Semiconductor Package Dam Structure for Underfill Overflow Control
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Solution Overview
Problem
Semiconductor packaging technologies face challenges in making packages thinner while preventing underfill overflow into the image sensing area, which affects image recognition.
Innovation Solution
A semiconductor package structure featuring a sensor die, substrate, light blocking layer, circuit layer, dam structure, and underfill, where the dam structure surrounds the image sensing area and contacts the sensor die and light blocking layer, with conductive bumps connecting the sensor die to the circuit layer, and underfill formed between the dam structure and conductive bumps to prevent overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the package thickness is reduced to make electronic products thinner, then the package becomes more compact and competitive, but the risk of underfill overflowing into the image sensing area increases, affecting image recognition
Solution Approach 1:
The patent divides the bonding area into two distinct zones: an image sensing area and a non-image sensing area (peripheral area). By segmenting the area where underfill can be present, the invention allows underfill to occupy the peripheral area without contaminating the image sensing area, thus enabling thinner packages while maintaining image recognition reliability.
Solution Approach 2:
The patent applies different requirements to different areas of the sensor die. The image sensing area requires strict control to prevent underfill contamination, while the peripheral area allows underfill presence. This local differentiation of quality requirements enables the package to be thinner while protecting the critical image sensing function.
2Ease of manufacture
If conventional packaging methods are used without area segmentation, then the manufacturing process is simpler, but underfill may overflow into the image sensing area and affect image recognition
Solution Approach 1:
The patent introduces area segmentation by defining an image sensing area and a peripheral area on the sensor die. This segmentation is implemented through existing manufacturing processes (forming conductive bumps in specific areas) rather than requiring completely new manufacturing steps, thus balancing manufacturing simplicity with improved reliability.
Solution Approach 2:
The patent uses the peripheral area as an intermediary zone that absorbs excess underfill. This intermediary area acts as a buffer between the underfill and the image sensing area, preventing direct contamination while maintaining a relatively simple manufacturing process.
3Productivity
If the package structure is simplified to reduce thickness, then productivity and cost improve, but control over underfill placement becomes more difficult
Solution Approach 1:
By segmenting the sensor die into image sensing and peripheral areas, the patent creates a tolerance zone (peripheral area) where underfill can be placed with less precision requirements. This allows for higher productivity while maintaining sufficient underfill placement precision for the critical image sensing area.
Solution Approach 2:
The patent allows for partial underfill coverage, where underfill can extend into the peripheral area beyond what would be minimally required. This partial excess action in the non-critical peripheral area provides manufacturing tolerance without affecting the critical image sensing area, thereby improving productivity.
Data Source
AI summary
A semiconductor package structure including a sensor die, a substrate, a light blocking layer, a circuit layer, a dam structure and an underfill is provided. The sensor die has a sensing surface. The sensing surface includes an image sensing area and a plurality of conductive bumps. The substrate is disposed on the sensing surface. The light blocking layer is located between the substrate and the sensor die. The circuit layer is disposed on the light blocking layer. The sensor die is electrically connected to the circuit layer by the conductive bumps. The dam structure is disposed on the substrate and surrounds the image sensing area. Opposite ends of the dam structure directly contact the sensor die and the light blocking layer. The underfill is disposed between the dam structure and the conductive bumps.