Reflow-Soldered Coin Cell Circuit Board Assembly With Capacity Ratio Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The process of manufacturing circuit board assemblies using coin-type secondary cells by reflow soldering often results in deteriorated cell performance due to high temperatures, which affects the overall performance of the assembly.
Innovation Solution
A circuit board assembly design that includes a coin-type secondary cell with a lithium composite oxide sintered positive electrode and a titanium-containing sintered negative electrode, where the capacity ratio of the positive to negative electrode (C/A) is adjusted to between 1.03 and 1.60, ensuring high cell performance even after reflow soldering, and the cell is mounted on a wiring board using reflow soldering with no additional electronic components post-soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reflow soldering is used to mount the coin-type secondary cell, then the manufacturing process is simplified, but cell performance deteriorates due to high temperature heating
Solution Approach 1:
The patent adjusts the capacity ratio parameter (C/A) between the positive electrode and negative electrode to a specific range (0.95 ≤ C/A < 1.05) to optimize cell performance. This parameter change allows the cell to maintain stability during reflow soldering heating, resolving the contradiction between simplified manufacturing and maintained reliability.
2Adaptability or versatility
If the capacity ratio of positive to negative electrode is not optimized, then manufacturing flexibility is improved, but cell performance deteriorates during heating
Solution Approach 1:
The patent defines a specific capacity ratio range (0.95 ≤ C/A < 1.05) as an optimal parameter window. Within this range, the cell achieves both manufacturing flexibility and heating resistance. This parameter optimization resolves the contradiction by providing a clear design guideline that balances adaptability with performance reliability.
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
The design maintains high cell performance, with the coin-type secondary cell retaining at least 65% of its capacity after reflow soldering, enabling efficient and reliable operation in IoT devices and other applications.
Implementation Method 1
a coin-type secondary cell that is a lithium secondary cell electrically connected to the wiring board by reflow soldering
Data Source
AI summary
A circuit board assembly includes a wiring board, a coin-type secondary cell that is a lithium secondary cell electrically connected to the wiring board by reflow soldering, and a wireless communication device electrically connected to the wiring board. The coin-type secondary cell includes a positive electrode including a sintered body, a negative electrode including a sintered body, an electrolyte layer provided between the positive electrode and the negative electrode, and a cell case having an enclosed space in which the positive electrode, the negative electrode, and the electrolyte layer are housed. When C is given as the capacity of the positive electrode and A is given as the capacity of the negative electrode, 1.03<C/A<1.60 is satisfied.