Semiconductor Package Dummy Pads for Interposer Bonding Reliability
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Solution Overview
Problem
Current semiconductor packages face challenges in achieving high-performance, high-speed, and compact designs while maintaining reliable electrical connections and preventing bonding failures between the interposer substrate and the package substrate.
Innovation Solution
The semiconductor package design includes a package substrate with interposer terminals, signal pads, and dummy pads, where the interposer substrate is bonded to the package substrate using a heat bonding process that applies heat and pressure through both signal and dummy pads, ensuring uniform heat transfer and stable bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only signal pads are used for heat transfer during bonding, then the bonding area is minimized, but heat distribution becomes uneven causing bonding failures
Solution Approach 1:
Dummy pads are introduced as intermediary elements between the signal pads and the interposer substrate. These dummy pads serve as thermal mediators that facilitate uniform heat distribution across the bonding area without being electrically connected to any circuit, thus resolving the contradiction between bonding reliability and device complexity by adding a specialized thermal management component
Solution Approach 2:
The dummy pads perform multiple functions: they serve as thermal conduction paths during bonding, provide mechanical support for the interposer substrate, and maintain structural integrity without electrical connections. This multi-functionality allows a single structural element to address both thermal management and mechanical stability requirements
2Reliability
If the interposer substrate is made larger to accommodate more signal pads, then electrical connectivity is improved, but the package size increases
Solution Approach 1:
The pad structure is segmented into two distinct types: signal pads for electrical connectivity and dummy pads for thermal and mechanical support. This segmentation allows the signal pads to be concentrated in areas requiring electrical connection while dummy pads are strategically placed in remaining areas to provide thermal management, thus achieving good electrical connectivity without unnecessarily increasing the overall package area
Solution Approach 2:
Different regions of the interposer substrate are assigned different functions: areas with signal pads provide electrical connectivity, while areas with dummy pads provide thermal conduction and mechanical support. This local differentiation optimizes the use of substrate area by giving each region its specific quality and function, preventing uniform expansion of the package
3Strength
If bonding temperature is increased to improve bonding strength, then bonding reliability improves, but heat transfer requirements increase causing thermal stress
Solution Approach 1:
Dummy pads act as thermal intermediaries that facilitate controlled heat distribution during the bonding process. By providing additional thermal conduction paths, they enable the use of optimized bonding temperatures that achieve sufficient bonding strength while reducing the risk of thermal stress and damage to sensitive components
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 enhances electrical characteristics and prevents bonding failures by ensuring effective heat transfer and contact between the interposer and package substrates, leading to improved reliability and performance.
Implementation Method 1
a heat bonding process that applies heat and pressure through both signal and dummy pads, ensuring uniform heat transfer and stable bonding
Implementation Method 2
a heat bonding process that applies heat and pressure through both signal and dummy pads
Data Source
AI summary
A semiconductor package includes a package substrate, a plurality of package terminals disposed on the bottom surface of the package substrate, and an interposer substrate disposed on the top surface of the package substrate, a plurality of interposer terminals disposed on the bottom surface of the interposer substrate and electrically connected to the package substrate, a first semiconductor chip disposed on the top surface of the interposer substrate, a second semiconductor chip disposed on the top surface of the interposer substrate and disposed to be horizontally separated from the first semiconductor chip, a first plurality of signal pads disposed on the top surface of the interposer substrate and electrically connected to wiring in the interposer substrate and one or more circuits in the first semiconductor chip, a second plurality of signal pads disposed on the top surface of the interposer substrate and electrically connected to wiring in the interposer substrate and to one or more circuits in the second semiconductor chip, and a plurality of dummy pads disposed outside of an area occupied by the first semiconductor chip or the second semiconductor chip from a top-down view and disposed on the top surface of the interposer substrate. Each pad of the first plurality of signal pads and the second plurality of signal pads is configured to transfer signals between the interposer substrate and a respective semiconductor chip, and each pad of the dummy pads is not configured to transfer signals between the interposer substrate and any semiconductor chip disposed thereon.