Endoscope Image Pickup Solder Bond Reliability
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in achieving bond reliability due to the need for small solder bumps for electrode pads and large solder bumps for signal cables, leading to potential short circuits and reliability issues.
Innovation Solution
The image pickup apparatus employs a configuration with first and second solder bumps of different heights, surrounded by protective films of varying thicknesses, to prevent solder spread and ensure reliable bonding between the image pickup device and wiring board, and between the wiring board and signal cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small solder bumps are used for bonding electrode pads to ensure proper spacing, then short circuit between adjacent bumps is prevented, but bond reliability is reduced
Solution Approach 1:
The patent applies different solder bump sizes at different locations: small first solder bumps (5-15 μm) for bonding electrode pads to adjacent bumps on the wiring board, and large second solder bumps (15-30 μm) for bonding signal cables to distant bumps. This local differentiation allows each bonding location to have optimal solder bump dimensions for its specific requirements, resolving the contradiction between preventing short circuits and ensuring bond reliability.
2Reliability
If large solder bumps are used for bonding signal cables to ensure bond reliability, then connection strength is improved, but solder spread occurs causing short circuits between adjacent bumps
Solution Approach 1:
The patent implements location-specific solder bump sizing where large second solder bumps (15-30 μm) are used exclusively for signal cable bonding locations, while small first solder bumps (5-15 μm) are used for electrode pad bonding locations. This prevents solder spread-induced short circuits at densely packed electrode pad areas while maintaining strong bonds at signal cable connection points.
Solution Approach 2:
The patent segments the solder bump population into two distinct groups based on function: first solder bumps for internal wiring board connections and second solder bumps for external signal cable connections. This segmentation allows independent optimization of each group's dimensions without compromising the other, preventing solder spread issues while ensuring reliable bonding.
3Reliability
If different sized solder bumps are used for different bonding purposes, then bond reliability for both electrode pads and signal cables is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the solder bump population into two distinct segments: first solder bumps for electrode pad bonding and second solder bumps for signal cable bonding. This segmentation simplifies the manufacturing process by creating clear distinctions between different bonding requirements, making it easier to control and manage the soldering process despite using multiple sizes.
Solution Approach 2:
The patent employs preliminary action by pre-defining and pre-positioning solder bumps of appropriate sizes at their respective bonding locations before the actual bonding process. First solder bumps are placed at electrode pad locations and second solder bumps are placed at signal cable locations in advance, allowing the soldering process to proceed smoothly without real-time decision-making about bump size selection.
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 bond reliability by preventing solder spread and ensuring reliable connections, even with differing solder bump sizes, thereby improving the overall performance of the image pickup apparatus.
Implementation Method 1
a transparent member configured to be adhered via an adhesive layer so as to cover the light receiving surface
Implementation Method 2
a plurality of first bonded electrodes that are bonded to the plurality of electrode pads of the image pickup device via a plurality of first solder bumps
Implementation Method 3
a first protective film which covers the first end portion of the first main surface, surrounds the plurality of first solder bumps
Data Source
AI summary
An image pickup apparatus includes an image pickup device configured such that a plurality of electrode pads are disposed in a row on an inclined surface; a wiring board configured such that a plurality of first bonded electrodes that are bonded to the plurality of electrode pads via first solder bumps, respectively, are disposed in a row on a first end portion, and a plurality of second bonded electrodes are disposed in a row on a second end portion; and a signal cable configured to be bonded to the plurality of second bonded electrodes via second solder bumps, respectively. The wiring board includes a first protective film which covers the first end portion, and a second protective film which covers the second end portion, and is of a thickness that is greater than a thickness of the first protective film and less than a height of the second solder bumps.