Power Semiconductor Lead Terminals with Asymmetric Base Portions
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Solution Overview
Problem
Power semiconductor devices face limitations in miniaturization due to the need for insulation and heat dissipation, and existing resin-sealed designs can lead to short-circuiting of lead terminals when mounted on substrates.
Innovation Solution
A power semiconductor device design featuring lead terminals with varying base portion lengths and a coating resin that extends over the base portions, ensuring adequate insulation and preventing short-circuiting, while allowing for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If lead terminals are only coated with resin as in PTL 1, then the distance between adjacent lead terminals can be reduced, but short-circuiting of soldered portions occurs when mounted on substrate
Solution Approach 1:
The patent applies different properties to different parts of the lead terminal structure. The base portion is covered with coating resin to provide insulation where soldering occurs, while the tip end portion remains exposed for electrical connection. This localized differentiation allows reduced overall distance between terminals while maintaining insulation where needed.
Solution Approach 2:
Adjacent lead terminals are designed with asymmetric base portion lengths, creating staggered positions for their soldered portions. This asymmetric arrangement increases the effective insulation distance between solder joints while allowing the overall device footprint to be reduced, resolving the contradiction between compact size and reliable insulation.
2Reliability
If insulation distance between lead terminals is increased, then short-circuiting is prevented, but device miniaturization is limited
Solution Approach 1:
Instead of increasing insulation distance in the horizontal plane (which would increase device size), the patent utilizes the vertical dimension by extending the base portion downward and applying coating resin to the soldered portions. This dimensional transition allows adequate insulation while maintaining a compact overall device footprint.
Solution Approach 2:
The coating resin acts as an intermediary insulating layer between adjacent lead terminals at their soldered portions. This intermediate protective layer provides reliable insulation without requiring increased physical separation between terminals, enabling device miniaturization while preventing short-circuiting.
3Ease of manufacture
If base portions of adjacent lead terminals are made equal in length, then manufacturing is simplified, but soldered portions may short-circuit when mounted
Solution Approach 1:
The patent intentionally introduces asymmetry in base portion lengths of adjacent lead terminals. This asymmetric design staggers the position of soldered portions, increasing the insulation distance between them while still allowing for practical manufacturing through standardized coating processes.
Solution Approach 2:
The patent modifies the geometric parameter of base portion length to create different lengths for adjacent terminals. This parameter change achieves better insulation between soldered portions while the coating resin application process remains sufficiently flexible to accommodate these variations without significantly complicating manufacturing.
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 effectively suppresses short-circuiting between lead terminals, enabling miniaturization of power semiconductor devices while maintaining effective insulation and heat dissipation.
Implementation Method 1
In forming the coating resin, a charged resin material diffused into a spray adheres to a surface of the base portion
Data Source
AI summary
A lead member includes a plurality of lead terminals, and the lead terminals extend from the inside to the outside of a mold resin. Each of the lead terminals has a base portion and a tip end portion on the outside of the mold resin. The base portion is disposed on a region side having a semiconductor element and extends in a direction protruding from the mold resin. The tip end portion extends in a direction different from the base portion and is disposed on the opposite side to a region having the semiconductor element as viewed from the base portion. The length by which the base portion extends differs between a pair of lead terminals adjacent to each other, among the lead terminals. At least a surface of the base portion of each of the lead terminals is covered with a coating resin.