Battery PCM PCB Structure for Direct Laser-Bonded Cell Tabs

Solution Overview

Problem

The existing methods for bonding a protection circuit module (PCM) to a battery cell using a printed circuit board (PCB) with an electrode lead tab require additional connection members to prevent laser damage, increasing process complexity and thickness due to direct laser irradiation through the PCB.

Innovation Solution

Incorporating a prepreg layer with carbon black between the copper foil layers in the PCB to absorb laser energy during bonding, eliminating the need for separate connection members and preventing inner layer damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate connection member is mounted on the PCB to block laser during bonding, then the PCB inner layers are protected from laser damage, but the device complexity and thickness increase

Engineering Contradiction:

ImprovePCB inner layer protection from laser damageVSAvoidconnection structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A laser absorbing layer is introduced as an intermediary substance within the PCB structure. This layer is positioned between the laser source and the PCB inner layers to absorb the laser energy and prevent it from damaging the inner layers, while eliminating the need for separate connection members

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The PCB is designed as a composite structure with multiple layers including a laser absorbing layer made of carbon-based materials or metal oxides. This composite structure combines the protective function of laser absorption with the electrical and structural functions of the PCB layers, eliminating the need for separate connection members

Inventive Principle:

Principle #40Composite materials

2Reliability

If a separate connection member is mounted on the PCB to block laser during bonding, then the PCB inner layers are protected from laser damage, but the thickness of the welded portion increases

Engineering Contradiction:

ImprovePCB inner layer protection from laser damageVSAvoidwelded portion thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

A laser absorbing layer is introduced as an intermediary substance within the PCB structure. This layer is positioned between the laser source and the PCB inner layers to absorb the laser energy and prevent it from damaging the inner layers, while eliminating the need for separate connection members

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective function against laser damage is merged into the PCB structure itself through the laser absorbing layer. This integration eliminates the need for separate connection members and reduces the overall thickness of the welded portion

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If direct laser irradiation is used for bonding the PCB to the battery cell, then the bonding process is simplified, but the PCB inner layers are damaged by the transmitted laser

Engineering Contradiction:

Improvebonding process simplicityVSAvoidPCB inner layer integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A laser absorbing layer is introduced as an intermediary substance within the PCB structure. This layer is positioned between the laser source and the PCB inner layers to absorb the laser energy and prevent it from damaging the inner layers, while eliminating the need for separate connection members

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful laser energy that would normally damage the PCB inner layers is converted into a beneficial protective mechanism. The laser absorbing layer absorbs the excessive laser energy, preventing damage while allowing the direct bonding process to proceed

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach simplifies the bonding process, reduces thickness, and enhances efficiency by directly bonding the electrode lead tab to the PCB without damaging the inner layers, thereby improving the connection structure between the battery cell and the PCM.

Implementation Method 1

an absorptive layer, that is, a first prepreg layer in which carbon black is mixed, between the first copper foil layer and the second copper foil layer

Methodology Applied

Scientific EffectLaser absorption: Absorption (EM radiation)

Data Source

PatentUS20240055672A1Battery pack including PCM having connection structure directly joined with battery cell

Publication Date: 2024.02.15 LG ENERGY SOLUTION LTD

AI summary

Discussed is a connection structure between a battery and a protection circuit module (PCM) in a battery pack in which a battery cell is connected to the PCM. The battery cell can include a battery cell main body, and an electrode lead tab electrically connected with the battery cell main body. The PCM can include a printed circuit board (PCB), which can include an insulation board, a second copper foil layer in contact with a first surface of the insulation board, a first copper foil layer above the second copper foil layer, and a first prepreg layer between the first copper foil layer and the second copper foil layer. The electrode lead tab of the battery cell can directly contact the first copper foil layer of the PCM.