Semiconductor Terminal Segmentation for Solder Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing power semiconductor modules face issues with insulation failure and separation between the circuit board and insulating plate due to solder spreading and heat stress during heat cycle or shock tests, limiting the degree of freedom in circuit board disposition.
Innovation Solution
The semiconductor device employs terminals with a cylindrical leading end and a wiring portion of a different shape, formed from a single conductive member, which reduces solder spreading and enhances joining reliability by using a conductive joining material that forms a fillet between the circuit board and terminal, preventing insulation failure and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal leading end is folded in an L-shape and soldered to the circuit board, then the terminal can be electrically and mechanically connected to the circuit board, but the melted solder may scatter and adhere to the side surface of the circuit board causing insulation failure
Solution Approach 1:
The terminal is divided into two distinct portions: a leading end portion with a cylindrical shape for soldering, and a wiring portion with a shape other than cylinder for electrical connection. This segmentation prevents the solder from scattering to the side surface of the circuit board while maintaining reliable electrical connection.
Solution Approach 2:
Different portions of the terminal are given different shapes tailored to their specific functions. The leading end portion has a cylindrical shape optimized for soldering, while the wiring portion has a different shape optimized for electrical connection, thereby preventing harmful solder scattering while ensuring connection reliability.
2Strength
If the melted solder spreads to the end portion of the circuit board, then the terminal can be sufficiently joined to the circuit board, but heat stress is generated due to the difference in linear expansion coefficient between the solder and the circuit board causing separation from the insulating plate
Solution Approach 1:
By segmenting the terminal into a cylindrical leading end portion for soldering and a non-cylindrical wiring portion for connection, the solder is confined to a controlled area that provides sufficient joining strength without spreading to the end portion of the circuit board, thereby preventing heat stress-induced separation.
Solution Approach 2:
The terminal's leading end portion is given a cylindrical shape that locally optimizes the soldering process, providing adequate joining strength while preventing excessive solder spread to areas where heat stress would cause separation from the insulating plate.
3Reliability
If measures are taken to space the joining position of the terminal from the end portion of the circuit board and increase the area of the circuit board, then insulation failure and separation are prevented, but the degree of freedom of disposition of the circuit board is limited
Solution Approach 1:
The terminal is segmented into a cylindrical leading end portion and a non-cylindrical wiring portion, which maintains insulation reliability by preventing solder spread while preserving the degree of freedom in circuit board disposition without requiring increased circuit board area or restricted positioning.
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
This configuration effectively prevents insulation failure and separation between the circuit board and insulating plate, while improving the degree of freedom in circuit board disposition and reducing manufacturing costs by minimizing the need for complex soldering processes.
Implementation Method 1
The solder melted by being heated coagulates in the vicinity of the leading end of the terminal due to surface tension
Implementation Method 2
the leading end of the terminal is lapped on a solder paste applied to the circuit board and is heated. The solder melted by being heated
Data Source
AI summary
A semiconductor device includes a laminated substrate having a circuit board; a semiconductor chip fixed to the circuit board; a terminal having a leading end portion with a cylindrical shape and a wiring portion with a shape other than the cylinder, the leading end portion and the wiring portion being formed of one conductive member; and a joining material which electrically and mechanically connects the circuit board and the leading end portion.