Semiconductor Package Moulding with Retractable Pins to Prevent Flash
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Solution Overview
Problem
Existing methods struggle to prevent flashes of encapsulating material on non-encapsulated sides of semiconductor devices during production, which can act as thermal insulation and are difficult to remove without increasing costs and time.
Innovation Solution
A method involving retractable pins that contact tie bars or clip-tie bars during encapsulation, forming notches in the encapsulating material to minimize flashes, using pins with a cross-section that increases towards the material, and applying holding pressure to stabilize the package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If encapsulation is performed from one side of the metal frame, then the manufacturing process is simplified, but flashes of encapsulating material occur on the other side of the frame
Solution Approach 1:
The retractable pins are positioned to contact the tie bars before the encapsulating material is injected into the mould. This preliminary positioning creates a physical barrier that prevents the material from flowing onto the sides of the frame, thereby preventing flashes before they can occur.
Solution Approach 2:
The retractable pins act as an intermediary element between the encapsulating material and the tie bars. By introducing this intermediate component, the patent prevents direct contact between the encapsulating material and the frame sides, thereby eliminating flash formation without complicating the overall encapsulation process.
2Manufacturing precision
If flashes are cleaned from encapsulated packages, then manufacturing precision is improved, but production time and costs increase significantly
Solution Approach 1:
The patent converts the potential harm of encapsulating material contact with the frame into a beneficial outcome by using the tie bars as intentional contact points. The material is directed to flow around the retractable pins and onto the tie bars, which are designed to accommodate this contact, thereby preventing unwanted flashes on the frame sides without requiring additional cleaning operations.
3Ease of operation
If the pin cross-section is smallest at the tip and increases towards the material, then pin withdrawal is eased and smooth side walls are obtained, but pin manufacturing complexity increases
Solution Approach 1:
The retractable pins feature a curved or tapered cross-section that increases from the tip towards the base. This curved geometry allows the pins to be easily withdrawn from the encapsulating material by reducing friction and stress concentration, while also ensuring that the pins create smooth side walls in the encapsulated product. The curved design is a standard manufacturing feature that balances operational ease with manufacturing simplicity.
Data Source
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AI summary
According to a first example of the disclosure, a method for manufacturing a singulated semiconductor product from a package is proposed. The method comprises the steps of a) providing the bottom frame with the clip matrix with at least one semiconductor component and placing them in a mould cavity, b) closing the mould, c) moving a number of retractable pins through openings in the mould, so that tips of the pins come into contact with the tie bars or the clip tie-bars of the clip matrix at predetermined locations, d) performing moulding operation using the encapsulating material, e) retracting said retractable pins away from the package, f) opening the mould, g) removing the package from the mould, and h) singulating the package into at least one separate product by sawing along predetermined lines and trimming the microleads. With the above steps at least one encapsulated and singulated semiconductor product is formed, that has notches formed on the sides thereof, that expose either tie bars or clip tie-bars.