Printed Wiring Board Metal Posts for Thermal Stress Reduction
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Solution Overview
Problem
Existing printed wiring boards with embedded electronic components face challenges in reliable connection and heat dissipation due to differences in thermal expansion coefficients and structural weaknesses, leading to potential malfunctions and reliability issues under heat cycles.
Innovation Solution
A printed wiring board design featuring a lowermost resin insulating layer with embedded electronic components, conductor posts, and metal posts that connect via conductors, enhancing connection reliability and heat dissipation by balancing structural strength and reducing warpage, while a shield structure further protects against electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electronic components are embedded in resin layers with through holes and plating conductors, then connection reliability is improved, but thermal expansion differences cause structural cracks and malfunctions under heat cycles
Solution Approach 1:
The patent uses a composite structure combining resin insulating layers, conductor posts, metal posts, and plating conductors. The metal posts (e.g., copper) embedded in the resin layer create a composite material system that balances thermal expansion characteristics, reducing stress concentration and preventing cracks during heat cycles while maintaining reliable electrical connections.
Solution Approach 2:
The patent changes the physical parameters of the connection structure by introducing metal posts with specific thermal expansion coefficients that match the resin layer, and by controlling the dimensions and positioning of conductor posts and plating conductors. This parameter optimization reduces thermal stress and prevents structural failure under temperature variations.
2Reliability
If conductor posts and via conductors are formed to connect conductor layers, then electrical connection is improved, but heat dissipation becomes insufficient due to thermal expansion differences
Solution Approach 1:
The metal posts act as intermediary elements between the resin insulating layer and the conductor layers. These metal posts serve dual functions: providing mechanical support to bridge thermal expansion gaps and acting as heat dissipation pathways. The plating conductors on the metal posts further enhance both electrical connection and thermal conduction, effectively managing heat generated by embedded electronic components.
Solution Approach 2:
The conductor posts and metal posts are designed to perform multiple functions simultaneously: electrical conduction, mechanical support, and heat dissipation. This multi-functionality resolves the contradiction by ensuring that the same structural elements that provide electrical connection also contribute to thermal management, eliminating the need for separate heat dissipation mechanisms.
3Strength
If metal posts are positioned at the lower surface of conductor posts, then structural strength is improved, but warpage occurs due to uneven heat distribution
Solution Approach 1:
The metal posts positioned at the lower surface of the conductor posts act as counterweights that balance the structural load and thermal stress distribution. By strategically placing these high-strength, high-thermal-conductivity elements, the patent compensates for uneven heat distribution and prevents warpage while maintaining overall structural integrity.
4Reliability
If via conductors connect first conductor layer to conductor posts and electronic component electrodes, then electrical connectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The metal posts and conductor posts are formed in advance during the PCB manufacturing process, creating pre-positioned connection structures. The via conductors are then formed to connect these pre-established elements, simplifying the overall manufacturing sequence. This preliminary action approach reduces manufacturing complexity by establishing a clear hierarchical structure that guides subsequent fabrication steps.
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
The design improves connection reliability and heat dissipation, reducing the risk of malfunctions and structural cracks, and enhances the overall reliability and performance of the printed wiring board by balancing structural strength and heat management.
Implementation Method 1
via conductors formed in the lowermost resin insulating layer and including a first via conductor and a second via conductor such that the first via conductor is connecting the first conductor layer and the upper surface of the conductor post and that the second via conductor is connecting the first conductor layer and the electrode of the electronic component
Implementation Method 2
metal post formed on a second surface of the lowermost resin insulating layer such that the metal post is protruding from the second surface of the lowermost resin insulating layer and is positioned at the lower surface of the conductor post
Data Source
AI summary
A printed wiring board includes a lowermost resin insulating layer, a first conductor layer formed on first surface of the lowermost layer, a conductor post having upper surface facing the first surface of the lowermost layer, a metal post formed such that the metal post is protruding from second surface of the lowermost layer and is positioned at lower surface of the conductor post, an electronic component embedded in the lowermost layer such that the component is positioned on second surface side of the lowermost layer and has an electrode facing the first surface of the lowermost layer, and via conductors formed in the lowermost layer and including first and second via conductors such that the first via conductor is connecting the first conductor layer and the upper surface of the conductor post and the second via conductor is connecting the first conductor layer and the electrode of the component.