Split Electrode Mounting Structure Prevents Solder Rise
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Solution Overview
Problem
Existing electronic component mounting technologies face challenges in solder mounting, particularly in small spaces, as solder can rise to the metal substrate causing short-circuit defects due to the proximity of split electrodes to the metal substrate.
Innovation Solution
The electronic component mounting structure features split electrodes with lands positioned inside the peripheral end portion of the metal substrate, ensuring solder applied to the lands does not reach the substrate, and a protective insulating layer prevents solder rise, allowing for flexible mounting in tight spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder mounting is performed on lands formed on the printed circuit board, then electrical connection is achieved, but solder rise from the lands to the metal substrate occurs causing short-circuit defects
Solution Approach 1:
The invention divides the electrode structure into separate components: split electrodes formed on the ceramic layer are electrically isolated from the metal substrate by insulating coatings. This segmentation prevents solder from creating electrical paths between the substrate and electrodes, eliminating short-circuit defects while maintaining reliable electrical connections through the intended solder joints on the split electrodes.
Solution Approach 2:
An insulating coating is introduced as an intermediary layer between the metal substrate and the solder. This intermediate insulating layer acts as a barrier that prevents solder from wetting and rising onto the metal substrate surface, thereby eliminating the short-circuit defect while allowing solder to properly attach to the split electrodes for electrical connection.
2Reliability
If wire bonding is used to connect to the electrode film, then electrical connection is achieved, but mounting in extremely small spaces becomes impossible
Solution Approach 1:
The invention replaces the mechanical wire bonding process with a solder mounting system. Instead of requiring manual or automated wire bonding operations that need substantial access space, the design enables direct solder attachment to the split electrodes. This substitution of the connection method eliminates the need for complex wire bonding equipment and operations, allowing mounting in extremely small spaces of 150 to 200 μm.
3Device complexity
If the metal substrate is used as one electrode and the electrode film as the other electrode, then a simple structure is achieved, but solder rise to the metal substrate causes short-circuit defects
Solution Approach 1:
The invention applies different properties to different parts of the electrode system: the metal substrate serves as the mechanical support and one electrode, while the split electrodes on the ceramic layer serve as the other electrode. The insulating coating is selectively applied to the metal substrate in areas where solder contact would cause short-circuits, creating local quality differentiation that maintains both structural simplicity and electrical reliability.
Data Source
Figure 1~2(B)
Figure 3~4
Figure 5(A)~6
AI summary
According to the present invention, there are provided an electronic-component mounting structure and an electronic-component mounting method, in each of which solder mounting can be performed, and solder rise is not likely to occur. The electronic-component mounting structure includes an electronic component which has a metal substrate, a semiconductor ceramic layer formed on the metal substrate, a pair of split electrodes formed on the semiconductor ceramic layer, and plating films formed on the split electrodes and the metal substrate; and a mounting body on which lands to be connected to the respective split electrodes of the electronic component are formed. The position of a peripheral end portion of each land to be connected to the corresponding split electrode is located inside than the position of a peripheral end portion of the split electrode. In addition, a plane area of the land is smaller than that of the split electrode.