Resin-Sealed Lead Frame Switch Assembly Against Solder Corrosion
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Solution Overview
Problem
The reliability of switch devices is compromised due to exposure of solder joints to moisture and sulfide gases, leading to corrosion and potential failures in electrical connections.
Innovation Solution
A switch device design featuring conductive lead frames with surface-mounted electric elements sealed with resin, along with a contact-separation mechanism, to prevent corrosion and ensure reliable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the resistor is attached to the holding member by soldering and accommodated in the case in an exposed state, then the manufacturing process is simple, but the reliability of the solder joint deteriorates due to corrosion from moisture and sulfide gases
Solution Approach 1:
The patent applies a resin sealing structure that encapsulates the soldered resistor, creating a protective barrier against moisture and sulfide gases. This sealing film prevents corrosive substances from reaching the solder joint while maintaining the simplicity of the original manufacturing process.
Solution Approach 2:
The resin sealing creates an inert protective environment around the solder joint, isolating it from corrosive atmospheric elements such as moisture and sulfide gases. This inert barrier prevents oxidation and corrosion reactions that would otherwise degrade the solder joint reliability.
2Reliability
If the electric element is surface-mounted on the lead frames and sealed with resin, then the reliability of solder joints is maintained, but the device complexity increases
Solution Approach 1:
The patent combines the sealing function with the existing case structure by integrating the resin sealing into the overall device housing. This merging approach adds protection without requiring a completely separate sealing system, thereby limiting the increase in device complexity.
Solution Approach 2:
The resin sealing is implemented as a thin protective film that conforms to the components it protects. This thin-film approach provides effective corrosion protection while adding minimal structural complexity and maintaining a compact device design.
Data Source
AI summary
A switch device includes a plurality of lead frames that is conductive and configured to electrically connectable to an external device, a contact-separation mechanism configured to allow the plurality of lead frames to be electrically connected to and separated from each other, and an electric element configured to connect the plurality of lead frames to each other. The electric element is surface-mounted on the lead frames and sealed with resin. In each of the lead frame, the boundary, such as a groove or a notch, is formed along the outer edge of the arrangement position of the electric element.