Flexible Wiring Board for Image Pickup Module Bonding
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Solution Overview
Problem
Bonding a signal cable to the external electrode of a stacked element in image pickup modules is challenging, leading to connection difficulties and potential damage during ultrasound bonding, which affects the reliability and compactness of the module.
Innovation Solution
A flexible wiring board with a bent section is used to connect the external electrode of the stacked element to the signal cable, allowing the external electrode to be positioned only in a specific region and extending the wiring board's length beyond the stacked element, thereby alleviating connection restrictions and reducing stress during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the signal cable is directly bonded to the external electrode of the stacked element, then the connection is more direct and compact, but the bonding process is difficult and may cause damage during ultrasound bonding
Solution Approach 1:
The patent introduces a flexible wiring board as an intermediary component between the stacked element and the signal cable. The external electrode of the stacked element is bonded to a front electrode on the wiring board, which then connects to the signal cable via a cable bonding section. This intermediary structure simplifies the bonding process and reduces the risk of damage during ultrasound bonding while maintaining reliable electrical connection.
Solution Approach 2:
The connection path is segmented into multiple sections: an interconnecting bonding section between the external electrode and front electrode, and a cable bonding section between the first electrode and the signal cable. This segmentation allows each bonding process to be optimized independently, making the overall manufacturing easier and more reliable.
2Volume of moving object
If the wiring board is made short to maintain compact module size, then the module is more compact, but the cable bonding becomes difficult and stress concentration increases
Solution Approach 1:
The wiring board is designed to be flexible rather than rigid, allowing it to be bent to accommodate the signal cable during bonding operations. This dynamic flexibility enables easier cable bonding while maintaining a compact overall module size, as the wiring board can be positioned optimally during assembly and then maintained in a compact configuration during operation.
Solution Approach 2:
The patent employs a flexible wiring board that can be bent and shaped to facilitate cable bonding. This flexible structure allows the wiring board to adapt to the bonding process requirements while maintaining a compact form factor in the final assembled module, resolving the contradiction between compactness and bonding ease.
3Adaptability or versatility
If the external electrode is positioned in both regions of the rear surface, then the connection flexibility is higher, but the module size increases and compactness is reduced
Solution Approach 1:
The external electrode is positioned only in the second region of the rear surface, concentrating the connection point in a specific location. This local positioning, combined with the flexible wiring board design, provides sufficient connection flexibility while maintaining a compact module size by avoiding unnecessary spatial occupation in the first region.
4Volume of moving object
If the wiring board length is made short, then the module is more compact, but stress concentration during bonding increases and may cause damage
Solution Approach 1:
The flexible wiring board acts as a stress-absorbing element that can deform during bonding operations, distributing mechanical stress along its length rather than concentrating it at a single point. This flexibility protects the bonded joints from damage while allowing the overall module to maintain a compact size.
Solution Approach 2:
The wiring board's flexibility and appropriate length provide beforehand cushioning against bonding stresses. The structure is designed to absorb and distribute mechanical stresses that occur during the bonding process, preventing stress concentration that could lead to damage, while still maintaining a compact final module configuration.
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 enhances the reliability and compactness of the image pickup module by allowing easier bonding and reducing the risk of damage during ultrasound bonding, while maintaining a short and small module size.
Implementation Method 1
a first wiring board (30) connected to the external electrode (20P) of the stacked element (10)
Implementation Method 2
the external electrode (20P) is connected to a front electrode (31) of the first wiring board (30) by an interconnecting bonding section (B3)
Data Source
AI summary
An image pickup module includes a stacked element in which an external electrode is disposed on a rear surface, a first wiring board where a front electrode connected to the external electrode by an interconnecting bonding section and a first electrode are disposed, and a first signal cable connected to the first electrode by a cable bonding section, in which the first wiring board is flexible and includes a bent section in a space defined by extending a first region out of the first region and a second region obtained by dividing the rear surface into two regions in an optical axis direction, and a length of the first wiring board from the interconnecting bonding section to the cable bonding section is longer than a length of the stacked element from the interconnecting bonding section to an end side in the first region.