Hermetic Package Sealing Geometry to Prevent Wafer Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hermetic package devices, stress concentration at the sealing part interface leads to cracking and malfunction due to the protrusion of bonding pads, causing circuit breakage and wiring disconnection.
Innovation Solution
A hermetic package device design featuring a sealing part with an inverted trapezoidal cross-section and inclined outer surface, which relieves stress by adjusting the positional shift and angle of the sealing part, preventing device wafer cracking and ensuring reliable vacuum sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding pads protrude relative to the lid wafer for electrical connection, then electrical connectivity is achieved, but stress concentration occurs at the sealing part interface causing device wafer cracking
Solution Approach 1:
The sealing part is designed with an inverted trapezoidal cross-section where the outer surface is inclined rather than vertical. This asymmetric geometry creates a gradual transition zone that distributes stress away from the device wafer interface, preventing stress concentration while maintaining the protruding bonding pad configuration for electrical connection
Solution Approach 2:
The solution moves from a two-dimensional planar sealing interface to a three-dimensional inclined surface. By introducing the inclination angle in the vertical dimension, the stress distribution is optimized across the sealing part interface, relieving concentration at the device wafer while preserving electrical connectivity functionality
2Ease of manufacture
If the sealing part has a vertical outer surface for simple manufacturing, then manufacturing complexity is reduced, but stress concentration causes device wafer cracking and malfunction
Solution Approach 1:
The sealing part employs an inverted trapezoidal cross-section with an inclined outer surface instead of a vertical wall. This asymmetric design, while slightly more complex to manufacture, reliably prevents device wafer cracking and ensures device functionality, representing an acceptable trade-off for achieving the primary reliability goal
3Strength
If the sealing part outer surface is inclined to relieve stress, then device wafer cracking is prevented, but manufacturing complexity increases
Solution Approach 1:
The sealing part geometry is defined by specific parameters including the inclination angle of the outer surface and the inverted trapezoidal cross-sectional dimensions. By optimizing these parameters, the design achieves stress relief and prevents device wafer cracking while keeping the manufacturing process within acceptable complexity limits through precise geometric control
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A hermetic package device comprises a device wafer (1) in which a semiconductor circuit (7) and bonding pads (8) are provided on a mounting surface (1ff), a lid wafer (2) arranged to be opposed to the device wafer (1), and a sealing part (6) that forms an hermetically sealed space (100s) in a vacuum atmosphere to house the semiconductor circuit (7) between the device wafer (1) and the lid wafer (2). A second installation region in which the bonding pads (8) are provided in the mounting surface (1ff) protrudes relative to the lid wafer (2), and an outer surface (6fx) of a portion in the sealing part (6) facing the second installation region is inclined such that a position thereon approaches the second installation region when getting closer from the device wafer (1) toward the lid wafer (2).