Die Stacking Recess Notches for Precise Angular Sensor Alignment

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Solution Overview

Problem

Existing methods for assembling multiple-axis sensors in a single package face challenges in achieving precise angular alignment of individual devices, leading to inaccuracies due to limitations in automated assembly systems.

Innovation Solution

The use of alignment recesses in covers with notches and protrusions to control the angular orientation of substrates and dies within a multi-chip package, allowing for precise angular separation of less than two degrees through mechanical features that constrain rotational alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automated assembly systems are used to assemble multiple-axis sensors, then productivity is improved, but manufacturing precision deteriorates due to inability to achieve precise angular alignment

Engineering Contradiction:
Improveassembly speedVSAvoidangular alignment accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The cover structure includes self-aligning features (notches and protrusions) that automatically guide the substrate into the correct angular position during assembly, eliminating the need for high-precision automated positioning systems while maintaining sub-degree alignment accuracy

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The alignment recesses and notches act as intermediary mechanical features between the cover and substrate, providing a physical reference system that translates loose automated placement into precise angular alignment, bridging the gap between low-precision automation and high-precision requirements

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If mechanical alignment features are added to control angular orientation, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improveangular alignment accuracyVSAvoidstructural complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cover incorporates asymmetric notches and corresponding protrusions at specific corners, creating a unique angular reference system that enables precise orientation control through simple geometric features rather than complex mechanical mechanisms

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The alignment function is segmented into discrete features (alignment recesses, notches, protrusions) that can be independently manufactured and assembled, allowing precise angular control through modular geometric elements rather than monolithic complex structures

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4480900B1Die stacking with controlled angular alignment
Publication Date: 2025.12.24 STMICROELECTRONICS INT NV
  • EP4480900B1 patent drawingFigure 1
  • EP4480900B1 patent drawingFigure 2A~2C
  • EP4480900B1 patent drawingFigure 3

AI summary

An alignment recess formed in a cover substrate such as a cover for a MEMS device allows a second substrate to be bonded to the cover substrate. The alignment recess is larger than the second substrate and has two corner regions diagonally opposite each other where a wall of the recess protrudes to form a notch. The notch is dimensioned such that when the second substrate is disposed within the recess with two opposing corners surrounded by respective notches of the recess, the angular position of the second substrate relative to the cover substrate can be controlled to within a desired amount of rotation.