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What Is A Logic Board On An iPhone? (Very Important!)

You’ve most likely found this article, wondering:

“What is a logic board on an iPhone, exactly?”

Well, the logic board on an iPhone is akin to a motherboard.

A motherboard is a printed circuit board (PCB) that hosts the main components of a computer or electronic device.

The logic board thus connects all hardware components within your iPhone. These components include the phone’s processor, random access memory (RAM), graphic cards, and internal drives.

The term ‘logic board’ is specific to Apple devices.

Since the board is the ‘mother’ component of the iPhone, the device will not function without it!

Furthermore, since the logic board is specific to iOS devices, motherboards from different devices will not operate on the iPhone.

Let’s now go ahead and take a detailed look at what the logic board does!

What Does A Logic Board Do On An iPhone?

Now that we know what a logic board is, it is necessary to understand its function.

The primary function of the logic board is to operate your device.

After the user’s commands are given, the logic board connects all the peripheral modules and it then translates them into concrete functions by passing information as electricity.

The chipset, storage, graphics processing unit (GPU), Central processing unit (CPU), RAM, cameras, and sound controllers are key functional components.

The board synchronizes these components to make the iPhone operate optimally.

These components all have different functions. However, they need to coordinate so that the functions manifest within your phone.

The logic board is the ‘commander-in-chief’ of this coordination, so to speak.

It undergoes a lot of work, and because of this the logic board has a tendency to heat up.

However, an onboard fan helps cool down the CPU and other crucial elements operating in tandem with the board.

Where Is The Logic Board On An iPhone?


The logic board location differs depending on the iPhone model.

The board is positioned on top of the L-shaped motherboard in older models, such as the six series till the 12 series. The SIM card slot rests above it.

In the latest iPhone 13, the logic board is on top of a rectangular motherboard. It is attached to the SIM card slot that is welded onto it.

In all models, it boasts a double-stacked compact design, positioned on the left side near the battery below the rear camera.

Logic boards vary in size, depending on your iPhone’s series and build. They’re unfortunately not very strong, and therefore are susceptible to damage.

What Causes Logic Board Failure?

Due to the frequency of use, there are many reasons why logic boards can fail.

The leading cause is the damage and disconnection of internal cables in the board itself.

The internal wires are responsible for prompt transmission within your device’s operating system. When the cables fail to function, so will your logic board.

Other factors leading to cable malfunction and overall failure are overheating, physical damage, dirt, and age. Let’s take a look at how each affects your board!


smartphone overheatCables can heat up and break away from the board when the internal circuit can’t withstand any more heat.

This occurrence causes disruptions in your phone’s functioning. Physical increase in temperature and radiation sources can cause the logic board to heat up.

Similarly, placing it on a hot surface such as microwaves, high-temperature metal and stovetops can damage the cables.

Overusing an iPhone can also cause overheating. This overuse includes actions such as excessively powering it on and off.

Disabling auto-lock can also overheat your phone as an active screen increases battery usage.

Another potentially hazardous practice is using the phone while charging it. Doing so can cause overheating and may ultimately result in damage to the battery.

Similarly, using incompatible and fast chargers will destabilize the power supply and eventually heat up the iPhone.


Moisture- primarily water- can interfere with the electricity that passes through the wiring in the logic board.

Exposure to moisture includes dropping your iPhone in water or other liquid, handling it with wet hands, putting it in the freezer, spilling liquid on its screen, taking it into the shower or ocean, and more!

When your iPhone comes in contact with water, it will lead to the deterioration of the board.

Even though some iPhones are very water-resistant, it’s always better to be safe than sorry.

Physical Damage

damaged iphoneExposing your smartphone to any kind of force that may apply pressure on its internal contents counts as physical damage.

This force could be dropping your phone, bouncing it off surfaces, or slamming it against a hard edge. All of these actions can break or impair your iPhone’s logic board.

This type of harm also results in cracked screens and dead pixels– especially in glass-encased models. When this happens, your phone’s internal components will be at heightened risk of exposure to moisture.


iphone dirty internal partsDirt and debris build-up can stagnate the logic board, making it faulty and slow.

If you notice a change in how your iPhone functions, the next step may be to detach the board and inspect it for any dirt.

If you are inexperienced when it comes to disassembling your phone’s components (or are rightly worried about voiding a warranty), take it to an official technician instead.

In case the issue is dirt, there are ways you can clean a dirty logic board effectively.

For instance, you can soak the detached board in isopropyl (otherwise commonly known as rubbing alcohol). This method cleans out any rust as well.

After soaking the component in isopropyl, rub the liquid off and leave it to air dry.


Your logic board’s age matters when it comes to operation failure. On average, a regular logic board will last a decade at maximum.

Aging leads to the breakdown of wires. Afterward, the wires begin to snap, leading to disconnection.

Once the cables fail, the board will inevitably stop working as well!

How Do You Know Your Logic Board Is Bad?

iphone7 disassembled showing components inside

The most tell-tale sign of a faulty logic board is when the iPhone stops responding to user commands.

The touch screen display may stop working, and as a result you might find yourself tapping the screen incessantly.

Actions and prompts become prolonged, and the screen gets stuck and constantly needs refreshing.

Another potential indicator is when the iPhone doesn’t respond to its charger.

The phone display will turn completely black- or not turn on at all! This can indicate that the logic board has burnt out or has faulty cables.

Speaking of response and recognition, your iPhone may also fail to recognize your headphones and other external devices.

A significant decline in battery life is also a critical indicator that the logic board is faulty.

Any little activity will drain the battery within a few hours and, in some cases, mere minutes!

Therefore, using heavy applications such as Instagram and Snapchat becomes a pipe dream.

Furthermore, the iPhone may shut down even when fully charged or at a reasonably high charge (such as 65%).

This prompts some users to keep the iPhone constantly connected to a charger.

However, this is not a long-term solution by any means. In fact, it will contribute to both your logic board and battery’s further damage.

Lastly, if you are unable to reboot your iPhone, then chances are that your board has malfunctioned.

Rebooting is necessary for refreshing your RAM, enabling applications to restart and function smoothly.

If you cannot reboot your smartphone, then the device is bound to break down at some point- reflecting what has happened to your logic board.

Can An iPhone Logic Board Be Repaired?

You can repair your iPhone’s logic board.

However, this does depend on how bad the damage is!

Minor issues within the board only require minor tweaks, while more serious problems will require the replacement of some components within the logic board.

If this is the case, you will need to take your device to a certified Apple dealer or repair store to fix the faulty parts. They can also clean the board if dirt is the issue.

On the other hand, the extent of logic board damage can be so great that no measure of repairs can fix it! In this scenario, you might need to replace the component entirely.

When Should You Replace Your Logic Board?

iphone repair

You should look to replace your logic board if it has suffered severe damage to its wiring. This could be due to physical damage, overheating, or exposure to moisture.

Such damage leads to burning out of certain components or a complete breakage of crucial parts within the board.

Contact your Apple dealer or phone technician to diagnose the extent of damage. They will be able to advise you on whether to replace it or not.

If the diagnosis requires you to replace the board, it is advisable to go ahead and do so!

Repairing one component might not be sufficient as other logic board parts may also be affected.

You will find yourself constantly repairing your board until you realize that you should have replaced it entirely.

Furthermore, repairing a damaged logic board may not only further deteriorate it but will also harm surrounding circuits.

This will damage additional components within your device and cause irreversible damage. Ultimately, you’ll probably have to buy a brand new phone!

If your device is old, then chances are that your logic board is as well.

Therefore, you’ll most likely need to replace it. As mentioned earlier, it’s normal for old boards to have faulty components. Replacing one will not guarantee a long-term fix.

With time, another essential part will fail as well! It’s therefore better to replace the board once and for all.

If you want to replace the logic board, it’s recommended that you visit an Apple Store or certified repair shop.

If not Apple, you can take your phone to an experienced technician specializing in soldering micro-parts.

However, ensure that the logic board they are replacing your old one with is legitimate and compatible with your phone model.

Do not replace the component yourself unless you have previous experience. Otherwise, you might damage other internal hardware components beyond repair!

How Can An iPhone’s Logic Board Be Replaced?

To replace the logic board, you’ll have to open the device and remove it from the internal hardware.

Again, this should only be attempted by yourself if you have the proper expertise.

First, shut down the iPhone for safety reasons.

Then remove the two Pentalobe screws at the sides of the charging port. Gently pry open the phone.

Using an iSclack, insert the iPhone inside the suction jaws and position it so that the jaws are on the screen above the home button.

If an iSclack isn’t available, suction cups will suffice. Once the iSlack or cups are attached, gently pull on them to open the iPhone using a plastic opening tool. Flip the screen upwards to reveal the inner contents.

The logic board is on top of the motherboard, which is much easier to detach. Unscrew the necessary screws and fold the metal connectors.

After that, remove the motherboard and use a heating platform to separate the board by melting the solder paste.

Replace and reassemble the components back together again.

What Happens When You Replace iPhone Logic Board?

By replacing your iPhone’s logic board, it’s possible to upgrade your storage gigabytes (GBs).

For example, some users upgrade from 16GB to 64GB by changing the hard disk on an otherwise identical board.

However, if you change the component, you should get one whose iCloud is unlocked.

Furthermore, confirm if it has the original home button with which the manufacturer paired it (on older models). Otherwise, your Touch ID will not work correctly!

In Summary

In closing, the logic board is essential for the functionality of an iPhone.

It serves as a central point that coordinates all of the iPhone’s components and features.

This makes them efficient in response to the user’s demands. Without it, your phone is as good as dead!

Logic boards vary in shape and size, and are positioned differently depending on your model.

They are relatively frail and are therefore susceptible to damage. Common causes of damage include physical impact, exposure to dirt and moisture, and overheating.

If your iPhone has a damaged logic board, you can quickly diagnose it with the help of a certified phone technician. They will advise you on whether you need to repair or replace it entirely.

Do not replace the board by yourself if you lack the experience and expertise!

We hope you now have a good idea of what a logic board is on your iPhone, what it does, and how to diagnose any potential malfunctions!

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