Elongated Bonded Structures for Semiconductor Package Reliability
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Solution Overview
Problem
The semiconductor industry faces manufacturing challenges in developing new packaging technologies for smaller electronic components, particularly due to thermal expansion differences between materials in semiconductor packages and substrates, leading to shifting of relative positions and potential shorting or delamination issues during thermal treatment.
Innovation Solution
The implementation of elongated bump structures and solder resist openings (SROs) that align axes towards the center of the package, reducing stress and preventing solder wetting on sides facing the package center, along with an underfill application to support bonded structures and improve flux cleaning, thereby reducing the likelihood of shorting and interfacial delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If new packaging technologies are developed for smaller electronic components, then integration density is improved, but thermal expansion differences cause shifting of relative positions leading to shorting or delamination
Solution Approach 1:
The patent applies different materials with different thermal expansion coefficients to different regions of the package structure. Specifically, it uses a low thermal expansion coefficient material for the package substrate and a high thermal expansion coefficient material for the interposer substrate, creating local quality variations that compensate for thermal stress and prevent delamination while maintaining high integration density
Solution Approach 2:
The patent employs composite material structures combining multiple substrates with different thermal expansion properties. The package includes a package substrate, an interposer substrate, and a carrier substrate, each made of materials selected for their specific thermal expansion characteristics. This composite approach allows the structure to manage thermal stresses effectively while achieving high integration density through advanced packaging technologies
2Reliability
If elongated bump structures are used to reduce stress, then thermal stress resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the bump structures by elongating them in specific directions. This parameter modification allows the bumps to better accommodate thermal expansion differences between substrates, improving thermal stress resistance while maintaining manufacturability through controlled changes in bump dimensions rather than fundamental design changes
3Reliability
If solder resist openings are aligned to prevent wetting, then shorting prevention is improved, but alignment precision requirements increase
Solution Approach 1:
The patent uses solder resist openings strategically positioned and sized to prevent solder from flowing into regions where shorting could occur. This preliminary protective measure is built into the substrate design before bonding, creating a barrier that prevents potential shorting paths without requiring extremely tight alignment tolerances during the bonding process
4Reliability
If underfill is applied to support bonded structures, then interfacial adhesion is improved, but process complexity increases
Solution Approach 1:
The patent introduces underfill material as an intermediary substance between the package substrate and the interposer substrate. This underfill acts as a mediator that distributes thermal stresses, improves interfacial adhesion, and provides mechanical support to the bonded structures. The addition of this intermediary layer, while adding a process step, significantly enhances reliability by preventing delamination and supporting the high-density interconnections
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 configuration enhances the reliability of bonded structures by reducing the chance of shorting between neighboring structures and improving interfacial adhesion, resulting in improved yield and reduced delamination failures.
Implementation Method 1
a solder layer filling an opening over a metal pad, and the solder layer is bonded to a metal pad of the substrate
Implementation Method 2
the copper post is bonded to the solder layer to form a bonded structure
Data Source
AI summary
The embodiments described provide elongated bonded structures near edges of packaged structures free of solder wetting on sides of copper posts substantially facing the center of the packaged structures. Solder wetting occurs on other sides of copper posts of these bonded structures. The elongated bonded structures are arranged in different arrangements and reduce the chance of shorting between neighboring bonded structures. In addition, the elongated bonded structures improve the reliability performance.