Magnetic Sensor Device Hole Corner Radius for Thermal Stress
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Solution Overview
Problem
Magnetic sensor devices face challenges in maintaining stable output characteristics due to adhesive issues and thermal stress caused by uneven thermal expansion of the sensor substrate, which affects the adhesion strength and connection reliability.
Innovation Solution
A magnetic sensor device design featuring a sensor substrate with a hole portion having corners with a radius of curvature of 5 μm or more, where the magnetic detection elements are positioned to avoid overlapping these corners, and an adhesive is used to fill the hole portion, enhancing adhesion strength and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hole portion is formed in the sensor substrate to improve adhesion, then adhesion strength is improved, but thermal stress concentration occurs at sharp corners affecting output stability
Solution Approach 1:
The patent applies curvature by rounding the corners of the hole portion in the sensor substrate. Specifically, the corner radius is designed to be 5 μm or more, which distributes thermal stress more evenly across the hole structure. This curvature modification prevents stress concentration at sharp corners, thereby maintaining both strong adhesion and stable output characteristics of the magnetic detection elements.
2Reliability
If the sensor substrate is bonded to the support substrate with adhesive, then connection reliability is improved, but uneven thermal expansion causes adhesion failure
Solution Approach 1:
The patent changes the geometric parameters of the hole portion by controlling the corner radius to be 5 μm or more. This parameter modification alters the thermal expansion characteristics of the sensor substrate, reducing uneven expansion during temperature changes. As a result, the adhesive bonding between the sensor substrate and support substrate maintains both connection reliability and adhesion strength under thermal variations.
Data Source
AI summary
A magnetic sensor device 1 includes a support substrate 2 and a sensor substrate 10 fixed to the support substrate 2. The sensor substrate 10 includes a first surface 10B facing the support substrate 2 and a second surface 10A that is located on an opposite side to the first surface 10B and that is provided with a functional film 20 including a plurality of magnetic detection elements E, a hole portion 11 is formed in the first surface 10B, an outline O11 of the hole portion 11 includes at least one corner C1, C2, C3 . . . , at least one corner C1, C2, C3 . . . includes a first corner C1 that overlaps at least one of the plurality of magnetic detection elements E in a plan view seen in a plane-normal direction Z from the second surface 10A to the first surface 10B, and the first corner C1 has a radius of curvature of 5 μm or more.