Image Sensor Chip Package Structure to Prevent Glass Sheet Cracking
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Solution Overview
Problem
The existing manufacturing processes for image sensor chip packages are time-consuming and prone to contamination, and the mismatch in thermal expansion coefficients between the molding material and the glass sheet can cause the glass sheet to break during the manufacturing of chip-scale packaging.
Innovation Solution
A chip package design that includes a carrier board, a chip, a light transmissive sheet, a supporting element, and a molding material, where the molding material is formed to have a top surface lower than the light transmissive sheet, and a manufacturing method that involves forming a supporting element on the light transmissive sheet, cutting trenches, bonding the supporting element to a wafer, and then cutting the wafer to form chips, allowing for wafer-level packaging and reducing the risk of contamination and thermal expansion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chip-scale packaging is used with sequential bonding of chips and glass sheets, then individual chip packaging is achieved, but processing time increases and contamination risk increases
Solution Approach 1:
The glass sheet is divided into multiple individual glass pieces, each corresponding to a chip. The supporting element is also segmented to match the chip layout. This segmentation allows parallel processing of multiple chips while maintaining individual packaging quality, thus improving productivity without sacrificing reliability.
Solution Approach 2:
The supporting element is formed on the glass sheet before chip mounting. This preliminary action provides a pre-prepared structure that facilitates subsequent chip bonding and wire bonding processes, reducing overall processing time and preventing contamination by establishing protective structures in advance.
2Reliability
If molding material covers the entire sidewall of the glass sheet, then complete encapsulation is achieved, but thermal expansion mismatch causes glass sheet to break
Solution Approach 1:
The molding material is applied selectively to specific regions rather than covering the entire glass sheet sidewall. The top surface of the molding material is positioned lower than the top surface of the glass sheet, creating a local encapsulation zone that provides protection where needed while avoiding thermal stress concentration that would cause cracking.
Solution Approach 2:
The height parameter of the molding material is controlled to be lower than the glass sheet top surface. This parameter change reduces the volume of molding material in contact with the glass sheet, thereby minimizing thermal expansion mismatch stresses and preventing glass sheet breakage during manufacturing and operation.
3Productivity
If wafer-level packaging is implemented, then processing efficiency improves, but contamination of sensing area may occur
Solution Approach 1:
The supporting element is segmented to precisely match the chip boundaries and sensing area locations. This segmentation creates physical barriers that prevent contamination from spreading to the sensing areas during wafer-level processing, while still allowing efficient batch processing of multiple chips.
Solution Approach 2:
The supporting element acts as an intermediary structure between the glass sheet and the chips. It provides a protective barrier that prevents contamination during the wafer-level packaging process while maintaining the integrity and accessibility of the sensing areas, thus enabling both high productivity and contamination prevention.
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 reduces processing time, prevents contamination of the sensing area, and minimizes the risk of the light transmissive sheet cracking due to thermal expansion mismatches, thereby improving product yield and reliability.
Implementation Method 1
The light transmissive sheet is located above the supporting element and covers the sensing area of the chip
Implementation Method 2
The molding material is located on the carrier board and surrounds the chip and the light transmissive sheet
Data Source
AI summary
A chip package includes a carrier board, a chip, a light transmissive sheet, a supporting element, and a molding material. The chip is located on the carrier board and has a sensing area. The light transmissive sheet is located above the supporting element and covers the sensing area of the chip. The supporting element is located between the light transmissive sheet and the chip, and surrounds the sensing area of the chip. The molding material is located on the carrier board and surrounds the chip and the light transmissive sheet. A top surface of the molding material is lower than a top surface of the light transmissive sheet.