Sensor Package With Truncated Via Plugs For Thin Panel Level Packaging
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Solution Overview
Problem
Current sensor package manufacturing technologies face challenges in achieving thinner packages and reducing manufacturing costs, particularly due to the complexity of molding and high accuracy requirements in through silicon via processes.
Innovation Solution
The implementation of a sensor package using a panel level packaging process and through outside silicon via (TOSV) technology, which includes a sensor, encapsulation layer, first redistribution layer, photo-imageable dielectric (PID) layer, and via plugs with truncated cone shapes, allowing for thinner packages and lower manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wire bound package technology is used to interconnect sensor pads to substrate leads, then electrical connection is achieved, but the package thickness increases due to the need to cover upward-extending wires
Solution Approach 1:
Instead of extending wires upward from the sensor to the substrate (conventional approach), the patent inverts the connection architecture by using through-silicon vias to conduct signals downward from the substrate through the sensor chip to the pads. This inversion eliminates the need for thick encapsulation to cover upward-extending wires, thereby reducing package thickness while maintaining electrical connectivity.
Solution Approach 2:
The patent transitions from a planar wire-bound connection approach to a vertical through-silicon via approach. By moving the electrical connection path into the vertical dimension (through the thickness of the sensor chip), the patent eliminates the horizontal wire extensions that would otherwise increase package thickness, effectively using dimensional repositioning to resolve the contradiction.
2Length of stationary object
If through silicon via process is used to form vertical interconnects, then package thickness is reduced, but manufacturing precision requirements and cost increase
Solution Approach 1:
The patent modifies the via formation process by changing the etching parameters and via dimensions to create a more robust process window. By optimizing via diameter, depth, and spacing parameters, the patent achieves the required thin package thickness while maintaining manufacturing precision within acceptable tolerances, effectively decoupling thickness reduction from precision escalation.
Solution Approach 2:
The patent performs preliminary actions in the sensor chip fabrication process by pre-forming the through-silicon via holes and applying protective coatings before final assembly. This preliminary preparation ensures that the via structures are ready and stable before subsequent packaging steps, reducing the need for high-precision adjustments during final assembly and thereby lowering overall manufacturing precision requirements.
3Ease of manufacture
If conventional sensor molding technology is used, then sensor encapsulation is achieved, but the process becomes complicated and production efficiency decreases
Solution Approach 1:
The patent merges the sensor chip fabrication process with the packaging process by integrating through-silicon via formation, pad alignment, and encapsulation into a single unified manufacturing flow. This consolidation eliminates separate molding and assembly steps, simplifying the overall process while significantly improving production efficiency through reduced handling and fewer process transitions.
Data Source
AI summary
A sensor package includes a sensor, an encapsulation layer, a redistribution layer, a photo-imageable dielectric (PID) layer and via plugs. The encapsulation layer exposes the active surface of the sensor, and the top surface of the encapsulation layer is coplanar with the active surface of the sensor. The redistribution layer covers the top surface of the encapsulation layer and the active surface of the sensor. The PID layer covers the redistribution layer, the encapsulation layer and the active surface of the sensor. The via plugs are disposed around the sensor and through the encapsulation layer. The via plugs are electrically connected to the redistribution layer and the active surface of the sensor. The cross section of the via plug at the top surface of the encapsulation layer has a first hole diameter, and the cross section of the via plug at the bottom surface of the encapsulation layer has a second hole diameter. The first hole diameter is less than the second hole diameter.