Electromagnetic Relay Laser-Vented Resin Cover
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Solution Overview
Problem
Conventional electromagnetic relays face hermeticity failures and operational issues due to thermal stress during reflow heating, leading to water and coating agent invasions, which cause contact failures, and existing solutions fail to maintain consistent bonding strength and air permeability.
Innovation Solution
The formation of stable air ventilating openings on the molded resin using laser beam irradiation, with diameters ranging from 0.1µm to 10µm, ensures high air permeability and water resistance, preventing invasion of water and coating agents while maintaining reliability under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromagnetic relay is fully hermetically sealed from the outside, then hermeticity occurs readily due to thermal stress, but water, solvent, or other substances invade from the outside causing operational failure and contacting failure
Solution Approach 1:
The patent applies a porous coating layer on the outer surface of the molded resin cover. This coating layer has pore diameters of 0.01 µm to 1 µm that allow air to pass through while blocking water and other harmful substances. The porous structure enables the relay to maintain air permeability for heat dissipation and pressure equalization during reflow heating, while simultaneously providing water resistance to prevent substance invasion that would cause operational failure.
Solution Approach 2:
The patent uses a composite structure combining the molded resin cover with a porous coating layer made of hydrophobic porous particles dispersed in a binder resin. This composite material configuration allows the coating layer to exhibit both air permeability and water resistance properties, resolving the contradiction between hermeticity and substance invasion prevention.
2Stability of the object's composition
If unsealed through-holes are used to maintain air permeability, then air can escape during reflow heating, but coating agents and water can easily invade into the electromagnetic relay causing operational failure
Solution Approach 1:
Instead of using unsealed through-holes with large apertures, the patent employs a porous coating layer with controlled pore sizes (0.01 µm to 1 µm). The pore size is specifically designed to be small enough to block coating agents and water while large enough to allow air molecules to pass through. This resolves the contradiction by providing air permeability without creating easy pathways for harmful substance invasion.
3Reliability
If conventional sealing resin is used, then the relay can be sealed, but bonding strength is insufficient under diverse reflow heating conditions and hermeticity failure occurs due to excessive thermal expansion
Solution Approach 1:
The patent replaces conventional sealing resin with a porous coating layer composed of hydrophobic porous particles and binder resin. This composite material provides superior bonding strength and thermal stability under diverse reflow heating conditions. The porous structure and hydrophobic properties enable the coating to withstand thermal expansion stresses while maintaining hermeticity and preventing substance invasion.
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 approach effectively prevents operational and contact failures by maintaining air permeability and water resistance, allowing for reflow heating and coating processes without increasing component counts, and ensures consistent performance across various conditions.
Implementation Method 1
one or more through-holes are formed by applying a laser beam to desired positions from an inner surface side thereof
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
An electromagnetic relay is provided which enables a coating process with a coating agent even after being mounted on a printed circuit board having undergone reflow heating by preventing invasion of water while maintaining air permeability. A main body (3) making up the electromagnetic relay includes an electrical contact portion, electromagnetic driving portion and molded resin base (4) and is covered with the molded resin cover (1). One or more through holes (6) are formed by applying laser beam from a rear side of the molded resin cover (1) . A spot diameter of each through hole on a surface of an outside of the molded resin cover (1) is 0.1µm to 10µm. Instead of the molded resin cover (1), through-holes (6) each having a size of 0.1µm to 10µm may be formed by applying the laser beam to the molded resin base (4) . Moreover, a liquid crystal polymer (8) may be used as the molded resin cover (1) or base having a filtering function, by forming holes (11, 12) to pass through only skin layers (9) making up the liquid crystal polymer (8) by applying the laser beam to the liquid crystal polymer (8).