Semiconductor Device Solder Joint Reliability
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Solution Overview
Problem
Conventional semiconductor devices face issues with solder absorption by the electrode plate during joining, leading to a lack of solder at the solder joint due to thermal deformation and warpage, which affects the reliability of the electrical connection.
Innovation Solution
A semiconductor device design where a metal member with a smaller area than the front electrode is fastened to an aluminum or aluminum alloy electrode plate, preventing solder from wetting and spreading on the electrode plate, ensuring a sufficient solder joint between the front electrode and the metal member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the electrode plate area is made larger than the front electrode, then the electrical connection area is improved, but solder is absorbed by the electrode plate causing insufficient solder at the joint
Solution Approach 1:
The electrode plate is divided into two functional zones: a solderable metal member portion (first area) that directly contacts the front electrode with solder, and a non-solderable aluminum portion (second area) that extends beyond the front electrode for electrical connection but does not absorb solder. This segmentation prevents solder absorption while maintaining adequate connection area.
Solution Approach 2:
Different regions of the electrode plate have different surface properties: the metal member portion has a solderable surface (e.g., copper, nickel, or tin plated) that attracts and holds solder, while the aluminum portion has a non-solderable surface that repels solder. This local quality differentiation ensures solder remains at the joint area.
2Ease of manufacture
If heating is applied during solder joining, then the solder melts and forms joints, but thermal deformation and warpage increase the distance between electrode plate and front electrode
Solution Approach 1:
The invention changes the material parameter of the electrode plate by using aluminum (which has high thermal conductivity and low density) for the non-solderable portion. This parameter change reduces the overall thermal mass and thermal deformation during soldering, minimizing warpage and maintaining positioning accuracy.
3Reliability
If solder is used to join the electrode plate to the front electrode, then electrical connection is achieved, but solder spreads and is absorbed by the electrode plate causing lack of solder at the joint
Solution Approach 1:
The metal member (copper, nickel, or tin plated surface) acts as an intermediary between the solder and the aluminum electrode plate. The solder wets and bonds to the metal member surface but does not spread onto the aluminum portion, which serves as a non-absorbing extension. This intermediary layer ensures solder remains concentrated at the joint.
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 prevents solder absorption by the electrode plate, maintaining a reliable and sufficient solder joint, enhancing the electrical connection and reducing thermal stress, while allowing for efficient heat dissipation and cost-effective manufacturing.
Implementation Method 1
a metal member having an area smaller than the front electrode of the semiconductor element in a two-dimensional view and formed of a metal different from the electrode plate, and fastened to the electrode plate to electrically connect the front electrode of the semiconductor element to the electrode plate
Implementation Method 2
the electrode plate having an area larger than the front electrode of the semiconductor element in a two-dimensional view and formed of aluminum or aluminum alloy
Data Source
AI summary
A semiconductor device includes a semiconductor element having a front electrode, an electrode plate having an area larger than the front electrode of the semiconductor element in a two-dimensional view and made of aluminum or aluminum alloy, and a metal member having a joint surface joined to the front electrode of the semiconductor element with solder, having an area smaller than the front electrode of the semiconductor element in a two-dimensional view, made of a metal different from the electrode plate, and fastened to the electrode plate to electrically connect the front electrode of the semiconductor element to the electrode plate.