Image Sensor Package Test Fixture With Wide-Area Vacuum Adsorption
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Solution Overview
Problem
Existing test apparatuses for image sensor packages suffer from high defect rates due to unstable vacuum adsorption, misalignment, and damage to circuit boards and sensor terminals, leading to poor test yield and pickup errors.
Innovation Solution
A test apparatus with a vacuum adsorption system using an inelastic insulating material and elastic conductive portions for stable surface adsorption, reducing contact resistance and preventing damage, and a wide vacuum adsorption area to enhance stability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a vacuum picker is used to adsorb the image sensor package, then the package can be moved to the test position, but the non-flat upper surface with solder balls prevents stable vacuum adsorption
Solution Approach 1:
The vacuum adsorption function is segmented from the mechanical support structure. A separate vacuum adsorption sheet is introduced that can be coupled to the pusher, allowing vacuum adsorption without requiring the pusher itself to have a flat surface. This segmentation enables stable adsorption while maintaining the ability to handle packages with non-flat surfaces.
Solution Approach 2:
The vacuum adsorption sheet acts as an intermediary between the vacuum source and the image sensor package. This sheet transfers vacuum pressure to the package surface, enabling stable adsorption without direct contact between the pusher and the non-flat package surface. The intermediary resolves the contradiction by providing a compliant interface that adapts to surface irregularities.
2Ease of manufacture
If pogo pins are used for electrical connection, then the circuit board and sensor terminal can be connected, but contact resistance increases and misalignment occurs
Solution Approach 1:
The upper socket is designed with a flexible structure that can deform to accommodate misalignment. This flexibility allows the socket to adapt its position and maintain good electrical contact even when the package is not perfectly aligned, thereby reducing contact resistance and improving connection reliability.
Solution Approach 2:
The upper socket is designed to be movable rather than fixed, allowing it to dynamically adjust its position to maintain optimal contact with the sensor terminal. This dynamic capability enables the system to compensate for alignment errors and maintain stable electrical connection throughout the testing process.
3Device complexity
If a narrow vacuum adsorption area is used, then the vacuum line can be formed, but pickup errors increase and test yield decreases
Solution Approach 1:
The vacuum adsorption sheet merges multiple functions into a single component: it provides vacuum adsorption, supports the package during handling, and ensures proper alignment. By combining these functions, the system achieves stable adsorption with a relatively simple structure, improving test yield without significantly increasing device complexity.
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
Stable vacuum adsorption and reduced contact resistance improve test yield by preventing misalignment and damage, ensuring accurate testing of image sensor packages without pickup errors.
Implementation Method 1
a pusher to which the upper circuit board on which a board vacuum hole is formed is coupled, having a cover vacuum hole through which vacuum pressure of a vacuum generator is transferred
Implementation Method 2
an upper socket made of an elastic insulating material containing a plurality of conductive particles, and having an elastic conductive portion that electrically connects the upper circuit board and the image sensor package
Data Source
AI summary
A test apparatus for testing image sensor packages. The test apparatus is configured to stably vacuum-absorb an image sensor package in a surface manner, wherein when a vacuum adsorption sheet having a package adsorption hole in the shape of a wide square surface is coupled to the bottom of the floating plate at which an upper socket is seated, a vacuum line is formed by connecting the cover vacuum hole of the pusher, the board vacuum hole of the upper circuit board, the plate vacuum hole of the floating plate, and the package adsorption hole of the vacuum adsorption sheet together.