Power Semiconductor Module Flat Contacts
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Solution Overview
Problem
Existing power semiconductor modules with high current density in plastic housings face challenges with heat loss dissipation and miniaturization due to high connecting resistance and reliability issues with bonding wires and clamping clip methods, which limit further integration and miniaturization.
Innovation Solution
A power semiconductor module with surface-mountable flat external contacts uses an insulation layer and metallic connecting layers to create large-area connections without additional substrates, allowing for reduced contact area sizes and improved heat dissipation, while avoiding the limitations of bonding wires and clamping clips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding wires are used for contact-making, then connections can be established between semiconductor chip and leadframe, but the small cross-sectional areas lead to high connecting resistance and obstacle to chip miniaturization
Solution Approach 1:
The patent extracts the bonding wire from the contact-making process and replaces it with a planar connecting technique using metallic layers deposited directly on the leadframe. This eliminates the wire's physical presence and its associated resistance and miniaturization obstacles.
Solution Approach 2:
The mechanical bonding wire system is replaced by a planar metallic connection system. Instead of using physical wires that require bonding and occupy space, the patent uses deposited metallic layers that create direct electrical and thermal pathways with lower resistance and no mechanical obstructions.
2Reliability
If bonding wires are used for contact-making, then connections can be established, but thermomechanical loading and bonding wire drifting during molding reduce reliability
Solution Approach 1:
The patent removes the bonding wire entirely from the system, eliminating it as a source of thermomechanical stress and drifting. The planar metallic connection remains fixed to the leadframe and is not subjected to the same mechanical vulnerabilities.
Solution Approach 2:
The planar metallic connection structure is designed to inherently withstand thermomechanical loading and molding processes. The direct deposition of metallic layers creates a robust connection that is pre-adapted to withstand the manufacturing and operational stresses without drifting or failing.
3Reliability
If clamping clip method is used for contact-making, then large-area contact reduces electrical resistance and improves heat dissipation, but the dimensions limit advancing integration and miniaturization
Solution Approach 1:
The patent transitions from the three-dimensional clamping clip structure to a two-dimensional planar connection system. The metallic layers are deposited in flat patterns on the leadframe surface, creating large-area contacts without the vertical height and physical bulk of clips, thereby enabling higher integration density.
Solution Approach 2:
The patent uses thin metallic films deposited on the leadframe to create large-area contact regions. These thin film connections provide extensive electrical and thermal pathways without the dimensional constraints of rigid clamping structures, allowing for compact and densely integrated designs.
4Reliability
If clip construction is used for contact-making, then heat dissipation is improved, but the low flexibility necessitates new clip constructions for each contact area arrangement
Solution Approach 1:
The patent applies metallic layers with locally optimized patterns and thicknesses to different regions of the leadframe. This allows each contact area to be tailored for its specific electrical and thermal requirements while maintaining the overall flexibility of the planar connection system to adapt to various arrangements.
Solution Approach 2:
The planar metallic connection system serves multiple functions simultaneously: it provides electrical connectivity, thermal pathways, and mechanical support. The same deposited metallic layers fulfill all these roles, eliminating the need for separate clip constructions and enabling universal application across different contact area arrangements.
5Reliability
If soldering is used for contact-making, then connections can be established, but flux residues adversely influence reliability and fatigue cracks reduce reliability
Solution Approach 1:
The chemical soldering process is replaced by physical deposition of metallic layers. Instead of using flux and heat to melt solder, the patent uses vapor deposition or sputtering to directly deposit conductive metallic films, completely eliminating flux residues and associated reliability issues.
Solution Approach 2:
The patent replaces the complex, multi-step soldering process with a simpler, more reliable metallic layer deposition. The deposited metallic layers serve as permanent, maintenance-free connections that do not require flux cleaning or suffer from fatigue cracks, effectively replacing a problematic process with a superior alternative.
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 solution enables low electrical resistance, efficient heat dissipation, increased integration density, and flexibility in module construction, reducing reliability issues and allowing for continuous miniaturization without the need for new clamping clips or external conductors.
Implementation Method 1
the connections are produced by means of bonding wires made of gold or aluminum, the contact between the bonding wires and the contact areas on the semiconductor chip and also the contact areas on a leadframe arising as a result of the metals involved being alloyed
Implementation Method 2
This is because said heat loss has to be dissipated within the plastic housing via connections with the highest possible electrical and thermal conductivity from the contact areas of the semiconductor chip to corresponding connection contacts of a metallic leadframe
Data Source
AI summary
A power semiconductor module having surface-mountable flat external contact areas and a method for producing the same is disclosed. In one embodiment, the top sides of the external contacts form an inner housing plane, on which at least one power semiconductor chip is fixed by its rear side on a drain external contact. An insulation layer covers the top side over the edge sides of the semiconductor chip as far as the inner housing plane whilst leaving free the source and gate contact areas on the top side of the semiconductor chip and also whilst partly leaving free the top sides of the corresponding external contacts. Arranged on the insulation layer is a connecting conductive layer between the source contact areas on the top side of the semiconductor chip and the top sides of the source external contacts, and also a gate connecting layer from the gate contact areas to the top side of the gate external contact.