Transfer Mold Cavity Venting for Void-Free Semiconductor Packaging
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Solution Overview
Problem
Transfer molding systems face challenges in preventing voids in molding compound layers due to constrained vent region sizes, leading to reduced mechanical stability and reliability of electrical component packaging, with voids potentially causing cracks and electrical shorts.
Innovation Solution
The transfer molding system incorporates an adjustable and enlarged vent region, positioned away from the printed circuit substrate, allowing for effective air removal and minimizing void formation by providing a larger volume for fluidic molding compound flow, which can be adjusted to ensure complete venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the vent region size is constrained to fit within the substrate area, then the device footprint is minimized, but voids form in the molding compound layer reducing mechanical stability
Solution Approach 1:
The vent region is extended from a two-dimensional area constrained to the substrate footprint into a three-dimensional volume by adding vertical height. The mold cavity includes a vent region that protrudes above the substrate surface, creating a reservoir volume that can accommodate air evacuation without increasing the lateral device footprint. This dimensional transition resolves the contradiction by providing adequate venting capacity while maintaining compact device dimensions.
2Reliability
If the vent region volume is increased to prevent voids, then mechanical stability is improved, but the device footprint increases
Solution Approach 1:
The solution transitions from increasing lateral vent region area to increasing vertical vent region height. The mold cavity is configured with a vent region that extends upward from the substrate surface, creating a vertical reservoir. This allows the vent volume to be increased without expanding the horizontal device footprint, as the additional volume is achieved through vertical dimension rather than lateral expansion.
3Reliability
If a larger vent region is used to eliminate voids, then reliability is improved, but the complexity of the mold structure increases
Solution Approach 1:
The mold cavity is segmented into distinct functional regions: a component region for enclosing electrical components and a vent region for air evacuation. The vent region is further segmented into a substrate-aligned portion and a protruding reservoir portion. This segmentation allows each region to be optimized for its specific function while maintaining overall structural simplicity. The cavity wall forming the vent region protrusion can be implemented as a straightforward geometric feature rather than a complex structure.
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 configuration prevents voids in the molding compound layer, enhancing the mechanical stability and reliability of electrical component packaging, enabling lower component heights, high-temperature processing, and eliminating the need for capillary underfill processes.
Implementation Method 1
direct a flow of a molding compound into the mold cavity
Implementation Method 2
curing the fluidic molding compound to form a molding compound layer
Data Source
AI summary
Various embodiments of a mold cavity structure of a transfer molding system are disclosed. The transfer molding system includes a first mold-forming structure and a second mold-forming structure. The second mold-forming structure includes a mold cavity. The mold cavity includes a gate region, a component region, and a vent region. The component region is configured to enclose an electrical component. A volume of the vent region is adjustable. The transfer molding system further includes an inlet port coupled to the gate region and configured to direct a flow of a molding compound into the mold cavity during an operation of the transfer molding system.