Transfer Molding System with Adjustable Cavity Gap
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Solution Overview
Problem
Conventional transfer molding techniques face challenges in reliably molding thin and large electronic packages due to high injection pressure and resistance issues, leading to potential damage and voids, especially when the gap between the die and molding surface is less than 0.1 mm.
Innovation Solution
A transfer molding system that incorporates a movable surface within the molding cavity to form a first gap for filling the molding compound and then reduces to a second, smaller gap to compress the compound, allowing for reliable filling and shaping of electronic devices using traditional solid pellets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional transfer molding is used with high injection speed to fill the molding cavity, then filling efficiency is improved, but the dice or wires are damaged due to high transfer pressure
Solution Approach 1:
The patent applies the dynamics principle by making the molding cavity height adjustable during the molding process. The cavity height is dynamically changed from an initial larger height to a final smaller height in two stages, allowing the injection speed and pressure to be optimized at each stage. This dynamic adjustment resolves the contradiction by enabling efficient filling at the first stage and proper compression at the second stage without damaging the dice or wires.
Solution Approach 2:
The patent applies parameter changes by varying the molding cavity height parameter during the molding process. The cavity height is changed from a first height to a second height, which corresponds to changing the injection parameters. This parameter change allows the system to achieve both high filling efficiency and prevent damage to the electronic components.
2Length of moving object
If the gap between the die surface and molding cavity is reduced to less than 0.1 mm to achieve thin packages, then package thickness is improved, but transfer pressure increases causing molding compound flow resistance and void formation
Solution Approach 1:
The patent applies preliminary action by first filling the molding cavity at a larger height before reducing the cavity height. This preliminary filling action allows the molding compound to be introduced without excessive pressure, and then the cavity height is reduced to achieve the desired thin package thickness. This sequential approach prevents void formation while achieving the target package thickness.
Solution Approach 2:
The patent uses dynamic adjustment of the molding cavity height to resolve the pressure-thickness contradiction. The cavity height is dynamically reduced after the initial filling, allowing the system to achieve thin package dimensions without subjecting the molding compound to excessive transfer pressure that would cause flow resistance and voids.
3Area of stationary object
If a wider molding cavity is used to mold larger dice, then device size capacity is improved, but molding compound filling becomes more difficult due to increased resistance
Solution Approach 1:
The patent applies dynamics by making the molding cavity height adjustable. For wider molding cavities used to accommodate larger dice, the system first fills the cavity at a larger height to ensure complete filling, then reduces the cavity height to achieve proper compression. This dynamic height adjustment ensures reliable filling of wide cavities without the molding compound getting stuck due to resistance.
Solution Approach 2:
The patent applies segmentation by dividing the molding process into two distinct stages: first filling the cavity at a larger height, then reducing to a smaller height for compression. This segmentation of the molding process allows the system to handle wide molding cavities effectively by addressing the filling and compression requirements separately.
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 enables reliable molding of thin and large electronic packages by reducing resistance and injection pressure, ensuring complete filling and preventing damage, while maintaining the efficiency of transfer molding.
Implementation Method 1
molding compound is introduced as a solid pellet into a mold supply pot of a molding system and melted with the application of heat and pressure to a liquid state
Implementation Method 2
molding compound is introduced as a solid pellet into a mold supply pot of a molding system and melted with the application of heat and pressure to a liquid state
Implementation Method 3
driving the movable surface to form a second gap between the movable surface and the electronic device which is smaller than the first gap, whereby to compress the molding compound in the molding cavity
Data Source
AI summary
A method and system for molding an electronic device which is located next to a molding cavity and clamped to the molding cavity during molding, comprising providing molding compound in a mold supply pot, discharging the molding compound from the mold supply pot into a runner, and distributing the molding compound through the runner into the molding cavity in order to fill the molding cavity. A movable surface comprised in the molding cavity is positioned to form a first gap between the movable surface and the electronic device when the molding cavity is being filled. After filling the molding cavity with molding compound, the movable surface is driven to form a second gap between the movable surface and the electronic device which is smaller than the first gap, thereby compressing the molding compound in the molding cavity. A molded electronic device thus produced is then separated from the molding cavity.