Open Cavity IC Ring Structure to Block Mold Compound Intrusion
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Solution Overview
Problem
Current open cavity package (OCP) fabrication processes are limited in creating small sensor cavities while preventing mold compound intrusion, requiring expensive and package-specific molding equipment, leading to increased design and manufacturing costs, and long development times due to the need for different equipment types for various OCPs.
Innovation Solution
The use of a mushroom-shaped ring with a cylindrical wall and partial circular cap positioned on a die, where a film assist material in the mold chase contacts the cap to prevent mold compound from entering the ring, forming a cavity around the sensor, allowing for the reuse of molding equipment across different OCP types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional molding processes are used to create small sensor cavities, then manufacturing precision is improved, but device complexity increases due to requiring package-specific molding equipment
Solution Approach 1:
A ring structure is formed on the die surface before the molding process, creating a predefined cavity boundary that guides mold compound flow and prevents intrusion into the sensor area, eliminating the need for complex package-specific molding equipment
Solution Approach 2:
The cavity formation is segmented into two independent steps: (1) forming a ring structure on the die surface that defines the cavity boundary, and (2) injecting mold compound that automatically conforms to the ring structure, separating the cavity definition function from the molding process
2Reliability
If mold compound is prevented from entering the cavity, then sensor protection is improved, but manufacturing time increases due to complex molding processes
Solution Approach 1:
The ring structure is pre-formed on the die surface with a cap that protrudes upward, creating an automatic barrier against mold compound intrusion before the molding process begins, ensuring sensor protection without requiring complex real-time control during molding
Solution Approach 2:
The ring structure acts as an intermediary barrier between the sensor and the mold compound, physically blocking the mold compound from entering the cavity while allowing the molding process to proceed quickly without complex intervention
3Manufacturing precision
If expensive package-specific molding equipment is used, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The ring structure methodology can be applied to multiple different OCP types using the same standard molding equipment, making the manufacturing process universal and eliminating the need for expensive package-specific equipment while maintaining cavity formation accuracy
Solution Approach 2:
The ring structure is a simple, inexpensive feature formed directly on the die surface using standard semiconductor fabrication processes, replacing the need for expensive specialized molding equipment with a low-cost structural feature
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 solution enables the efficient fabrication of open cavity packages with small sensor cavities while preventing mold compound intrusion, reducing manufacturing costs and time by allowing the reuse of molding equipment across multiple OCP types, thus enhancing the cost-effectiveness and scalability of OCP production.
Implementation Method 1
The mold chase clamps the die and the substrate such that the film assist material layer contacts cap of the ring. A mold compound is injected into the mold chase and abuts an outer surface of the ring. The ring and the film assist material layer prevent the mold compound from entering an interior of the ring.
Implementation Method 2
Metal is electroplated on the seed layer in the ring shaped opening to form a metal ring
Data Source
AI summary
An electronic device includes a substrate and a die having an active surface disposed on the substrate. A sensor is in communication with the active surface of the die. A ring encircles the sensor and includes a cylindrical wall and a cap, where the cap has a partial circular shape that extends beyond each side of the wall. A mold compound covers the die and abuts an outer surface of the wall thereby forming a cavity in the mold compound to expose the sensor to an environment external to the electronic device.