Solid-State Battery Module Circuit With PTC Reflow Protection
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Solution Overview
Problem
All-solid-state batteries, when solder-bonded to a circuit board, can cause current to flow to adjacent electronic components, potentially damaging them due to unstable semiconductor operation during reflow mounting.
Innovation Solution
Incorporating a PTC element in series with the all-solid-state battery and semiconductor elements, tripping before the semiconductor reaches its junction temperature to cut off current flow during reflow soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all-solid-state battery is solder-bonded to circuit board during reflow process, then the battery can be mounted together with other electronic components, but current flows from the battery to other electronic components causing damage
Solution Approach 1:
A PTC element is introduced as an intermediary component between the all-solid-state battery and the semiconductor element. This PTC element acts as a protective mediator that responds to temperature increases during reflow soldering by transitioning to a high-resistance state, thereby blocking harmful current flow to the semiconductor element while allowing normal operation at lower temperatures.
Solution Approach 2:
The PTC element is pre-configured in the circuit with specific thermal characteristics before the reflow process begins. Its trip temperature is deliberately set below the semiconductor element's junction temperature but above the battery's operating temperature, so that during reflow heating, the PTC element proactively trips first to prevent the semiconductor element from reaching damaging temperatures.
2Reliability
If PTC element is connected in series between battery terminal and semiconductor element, then current is cut off before semiconductor reaches junction temperature, but the circuit structure becomes more complex
Solution Approach 1:
The PTC element serves as a sacrificial protective component that is deliberately designed to fail (trip) under specific thermal conditions to save more critical components. It is a relatively simple, low-cost component compared to the semiconductor element it protects, and its temporary failure state (high resistance) is acceptable as long as it prevents damage to the more valuable semiconductor element.
Solution Approach 2:
The solution changes the thermal parameter characteristics of the circuit by introducing a component with a specific trip temperature that lies between the battery operating temperature and the semiconductor junction temperature. This parameter-based protection approach uses temperature as the controlling variable to automatically switch the circuit state without requiring complex control logic.
3Productivity
If all-solid-state battery has voltage exceeding 0V during mounting, then the battery can be directly mounted by reflow, but current flows to electronically connected components
Solution Approach 1:
The PTC element serves as a thermal-responsive intermediary that allows the battery to maintain its voltage during mounting while providing automatic current isolation. When the reflow process heats the circuit board, the PTC element detects the temperature rise and transitions to high resistance, thereby mediating between the live battery and the temperature-sensitive semiconductor elements.
Solution Approach 2:
The solution exploits the temperature-dependent resistance parameter of the PTC element to dynamically control current flow during the mounting process. At mounting temperatures, the PTC element's resistance increases dramatically, automatically adjusting the circuit parameter to block harmful current while allowing the battery to remain electrically active.
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
Prevents short-circuit currents, protects semiconductor components, and ensures safe reflow mounting without deep discharging the battery, allowing reliable power output post-mounting.
Implementation Method 1
a technique using PTC (Positive Temperature Coefficient) is described
Data Source
AI summary
A battery module includes: an all-solid-state battery having a voltage exceeding 0 V; a semiconductor element; a PTC element; and a circuit board, wherein the all-solid-state battery, the semiconductor element, and the PTC element are solder-bonded to the circuit board, the all-solid-state battery has a positive electrode terminal and a negative electrode terminal, the semiconductor element is electrically connected between the positive electrode terminal and the negative electrode terminal, and the PTC element is connected in series between the positive electrode terminal or the negative electrode terminal and the semiconductor element.