Metal-Frame Power Module Assembly to Cut Cost and Yield Loss
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Solution Overview
Problem
The high cost and complexity of producing custom power modules with integrated power electronic substrates, such as DBC, IMS, and AMB substrates, make them prohibitively expensive for lower volume applications, and the risk of yield losses due to single die failures in multi-die modules is significant.
Innovation Solution
A power module design featuring a metal frame with device attach pads and semiconductor packages encapsulated in a potting compound, where the semiconductor packages are mounted on the metal frame with electrical connections to interconnect bars and circuit boards, allowing for pre-qualification of packages and reduced yield losses, and utilizing standard metal processing techniques for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If custom power modules with integrated power electronic substrates (DBC, IMS, AMB) are used, then power electronic circuitry performance is improved, but production cost increases significantly
Solution Approach 1:
The invention divides the power module into separate functional components: pre-assembled semiconductor packages (containing power electronic circuitry) and a metal frame structure. This segmentation allows the expensive power electronic substrates to be replaced with simpler, lower-cost metal frame and PCB assemblies, significantly reducing production costs while maintaining electrical functionality
Solution Approach 2:
The metal frame serves multiple functions: it provides structural support, acts as an electrical interconnection system, and enables mounting of semiconductor packages. This multi-functionality eliminates the need for specialized power electronic substrates (DBC, IMS, AMB), allowing use of standard, lower-cost metal fabrication processes
2Device complexity
If multiple semiconductor dies are provided in a single power module, then integration is improved, but yield loss increases due to single die failures
Solution Approach 1:
The invention uses separate, pre-tested semiconductor packages instead of integrating multiple dies into a single module. Each package is independently qualified before assembly, so if one package fails in the final module, only that single package needs replacement rather than discarding the entire module. This maintains integration benefits while reducing yield loss
Solution Approach 2:
Semiconductor packages are pre-assembled and pre-qualified (tested) before being integrated into the final power module. This preliminary qualification ensures each package is functional and reliable before system assembly, preventing propagation of defects and reducing the impact of failures on overall module yield
3Ease of manufacture
If standard metal processing techniques are used instead of specialized substrate processing, then manufacturing cost is reduced, but manufacturing precision may be affected
Solution Approach 1:
The invention separates precision-critical semiconductor package assembly (done using proven, precise processes in separate packages) from the lower-precision metal frame fabrication. This allows standard metal processing to be used for the frame and PCB assemblies without compromising the precision requirements of the power electronic connections, which are handled in the pre-qualified packages
Solution Approach 2:
The invention introduces intermediate connection structures (PCB assemblies, connection spans, interconnect bars) that bridge the metal frame and semiconductor packages. These intermediaries provide precise electrical and mechanical connections, compensating for any tolerances in the standard metal processing of the frame structure
Data Source
AI summary
A power module includes a metal frame a metal frame having first and second device attach pads, first and second semiconductor packages each having an encapsulant body and a plurality of leads protruding out from the encapsulant body, and a potting compound that encapsulates both of the first and second semiconductor packages, wherein the first semiconductor package is mounted on the first device attach pad, wherein the second semiconductor package is mounted on the second device attach pad, and wherein terminals from each of the first and second semiconductor packages are electrically accessible from outside of the potting compound.