Stacked Semiconductor Package via Resin-Encapsulated Solder Interconnects
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Solution Overview
Problem
The integration of multiple semiconductor chips or packages into a single semiconductor package poses challenges such as bridge defects and non-wet defects, which affect the electrical connection and integration density, and existing methods to enhance capacity and function in a wafer state require significant investment and are prone to manufacturing issues.
Innovation Solution
A stack-type semiconductor package is designed with a lower and upper printed circuit board, each covered with a molded resin compound, featuring via holes and solder balls that form connection conductors upon reflow, allowing for improved integration density and preventing defects like bridge and joint cracks, while using a side gate transfer mold method to cover the entire printed circuit board for stress resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple semiconductor chips are integrated into one package to increase capacity and function, then integration density is improved, but manufacturing complexity and defect risk increase
Solution Approach 1:
The patent divides the semiconductor package into multiple independent chip modules (first chip, second chip, third chip) that can be manufactured separately and then integrated through stacking. Each chip is mounted on its own substrate with independent molding, allowing parallel manufacturing and reducing overall process complexity while achieving high integration density.
Solution Approach 2:
The patent transitions from planar integration to three-dimensional stacking by vertically arranging multiple chip packages (lower chip package, upper chip package) connected through connection conductors. This vertical integration approach increases capacity without proportionally increasing manufacturing complexity, as each layer can be processed independently.
2Reliability
If solder balls are used to connect stacked packages, then electrical connection is improved, but bridge defects occur when neighboring solder balls contact
Solution Approach 1:
The patent introduces a molded resin compound as an intermediary material that encapsulates the solder balls and connection conductors. This resin barrier physically separates neighboring solder balls, preventing bridge defects while maintaining electrical connectivity through the controlled solder ball connections to ball lands.
Solution Approach 2:
The patent nests the solder balls within the molded resin compound structure, where the resin encapsulates and protects the solder joints. This nested configuration isolates each solder ball connection, eliminating the risk of unintended contact between adjacent solder balls while preserving the electrical connection function.
3Reliability
If molded resin compound is used to cover chips, then protection is improved, but non-wet defects occur when upper solder balls fail to contact lower package
Solution Approach 1:
The patent forms the molded resin compound in the lower chip package before mounting the upper chip package. This preliminary molding creates pre-formed via holes with precise dimensions and positions, establishing accurate alignment references before the upper package is attached, thereby preventing non-wet defects caused by misalignment.
Solution Approach 2:
The patent performs alignment verification between the via holes in the lower molded resin compound and the solder balls on the upper package before final reflow bonding. This preliminary alignment check ensures precise positioning, preventing non-wet defects where upper solder balls would fail to contact the lower package ball lands.
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 solution enhances integration density, prevents defects, and allows for a thinner profile by ensuring complete coverage of the printed circuit board with molded resin, thereby improving the reliability and efficiency of semiconductor package stacking.
Implementation Method 1
connection conductors passing through the lower molded resin compound to be in contact with the ball lands for connection are disposed
Data Source
AI summary
A method of forming a stack-type semiconductor package includes preparing a lower printed circuit board including a plurality of interconnections and a plurality of ball lands for connection on an upper surface thereof. One or more first chips, which are electrically connected to the plurality of interconnections and sequentially stacked, are mounted on the lower printed circuit board. A lower molded resin compound is formed on the lower printed circuit board to cover the first chips, and is formed to have via holes exposing the ball lands for connection. An upper chip package, under which solder balls are formed, is aligned so that the solder balls correspond to the via holes of the lower molded resin compound, respectively. The solder balls are reflown to form connection conductors filling the via holes. A stack-type semiconductor package structure and an electronic system including the same are also provided.