improves stress relief, and enhances the reliability of the semiconductor package.
Implementation Method 1
A dummy pad structure with dummy bumps is formed near the die corner outside the seal ring structure to anchor the underfill, enhance adhesion, and provide stress relief
Implementation Method 2
A dummy pad structure with dummy bumps is formed near the die corner outside the seal ring structure to anchor the underfill, enhance adhesion, and provide stress relief
Data Source
AI summary
A semiconductor package includes a semiconductor die, an interposer disposed below the semiconductor die, first joints electrically coupling the semiconductor die to the interposer, at least one second joint coupling the semiconductor die to the interposer, and a first underfill disposed between the semiconductor die and the interposer to surround the active and second joints. The semiconductor die includes a first region, a seal ring region surrounding the first region, and a second region between the seal ring region and a die edge. The first joints are located within the first region, and the second joint is disposed at a die corner within the second region and is electrically floating in the semiconductor package.