Image Sensor Packaging Hollow Cavity Prevents Rewiring Detachment
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Solution Overview
Problem
Current wafer level chip size packaging technologies face challenges in maintaining the reliability of image sensing chip packages due to the detachment of rewiring layers from contact pads during thermal expansion and contraction, leading to defective products.
Innovation Solution
The method involves forming a hollow cavity in the openings of the image sensing chip package by using a first photosensitive ink with lower viscosity to fill the cutting trenches and a second photosensitive ink with higher viscosity to cover the openings, preventing the rewiring layer from contacting the solder mask ink and reducing the risk of detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photosensitive ink is applied to fill the cutting trenches and openings, then the package structure is enhanced, but the complexity of the packaging process increases
Solution Approach 1:
The patent segments the solder mask application process into two distinct steps using two different photosensitive inks with different viscosities. The first ink is applied to cutting trenches, and the second ink is applied to openings with a hollow cavity formation. This segmentation allows each step to be optimized independently, enhancing package structure while managing process complexity through systematic division.
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 approach effectively enhances the yield and reliability of the image sensing chip package by preventing the rewiring layer from detaching from the contact pad, thus improving the overall package reliability.
Implementation Method 1
filling the cutting trenches with a first photosensitive ink
Implementation Method 2
applying a second photosensitive ink on the second surface of the wafer to cover the opening with the second photosensitive ink and form a hollow cavity in the opening
Data Source
AI summary
A packaging method and a package for an image sensing chip are provided. The packaging method includes: providing a wafer including a first surface and a second surface opposite to the first surface, where the wafer has multiple image sensing chips arranged in a grid, each of the image sensing chips has an image sensing region and contact pads arranged on a side of the first surface; forming an opening corresponding to each of the contact pads and cutting trenches on a side of the second surface of the wafer, where the contact pad is exposed through the opening; filling the cutting trenches with a first photosensitive ink; and applying a second photosensitive ink on the second surface of the wafer to cover the opening with the second photosensitive ink and form a hollow cavity in the opening.