Semiconductor Molding Flow Control to Eliminate Package Voids
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Solution Overview
Problem
Conventional semiconductor packaging technologies often result in voids forming between the substrate and semiconductor chips due to uneven molding material flow, leading to reduced durability under thermal stress and potential breakage of bump electrodes, which compromises the reliability of the semiconductor package.
Innovation Solution
A molding apparatus with a dynamic part that moves relative to the upper mold to control the flow of molding material, ensuring it fills the gap between the semiconductor device and the substrate without voids, by initially directing the material to fill the lower part of the device receiving region and then moving to fill the sides, thereby eliminating voids and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If molding material is injected to encapsulate the chip and fill the gap between substrate and chip, then the gap is filled with molding material, but voids form in the region where bump electrodes exist due to uneven flow velocity
Solution Approach 1:
The patent applies preliminary action by injecting molding material into the gap between the substrate and chip before the main encapsulation process. This preliminary injection ensures that the gap is pre-filled with molding material, preventing void formation during subsequent curing. The material is injected through injection ports positioned at specific locations to ensure uniform distribution before the chips are fully encapsulated.
Solution Approach 2:
The patent applies local quality by positioning injection ports at specific locations where voids are most likely to form, particularly in regions with bump electrodes. The molding material is injected locally into these critical areas first, ensuring that regions with different flow characteristics (such as areas with bump electrodes that cause flow resistance) receive adequate material before the general encapsulation process.
2Productivity
If molding material flows faster in regions without bump electrodes, then filling efficiency is improved, but voids occur in regions with bump electrodes due to roundabout flow
Solution Approach 1:
The patent introduces an intermediary substance (molding material) that is injected into the gap between the substrate and chip to mediate the flow dynamics. This intermediary material fills the gap uniformly and prevents the formation of voids by acting as a buffer that equalizes flow velocity differences caused by bump electrodes, ensuring both efficient filling and reliable encapsulation.
Solution Approach 2:
The patent performs preliminary injection of molding material into the gap before main encapsulation. This preliminary action ensures that the gap is pre-filled in regions with bump electrodes that would otherwise experience slow flow, balancing the filling process and preventing void formation while maintaining overall productivity.
3Ease of manufacture
If thermal setting treatment is performed after filling gaps with molding material, then the molding material is cured, but stress is caused in the package by thermal expansion and contraction reducing durability
Solution Approach 1:
The patent applies preliminary injection of molding material into the gap between substrate and chip before the thermal setting treatment. This ensures that the gap is pre-filled and void-free before curing, so that when thermal expansion and contraction occur during the setting process, there are no voids to concentrate stress, thereby maintaining package strength and durability.
Solution Approach 2:
The patent controls the injection parameters of the molding material, including injection pressure, temperature, and flow rate, to ensure optimal filling of the gap before thermal setting. By adjusting these parameters, the material achieves proper placement and distribution, reducing stress concentration during subsequent thermal processing and improving overall package reliability.
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 reduces or eliminates voids in the molding material, enhancing the mechanical strength and reliability of the semiconductor package by ensuring complete encapsulation without thermal stress-induced delamination or pop corn effects.
Implementation Method 1
molding material are formed on top of the substrate to encapsulate the chips
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
Implementation Method 3
stress is caused in the package by thermal expansion and thermal contraction
Data Source
AI summary
A molding apparatus is configured for molding a semiconductor device and includes a lower mold and an upper mold. The lower mold is configured to carry the semiconductor device. The upper mold is disposed above the lower mold for receiving the semiconductor device and includes a mold part and a dynamic part. The mold part is configured to cover the upper surface of the semiconductor device. The dynamic part is disposed around a device receiving region of the upper mold and configured to move relatively to the mold part. A molding method and a molded semiconductor device are also provided.