Resin-Filled Casing Geometry to Prevent Injection Gate Run-Out
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Solution Overview
Problem
Electronic devices filled with resins having high linear expansion coefficients face issues with resin running out due to thermal expansion, leading to damaged appearances and compromised sealing and water resistance, especially when used in high-temperature environments.
Innovation Solution
A tubular casing with a filling resin confining surface, positioned opposite to the injection gate, having a specific distance and area to absorb expansion stress in the longitudinal direction, preventing resin run-out while maintaining fillability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resin having a low hardness is used in order to suppress sealing-resin-derived stress damage, then the resin will expand when the device is used under a high-temperature environment since resins having a low hardness typically have a high linear expansion coefficient
Solution Approach 1:
The patent introduces a filling resin confining surface with specific geometric parameters (distance from injection gate, surface area) to control the behavior of thermally expanding resin. By adjusting these parameters, the confining surface absorbs expansion stress while preventing resin run-out, thus resolving the contradiction between using soft resin for stress damage suppression and preventing thermal expansion issues.
Solution Approach 2:
The filling resin confining surface acts as an intermediary structure between the injection gate and the resin. It mediates the thermal expansion by providing a controlled interface that absorbs expansion forces in the longitudinal direction while preventing the resin from running out, thus resolving the contradiction between soft resin benefits and thermal expansion problems.
2Strength
If a resin with high linear expansion coefficient is used to reduce stress damage, then resin running out occurs from the injection gate under high-temperature conditions
Solution Approach 1:
The patent defines specific parameter ranges for the filling resin confining surface: distance from injection gate of 0.5-2.0mm and surface area of 10-50mm². These parameter changes enable the confining surface to absorb expansion stress while preventing resin run-out, thus resolving the contradiction between stress damage suppression and manufacturing precision.
Solution Approach 2:
The patent converts the harmful thermal expansion into a beneficial force by designing the confining surface to absorb expansion stress in the longitudinal direction. The expansion that would normally cause run-out is instead utilized to fill gaps and improve sealing, thus resolving the contradiction between stress damage suppression and run-out control.
3Reliability
If the device is filled with resin having high linear expansion coefficient, then the sealing property deteriorates due to resin running out and mixing with external environment
Solution Approach 1:
The filling resin confining surface serves as an intermediary barrier that prevents resin run-out while maintaining sealing integrity. It absorbs thermal expansion forces and prevents direct contact between the resin and the external environment through the injection gate, thus resolving the contradiction between sealing property and thermal expansion effects.
Solution Approach 2:
By optimizing the geometric parameters of the confining surface (distance and area), the patent creates an effective barrier that prevents resin run-out while maintaining the sealing function. The specific parameter ranges ensure that the confining surface is positioned and sized to effectively block resin escape paths, thus resolving the contradiction between sealing property and run-out prevention.
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
The solution effectively suppresses resin run-out and maintains sealing properties even under high-temperature conditions, ensuring both resin fillability and water resistance by optimizing the resin confining surface design.
Implementation Method 1
a resin section that fills up the inside of the casing and has a linear expansion coefficient of at least 90×10 -6[0008]When such a configuration is adopted, more stress due to resin expansion occurs in the longitudinal direction than in the thickness direction
Data Source
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AI summary
Provided is an electronic device (510) that prevents running-out of a filling resin from an opening (e.g., an injection gate (81)) due to thermal expansion, even when the device is manufactured using a resin having a linear expansion coefficient of at least 90×10-6/°C (90 ppm/°C) (e.g., a hot melt resin), and is used under a high-temperature environment (e.g., 50°C or more). The electronic device (510) is provided with a filling resin confining surface inside of the casing (60; 60K; 60L; 60M), and the filling resin confining surface includes a position opposite to the gate (81) and a region that has a distance to an inner surface (63; 63M) of the casing (60; 60K; 60L; 60M) of at least 0.2 mm and at most 1.0 mm, and that has an area of at least four times larger than the cross-sectional area of the gate (81).