Flexible Substrate Adhesive Land Dimensions for Peeling Prevention
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Solution Overview
Problem
The existing distance measurement apparatuses for vehicles face a decrease in measurement accuracy due to snow or rainwater attachment on the transmission window, and the use of a flexible substrate with a heater wire leads to peeling issues at the adhesive interface, affecting electrical reliability.
Innovation Solution
A distance measurement apparatus with a flexible substrate that includes a surface-mounted-type electronic component, a land, and a conductive adhesive, where the electrode of the electronic component is electrically connected to the land, and the conductive adhesive is formed on the land to adhere the electrode and the land, ensuring a contact surface length equal to or greater than twice the length of the electronic component's mounting surface, preventing peeling and maintaining high electrical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a heater wire is mounted on a flexible substrate using conventional adhesive methods, then the transmission window can be heated to prevent snow or rainwater attachment, but the adhesive interface peels due to thermal expansion differences, affecting electrical reliability
Solution Approach 1:
The patent changes the geometric parameters of the adhesive application by extending the land pattern dimensions. Specifically, the land length L1 in the longitudinal direction is made equal to or greater than twice the electrode length L2, and the land width W1 is made equal to or greater than twice the electrode width W2. This parameter change increases the adhesive contact area and creates a larger overlap region between the adhesive and electrode, preventing peeling caused by thermal expansion differences during heater operation.
Solution Approach 2:
The patent extends the land pattern in both longitudinal and lateral dimensions relative to the electrode footprint. By making the land dimensions (L1×W1) significantly larger than the electrode dimensions (L2×W2), the adhesive bond is distributed over a larger area in multiple dimensions, reducing stress concentration and preventing peeling at the adhesive interface during thermal cycling.
2Measurement precision
If the transmission window is heated to maintain measurement accuracy in snowy or rainy conditions, then measurement precision is improved, but thermal expansion causes peeling at the adhesive interface
Solution Approach 1:
The patent modifies the land pattern dimensions to create a larger adhesive bonding area. The land length L1 is set to ≥2×L2 and land width W1 is set to ≥2×W2, where L2 and W2 are the electrode dimensions. This parameter change ensures that the adhesive interface can withstand thermal expansion forces while maintaining electrical connectivity and preventing peeling during heated operation.
3Ease of manufacture
If the land size is minimized to reduce material usage, then manufacturing cost is reduced, but the adhesive contact area becomes insufficient, leading to peeling under thermal stress
Solution Approach 1:
The patent establishes specific dimensional relationships for the land pattern: length L1 ≥ 2×L2 and width W1 ≥ 2×W2, where L2 and W2 are the electrode dimensions. This parameter specification ensures adequate adhesive bond strength and peeling resistance while maintaining manufacturing efficiency through standardized pattern design that can be implemented using conventional PCB fabrication processes.
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 prevents peeling of the electronic component on the flexible substrate, ensuring high electrical reliability and maintaining accurate distance measurements even under temperature changes.
Implementation Method 1
a heater wire 51 that heats the transmission window 41
Implementation Method 2
a conductive adhesive 7 that adheres an electrode 6a of the electronic component 6 and a land 53
Data Source
AI summary
A distance measurement apparatus measures a distance to an object by irradiating emission light and detecting reflected light from the object onto which the emission light is irradiated. This apparatus includes a transmission window, a heater wire, and a flexible substrate that is provided in the transmission window. The flexible substrate includes: a surface-mounted-type electronic component; a land to which an electrode of the electronic component is electrically connected, and a conductive adhesive that is formed on the land and adheres the electrode of the electronic component and the land. When a longitudinal direction of a surface of the electronic component that opposes the land is a reference direction, a length along the reference direction of a contact surface between the land and the conductive adhesive is equal to or greater than twice a length along the reference direction of a mounting surface of the electrode of the electronic component.