Molded Package with Segmented Thick and Thin Lead Electrodes
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Solution Overview
Problem
Conventional molded packages operating at high frequencies or high outputs face challenges in achieving effective heat dissipation and high-frequency characteristics due to thin lead electrodes with low heat capacity, leading to increased temperature and parasitic inductance and capacitance, making it difficult to perform electrical grounding and heat dissipation separately.
Innovation Solution
A molded package design featuring a thick-film lead electrode for heat dissipation and a thin-film lead electrode for input/output, with a wire connecting the semiconductor chip, allowing for separate exposure of heat dissipating and grounding electrodes, enabling improved heat dissipation and high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin-film lead electrodes are used, then the device complexity is reduced and manufacturing is easier, but the heat dissipation effect is insufficient and temperature increases
Solution Approach 1:
The lead electrode is segmented into two distinct types: thin-film lead electrodes for input/output functions and a thick-film lead electrode for heat dissipation and grounding. This segmentation allows each electrode type to be optimized for its specific function, with the thick-film electrode providing sufficient heat capacity without complicating the overall manufacturing process
Solution Approach 2:
Different regions of the package have different electrode thicknesses tailored to local requirements. The thick-film lead electrode is specifically positioned at the heat dissipation region where high heat capacity is needed, while thin-film electrodes are used in input/output regions where lower profile and easier manufacturing are advantageous
2Device complexity
If thin-film lead electrodes are used, then the device structure is simpler, but the high-frequency characteristics deteriorate due to increased parasitic inductance and capacitance
Solution Approach 1:
The electrical connection system is segmented into thin-film lead electrodes for signal input/output and a thick-film lead electrode for grounding. This segmentation creates a dedicated low-inductance ground path that improves high-frequency characteristics without adding complexity to the signal path
Solution Approach 2:
The thick-film lead electrode provides excessive ground capacity beyond what is minimally required, ensuring that parasitic inductance and capacitance are sufficiently reduced to maintain excellent high-frequency characteristics across a wide bandwidth
3Temperature
If a large heat sink is used to improve heat dissipation, then the temperature control is improved, but the device volume and weight increase
Solution Approach 1:
The heat dissipation function is extracted from the external environment and integrated into the lead electrode structure itself. The thick-film lead electrode serves as an internal heat sink, eliminating the need for large external heat sinks and reducing overall package volume
Solution Approach 2:
The thick-film lead electrode performs multiple functions simultaneously: it provides electrical grounding, serves as a heat dissipation path, and acts as a mechanical support structure. This multi-functionality eliminates the need for separate dedicated heat sink components
4Device complexity
If the same lead electrode is used for both grounding and heat dissipation, then the device structure is simpler, but electrical grounding and heat dissipation cannot be performed separately
Solution Approach 1:
The electrode system is segmented into functionally distinct components: thin-film lead electrodes for input/output, and a thick-film lead electrode that is further divided into grounding and heat dissipation regions. This segmentation enables independent optimization and separate performance of grounding and heat dissipation functions
Solution Approach 2:
The thick-film lead electrode acts as an intermediary structure that connects the semiconductor chip to both the grounding system and the heat dissipation system. Its upper surface provides grounding connection while its lower surface provides heat dissipation connection, mediating between electrical and thermal management requirements
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 solution allows for enhanced heat dissipation and high-frequency performance by separating electrical grounding and heat dissipation, reducing ground inductance and resistance, and preventing excessive temperature increase, even with low heat sink capacity.
Implementation Method 1
a thick-film lead electrode to which the semiconductor chip is die-bonded
Implementation Method 2
a wire which electrically connects the semiconductor chip and the thin-film lead wire
Data Source
AI summary
A semiconductor device having a molded package includes a semiconductor chip, a thick-film lead electrode to which the semiconductor chip is die-bonded, a thin-film lead electrode having a thickness smaller than that of the thick-film lead electrode, a wire which electrically connects the semiconductor chip to the thin-film lead wire, and a molding material in which the semiconductor chip and the wire are encapsulated. A portion of a lower surface of the thick-film lead electrode is exposed at a package lower surface as a heat dissipating electrode. A portion of an upper surface of the thin-film lead electrode is exposed at a package upper surface as an input/output electrode. A portion of an upper surface of the thick-film lead electrode is exposed at the package upper surface as a grounding electrode.