Thin Semiconductor Package with Removable Substrate and Dual Encapsulation
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Solution Overview
Problem
Current manufacturing methods for semiconductor packages fail to produce thin enough packages without defects, particularly due to the trampoline effect during wire bonding, which causes faulty connections.
Innovation Solution
A method involving a flagless lead frame with a removable substrate and dual encapsulation process to provide a thin semiconductor package, where the substrate supports the semiconductor die and connection leads, reducing the trampoline effect through a firm and rigid encapsulant support during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of semiconductor packages is reduced to meet size requirements, then the package becomes thinner and meets size constraints, but defects occur during wire bonding due to the trampoline effect
Solution Approach 1:
The patent applies preliminary action by pre-encapsulating the lead frame and semiconductor die with a first encapsulant before wire bonding. This creates a firm and rigid support structure in advance that prevents the trampoline effect during subsequent wire bonding operations, thereby solving the reliability issue while maintaining thin package thickness.
2Length of moving object
If a flagless lead frame is used to reduce package thickness, then the package becomes thinner, but the support structure during wire bonding becomes insufficient causing defects
Solution Approach 1:
The patent applies segmentation by dividing the encapsulation into two distinct stages: first encapsulation before wire bonding to provide support, and second encapsulation after wire bonding to complete the package. This segmented approach allows the lead frame to remain flagless and thin while still providing adequate support during critical manufacturing steps.
3Reliability
If dual encapsulation is used to provide support during wire bonding, then wire bond quality improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies merging by combining the support function and encapsulation function into a single first encapsulation step that occurs before wire bonding. This eliminates the need for separate support structures and integrates the support function directly into the encapsulation process, thereby improving wire bond quality without proportionally increasing manufacturing complexity.
Data Source
AI summary
A method for manufacturing a thin semiconductor package includes providing a lead frame with a removable substrate that has an attaching surface attached to a first surface of the lead frame. The lead frame is formed from an electrically conductive sheet and has leads that extend inwardly from a lead frame boundary towards a central region of the lead frame. A semiconductor die is mounted on the removable substrate at the central region. The semiconductor die has a connection pad surface with die pads on it, and the connection pad surface is attached to the attaching surface of the removable substrate. The lead frame and die are encapsulated with a first encapsulant so that the lead frame is sandwiched between the first encapsulant and the removable substrate. The removable substrate is removed from the lead frame to expose the first surface of the lead frame and then the die pads are electrically connected to respective ones of the leads. The die and lead frame then are encapsulated with a second encapsulant so that the lead frame and die are sandwiched between the first and second encapsulants. Part of the first encapsulant is then removed to reduce the thickness of the package and expose the leads.