Patterned Metal Sheet Roughness for Lower Thermal Resistance Packaging
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Solution Overview
Problem
Semiconductor packages face increased thermal resistance due to uneven electrolytic layers formed during soldering, which can hinder efficient heat dissipation from the semiconductor chip to the heat sink.
Innovation Solution
A metal sheet with a pattern of first subdivisions having a higher average roughness and second subdivisions with a lower average roughness is used, which directs the electrolytic layer to accumulate primarily over the smoother areas, minimizing unevenness and reducing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrolytic layers are applied during soldering, then the semiconductor package can be soldered to a circuit board, but unevennesses arise in the electrolytic layers which enlarge the heat conducting path and increase thermal resistance
Solution Approach 1:
The metal sheet is divided into different regions with different surface roughness characteristics. First subdivisions have a first average roughness while second subdivisions have a second average roughness that is lower than the first. This local variation in surface quality directs the electrolytic layer to accumulate primarily over the smoother second subdivisions, minimizing unevenness in the solderable areas while maintaining soldering capability.
2Ease of manufacture
If electrolytic layers are applied during soldering, then the semiconductor package can be soldered to a circuit board, but the heat conducting path between semiconductor chip and heat sink is enlarged, increasing thermal resistance
Solution Approach 1:
The metal sheet is divided into different regions with different surface roughness characteristics. First subdivisions have a first average roughness while second subdivisions have a second average roughness that is lower than the first. This local variation in surface quality directs the electrolytic layer to accumulate primarily over the smoother second subdivisions, minimizing unevenness in the solderable areas while maintaining soldering capability.
3Manufacturing precision
If the first sheet surface has a pattern with varying roughness, then the electrolytic layer unevenness is minimized and thermal resistance is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The surface roughness parameter of the metal sheet is intentionally varied across different regions. First subdivisions have a first average roughness while second subdivisions have a second average roughness that is lower than the first. This controlled variation in the roughness parameter creates predictable accumulation behavior for the electrolytic layer, minimizing unevenness while the pattern can be produced using standard manufacturing techniques.
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 pattern effectively reduces the maximum depth of unevenness in the electrolytic layer, enhancing heat dissipation by minimizing thermal resistance between the semiconductor chip and the heat sink, while maintaining a more cost-effective and straightforward production process.
Implementation Method 1
During the soldering process, for example, unevennesses can arise in such electrolytic layers and they enlarge the heat conducting path between semiconductor chip and heat sink
Data Source
AI summary
A semiconductor package includes a semiconductor chip, an encapsulation body encapsulating the semiconductor chip, and a metal sheet having a first sheet surface and an opposite second sheet surface. The first sheet surface is exposed at the encapsulation body. The semiconductor chip is arranged at the second sheet surface. The first sheet surface has a pattern having first subdivisions having a first average roughness and second subdivisions having a second average roughness. The first average roughness is greater than the second average roughness.