Die-Up IC Package With Grounded Stiffener
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Solution Overview
Problem
Existing integrated circuit (IC) packaging methods are costly and complex, particularly in achieving optimal thermal performance and requiring wire bonding to a stiffener, which complicates the assembly process.
Innovation Solution
A die-up IC packaging structure where the IC die is wire bonded directly to the printed circuit substrate through open slots in the stiffener, eliminating the need for wire bonding to the stiffener, and using solder balls attached to the substrate and stiffener for ground and heat dissipation, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is performed to the stiffener, then electrical connection is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the wire bonding operation from the stiffener by introducing open slots that allow wire bonds to pass through directly to the substrate. This eliminates the need to bond wires to the stiffener itself, reducing assembly complexity while maintaining electrical connectivity functionality.
Solution Approach 2:
The open slots in the stiffener act as intermediaries that allow wire bonds to pass through without requiring attachment to the stiffener. The slots mediate between the die and substrate, enabling electrical connection while simplifying the bonding process.
2Temperature
If the stiffener is used as a ground plane and heat sink, then thermal performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into the stiffener: it serves as a mechanical support, a ground plane for electrical connections, and a heat sink for thermal management. By combining these functions into a single component, the overall device complexity is reduced while achieving optimal thermal performance.
Solution Approach 2:
The stiffener is designed as a multi-functional component that simultaneously provides structural support, electrical grounding, and thermal dissipation. This universal approach eliminates the need for separate components for each function, simplifying manufacturing while improving thermal performance.
3Productivity
If solder balls are directly attached to the stiffener through the substrate, then assembly steps are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The substrate is pre-configured with open holes or plated through-holes at precise locations before the stiffener is attached. This preliminary preparation of the substrate ensures that subsequent solder ball attachment to the stiffener through these pre-positioned holes requires less precision during the actual assembly process, thereby improving productivity.
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 simplifies the packaging process, reduces costs, and enhances thermal performance by utilizing the stiffener as a ground plane and heat sink without the need for wire bonding on the stiffener, thereby improving manufacturability and thermal management.
Implementation Method 1
the stiffener function as a ground plane and as a heat sink for power dissipation
Implementation Method 2
Solder balls are attached on a bottom side of the substrate and electrically connected to ground bond fingers of the substrate
Data Source
AI summary
A printed circuit substrate is disposed on a bottom side of a stiffener. An IC die is disposed on a top side of the stiffener. The die is electrically connected onto the printed circuit substrate by wire bonding through an open slot in the stiffener. The die is not wire bonded to the stiffener. Solder balls are attached on a bottom side of the substrate and electrically connected to ground bond fingers of the substrate, and also are directly attached to solderable pads on the bottom side of the stiffener through open holes or plated through-holes on the substrate, so as to have the stiffener function as a ground plane and as a heat sink for power dissipation.