Circuit Board Assembly Reflow with Controlled Battery SOC
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Solution Overview
Problem
Lithium ion secondary batteries experience performance deterioration when subjected to reflow soldering, especially in high-temperature and high-humidity environments, due to increased battery resistance.
Innovation Solution
A method for producing a circuit board assembly that involves connecting a lithium ion secondary battery with a state of charge (SOC) of 30 to 100% during reflow soldering, using a ceramic positive electrode plate and a titanium-containing negative electrode plate, and employing a specific electrolyte solution to reduce moisture ingress and internal pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reflow soldering is performed on lithium ion secondary batteries, then circuit board assembly is achieved, but battery performance deteriorates due to increased resistance in high-temperature and high-humidity environments
Solution Approach 1:
The battery is charged to a specific SOC range (30-100%) before reflow soldering to prepare it in advance for the thermal stress, preventing performance deterioration during the assembly process
Solution Approach 2:
The state of charge (SOC) parameter is controlled within a specific range (30-100%) during reflow soldering to optimize battery performance and reduce resistance increase in high-temperature and high-humidity environments
2Ease of operation
If powder-dispersed positive electrodes with binders and conductive agents are used, then electrode flexibility and conductivity are improved, but packing density of active material decreases
Solution Approach 1:
The invention extracts and removes binders and conductive agents from the positive electrode, using only lithium complex oxide particles to achieve high packing density while maintaining necessary conductivity through particle contact
Solution Approach 2:
The positive electrode uses a composite structure of lithium complex oxide particles with specific morphology and size distribution to achieve both high packing density and adequate conductivity without traditional binders and conductive agents
3Ease of manufacture
If lithium ion secondary batteries are subjected to high-temperature reflow soldering, then circuit board connection is achieved, but battery resistance increases and performance deteriorates
Solution Approach 1:
The battery is pre-charged to optimal SOC levels before reflow soldering to prepare the electrochemical system for thermal stress, minimizing resistance increase during high-temperature processing
Solution Approach 2:
Controlling the SOC parameter within 30-100% range during reflow soldering optimizes the battery's thermal and electrochemical stability, reducing harmful resistance increase in high-temperature environments
Data Source
AI summary
Provided is a method for producing a circuit board assembly, capable of effectively suppressing the deterioration of the battery performance in a high-temperature and high-humidity environment that can occur due to reflow soldering, while employing reflow soldering. The production method includes connecting a lithium ion secondary battery to a circuit board by reflow soldering, wherein the lithium ion secondary battery has a state of charge (SOC) of 30 to 100% during reflow soldering.