Leadframe Spacer Assembly for Double-Sided Power Module Reliability
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Solution Overview
Problem
Conventional semiconductor power module packaging faces challenges with coefficient of thermal expansion (CTE) mismatches between spacers and substrates, leading to mechanical stress, delamination, and peeling at solder joints, which affects electrical and thermal reliability.
Innovation Solution
A leadframe spacer with a shared die attach pad (DAP) and downsets provides a single, cost-effective solution that reduces thermal and mechanical stress, improving mechanical reliability and thermal resistance by enclosing semiconductor devices within a recess, and allowing for dual-sided cooling configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional spacers are used in power module packaging, then mechanical support is provided, but CTE mismatch causes mechanical stress, delamination, and peeling at solder joints
Solution Approach 1:
The patent combines the spacer and leadframe into a single integrated leadframe spacer structure. This merging eliminates the CTE mismatch interface between separate spacer and substrate materials, as the leadframe spacer is made from the same material as the leadframe, providing both mechanical support and electrical connectivity without delamination or peeling issues
Solution Approach 2:
The leadframe spacer utilizes composite construction with a metal leadframe body providing structural support and copper traces providing electrical connectivity. This composite approach allows optimization of each function while using materials with matched CTE properties throughout the structure, eliminating interfacial stress from material mismatches
2Adaptability or versatility
If multiple separate components are used for spacer and leadframe, then functional requirements are met, but manufacturing cost and complexity increase
Solution Approach 1:
The patent integrates the spacer function and leadframe function into a single component called the leadframe spacer. This consolidation reduces the number of discrete parts from two (spacer + leadframe) to one, simplifying assembly procedures, reducing manufacturing steps, and lowering overall complexity while maintaining all required functions of both original components
Solution Approach 2:
The leadframe spacer serves multiple functions simultaneously: it provides mechanical support as a spacer, establishes electrical connections as a leadframe, and offers thermal pathways. This multi-functionality eliminates the need for separate dedicated spacer and leadframe components, reducing device complexity while maintaining full functional capability
3Reliability
If conventional packaging is used, then basic electrical connection is achieved, but thermal resistance is high and power capability is limited
Solution Approach 1:
The leadframe spacer acts as an intermediary thermal pathway between the semiconductor devices and the heat sink. The copper traces and downset surfaces of the leadframe spacer provide low thermal resistance pathways that mediate heat transfer, improving thermal management while maintaining electrical connection functions
Data Source
AI summary
A semiconductor device module may include a leadframe spacer that provides the functions of both a leadframe and a spacer, while enabling a double-sided cooling configuration. Such a leadframe spacer may include a leadframe surface that provides a die attach pad (DAP) that is shared by at least two semiconductor devices. The leadframe spacer may include at least one downset, where the semiconductor devices may be attached within a recess defined by the at least one downset. A first substrate may be connected to a first side of the leadframe. A second substrate may be connected to downset surfaces of the at least one downset, and positioned for further connection to the semiconductor devices in a double-sided assembly.