Lead Joint Geometry to Prevent Substrate Contact Under Impact
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Solution Overview
Problem
The electronic device in JP-A-2022-046922 is prone to warping due to moisture absorption and expansion of the mold portion, leading to degraded sensor detection characteristics and potential electrical continuity failures, and omitting the mold portion results in lead deformation and breakage from impacts.
Innovation Solution
The electronic device incorporates a substrate with leads joined via conductive joint members, where the lead configuration includes a base end portion extending along the substrate, a distal end portion with a terminal surface, and a coupling portion, satisfying the condition θ1>θ2, to prevent contact between the lead and substrate during elastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mold portion is provided to fix the base end portions of the leads, then the leads are protected from deformation and breakage, but the substrate may warp due to stress generated by moisture absorption and expansion of the mold portion, degrading sensor detection characteristics
Solution Approach 1:
The invention extracts and eliminates the mold portion from the electronic device structure. Instead of using a mold portion to fix and protect the leads, the patent employs a different approach where the leads are directly mounted on the substrate with their base end portions positioned to extend along the substrate surface, achieving protection without the harmful mold portion that causes warping.
Solution Approach 2:
The invention changes the geometric parameters of the lead configuration, specifically the angle θ1 formed by the lead and substrate, to optimize the lead's ability to withstand impact while preventing contact with the substrate. By controlling the angle and positioning, the lead can deform elastically without contacting the substrate, achieving protection without requiring a mold portion.
2Reliability
If a mold portion is provided to fix the base end portions of the leads, then the leads are protected from deformation and breakage, but microscopic gaps may not be sufficiently filled with molding material, causing electrical continuity failure
Solution Approach 1:
The invention eliminates the mold portion entirely, removing the source of the gap-filling problem. Without a mold portion, there are no microscopic gaps that need to be filled with molding material, thus preventing electrical continuity failures while still protecting the leads through alternative means.
3Stability of the object's composition
If the mold portion is omitted to prevent substrate warping, then sensor detection characteristics are maintained, but the base end portions of the leads are not fixed and may be deformed by impact, causing the leads and substrate to break
Solution Approach 1:
The invention makes the lead configuration dynamic by allowing elastic deformation. The lead is designed with a specific angle θ1 and positioning that enables it to flex and absorb impact energy through elastic deformation rather than rigid fixation. This dynamic approach allows the lead to withstand impact forces without breaking or causing substrate damage.
Solution Approach 2:
The invention changes the spatial arrangement of the lead by extending the base end portion along the substrate surface at a specific angle θ1 rather than perpendicular to it. This dimensional change in the lead's orientation provides better impact resistance and prevents contact with the substrate during deformation, achieving protection without a mold portion.
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 configuration effectively suppresses lead and substrate breakage, ensuring higher mechanical strength and reliability by preventing contact between the leads and substrate during deformation, while maintaining stable sensor performance.
Implementation Method 1
the leads may be deformed by an impact or the like
Data Source
AI summary
An electronic device includes a substrate having a first surface and a second surface in a front-back relation, a first electronic component mounted on the second surface, and a lead joined to the second surface of the substrate via a conductive joint member, wherein the lead includes a base end portion extending in a direction along the substrate and joined to the second surface via the joint member, a distal end portion located distally from the substrate with respect to the base end portion in a thickness direction of the substrate and having a terminal surface, and a coupling portion coupling the base end portion and the distal end portion, and θ1>θ2, wherein, as seen from a direction orthogonal to a plane along which the lead extends, an angle formed by a line connecting an outermost position in which the joint member contacts the base end portion and an outer edge of the substrate and the base end portion is θ1, a distance between the first electronic component and the terminal surface in the thickness direction of the substrate is d1, a distance between a boundary part between the base end portion and the coupling portion and the joint member in the direction along the substrate is d2, and arctan(d1/d2)=θ2.