Segmented Pull-Back Substrate Layout to Prevent Metallization Cracks
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Solution Overview
Problem
Power semiconductor module substrates with pull-back designs face increased risks of cracks in metallization layers when heated, due to high tensions in the dielectric insulation layer caused by temperature and the bi-metallic effect.
Innovation Solution
A substrate design featuring a dielectric insulation layer with alternating sections of full pull-back and reduced or no pull-back, where the difference in distances between the metallization layers and the dielectric insulation layer's edge varies, reducing tensions and crack formation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pull-back design is used where the second metallization layer is smaller than the first metallization layer, then the solder area is reduced and the risk of solder leak and solder splash is reduced, but the risk of cracks forming in the metallization layers increases when heated
Solution Approach 1:
The outer edge of the dielectric insulation layer is divided into multiple sections (first sections and second sections) with different pull-back characteristics. The first sections have a first pull-back distance while the second sections have a second pull-back distance, creating segmented zones that distribute thermal stress differently across the substrate structure.
Solution Approach 2:
Different sections of the substrate are given different local properties: some sections have larger pull-back distances to reduce solder area and prevent solder leakage, while other sections have smaller pull-back distances to maintain metallization layer integrity and prevent cracks under thermal stress.
2Area of stationary object
If the size of the second metallization layer is made larger than the first metallization layer, then the mounting surface area is increased, but the risk of solder leak and solder splash increases
Solution Approach 1:
The substrate structure is segmented into different radial zones with varying metallization layer sizes and pull-back distances, allowing simultaneous optimization of mounting area and solder containment in different sections.
Solution Approach 2:
The solution moves from a uniform two-dimensional metallization layer design to a three-dimensional structured approach with varying pull-back distances at different radial positions, creating zones of different functionality within the same substrate plane.
3Ease of manufacture
If uniform pull-back distance is applied around the entire substrate, then the manufacturing process is simplified, but the risk of cracks in metallization layers increases under thermal stress
Solution Approach 1:
The uniformly simple manufacturing process is segmented into different zones with specific pull-back characteristics, where first sections and second sections are defined with different distance relationships between the dielectric insulation layer edge and metallization layer edges.
Solution Approach 2:
Instead of uniform properties throughout, the substrate implements local quality variations where specific sections have optimized pull-back distances tailored to their functional requirements, balancing manufacturing feasibility with crack prevention.
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 design combines the advantages of pull-back and no-pullback designs, significantly reducing the risk of cracks in metallization layers while maintaining the benefits of pull-back configurations, particularly at sensitive corners and areas prone to cracking.
Implementation Method 1
When the metallization layers are heated to temperatures above defined threshold temperatures... increased tensions in the dielectric insulation layer due to temperature and the bi-metallic effect
Implementation Method 2
increased tensions in the dielectric insulation layer due to temperature and the bi-metallic effect
Data Source
AI summary
A substrate includes a dielectric insulation layer, a first metallization layer arranged on a first surface of the dielectric insulation layer, and a second metallization layer arranged on a second, opposite surface of the dielectric insulation layer. The dielectric insulation layer includes an outer edge extending between the first and second surfaces. The outer edge includes first sections and second sections. Along each first section, a difference between a first distance and a second distance has a first value. Along each second section, the difference between the first and second distances has a second value that is different from the first value. The first distance is a distance between the outer edge of the dielectric insulation layer and an outer edge of the first metallization layer. The second distance is a distance between the outer edge of the dielectric insulation layer and an outer edge of the second metallization layer.