Image Sensor Package Dam Structure for Glue Overflow Control
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Solution Overview
Problem
Conventional image sensor packages face yield reduction due to residual liquid glue contaminating the photosensitive layer during the bonding process.
Innovation Solution
An image sensor package design featuring a metal dam on the non-sensitive area of the image sensor chip, aligned with a thinner glue dam on the transparent substrate, preventing liquid glue from flowing towards the photosensitive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a liquid glue is used to form a glue dam for bonding the image sensor chip to the transparent substrate, then the bonding process can be completed, but the liquid glue flows inward and contaminates the photosensitive layer, reducing yield
Solution Approach 1:
The dam structure is segmented into two distinct parts: a metal dam portion formed on the image sensor chip and a glue dam portion formed on the transparent substrate. This segmentation allows each portion to serve its specific function - the metal dam provides a rigid barrier to prevent glue overflow, while the glue dam provides adhesive bonding. The segmentation resolves the contradiction by creating a controlled barrier system that prevents glue contamination while maintaining ease of manufacture.
Solution Approach 2:
The metal dam portion acts as an intermediary barrier between the glue dam and the photosensitive layer. Instead of relying solely on the glue dam to prevent contamination, the metal dam serves as an intermediate protective structure that physically blocks glue flow toward the sensitive area. This intermediary structure resolves the contradiction by providing an additional layer of protection against glue contamination.
2Object-affected harmful factors
If a thick glue dam is used to prevent glue from flowing toward the photosensitive layer, then contamination is reduced, but the amount of liquid glue increases
Solution Approach 1:
The dam structure divides the barrier function into two portions with different thicknesses and material properties. The metal dam portion provides the primary barrier function with minimal glue quantity, while the thinner glue dam portion provides adhesive bonding. This segmentation resolves the contradiction by reducing the overall glue quantity needed while maintaining effective contamination prevention through the metal barrier.
Solution Approach 2:
The invention changes the material parameter of the dam structure from purely adhesive (liquid glue) to a combination of rigid barrier (metal) and adhesive (glue). By changing the material parameter, the dam can provide effective contamination prevention with a reduced thickness of the glue portion, thereby reducing the total quantity of liquid glue required while maintaining prevention effectiveness.
3Object-affected harmful factors
If a metal dam is added to the structure to prevent glue flow, then contamination is reduced, but the device complexity increases
Solution Approach 1:
The dam structure is segmented into functionally distinct portions: the metal dam portion on the chip side provides contamination prevention, while the glue dam portion on the substrate side provides bonding. This segmentation allows each portion to be optimized for its specific function and simplifies the overall manufacturing process by assigning clear roles to each component, thereby reducing the perceived complexity despite adding functionality.
Solution Approach 2:
The combined dam structure serves multiple functions: the metal dam portion provides contamination prevention and structural support, while the glue dam portion provides adhesive bonding and sealing. This multi-functionality resolves the contradiction by consolidating multiple roles into a single integrated structure, reducing the need for separate components and processes.
Data Source
AI summary
An image sensor package includes an image sensor chip having a chip body, a metal dam, and a transparent substrate having a surface. The chip body has an active surface including a photosensitive area and a non-sensitive area surrounding the photosensitive area. The metal dam is formed on the non-sensitive area of the active surface, surrounds a photosensitive layer formed on the photosensitive area at intervals, is electrically insulated from the chip body, and has a thickness. A glue dam is formed on the surface and is aligned with and is bonded to the metal dam. A thickness of the glue dam is less than the thickness of the metal dam. Accordingly, the metal dam and the glue dam are combined to form a dam structure, and the quantity of liquid glue to form the glue dam is decreased. Thus, the yield of the image sensor package is enhanced.