Push Switch External Terminal Solder Reservoir Design
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Solution Overview
Problem
The existing push switch terminal structure requires a larger mounting area due to excessive solder accumulation, which interferes with device miniaturization and increases manufacturing costs due to complex mold processes for bending terminal portions.
Innovation Solution
The push switch design includes an insulative case with external connecting terminals that have a first portion opposing the land and a second portion with a larger area to accommodate excessive solder, preventing terminal lifting and reducing the mounting area, while eliminating the need for complex mold processes by integrating terminal portions within the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the land is extended to the outside of the push switch to save excessive solder, then the terminal lifting problem is prevented, but the mounting area increases
Solution Approach 1:
The external connecting terminal is designed with a two-layer structure: a first layer opposing the land for solder connection, and a second layer extending in a different spatial dimension (parallel to the circuit board) to provide solder storage capacity. This dimensional transformation allows the terminal itself to serve as a solder reservoir without requiring land extension, thereby maintaining compact mounting area while ensuring reliable fixing.
2Reliability
If excessive solder remains between the terminal portion and the land, then the conductive state is maintained, but the terminal portion is pushed up causing the push switch to lift
Solution Approach 1:
The harmful effect of excessive solder is extracted and redirected from the vertical space between the terminal and land to the horizontal extension of the terminal itself. The second layer of the external connecting terminal acts as a dedicated solder storage zone, separating the solder accumulation function from the electrical connection function, thus preventing terminal lifting while maintaining conductivity.
3Ease of manufacture
If the terminal portions are bent upward to form external connection terminals, then the electrical connection is achieved, but the manufacturing process becomes complex
Solution Approach 1:
The external connecting terminal is designed as an integrated structure formed in a single molding process, combining the electrical connection function and the solder storage function into one unified component. The two-layer structure is created during the initial molding of the switch housing, eliminating the need for separate bending or forming operations, thus simplifying the manufacturing process while achieving the desired electrical and mechanical functions.
Data Source
AI summary
A switch includes an insulative case with fixed electrodes and a movable electrode therein. The case includes a first surface configured to contact with a circuit board and a second surface configured to oppose to the circuit board via a gap. The movable electrode moves between a first position for placing the fixed electrodes in a conductive state and a second position for placing the fixed electrodes in a nonconductive state. Each of the fixed electrodes includes a contact terminal which contacts with the movable electrode and an external connecting terminal exposed on the second surface and soldered to a land of a wiring terminal on the circuit board. The external connecting terminal includes a first portion opposed to the land and a second portion connected to the first portion that has an area larger than an area of the first portion.