Battery Protection PCB With Laser Reflective Layer for Lead Bonding
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Solution Overview
Problem
The existing bonding method using a laser to connect the battery cell and protection circuit module is ineffective in preventing damage to the intermediate layers due to high transmittance, allowing the laser to pass through and potentially damaging the protection circuit module.
Innovation Solution
Incorporating a laser reflective layer with a reflectance of 95% or more for wavelengths between 1000 nm to 1100 nm, made of silver, between the upper and intermediate layers in the printed circuit board to reflect the laser and prevent it from reaching the lower insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser is used to bond the lead parts to the protection circuit module, then bonding efficiency and precision are improved, but the laser passes through the prepreg layer and damages the intermediate layers
Solution Approach 1:
A laser reflective layer is introduced as an intermediary component between the upper copper layer and the intermediate layers. This reflective layer acts as a mediator that redirects the laser energy away from the intermediate layers, preventing damage while maintaining the bonding function. The reflective layer has high reflectance (95% or more) for laser wavelengths of 1000 nm to 1100 nm, effectively blocking harmful laser transmission.
Solution Approach 2:
The harmful laser energy that would otherwise damage the intermediate layers is converted into a beneficial reflection. The laser reflective layer transforms the potentially destructive laser transmission into useful laser reflection, directing the energy back upward where it can be effectively used for bonding the lead parts to the upper copper layer without causing damage to underlying structures.
2Volume of moving object
If the prepreg layer is made thin to reduce module thickness, then compactness is improved, but laser transmittance increases causing damage to lower layers
Solution Approach 1:
The laser reflective layer serves as a protective intermediary positioned between the upper copper layer and the intermediate layers. It mediates the interaction between laser energy and the module structure, reflecting harmful laser wavelengths (1000 nm to 1100 nm) with 95% or higher reflectance. This allows the use of thin prepreg layers for compactness while preventing laser damage to lower layers through the high-reflectance barrier.
3Object-affected harmful factors
If the laser reflective layer is made thick to improve laser reflection, then laser protection is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The laser reflective layer applies the principle of local quality by providing high laser reflectance (95% or more) specifically at the interface where laser energy is most intense. Rather than making the entire module structure complex or thickening all layers, the solution focuses the protective function in a localized thin layer with optimized reflective properties. This thin reflective layer prevents laser damage without significantly increasing overall device complexity or manufacturing difficulty.
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
Effectively suppresses the laser from being incident on the intermediate layer, thereby preventing damage to the protection circuit module and ensuring reliable bonding without harming the module.
Implementation Method 1
a laser reflective layer provided between the upper layer and the first insulating layer and reflecting a laser
Data Source
AI summary
Discussed is a protection circuit module that may include a printed circuit board configured to be connected to a positive lead part and a negative lead part connected to a battery cell, wherein the printed circuit board includes an upper layer bonded to the positive lead part and the negative lead part so as to be electrically connected; an intermediate layer including a first insulating layer including a material containing an epoxy resin and provided below the upper layer; and a laser reflective layer provided between the upper layer and the first insulating layer and reflecting light from a laser.