Protruding Pad Leadframe for IC Package Mold Flash Reduction
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Solution Overview
Problem
The electronics industry faces challenges in reducing the size and weight of electronic devices while minimizing mold flash during encapsulation of integrated circuits, which increases manufacturing costs and requires additional labor for mold cleaning.
Innovation Solution
The use of protruding pad leadframes that eliminate the need for adhesive films by providing stable clamping during wire bonding and encapsulation, reducing mold flash through improved sealing and distribution of clamping forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If adhesive films are used to secure leadframes during encapsulation, then the leadframes are held in position, but mold flash occurs and additional cleaning steps are required
Solution Approach 1:
The patent removes the adhesive film from the system entirely. Instead of using adhesive to secure the leadframe, the mold cavity geometry itself provides the positioning and securing function. The leadframe is held in place by the physical constraints of the mold cavity walls and bottom, eliminating the need for adhesive and consequently eliminating mold flash caused by adhesive interference.
Solution Approach 2:
The mold cavity acts as an intermediary structure that provides both positioning and securing functions. The cavity geometry serves as the mediating element between the leadframe and the encapsulation process, replacing the adhesive film's function while avoiding its harmful side effects of generating mold flash.
2Object-generated harmful factors
If high pressure is applied to seal the mold halves, then flash is reduced, but excessive force causes coining of lead frames and rapid mold wear
Solution Approach 1:
The patent applies clamping force locally at specific points where the mold closes on the leadframe package, rather than distributing high pressure across the entire mold interface. The protruding pad structure provides a localized clamping point that secures the leadframe without requiring excessive overall pressure, thereby preventing coining and mold wear while still preventing flash.
Solution Approach 2:
The leadframe is preliminarily positioned and secured by the mold cavity geometry before the encapsulation pressure is applied. The cavity walls and bottom provide pre-positioning constraints that stabilize the leadframe, allowing the subsequent encapsulation pressure to be applied without causing coining or excessive mold wear.
3Object-generated harmful factors
If adhesive is used to reduce mold flash, then sealing is improved, but additional cleaning steps and cost are required
Solution Approach 1:
The patent extracts the adhesive cleaning step from the manufacturing process by eliminating adhesive usage entirely. The mold cavity geometry provides the sealing and positioning function without introducing adhesive, thereby eliminating the subsequent cleaning step and reducing overall process complexity.
4Measurement precision
If protruding pads are used to provide clamping points, then wire bonding accuracy is improved, but the leadframe structure becomes more complex
Solution Approach 1:
The protruding pad serves multiple functions: it provides a clamping point for securing the leadframe during encapsulation, provides a stable reference surface for wire bonding operations, and maintains leadframe positioning throughout the process. By consolidating these functions into a single structural feature, the patent achieves wire bonding accuracy without proportionally increasing overall complexity.
Data Source
AI summary
An integrated circuit package system is provided. A protruding pad is formed on a leadframe. A die is attached to the leadframe. The die is electrically connected to the leadframe. At least portions of the leadframe, the protruding pad, and the die are encapsulated in an encapsulant.