Imaging Device Recessed Substrate Joint Strength
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Solution Overview
Problem
Conventional imaging devices face challenges in achieving compactness while maintaining the strength of the joint between outside terminals and the external circuit board, as the reduced width of lateral wall portions leads to thermal stress and potential peeling off of terminals due to differing thermal expansion coefficients.
Innovation Solution
The imaging device features a recessed structure on both the first and second insulating substrates, increasing the surface area of the joint between outside terminals and wiring conductors, and using materials with matching thermal expansion coefficients to reduce thermal stress, along with a light-transmitting plate for protection and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of lateral wall portions is reduced to make the wiring substrate more compact, then the compactness of the imaging device is improved, but the surface area of the joint portion between outside terminals and external circuit board is reduced, lowering joint strength
Solution Approach 1:
The invention introduces a recess portion that extends in the thickness direction (vertical dimension) to increase the joint surface area. By utilizing the vertical dimension rather than expanding lateral dimensions, the joint strength is improved without compromising the compactness of the imaging device in the planar direction.
Solution Approach 2:
The recess portion is formed within the wiring substrate structure, creating a nested configuration where the joint portion is embedded inside the substrate. This nested structure allows the joint surface to be positioned within the substrate thickness, effectively increasing the bonding area without increasing the overall footprint of the device.
2Volume of moving object
If the width of lateral wall portions is reduced to make the wiring substrate more compact, then the compactness of the imaging device is improved, but thermal stress increases due to smaller joint surface area, causing potential peeling off of terminals
Solution Approach 1:
By extending the joint portion vertically through the recess portion rather than relying on lateral wall width, the invention creates a larger thermal stress distribution area. This vertical extension allows heat-induced expansion forces to be distributed over a greater surface area, reducing the stress concentration that would otherwise cause terminal peeling in compact designs.
Solution Approach 2:
The recess portion structure acts as a cushioning mechanism against thermal stress. The increased surface area and embedded configuration of the joint portion provide a buffer that absorbs and distributes thermal expansion forces before they can cause damage to the terminal connections, preventing peeling off in advance.
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 design enhances the strength and reliability of the joint, suppresses thermal stress, and prevents unnecessary light from reaching the light-receiving portion, resulting in a compact imaging device with high image quality and durability.
Implementation Method 1
light (images) entering the light-receiving portion of the imaging element through the through hole is converted by the imaging element into an electrical signal
Implementation Method 2
when heat is applied to an external circuit board and lateral wall portions having different thermal expansion coefficients, the joint portion may break due to the thermal stress occurring between the external circuit board and the lateral wall portions caused by the difference in thermal expansion
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(b)
AI summary
[Problem] Provided is a wiring substrate, an imaging device as well as an imaging device module that can be made compact and with which the reliability of the joint to the external circuit board can be improved. [Solution] A imaging device includes a first insulating substrate (1a) having a through hole (2), a connection electrode (4) and a first wiring conductor (3a), a second insulating substrate (1b) having outside terminals (5) and a second wiring conductor (3b), and an imaging element (6) including a light-receiving portion (6a) arranged at a center portion on an upper surface thereof and a connection terminal (6b) arranged at an outer peripheral portion thereof, at least one of the lower surface of the first insulating substrate (1a) and the upper surface of the second insulating substrate (1b) including a recess portion (7), the through hole (2) being located on an inner side thereof, the imaging element (6) being arranged below the first insulating substrate (1a) such that the light-receiving portion (6a) is located within the through hole (2), the connection terminal (6b) being electrically connected to the connection electrode (4), the imaging element being accommodated inside the recess portion (7), outer peripheral portions of the first insulating substrate (1a) and the second insulating substrate (1b) being electrically connected to each other. Since the outside terminals (5) can be formed on the lower surface of the imaging device with a larger surface area, peeling off of the outside terminals (5) from the external circuit board can be suppressed.