Composite Solder Ball with Barrier Layer for Reflow Integrity
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Solution Overview
Problem
The increasing demand for miniaturization of semiconductor packages to achieve high integration and performance while reducing manufacturing costs poses challenges, particularly in maintaining the structural integrity and density of solder balls during the reflow process, where existing solutions fail to prevent core deformation and electrical shorts.
Innovation Solution
A composite solder ball design featuring a core, a barrier layer with a higher melting point than the core, and an encapsulating layer with a lower melting point than the core, where the barrier layer restricts the core's deformation and the encapsulating layer ensures electrical connectivity, allowing for increased density and reduced package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple solder ball structure is used, then manufacturing is easier and cost is lower, but core deformation and electrical shorts occur during reflow process
Solution Approach 1:
The solder ball is segmented into three distinct layers: a core material layer, a barrier layer, and an encapsulating layer. Each layer serves a specific function - the core provides structural support, the barrier layer prevents deformation, and the encapsulating layer ensures electrical connectivity. This segmentation allows the solder ball to maintain structural integrity while preventing core deformation and electrical shorts during the reflow process.
Solution Approach 2:
The invention uses composite materials with different melting points arranged in layers. The core material has a lower melting point than the barrier layer, which in turn has a lower melting point than the encapsulating layer. This composite structure enables the barrier layer to restrict core deformation at higher temperatures while the encapsulating layer melts first to ensure electrical connectivity, thus resolving the contradiction between reliability and structural complexity.
2Volume of moving object
If solder ball size is reduced for high density integration, then package size is reduced, but manufacturing precision and reliability become more difficult to maintain
Solution Approach 1:
By segmenting the solder ball into functional layers, each layer can be optimized independently for miniaturization. The core material can be reduced in size for high density, while the barrier and encapsulating layers provide protective functions that maintain reliability even at smaller dimensions. This segmentation allows precise control over manufacturing parameters for each layer.
Solution Approach 2:
The invention changes the melting point parameters of different layers to achieve reliable miniaturization. The core material is selected with a lower melting point than the barrier layer, allowing the core to be smaller while the barrier layer maintains structural integrity at reduced sizes. This parameter optimization enables high density integration while maintaining manufacturing precision.
3Productivity
If heating rate is increased for faster manufacturing, then productivity improves, but core deformation and electrical shorts increase
Solution Approach 1:
The invention changes the thermal parameters by using materials with different melting points in each layer. The barrier layer has a higher melting point than the core, allowing faster heating rates during reflow. The barrier layer restricts core deformation even at higher temperatures and faster heating rates, while the encapsulating layer melts first to ensure electrical connectivity, thus enabling increased productivity without compromising reliability.
Solution Approach 2:
The barrier layer is pre-positioned around the core material to provide preliminary protection against deformation during the reflow process. This preliminary protective structure allows the core to withstand faster heating rates without deforming, enabling increased productivity while maintaining core integrity.
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 prevents core deformation and electrical shorts, enabling higher density and reduced package size, thereby addressing the need for miniaturization and cost-effectiveness in semiconductor packages.
Implementation Method 1
the barrier layer restricts the core's deformation
Implementation Method 2
an encapsulating layer with a lower melting point than the core, where the barrier layer restricts the core's deformation and the encapsulating layer ensures electrical connectivity
Implementation Method 3
the encapsulating layer ensures electrical connectivity
Data Source
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AI summary
A semiconductor package includes a first substrate, a second substrate, a composite solder ball and a first semiconductor component. The composite solder ball includes a core, an encapsulating layer and a barrier layer. The composite solder ball is disposed between the first substrate and the second substrate for electrically connecting the first substrate and the second substrate. The barrier layer is disposed between the core and the encapsulating layer. Wherein a melting point of the barrier layer is higher than a melting point of the core, the melting point of the core is higher than a melting point of the encapsulating layer. The first semiconductor component is disposed between the first substrate and the second substrate.