Semiconductor Package Header Layout for Impedance and Cooling
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Solution Overview
Problem
In semiconductor packages with cooling elements, the long transmission line lengths from signal leads to light emitting elements can disrupt the characteristic impedance and cooling efficiency, necessitating a configuration that balances both factors.
Innovation Solution
A header design featuring an eyelet with through holes, insulating substrate, and conductive layers that reduce heat return and adjust impedance, using materials with different thermal conductivities to minimize heat transfer back to the light emitting element while maintaining signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling element is provided in the semiconductor package, then cooling performance is improved, but transmission line length increases and characteristic impedance cannot be obtained
Solution Approach 1:
An insulating substrate is introduced as an intermediary component between the cooling element and the light emitting element. This substrate serves as a mediator that provides an insulating layer with controlled thickness and material properties, enabling the transmission line to achieve predetermined characteristic impedance while maintaining effective cooling performance through the cooling element below.
2Temperature
If a cooling element is provided in the semiconductor package, then cooling performance is improved, but heat may be returned toward the light emitting element, reducing cooling efficiency
Solution Approach 1:
The insulating substrate exhibits different thermal conductivity properties in different regions and directions. By selecting materials and designing structures with specific local thermal properties, the substrate allows heat to be effectively conducted away from the light emitting element toward the cooling element while preventing heat from the cooling element from returning to the light emitting element, thus maintaining high cooling efficiency.
3Reliability
If transmission line length is reduced, then characteristic impedance is improved, but the structure becomes more complex due to the need for insulating substrate with specific properties
Solution Approach 1:
The insulating substrate performs multiple functions simultaneously: it provides electrical insulation between conductive layers, establishes predetermined characteristic impedance for transmission lines, maintains mechanical spacing between components, and facilitates thermal management by controlling heat flow paths. This multi-functionality reduces the need for additional separate components and simplifies the overall device structure.
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 achieves optimal characteristic impedance and cooling performance by reducing heat return and parasitic inductance, enabling efficient high-frequency signal transmission and maintaining light emitting element characteristics.
Implementation Method 1
a first conductive layer is formed on an inner wall defining the first through hole, and the first conductive layer extends to an upper surface of the insulating substrate, the one end of the first lead is electrically connected to the first conductive layer
Implementation Method 2
the insulating substrate has a thermal conductivity lower than a thermal conductivity of the first lead
Implementation Method 3
a space is provided above the one end of the first lead inside the first through hole
Data Source
AI summary
A header for a semiconductor package, includes an eyelet having a through hole penetrating the eyelet from an upper surface to a lower surface of the eyelet, a first lead inserted inside the through hole, and an insulating substrate disposed on the upper surface of the eyelet, and provided with a first through hole at a position overlapping one end of the first lead in a plan view. The insulating substrate has a thermal conductivity lower than a thermal conductivity of the first lead. A first conductive layer is formed on an inner wall defining the first through hole, and the first conductive layer extends to an upper surface of the insulating substrate. The one end of the first lead is electrically connected to the first conductive layer, and a space is provided above the one end of the first lead inside the first through hole.