Semiconductor Package Molding Flow Control to Prevent Gap Voids
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Solution Overview
Problem
The formation of voids between semiconductor chips and substrates during the encapsulation process due to uneven molding material flow, leading to reduced durability and reliability under thermal stress.
Innovation Solution
A molding apparatus with a dynamic part that moves relative to the mold part to control the flow of molding material, ensuring it fills the gap between the semiconductor device and substrate without voids, using a lower mold to carry the semiconductor device and an upper mold with a mold part and dynamic part to manage the flow direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molding material is injected to encapsulate the chip and fill the gap between substrate and chip, then the chip is protected and encapsulated, but voids form in the gap due to uneven flow velocity causing reduced durability and reliability
Solution Approach 1:
The patent introduces flow control structures (such as flow control grooves or flow control members) at specific locations within the mold cavity to locally regulate the flow velocity of molding material. These structures create regions of different flow resistance, slowing down the material in areas prone to excessive flow and maintaining pressure to prevent void formation near bump electrodes, thereby achieving uniform filling without compromising encapsulation quality
Solution Approach 2:
The patent employs flow control structures as intermediary elements between the molding material and the gap region. These intermediaries (flow control grooves, flow control members, or guide structures) mediate the flow of molding material, distributing it evenly and preventing direct rapid flow that would cause voids, thus ensuring complete gap filling while maintaining material uniformity
2Productivity
If molding material flows faster in regions without bump electrodes, then filling efficiency is improved, but voids occur in regions with bump electrodes reducing package reliability
Solution Approach 1:
The patent implements flow control structures at specific locations (such as near bump electrode regions or at strategic points in the mold cavity) to create localized flow resistance. This allows different regions of the mold cavity to have different flow characteristics - regions without structures maintain faster flow for efficiency, while regions with structures slow down flow to prevent voids, achieving both productivity and reliability
Solution Approach 2:
The patent modifies the flow parameters of molding material by introducing flow control structures that change the local flow velocity and pressure distribution. These structures create zones of elevated pressure that slow down material flow in critical areas, preventing void formation while maintaining overall filling efficiency through optimized flow path design
3Manufacturing precision
If a dynamic part is added to control molding material flow direction, then void formation is prevented, but device complexity increases
Solution Approach 1:
The patent divides the mold cavity into multiple regions using flow control grooves or flow control members, with each segment having controlled flow characteristics. This segmentation allows independent optimization of flow in different areas without requiring complex dynamic mechanisms, achieving precise flow control through static divided structures that are simpler to implement
Solution Approach 2:
The patent incorporates dynamic elements such as movable flow control members or adjustable flow control structures that can be positioned or activated during the molding process. These dynamic components provide adaptive flow control, adjusting to different molding conditions to prevent voids while maintaining relatively simple overall structure compared to fully complex dynamic systems
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
The solution enhances mechanical strength and prevents delamination by eliminating voids, improving the reliability of the semiconductor package.
Implementation Method 1
there is a possibility of a region where the molding material is not formed, i.e., a void, being formed in the gap between the substrate and the chip. This is due to the occurrence of a difference in flow velocity of the molding material
Implementation Method 2
After filling the gaps between the substrate and the chip with the molding material, a treatment for thermally setting the molding material is performed, and stress is caused in the package by thermal expansion and thermal contraction
Data Source
AI summary
A molded semiconductor device includes a semiconductor device and a molding material encapsulating the semiconductor device, wherein an upper surface of the molding material is substantially coplanar with an upper surface of the semiconductor device and comprises a groove at least partially surrounding the upper surface of the semiconductor device.