Heat Sink Protruding Structures for Lead-Free Soldering
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Solution Overview
Problem
In the context of printed circuit boards with high-power components, existing heat sinks made of copper or brass with large thickness face challenges in achieving complete soldering with lead-free tin due to high heat dissipation, leading to incomplete soldering and insufficient current conduction.
Innovation Solution
A heat sink design featuring a soldering portion with uniformly arranged protruding structures, such as strip-shaped or triangular teeth, that reduces heat dissipation and guides lead-free tin upwardly, ensuring complete soldering and adequate current conduction without the need for holes, allowing for effective heat dissipation and large current conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the copper sheet or heat sink is made of large thickness to conduct large current, then the current conduction capability is improved, but the lead-free tin solidifies quickly due to high heat dissipation resulting in incomplete soldering
Solution Approach 1:
The soldering portion is segmented into multiple protruding structures (teeth) that distribute the soldering area. This segmentation reduces the overall heat dissipation area while maintaining sufficient current conduction cross-section, allowing lead-free tin to remain molten long enough for complete soldering while still supporting large current flow through the thick copper sheet
Solution Approach 2:
The heat sink employs different structural characteristics in different regions: the soldering portion features protruding teeth with reduced cross-sectional area for minimized heat dissipation and improved soldering, while the main body maintains large thickness for adequate current conduction. This local differentiation resolves the contradiction between heat dissipation control and current carrying capacity
2Manufacturing precision
If a hole is formed over the soldering portion to reduce heat dissipation, then the soldering completeness is improved, but the current conduction capability deteriorates due to insufficient cross section
Solution Approach 1:
Instead of creating a hole that removes material, the invention segments the soldering portion into protruding teeth that distribute the soldering function across multiple small contact points. This maintains the overall cross-sectional area for current conduction while reducing the effective heat dissipation area during soldering, avoiding the need to compromise current conduction by forming holes
3Temperature
If the copper sheet or heat sink has high heat dissipation to maintain heat dissipation function, then the heat dissipation capability is improved, but the lead-free tin solidifies quickly causing incomplete soldering
Solution Approach 1:
The soldering portion is divided into multiple protruding teeth structures that collectively reduce the heat dissipation area during soldering. This segmentation allows the heat sink to maintain its heat dissipation function through the main body while the segmented soldering portion minimizes heat loss to keep lead-free tin molten during the soldering process
Solution Approach 2:
The heat sink exhibits local quality differentiation where the soldering portion has reduced heat dissipation characteristics (protruding teeth with smaller surface area) compared to the main body (large thickness for heat dissipation). This local variation enables the soldering area to retain heat for complete soldering while the overall structure maintains effective heat dissipation functionality
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 ensures perfect soldering quality and maintains a sufficient area for current conduction, enabling the heat sink to serve as a conductive frame for large current applications while preventing premature solidification of lead-free tin.
Implementation Method 1
the melted lead-free tin, which is provided by a lead-free tin soldering pot, is drawn upwardly along the soldering portion by capillarity
Implementation Method 2
it is very easy and fast for the copper sheet or heat sink to dissipate heat from the lead-free tin due to high heat dissipation of the copper sheet or heat sink itself
Data Source
AI summary
A heat sink for a printed circuit board of power server includes at least one soldering portion. The heat sink is soldered to the printed circuit board at the soldering portion by a lead-free tin soldering process. A plurality of protruding structures protrudes from the soldering portion uniformly. The protruding structures are beneficial for getting a better soldering quality.