Power Semiconductor Package Electrode Structure for Reliable Solder Bonding
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Solution Overview
Problem
Conventional power semiconductor devices face challenges in securing a favorable solder bonding portion due to difficulties in raising the temperature of the lead frame and the low thermal conductivity of insulating resin spacers, leading to inadequate bonding thickness and reliability.
Innovation Solution
A power semiconductor device configuration that includes a semiconductor element mounted on a heat radiation fin with an insulating layer, a case bonded to the fin, and internal and external electrodes, using conductive bonding materials like solder with Ni plating for improved wettability, and a manufacturing method that involves bonding the semiconductor element to the circuit pattern and electrodes with heat conduction from the fin, ensuring secure bonding thickness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first lead frame and semiconductor chip are bonded with interposition of solder requiring heating to melt the solder, then solder bonding can be achieved, but the temperature rise is insufficient due to the low thermal conductivity of the first spacer made of insulating resin, resulting in inadequate bonding thickness and reliability
Solution Approach 1:
The patent introduces a heat radiation fin made of heat-conductive resin as an intermediary component between the solder joint and the insulating spacer. This fin serves as a thermal bridge that efficiently conducts heat from the solder bonding zone to the heat dissipation structure, resolving the temperature rise insufficiency caused by the low thermal conductivity of the insulating spacer while maintaining electrical insulation properties
Solution Approach 2:
The patent employs composite materials strategy by using heat-conductive resin for the lead frame and heat radiation fin, which combines the advantages of electrical insulation (from resin) with thermal conduction (from filler particles). This composite structure enables simultaneous achievement of electrical insulation and effective heat dissipation, solving the contradiction between maintaining insulating properties and achieving sufficient temperature rise for reliable solder bonding
2Stability of the object's composition
If a new adhesive preparation and bonding step is added to bond the first spacer to the circuit pattern and first lead frame, then the spacer can be securely attached, but the manufacturing process complexity increases and productivity decreases
Solution Approach 1:
The patent merges the spacer attachment function with the existing lead frame structure by forming the second spacer as an integrated part of the lead frame. This eliminates the need for separate adhesive application and bonding steps, as the spacer is inherently attached to the lead frame through the molding process, thereby reducing manufacturing process complexity while maintaining attachment stability
Solution Approach 2:
The lead frame structure is designed to self-attach the spacer through its own geometric features and material properties. The second spacer is formed as an integral extension of the lead frame, creating a self-supporting and self-attached structure that does not require external adhesives or additional bonding processes, thus simplifying the manufacturing workflow
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 achieves high-quality and highly reliable bonding with secured thickness, improving the productivity of the manufacturing process and enhancing the thermal management of the semiconductor device, preventing overheating and ensuring stable operation.
Implementation Method 1
bonding the semiconductor element to the circuit pattern and electrodes with heat conduction from the fin
Implementation Method 2
bonding the semiconductor element to an internal electrode, and bonding the internal electrode to the circuit pattern
Implementation Method 3
bonding materials like solder with Ni plating for improved wettability
Implementation Method 4
conductive bonding materials like solder with Ni plating for improved wettability
Data Source
AI summary
A semiconductor element is bonded to a circuit pattern integrated with an insulating layer and a heat radiation fin, a case is bonded to a peripheral edge of the heat radiation fin so as to surround the semiconductor element, the circuit pattern, and the insulating layer, and a sealing resin is sealed in a region surrounded by the insulating layer, the circuit pattern, and the case. An internal electrode includes a flat plate-shaped portion, and is provided with a through hole and a pair of bent and inclined-shaped support portions. The support portion is bonded to the circuit pattern, and the upper surface of the semiconductor element, the through hole, and an embossed portion provided around the through hole are bonded. The internal electrode, and an external electrode integrally molded with the case, are bonded.