Protection Circuit Module Connection Tab Welding Design
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Solution Overview
Problem
Existing battery packs face issues where the protection circuit module's printed circuit board is adversely affected during the welding of a connection tab and a PTC device, leading to potential solder failures and dislodgment of the connection tab.
Innovation Solution
The solution involves a protection circuit module design where a PTC device is welded to a connection tab at a spaced-apart portion on the printed circuit board, preventing the soldered portion from melting and ensuring the connection tab remains securely attached, thereby protecting the board from external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protection device is welded directly to the bottom surface of the protection circuit module, then electrical connection is achieved, but external impacts cause breaking of the soldered portion
Solution Approach 1:
The connection tab is divided into multiple regions: a first region for welding the protection device, a second region for soldering to the printed circuit board, and a connecting portion linking them. This segmentation allows each region to be optimized for its specific function, preventing stress concentration at a single weak point.
Solution Approach 2:
The connection tab serves as an intermediary component between the protection device and the printed circuit board. It transfers electrical connection and mechanical stress away from the vulnerable soldered portion, acting as a buffer that protects the solder joint from direct impact forces.
2Reliability
If welding is performed on the printed circuit board, then electrical connectivity is established, but the soldered portion melts during welding causing electric shorts or dislodgment
Solution Approach 1:
The welding operation is extracted from the printed circuit board area and relocated to the connection tab's first region. This separates the high-heat welding process from the sensitive soldered portion on the circuit board, eliminating the harmful thermal effect while maintaining electrical connectivity.
Solution Approach 2:
The connection tab acts as an intermediary that receives the welding heat at its first region while protecting the second region (soldered to the circuit board) from thermal damage. The tab's thermal mass and geometry serve to dissipate and isolate heat, preventing it from reaching the vulnerable solder joint.
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 design effectively prevents solder failures and dislodgment of the connection tab, ensuring the integrity of the printed circuit board and maintaining electrical connectivity during welding and external stress conditions.
Implementation Method 1
a positive temperature coefficient (PTC) device. The PTC device may have a first lead coupled to a bottom surface of the connection tab, a PTC body electrically connected to the first lead, and a second lead electrically connected to the PTC body
Data Source
AI summary
A protection circuit module which is welded to a connection tab and a PTC device without affecting a printed circuit board, and a battery pack including the same are provided. One embodiment of the present invention provides a battery pack having a bare cell and a protection circuit module electrically connected to the bare cell. The protection circuit module includes a printed circuit board, a connection tab positioned on a bottom surface of the printed circuit board, and a positive temperature coefficient (PTC) device electrically connected to the connection tab. The PTC device has a first lead coupled to a bottom surface of the connection tab, a PTC body electrically connected to the first lead, and a second lead electrically connected to the PTC body.