Capless MEMS Semiconductor Package for Compact Sensor Exposure
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Solution Overview
Problem
Existing semiconductor packages with MEMS dies face challenges in reducing size, footprint, and thickness while maintaining sensor exposure and functionality, and the manufacturing cost is high due to the need for precise cap attachment and increased manufacturing steps.
Innovation Solution
A capless semiconductor package design where a molding compound covers the MEMS die sidewalls and surfaces, exposing the sensor through an opening in the substrate, eliminating the need for a cap and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap is used to protect the MEMS die and expose the sensor to the external environment, then the sensor functionality is maintained, but the package size, footprint, and thickness increase
Solution Approach 1:
The patent removes the cap from the package structure entirely. The molding compound is extended to directly cover and protect the MEMS die sidewalls, eliminating the need for a separate cap component while maintaining sensor exposure through the substrate opening.
Solution Approach 2:
The patent merges the protective function previously performed by the cap with the molding compound. The molding compound now serves both as structural encapsulation and as the protective element that replaces the cap, reducing the number of discrete components.
2Reliability
If a cap is used to protect the MEMS die, then the sensor is exposed to the external environment, but the manufacturing cost increases due to precise cap attachment requirements
Solution Approach 1:
The patent eliminates the cap attachment process entirely by removing the cap from the design. This eliminates the need for high-accuracy cap attach machines and associated precision manufacturing steps, significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The molding compound performs multiple functions: it provides structural encapsulation, protects the MEMS die sidewalls, and eliminates the need for separate cap attachment processes. This multi-functionality simplifies the manufacturing process.
3Volume of moving object
If the package size is reduced, then the footprint and thickness decrease, but it becomes difficult to provide sufficient clearance for sensor exposure
Solution Approach 1:
By removing the cap entirely, the patent eliminates the clearance requirements between the cap and MEMS die that previously constrained package size reduction. The molding compound can be formed directly against the MEMS die sidewalls without requiring precision clearance gaps.
Solution Approach 2:
The patent changes the geometric parameters of the molding compound to directly contact and cover the MEMS die sidewalls. This eliminates the need for precise clearance positioning and allows for more relaxed manufacturing tolerances while maintaining compact package dimensions.
4Reliability
If more components are used to protect and expose the MEMS die, then the sensor functionality is maintained, but the number of manufacturing steps increases
Solution Approach 1:
The patent combines the protective function of the cap with the encapsulation function of the molding compound into a single integrated structure. This reduces the number of discrete components from two (cap and molding compound) to one (molding compound only).
Solution Approach 2:
The molding compound is designed to perform multiple functions simultaneously: structural encapsulation of the MEMS die, protection of the die sidewalls, and facilitation of sensor exposure. This multi-functionality reduces the overall component count and manufacturing steps.
Data Source
AI summary
A semiconductor package that contains an application-specific integrated circuit (ASIC) die and a micro-electromechanical system (MEMS) die. The MEMS die and the ASIC die are coupled to a substrate that includes an opening that extends through the substrate and is in fluid communication with an air cavity positioned between and separating the MEMS die from the substrate. The opening exposes the air cavity to an external environment and, following this, the air cavity exposes a MEMS element of the MEMS die to the external environment. The air cavity separating the MEMS die from the substrate is formed with a method of manufacturing that utilizes a thermally decomposable die attach material.