Dam Material Openings for Void-Free Underfill
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to efficiently deposit mold underfill between a large semiconductor die and substrate without forming voids, especially with increasing die size and high I/O count, which complicates encapsulation and increases manufacturing costs.
Innovation Solution
A method involving the formation of a dam material with multiple openings around the semiconductor die, using a dispenser to deposit mold underfill through one opening and a vacuum to spread it over the area between the die and substrate, ensuring complete and uniform coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional encapsulation methods are used for large semiconductor die, then void formation occurs, but the patent introduces multiple openings with dispenser and vacuum assist to eliminate voids
Solution Approach 1:
The encapsulation process is segmented into multiple stages: initial material deposition through the first opening, vacuum application through the second opening to remove air pockets, and controlled material flow. This segmentation allows each stage to address specific challenges, eliminating voids while maintaining manageable process complexity
Solution Approach 2:
The patent introduces a vacuum system as an intermediary element that mediates between the encapsulant material and the air pockets. The vacuum acts as a mediator to actively remove air during encapsulation, preventing void formation without requiring complete process redesign
2Adaptability or versatility
If die size is increased for higher functionality, then manufacturing difficulty increases, but the patent uses controlled material flow to simplify encapsulation
Solution Approach 1:
The encapsulation process is made dynamic through controlled material flow. The system transitions from static material deposition to dynamic flow control, where encapsulant material is actively pumped and directed through openings to adapt to large die geometries, making the process easier to control despite increased die size
Solution Approach 2:
The patent employs pneumatic principles by using vacuum pressure through the second opening to control material flow and remove air pockets. This pneumatic control mechanism simplifies the encapsulation of large dies by providing active pressure management rather than relying on passive material flow
3Manufacturing precision
If encapsulant viscosity is high, then flow rate decreases and encapsulation time increases, but the patent uses vacuum assist to improve material distribution
Solution Approach 1:
The vacuum is applied in advance and continuously during material deposition through the first opening. This preliminary and concurrent vacuum action prevents air pocket formation before they can trap material, ensuring uniform distribution without requiring extended waiting times for air to escape naturally
Solution Approach 2:
The vacuum assistance operates continuously throughout the encapsulation process rather than in discrete stages. This continuous action maintains constant pressure differential, ensuring uninterrupted material flow and consistent air removal, which improves distribution uniformity while maintaining efficient timing
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 prevents void formation, reduces thermal stress, and allows for faster and more cost-effective encapsulation of large semiconductor dies with high I/O counts, maintaining the integrity of the semiconductor device.
Implementation Method 1
drawing a vacuum on a second opening in the dam material to cause the underfill material to cover an area between the first semiconductor die and substrate
Data Source
AI summary
A semiconductor wafer contains a plurality of semiconductor die separated by saw streets. A dam material is formed over the saw streets around each of the semiconductor die. A plurality of openings is formed in the dam material. The openings in the dam material can be formed on each side or corners of the first semiconductor die. The semiconductor wafer is singulated through the dam material to separate the semiconductor die. The semiconductor die is mounted to a substrate. A mold underfill is deposited through a first opening in the dam material. A vacuum is drawn on a second opening in the dam material to cause the underfill material to cover an area between the first semiconductor die and substrate without voids. The number of second openings can be greater than the number of first openings. The first opening can be larger than the second opening.