How To Mount Battery on Flex PCB


Oakley Mae

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When designing and manufacturing PCBs, people are left wondering and undecided on the best approach to mounting batteries on flex PCB.

They don’t know that the task is straightforward and requires only a reliable battery. But why mount a battery on your flex PCB?

Generally, manufacturers design and develop mobile and wearable devices that draw high currents.

And since this trend is not stopping anytime soon, there is a need to develop and mount smaller, lighter batteries.

Therefore, the connector between your battery and flex PCB should be smaller but drawing greater currents. 

Today’s piece takes you through how to mount batteries on flex PCB and other related information. Let’s get rolling. 

Table of Contents

What Is Battery Flexible PCB?

Flexible circuit boards are designed with ultrathin lithium ceramic batteries from traditional lithium battery procedures.

The battery FPC integrates flex circuit boards as base material and packaging material.

And what’s interesting is that these batteries are small and thus easy to carry. 

Battery FPC is also safe, with no potential to cause combustion, fire, and explosion.

For example, they won’t explode or catch fire even if you expose them to overcharge testing through ultrahigh external voltage.

Moreover, the batteries can withstand physical impact, low and high temperatures.

Manufacturers find these batteries easy to manufacture and have a flexibility radius ranging between 15 to 17 mm. 

Generally, the battery FPC protects the lithium-ion battery pack.

Furthermore, FPC is a protection module common in flexible devices like smartwatches, wearables, and medical monitoring devices.

You graft on a flex copper clad to manufacture FPC and cut them into different layer sizes. 

Features of Battery FPC

An open smartphone showing battery and PCB components

(An open smartphone showing battery and PCB components)

Battery FPC has the following features that enable it to perform its functions:

High retention force: Although these batteries have a thin and small profile, they feature a high retention force.

Therefore, they can store electric charge for extended periods and provide high performance for electronics. 

High connection reliability: Despite having a thin profile, they have high reliability.

Therefore, you can use them as battery connectors for all types of mobile electronics. 

High Assembly efficiency: The battery achieves high assembly efficiency, especially when you link the socket to the header. 

Overcharge protection: Generally, overcharging a battery produces serious damage.

Therefore, a battery FPC cuts off the power supply when the battery reaches maximum charging. As a result, it eliminates cases of overcharging. 

Over-discharge protection: Besides overcharging, batteries are also damaged because of over-discharge.

Therefore, a battery PCB detects voltage drops below the set limits to prevent further discharge and leakages. 

Short-circuit protection: Short-circuit results from direct contact between positive and negative terminals.

As a result, a battery will discharge and lose power. Battery FPCs have integrated circuits responsible for detecting such occurrences, thus limiting battery damage. 

High-quality base material: Furthermore, battery FPC has high-quality and durable material that resists vibrations, heat, and high temperatures. 

Temperature monitoring: Finally, battery FPC has temperature sensors that monitor the battery temperature.

Therefore, when the temperature exceeds the expected limits, it’ll shut off the power supply to safeguard the battery. 

PCB Battery Management System

A circuit board battery management system (BMS) monitors the battery by controlling its charging and discharging.

In other words, it maintains the battery’s health by limiting overheating, discharging, and overcharging cases.

The main components of a BMS include current sensors, several protection boards, temperature sensors, and the main circuit board. 

The BMS performs supervisory roles on the battery in the following ways:

  • Delivering battery protection
  • Keeps track of your battery
  • It appraises the battery running state
  • Communicated the battery’s working status to external electronics

Benefits of BMS

The role played by circuit board BMS presents the following benefits: 

Lifespan and reliability: A BMS manages the thermal and electrical aspects of the battery, thus ensuring safe usage.

For example, the battery doesn’t explode under aggressive use, charging, or discharging when you use a BMS.

Therefore, your battery will have high reliability over a long period. 

Performance and range: The circuit board BMS ensures discharge/charge proceedings.

Also, they allow for the battery pack’s general aging and temperature results, thus facilitating the maximum battery capacity. 

Functional safety: Battery management systems don’t provide room for errors such as fire and explosion. Therefore, they offer the battery, circuit boards, and users safety. 

The Lithium Battery PCB

A lithium-ion battery for the camera

(A lithium-ion battery for the camera)

Lithium batteries are smart batteries that contain protection PCB to help monitor their performance. They have a thin PCB that protects the battery while discharging and charging.

Also, the battery can identify any short circuit situation to help enhance the battery life. 

As a result, your lithium battery will be free from the explosion resulting from over-voltage, overcharging, and high temperatures.

Furthermore, the lithium battery PCB provides balanced protection in energy conversion and consumption modes. 

The lithium battery PCB monitoring and protection process happens in the following levels.

Battery balancing circuits: This protection and monitoring level balances each lithium battery cell’s voltage while charging.

Therefore, a balanced circuit involves having all cell voltages at a tolerable level. 

Lithium BMS: This is the most advanced control level with more features than the balancing circuits.

Besides the features in the balancing circuits, lithium BMS also includes the battery history, health state, charge function state, and cycle count. 

The battery protective circuit module protects the lithium battery against over-discharging and overcharging resulting from high temperature, voltage, and current. 

Choosing A Flex PCB Battery Manufacturer

A flexible circuit board

(A flexible circuit board)

The best battery can only come from a reputable and competent manufacturer. Therefore, there are critical manufacturer considerations every buyer or end user must focus on.

First, the manufacturer must abide by quality control processes while manufacturing batteries.

Also, the manufacturer should have long-term battery manufacturing experience; you can only know this by inquiring or checking customer reviews.

Moreover, should you need a custom battery specific to your requirements, the manufacturer must be able to deliver without fail. 

Lastly, compare quotes from several manufacturers and choose an affordable manufacturer that guarantees quality battery PCBs.  

Parts of An FPC Connector

FPC connector for a smartphone

(FPC connector for a smartphone)

We use FPC connectors to link flexible PCBs and printed circuit boards. And these components have three critical parts:

Terminal: This part guarantees a stable contact performance by integrating a narrow contact method.

Plastic body: This is a barrier framework you put into place after installation. Therefore, it must be strong and rigid to provide the required stabilization force. 

Card lock: Finally, we have fastening parts that lock FPC or FFC to preserve the required contact force. Therefore, for greater performance, the card locks must be rigid. 


What is a lithium battery PCBA made of?

You must understand lithium battery PCBA to understand lithium batteries better. Generally, a lithium battery PCBA is a system with the following: 

  • Small lithium-ion batteries in rows and series
  • Flexible and FR-4 PCBs with the relevant electronic components
  • A battery management system with a PCB inside

What’s battery flex PCB material

Battery-flexible PCB materials contribute immensely to determining the performance and quality of the battery.

Generally, the material you choose will affect the safety and durability of the battery.

Manufacturers often use quality materials like CEM-3 and FR-4 to develop the battery FPC.

Such materials are heat resistant, thus supporting functionality in high or low-temperature conditions. 

Final Remarks

We hope that you now understand what battery flex PCB involves.

But generally, you can use these batteries in electronics that integrate embedded batteries.

Some of the electronics include wearables and smartphones.

An important element of these batteries is the battery management system which monitors the battery and controls its charging and discharging.

BMS guarantees the safety of the PCB, battery, and users.