RTC Terminal Layout and Switching Circuit Against Solder Cracks
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Solution Overview
Problem
Real-time clock devices face functional failures due to cracks in solder mounts caused by stress, leading to coupling failures at external terminals.
Innovation Solution
The real-time clock device incorporates a package with external terminals arranged such that the functional signal terminal is outside the high-potential and low-potential power supply terminals and clocking signal terminals, and includes a switching circuit to control the coupling between the functional signal terminal and the functional circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If external terminals are arranged in a compact configuration within the package, then the device size is reduced and integration is improved, but the solder mounting becomes more susceptible to stress-induced cracks
Solution Approach 1:
The external terminals are segmented into different functional groups (power supply terminals, clocking signal terminals, and functional signal terminals) and arranged in distinct regions. This segmentation allows the functional signal terminals to be positioned in less stressed areas while maintaining compact overall package dimensions, thus reducing solder crack risk without sacrificing integration.
Solution Approach 2:
The patent utilizes the package surface area more effectively by arranging terminals in a two-dimensional layout that optimizes stress distribution. Functional signal terminals are positioned at locations that minimize exposure to mechanical stress during solder mounting, while still maintaining a compact form factor through strategic spatial arrangement.
2Device complexity
If the functional signal terminal is positioned inside the arrangement of power supply and clocking signal terminals, then wiring complexity is reduced, but the functional circuit becomes more vulnerable to solder cracks
Solution Approach 1:
The functional signal terminal is extracted from the inner arrangement of power supply and clocking signal terminals and positioned in a separate, less stressed region. This extraction increases wiring complexity slightly but significantly improves reliability by placing the functional signal terminal in a location less susceptible to solder mounting cracks.
Solution Approach 2:
Different regions of the package are assigned different qualities based on their functional requirements. The power supply and clocking signal terminals are positioned in regions optimized for their specific functions, while the functional signal terminal is positioned in a region with reduced mechanical stress, creating local quality differences that enhance overall system reliability.
3Reliability
If all external terminals are made permanently coupled to their respective circuits, then signal transmission is ensured, but crack propagation can cause complete functional failure
Solution Approach 1:
The coupling between the functional signal terminal and the functional circuit is made dynamic rather than permanent. The switching circuit allows the functional signal terminal to be coupled to the functional circuit only when needed, providing adaptability that enhances reliability by isolating the functional circuit from stress-induced cracks when the functional function is not required.
Solution Approach 2:
A switching circuit is introduced as an intermediary between the functional signal terminal and the functional circuit. This intermediary component provides controlled coupling, allowing the system to maintain signal transmission reliability when needed while protecting the functional circuit from crack propagation by enabling decoupling when stress is detected or when the functional function is not required.
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 configuration reduces the likelihood of functional circuit failures even if cracks occur in the solder, ensuring the basic clocking functions remain operational.
Implementation Method 1
a resonator; an oscillation circuit that oscillates the resonator
Data Source
AI summary
A real-time clock device includes a package that houses a resonator, an oscillation circuit, a clocking circuit, and a functional circuit, and on which external terminals are formed. The external terminals include a high-potential power supply terminal coupled to a high-potential power supply, a low-potential power supply terminal coupled to a low-potential power supply, a clocking signal terminal used at least for controlling the clocking circuit, and a functional signal terminal used for controlling the functional circuit, the functional signal terminal is arranged outside the high-potential power supply terminal, the low-potential power supply terminal, and the clocking signal terminal in a direction in which the external terminals are arranged, and the real-time clock device further includes a switching circuit that switches between a state in which the functional signal terminal and the functional circuit are coupled and a state in which the functional signal terminal and the functional circuit are not coupled.