Cavity-Based Electrical Connection Structure for PoP Height Reduction
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Solution Overview
Problem
Conventional package-on-package (PoP) stacks are excessively high due to the use of ball grid array (BGA) substrates and thick solder balls, which hinder the reduction of stacked package height in mobile applications.
Innovation Solution
An electrical connection structure featuring a substrate with a cavity and a protruding interconnect structure, where a connection element, such as a solder ball, is received within the cavity to establish an electrical connection, reducing the interconnect height between the top and bottom packages, and utilizing a hemispherical cavity to enclose the solder bump, thereby decreasing the package gap and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional BGA substrate and thick solder balls are used to connect top and bottom packages, then electrical connection reliability is improved, but package height increases significantly
Solution Approach 1:
The patent extracts the BGA substrate from the PoP structure, eliminating it entirely. Instead of using a separate BGA substrate with thick solder balls, the invention integrates the interconnect structure directly into the mold compound, thereby removing the height-contributing BGA substrate while maintaining electrical connection functionality
Solution Approach 2:
The patent embeds the interconnect structure within the mold compound, nesting the conductive elements inside the packaging material rather than placing them on external substrates. This nesting approach allows the interconnects to be contained within the package volume, reducing the overall package height while maintaining connection reliability
2Strength
If thick solder balls are used for connecting top and bottom packages, then electrical connection strength is improved, but interconnect height increases
Solution Approach 1:
The patent transitions from using tall, thick solder balls (vertical dimension) to creating wide, planar trace patterns (lateral dimension). The trace interconnects spread out horizontally within the mold compound, providing electrical connection strength through increased surface area and distributed pathways rather than through vertical thickness
Solution Approach 2:
The patent changes the geometric parameters of the interconnect structure from spherical/thick (solder balls) to planar/trace-like forms. By altering the shape and dimensional distribution of the conductive elements, the invention achieves equivalent or superior electrical connection strength with reduced height, as the trace patterns can extend laterally to provide multiple parallel conduction paths
3Ease of manufacture
If BGA substrate is used in PoP stack, then manufacturing process is simplified, but device complexity increases due to additional layers
Solution Approach 1:
The patent merges the interconnect structure with the mold compound into a single integrated component. By combining what were previously separate elements (substrate, interconnects, and packaging material) into one unified structure formed through co-molding or post-molding processes, the invention reduces the total number of discrete layers and components, thereby simplifying the overall device complexity while maintaining ease of manufacture
Solution Approach 2:
The mold compound serves multiple functions simultaneously: it provides mechanical packaging protection, structural support, and electrical interconnection pathways. This multi-functionality eliminates the need for dedicated BGA substrate layers, reducing the number of components required and simplifying the overall manufacturing process by consolidating functions into a single material system
Data Source
AI summary
Various embodiments may provide an electrical connection structure. The electrical connection structure may include a first substrate having a first surface defining a cavity, and an inner wall defining a via extending from the cavity. The electrical connection structure may also include an interconnect structure provided in the via so that at least a portion of the interconnect structure protrudes into the cavity. The electrical connection structure may further include a second substrate having a second surface facing the first surface. The electrical connection structure may additionally include a connection element on the second surface. At least a portion of the connection element may be received in the cavity so that the connection element is in electrical connection with the interconnect structure.