Semiconductor Package Locking Structure for Delamination Resistance
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Solution Overview
Problem
Existing power semiconductor packages face delamination issues due to thermomechanical stress caused by temperature cycling and power cycling, exacerbated by screw elements that increase stress and lead to cracking between the epoxy and baseplate, as well as between the substrate and epoxy.
Innovation Solution
Incorporating a baseplate with through holes and an insulating body featuring locking structures with chamfered shapes that extend through the baseplate, which are filled with epoxy to securely attach the insulating body to the baseplate, reducing delamination by distributing stress and preventing movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screw elements are used to couple the baseplate to the heatsink and busbar assembly, then mechanical connection and electrical conduction are achieved, but inner stress and delamination increase
Solution Approach 1:
The baseplate is divided into multiple segments with individual locking structures (protrusions and recesses) distributed across its surface. This segmentation allows stress to be distributed across multiple localized connection points rather than concentrated at screw locations, reducing overall delamination risk while maintaining mechanical strength
Solution Approach 2:
The locking structures combine mechanical interlocking (protrusions fitting into recesses) with epoxy bonding in a unified system. This merging of mechanical and chemical bonding mechanisms provides both immediate structural strength and long-term stress distribution, addressing both connection strength and delamination resistance
2Ease of operation
If through hole technology with nuts is used to facilitate busbar assembly placement, then ease of assembly is improved, but device complexity and stress concentration increase
Solution Approach 1:
The nut component is extracted from the design and replaced with integrated locking structures (protrusions and recesses) formed directly in the baseplate. This eliminates the need for separate nuts while maintaining the ease of assembly function, as the locking features are built-in and require no additional parts
Solution Approach 2:
The locking structures serve multiple functions: they provide mechanical interlocking, distribute stress, and facilitate assembly. By making the baseplate features multi-functional, the design eliminates the need for separate components like nuts, reducing complexity while maintaining ease of operation
3Reliability
If epoxy is used to provide mechanical support and electrical insulation, then electrical insulation and protection are achieved, but thermomechanical stress causes delamination between epoxy and baseplate
Solution Approach 1:
Locking structures (protrusions and recesses) are built into the baseplate before epoxy application. These pre-formed features create mechanical interlocking that cushions and resists the delamination forces generated by thermomechanical stress, protecting the epoxy-baseplate bond while maintaining electrical insulation properties
Solution Approach 2:
The solution creates a composite bonding system combining epoxy (chemical bonding) with mechanical interlocking features (physical bonding). This composite approach leverages both chemical and mechanical bonding mechanisms to achieve superior bond strength and delamination resistance while maintaining the electrical insulation function of the epoxy
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 effectively reduces delamination and stress-related cracking by maintaining a secure attachment between the insulating body and baseplate, enhancing the structural integrity and reliability of the semiconductor package.
Implementation Method 1
forming the insulating body as a monolithic moldable material, wherein the monolithic moldable material flows into the plurality of lock holes
Data Source
AI summary
A power semiconductor device package. The package may include a baseplate that has a plurality of through holes. The package may also include an insulating body, affixed to a top side of the baseplate The insulating body may include a main portion, to enclose a set of semiconductor devices therein, and a plurality of locking structures, the plurality of locking structures disposed along a lower periphery of the main portion, and integrally formed within the insulating body, wherein the plurality of locking structures extend through the baseplate.