Semiconductor Package Lateral Bump Bonding Structure
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Solution Overview
Problem
Conventional semiconductor packages face challenges in preventing solder cracks and non-wet defects, especially in fine pitch bump structures, due to deformation and volume issues with copper pillar bumps during the reflow process.
Innovation Solution
The semiconductor package employs a lateral bump bonding structure with high melting point metal pillars and low melting point metal layers, where the pillars and layers are joined through side surfaces, increasing the junction area and allowing for a finer pitch without deformation, and using an encapsulation or underfill member to protect the chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If copper pillar bumps are used in fine pitch structures, then productivity and integration density are improved, but solder cracks and non-wet defects occur due to deformation during reflow process
Solution Approach 1:
The invention uses a composite bump structure consisting of a copper pillar core combined with a solder layer. The copper pillar provides structural support and electrical connection, while the solder layer enables reliable bonding to the substrate during reflow. This composite structure prevents deformation and cracking while maintaining fine pitch capability.
Solution Approach 2:
The invention changes the material parameters of the bump structure by using materials with different melting points and mechanical properties. The copper pillar maintains dimensional stability during reflow, while the solder layer provides proper wetting characteristics. This parameter optimization prevents both deformation and cracking issues.
2Productivity
If bump pitch is reduced to increase integration density, then productivity is improved, but short-circuiting occurs due to deformation and volume issues
Solution Approach 1:
The copper pillar-solder layer composite structure provides superior dimensional stability compared to pure solder bumps. The copper pillar acts as a rigid support that prevents lateral deformation and volume expansion during reflow, enabling tighter pitch control and reducing short-circuit risks.
Solution Approach 2:
The invention applies different material properties to different parts of the bump structure. The copper pillar core provides structural rigidity and dimensional stability, while the outer solder layer provides bonding capability. This local differentiation of material properties enables precise pitch control.
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 effectively prevents solder cracks and non-wet defects by maintaining the bump height and shape, enabling a smaller pitch without short-circuiting, while the high melting point pillars support the low melting point layers to retain the necessary bump height and shape.
Implementation Method 1
bumps respectively formed over the bonding pads of the semiconductor chip, and including pillars and layers which are formed over first side surfaces of the pillars and are joined with the terminals of the substrate
Data Source
AI summary
A semiconductor package may be provided. The semiconductor package may include a substrate having a first surface over which bond fingers are arranged, the other surface facing away from the first surface and over which ball lands are arranged, and terminals which are respectively formed over the bond fingers. The semiconductor package may include a semiconductor chip disposed over the first surface of the substrate, and having an active surface facing the first surface and over which bonding pads are arranged. The semiconductor package may include bumps respectively formed over the bonding pads of the semiconductor chip, and including pillars and layers which are formed over first side surfaces of the pillars and are joined with the terminals of the substrate.