Vacuum Molding Apparatus Leadframe Seal
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Solution Overview
Problem
Conventional molding processes for semiconductor devices face issues with seal ring wear and damage due to heat exposure and accidental contact, leading to unreliable vacuum maintenance and potential mold bleed.
Innovation Solution
The solution involves integrating vacuum suction holes within the leadframe-receiving area of the mold, utilizing the leadframe as a seal by clamping it to maintain vacuum pressure, eliminating the need for external seal rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring is used to surround the vacuum holes to maintain vacuum pressure, then vacuum sealing is achieved, but the seal ring is vulnerable to wear failure and damage after prolonged use and exposure to heat
Solution Approach 1:
The invention removes the seal ring component entirely from the system. Instead of using a separate sealing element that surrounds the vacuum holes, the leadframe itself is utilized as the sealing element through its interaction with the mold cavity and clamping mechanism, thereby eliminating the component subject to wear and thermal degradation
Solution Approach 2:
The leadframe is given multiple functions: it serves as both the electrical carrier for semiconductor chips and as the sealing element for maintaining vacuum pressure. By integrating the sealing function into the existing leadframe structure, the invention eliminates the need for a dedicated seal ring while improving overall system reliability
2Reliability
If a seal ring is used to seal the vacuum area, then vacuum pressure is maintained, but the seal ring is prone to damage from accidental contact with sharp foreign material during mold closing
Solution Approach 1:
The vulnerable seal ring is extracted from the system and replaced with the leadframe as the sealing element. The leadframe, being a robust structural component designed to withstand molding forces, is inherently more resistant to damage from foreign material contact during mold closing operations
3Reliability
If a seal ring is used to maintain vacuum pressure, then air evacuation is effective, but mold bleed may occur during molding causing damage to the seal ring
Solution Approach 1:
By removing the seal ring from the system and using the leadframe as the sealing element, the invention eliminates the vulnerability to mold bleed damage. The leadframe's structural integrity and positioning within the mold cavity make it resistant to damage from molding compound exposure
Solution Approach 2:
The invention effectively makes the sealing function disposable with each leadframe insertion. Each new leadframe provides a fresh sealing surface, eliminating the accumulation of wear and damage that would occur with a reusable seal ring exposed to high-temperature molding compounds
4Productivity
If vacuum holes are formed near the periphery of the mold chase, then air evacuation paths are created, but a seal ring must be used which requires maintenance and replacement
Solution Approach 1:
The seal ring component is removed from the system. The vacuum holes remain positioned near the periphery for effective air evacuation, but the sealing function is transferred to the leadframe, eliminating maintenance and replacement requirements
Solution Approach 2:
The leadframe serves its own dual purpose of both carrying electrical connections and providing the sealing function. This self-service approach eliminates the need for separate sealing components and their associated maintenance, as the leadframe is replaced anyway during normal production cycles
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 provides a durable and reliable vacuum sealing method, reducing downtime and maintenance costs by using the leadframe as a seal, ensuring consistent vacuum conditions without external seal ring wear or damage.
Implementation Method 1
a vacuum condition in a molding cavity is to be maintained. To this end, vacuum holes are formed in the mold chase and are connected to a vacuum pump to suck out air from the molding cavity
Data Source
AI summary
A molding apparatus is provided for molding a leadframe, the molding apparatus comprising a mold having a leadframe-receiving area on its surface that is configured to receive and clamp the leadframe in the leadframe-receiving area. At least one molding cavity and a plurality of vacuum suction holes formed adjacent to the molding cavity are located within the leadframe-receiving area. The vacuum suction holes are operative to evacuate air from the mold surface, especially the molding cavity, through air vents connecting the vacuum suction holes to the molding cavity.