Endoscope Image Pickup Device Ultrasonic Bonding Grooves
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Solution Overview
Problem
The reliability of bonding between external electrodes of an image pickup device and end portion electrodes of a wiring board in endoscopes is compromised by high-temperature processing and vibration during ultrasonic bonding, leading to potential slippage and reduced bonding strength.
Innovation Solution
Inclined grooves are formed on the back face of the image pickup device, orthogonal to the ultrasonic vibration direction, to enhance anti-slip properties and ensure strong bonding by preventing slippage during ultrasonic bonding, thereby improving the reliability of the bonding between the image pickup device and the wiring board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic bonding is used to bond external electrodes to end portion electrodes, then bonding strength is improved at low temperature, but slippage occurs during bonding due to vibration
Solution Approach 1:
Grooves are formed on the back surface of the image pickup device before ultrasonic bonding to prevent slippage during the bonding process. This preliminary structural modification ensures that when ultrasonic vibration occurs, the grooves engage with the anvil to prevent relative movement, thereby maintaining bonding reliability while achieving strong bonds at low temperature
2Reliability
If anti-slip mechanisms such as vacuum mechanisms and side clamps are added to the anvil, then slippage is prevented, but device complexity increases
Solution Approach 1:
Instead of modifying the anvil structure to prevent slippage (adding vacuum mechanisms or side clamps), the invention inverts the approach by modifying the image pickup device itself. Grooves are formed on the back surface of the image pickup device, which then interact with the simple anvil surface to prevent slippage. This inversion eliminates the need for complex anvil modifications while achieving the same reliability goal
3Reliability
If grooves are formed on the back face of the image pickup device, then anti-slip effect is improved, but manufacturing complexity increases
Solution Approach 1:
The grooves are formed by controlling the orientation and parameters of the image pickup device during the wafer fabrication process. By adjusting the cutting direction and groove formation parameters during manufacturing, the grooves are created at the appropriate angle and depth on the back surface. This approach integrates the anti-slip feature into the existing manufacturing workflow without requiring separate complex processing steps
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
The inclined grooves provide a significant anti-slip effect, ensuring high bonding reliability and preventing cracking, even with ultracompact image pickup devices, by maintaining surface roughness within specific ranges and angles, thus enhancing the overall performance of the endoscope's image pickup apparatus.
Implementation Method 1
end portion electrodes ultrasonically bonded to the external electrodes
Implementation Method 2
ultrasonic bonding enabling strong bonding at a low temperature
Data Source
AI summary
An image pickup apparatus for an endoscope includes: an image pickup device including a row of external electrodes provided on an end portion of a light receiving surface; and a wiring board including end portion electrodes ultrasonically bonded to the external electrodes, in which a plurality of grooves are formed in a back face of the image pickup device, and the plurality of grooves are inclined relative to a vibration direction of ultrasonic vibration during the ultrasonic bonding.