Mold Flash Prevention in IC Packages Using Solder Mask Flange
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Solution Overview
Problem
Integrated circuit packages face issues with mold flash obscuring electrical solder ball pad sites, leading to poor electrical interconnections and increased production costs due to the close clearance between mold and solder ball pads, which existing technologies have not effectively addressed.
Innovation Solution
An integrated circuit package system that employs a first mold with a projection and recess configuration to prevent mold flash dispersion, where the projection forms a seal with the solder mask flange and the recess collects any escaping encapsulant, thereby preventing mold flash from obscuring electrical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the mold is positioned close to the solder ball pad sites to achieve higher density integration, then the package density and vertical integration are improved, but mold flash invades the solder ball pad sites and obscures the electrical patterns
Solution Approach 1:
A mold flash prevention structure is introduced as an intermediary element between the mold and the solder ball pad sites. This structure includes a first surface that contacts the mold and a second surface that contacts the encapsulant, creating a barrier that prevents mold flash from reaching and obscuring the electrical patterns while allowing the mold to maintain its close position for high-density integration.
Solution Approach 2:
The mold interface is segmented into distinct functional zones: a mold contact region, a transition region with the prevention structure, and a solder ball pad region. This segmentation allows each zone to perform its specific function - the mold contact region maintains positioning, the prevention structure blocks flash, and the solder ball pad region remains clear for electrical connections.
2Productivity
If the clearance between mold and solder ball pad is reduced to increase circuit density, then more circuits can be integrated vertically, but mold flash obscures the solder ball pad sites leading to poor electrical interconnections
Solution Approach 1:
The mold flash prevention structure serves as a mediator that enables close clearance positioning for high-density integration while simultaneously protecting the solder ball pad sites from mold flash contamination, thus maintaining both productivity and reliability.
Solution Approach 2:
The prevention structure is positioned in advance to counteract the harmful effect of mold flash before it can reach the solder ball pad sites. This preliminary protective action ensures that even with reduced clearance, the electrical interconnection quality remains high by preventing flash contamination upfront.
3Device complexity
If the mold is positioned adjacent to the solder ball pad sites for board-on-chip design, then compact package structure is achieved, but mold flash invades and obscures the electrical patterns causing failed electrical interconnections
Solution Approach 1:
The prevention structure acts as an intermediary barrier that allows the mold to be positioned adjacent to the solder ball pad sites for compact board-on-chip design while maintaining clear electrical pattern definition by blocking mold flash from invading the pad sites.
4Volume of moving object
If close clearance between mold and solder ball pad is used to meet customer demand for higher density, then package size is reduced, but mold flash causes unacceptable package yields and device failures
Solution Approach 1:
The mold flash prevention structure enables close clearance positioning that reduces package size while simultaneously protecting against mold flash contamination, thereby maintaining high package yield and reliability despite the compact dimensions.
Data Source
AI summary
An integrated circuit package system that includes: a support structure including an electrical contact; a solder mask over the support structure, the solder mask including a solder mask flange, the solder mask flange directly on a support structure first surface; an integrated circuit over the support structure; and encapsulant over the integrated circuit and in contact with the solder mask flange. A mold system that includes a first mold having a projection along a first mold bottom surface, the projection between a first cavity and a recess.