Resin Mold Gate Orifice Design for Semiconductor Wire Sweep Control
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Solution Overview
Problem
In resin mold-type semiconductor device fabrication, the high flow velocity of resin into the last cavity causes wire deformation and makes it difficult to continuously perform the molding process due to breakage and scattering of the resin sump, leading to reliability issues.
Innovation Solution
The method involves a mold design with larger orifices for the first gates compared to the second gates, allowing resin to flow through runners and dummy cavities, which reduces the flow velocity into the last cavity, preventing wire deformation and ensuring continuous molding by maintaining the resin sump integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If resin is injected into multiple cavities via runners with constant feed rate, then all cavities are filled, but the last cavity receives resin at high injection speed causing wire sweep
Solution Approach 1:
The patent applies local quality by making the gate orifice sizes different for different cavities. Specifically, the gate orifice for the last cavity to be filled is made smaller than other gates, so that while all cavities receive resin, the last cavity receives it at a controlled, reduced flow velocity that prevents wire sweep and deformation.
2Reliability
If a resin sump is formed adjacent to the movable gate, then resin flow is controlled, but the resin sump breaks and scatters during demolding causing continuous molding difficulty
Solution Approach 1:
The patent extracts the problematic resin sump structure from the mold and replaces it with a lead frame configuration that includes a resin pool formation. The lead frame has a resin pool portion that can accommodate excess resin without causing breakage and scattering during demolding, thus maintaining molding process continuity while preserving resin sump integrity.
3Productivity
If product cavities are last injected with resin at high flow velocity, then resin fills all cavities, but wires are easily deformed
Solution Approach 1:
The patent applies local quality by making the gate orifice sizes different for different cavities. Specifically, the gate orifice for the last cavity to be filled is made smaller than other gates, so that while all cavities receive resin, the last cavity receives it at a controlled, reduced flow velocity that prevents wire sweep and deformation.
Solution Approach 2:
The patent changes the physical parameter of gate orifice size to control resin flow velocity. By making the gate orifice for the last cavity smaller, the resin flow velocity into that cavity is reduced, preventing wire deformation while still achieving complete cavity filling.
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 improves the quality and reliability of semiconductor devices by preventing wire deformation and enabling stable resin flow, allowing for efficient encapsulation and reducing material costs through optimized resin distribution.
Implementation Method 1
forming encapsulation bodies that encapsulate the semiconductor chips by flowing encapsulating resin into the cavities through the runner
Data Source
AI summary
The method of the present invention improves quality and reliability of resin mold-type semiconductor devices. The method includes the steps of placing a lead frame such that cavities of a mold match with device formation regions of the lead frame, respectively, and forming encapsulation bodies that encapsulate semiconductor chips by flowing encapsulating resin into the cavities. The mold with an upper mold half and a lower mold half clamped together has a plurality of first gates that allow the cavities to communicate with a runner, and a dummy-cavity gate that allows a dummy cavity to communicate with the runner. During a resin molding process, from the time when the resin starts flowing into the mold to the time when the encapsulation bodies are formed, an orifice of each cavity gate is larger in size than an orifice of the dummy-cavity gate.