Semiconductor Bonding Substrate Structure for Solder Cavity Suppression
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Solution Overview
Problem
Solder shrinkage cavities occur during the bonding of semiconductor elements to substrates, leading to reduced heat radiation properties and electrical characteristics, particularly in high-temperature and high-current-density applications, necessitating a solution to suppress cavity formation and improve heat radiation.
Innovation Solution
A semiconductor element bonding substrate with a metal pattern featuring concave or grooved regions near the edge of the bonding area, where the solder is supplied and clotted, and varying heights or conductivities to control solder shrinkage, thereby reducing shrinkage cavities and enhancing heat radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-eutectic solder is used for bonding semiconductor elements to insulating substrates, then high reliability is secured, but solder shrinkage cavities easily occur
Solution Approach 1:
The metal pattern is designed with a three-dimensional structure featuring a first region (center) and a second region (periphery) with different heights. This local quality differentiation controls solder flow and solidification patterns, preventing shrinkage cavities while maintaining bonding reliability with non-eutectic solder
Solution Approach 2:
The invention transitions from a conventional planar metal pattern to a three-dimensional structure with varying heights. The first region protrudes higher than the second region, creating a stepped configuration that guides solder distribution and prevents cavity formation during solidification
2Temperature
If solder shrinkage cavity occurs immediately below semiconductor element, then heat radiation property is reduced, but it leads to reduction in electrical characteristics
Solution Approach 1:
The differentiated height structure creates zones with different thermal and mechanical properties. The first region provides superior heat radiation due to better solder contact, while the second region controls shrinkage behavior, thereby maintaining both thermal and electrical characteristics
3Reliability
If shrinkage cavity occurs in solder, then heat radiation property and electrical characteristics are reduced, but it requires melting solder again or discarding element, reducing productivity
Solution Approach 1:
The three-dimensional metal pattern structure is prepared in advance to preemptively control solder solidification behavior. The height-differentiated design pre-establishes pathways for solder flow and shrinkage, preventing cavity formation before it occurs and eliminating the need for remelting or discarding
Solution Approach 2:
The invention converts the natural solder shrinkage phenomenon from a harmful effect into a beneficial one by designing the metal pattern to guide shrinkage away from the semiconductor element contact area. The second region's lower height allows controlled shrinkage that does not compromise the bonding quality or create cavities
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 suppresses solder shrinkage cavities, improving heat radiation properties and maintaining stable operation in semiconductor devices, especially those using wide bandgap semiconductors like SiC and GaN.
Implementation Method 1
When the melted solder is clotted, the solder filling the inner side of the concave part shrinks
Data Source
AI summary
A semiconductor element bonding substrate according to the present invention includes an insulating plate, and a metal pattern bonded to a main surface of the insulating plate. A main surface of the metal pattern on an opposite side of the insulating plate includes a bonding region to which a semiconductor element is bonded by a solder. The metal pattern includes at least one concave part located in the main surface. The at least one concave part is located closer to an edge of the bonding region in relation to a center part of the bonding region in the bonding region.