How To Repair PCB- Everything You Need To Know in 2022

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Introduction

Perfect PCB assembly is a myth in the electronic world. That’s why knowing how to repair PCB has great importance in PCB manufacturing services.

PCB manufacturers usually intend to apply high-quality PCB materials during manufacturing. But all components need to go through specific unavoidable issues that hamper their functioning.

That’s why it is necessary to have a clear conception of the ins and outs of PCB repair services. Do you know how to repair PCB?

We are here with a detailed explanation about different PCB failures and their safe repairing. Let’s make a move.

PCB Repairing Service

PCB Repairing Service

What Are Common Failures Of A PCB?

It is widespread for a PCB manufacturer to deal with different failed PCB. If you want to understand how to repair PCB, you need to know about the failures of a PCB. The most common PCB failures include-

Breakage of Shielding

A printed circuit board usually consists of various shields to protect the components.  Besides, EMI shields deliver significant support to resist electromagnetic waves. These protections get broken due to mechanical and thermal forces. Then, the PCB becomes exposed to the environment and loses its efficiency.

Leakage of Chemical

The unwanted chemical leakage causes severe damage to PCB components. It creates short connections and makes the PCB corrosive to a large extent.

Improper Soldering

Improper soldering causes flux contamination. Sometimes, the residues of solder flux absorb moisture and dust that hampers the functionality of PCB.

Besides, it creates short or open connections in the circuit board.  Poorly processed soldering also results in solder flux impurity.

Substandard Thermal Management

In some cases, PCB delivers low-quality thermal management due to substandard materials and poor connections. Then, you need to deal with overheating, burning, overloading, etc. If a circuit board consists of materials having poor thermal conduction, it goes through these failures on a regular basis.

Damage On PCB Trace

Another common PCB failure is damage or cracks on a PCB trace. It occurs due to keeping the PCB in high temperatures and vibrations.

Faulty Components  

High moisture absorption rate and overloads often make the PCB components faulty. Besides, poor manufacturing, improper handling,  and lack of cleanliness are the primary causes of defects in parts.

PCB Failure Analysis

PCB Failure Analysis

What Are The Inspection Processes Of PCBs?

Regular inspection improves the functionality of a PCB. Do you have any idea about PCBs inspection processes?

You can test a circuit board manually or automatically. Different automated inspections are reliable for PCB fault detection. Let’s have a look.

AXI (Automated X-ray Inspection)

The AXI test is adequate to identify dimensional faults, such as improper solder joints, conformal coatings,  drilled holes, etc. Here, a high-quality X-ray machine uses the penetration power of X-ray and detects these faults.

This test is expensive for small-scale PCB manufacturing.  But you can depend on its output without any hesitation.

AOI (Automated Optical Inspection) 

The automated optical inspection is a photograph-based test. In this case, an AOI machine that consists of a high-level image capturing device takes 2D and 3D photographs of a tested PCB.

Then, this machine compares the captured images with an ideal PCB design and detects faults, cracks, etc. The AOI test is also expensive but effective. You can rely on this test for high-volume PCB manufacturing.

Besides, various manual inspections like the flying probe, peel, and electrical tests are also popular to identify a faulty circuit board.

Reliable PCB Inspection Process

Reliable PCB Inspection Process

Significant Causes Of PCB Failure

Haven’t you ever been astonished thinking how a PCB fails?

PCBs get defective because of various reasons. The most significant causes are-

  • High thermal stress
  • Poor manufacturing
  • Improper storage
  • External contaminants, like moisture, dust, etc.
  • High current loads
  • Lack of cleanliness
  • High vibration and mechanical pressures
  • Low-quality materials
  • Electromagnetic interference

These factors lead you to repair or rework a circuit board. That’s why you should keep these things in mind to avoid additional complications while using an electronic appliance.

Failure Due To Improper Connections In Printed Circuit Boards

Failure Due To Improper Connections In Printed Circuit Boards

Required Materials For PCB Repairing

What are the required materials for PCB repairing?

Its answer depends on what kind of repair. But the essential tools are almost the same for all PCB repair services.

The common materials for PCB repair service are-

  • Soldering iron
  • Desoldering wire and pump
  • Circuit board holder
  • Magnifying glass
  • Multimeter
  • Solder remover
  • Conductive pen
  • Coating remover pen

Common PCB Repair Materials

Common PCB Repair Materials

If you have a PCB repair tool kit, you don’t need to collect all materials separately. You need to manage the materials from a reliable source to achieve the optimum output in PCB repair. Watch this video about PCB repair materials:

 

What Is The Safest Way To Handle PCBs When Repairing Them?

Sometimes, improper handling of PCB during repair causes severe problems. YourPCB repair services don’t have any significant outcome in those cases. So, you have to maintain some precautions while repairing circuit boards. Such as

Unplug The Circuit Board

The first and foremost thing is to unplug the circuit board that you want to repair. Sometimes, PCBs hold some additional components for better output. You should also disconnect these components before starting the repair service.

Discharging Of PCB

The presence of charge in the circuit board causes a short circuit during the repair. So, you should ensure full discharge of PCB components that contain electrical charges. Then, it is essential to discharge the PCB.

Reliable PCB Repair And Rework

Reliable PCB Repair And Rework

Using Safety Glasses

The splattering of PCB solders is very common when repairing a circuit board. Besides, you can face flying parts of leads in some cases. So, wearing safety glasses is an effective way to protect your face and eye from these harmful elements.

Prevention Of ESD

ESD (Electrostatic Discharge) is a common incident in electronic devices. It happens when there is a significant electron difference between different PCB surfaces. You should use grounded wrist strips while performing the repair services.

Besides, the implementation of an ESD-free mat is also an effective way. Both of these processes impede ESD through the use of conductive surfaces.

Reduction Of Manual Contamination

Printed circuit boards get contaminated from your hands while repairing. It causes poor solderability. External contaminants are also supportive of corrosion, a common cause of PCB failure.

So, you must wash your hand correctly and implement electronically safe hand lotions.

Holding The PCB Properly

The way you hold a damaged circuit board is essential when repairing PCB. You should hold the PCB by the edges and avoid direct contact. It significantly helps resist external contamination in any sensitive portion of the circuit board.

Safe Handling Of A PCB During Repair

Safe Handling Of A PCB During Repair

How  Does Static Electricity Affect While Handling A PCB?

Static electricity has a major impact on PCB performance. It affects PCB repairing in many aspects.

Electrostatic discharge occurs in less-humid atmospheres. Dry environments support insulators to produce hotspots of anions. When multiple insulators come closer, these hotspots start discharging electrons to create equilibrium.

It causes generating high voltage in different PCB components like SMOS logic devices, microprocessors, EPROM, etc. These elements have a specific tolerance limit for voltages. For example, microprocessors can handle around 10Volts  where logic elements support more than 2500 Volts.

So, static electricity damages the functional quality of these sensitive PCB materials. You must take the necessary steps to reduce electrostatic discharge while handling a PCB.

Burning Issues Due To Static Electricity

Burning Issues Due To Static Electricity

How Can You Resolve The PCB Soldering Problems?

PCB soldering refers to connecting metals on the PCB surface using wires, fluxes, etc. Sometimes, you can’t ensure the desired soldering in electronic devices. So, what can you do in that case?

It’s simple. You have to resolve the soldering problems. You can apply the following ways to remove solder from the PCB surface.

Desoldering Station

The desoldering station is an effective method of desoldering. It is used in drawing up the melted solder quickly. This station consists of a soldering tip containing a hole in the center position.

You can apply the desoldering station only on coverless portions. That’s why you need to eliminate the coverings of components before desoldering.

Solder Wick

The solder wick is a reliable way of solder absorption. Usually, a combination of solder wick and flux helps remove hard solder. You can quickly draw the melted solder by using a capillary instrument.

Again, you have an opportunity of removing isolated PCB components through the solder wick. You don’t need to apply heat to the entire circuit board for that purpose. Like the desoldering station, the solder wick is applicable for exposed soldering.

HAS Sation

HAS (Hot Air Solder) station effectively removes faulty components without difficulties. It delivers hot air to the specific zone for PCB repair. Then, you can disintegrate the damaged element by using a tweezer.

Solder Sucker

It is a vacuum-based desoldering method. This vacuum consists of a spring. It is time-consuming because it allows you to remove a small portion of solder. Temperature change is a vital issue in this case. Excessive temperature causes thermal pressure on solder connections.

Except for these methods, you can apply the hot tweezers and hot plates to draw the solder without hampering the components.

PCB Solder Repairing

PCB Solder Repairing

Types Of Flux Used In PCB Repairing

Flux is a crucial element of PCB repair service. It delivers adequate protection against oxidation. The followings are the most used fluxes while repairing a circuit board.

  • Tacky flux
  • Flux pen
  • Liquid flux

Tacky flux and flux pen are easier to use compared to liquid flux. You can use these fluxes in replacing PCB components.

Solder Flux Remove From PCB

Solder Flux Remove From PCB

The Way You Can Ensure Reliable Desoldering

PCB desoldering is a sensitive task. It requires close attention for the desired output. But, how can you ensure a reliable desoldering?

Let’s find out.

Using High-Quality Flux Remover

You must apply high-quality solder flux remover while desoldering. If a small amount of solder remains due to improper desoldering, it causes corrosion and dendritic growth.

These cause malfunctioning of PCB components. So, don’t think of using substandard flux remover during the PCB repair.

Implementation Of Clean Soldering Iron

Usually, oxidized and burnt soldering iron tips are unsuitable for heat conduction. It is required to implement clean soldering iron for better thermal management during desoldering. Besides, a polished soldering iron is reliable for quick solder wicking.

Keeping Solder Joint And Wick Width Matched

Unmatched solder joints and desoldering wicks both are problematic issues for desoldering. Thinner desoldering wick can’t draw a high amount of solder at a time. So, you need to remelt the solder multiple times.

Besides, a thicker wick requires more time to melt. You have to use a desoldering wick match with the solder joint to avoid this issue.

Using Solder Flux Compatible With Cleaning Method

Solder flux type is a vital issue for desoldering. You should choose a suitable solder flux that matches the cleaning method. But do you know about the features of different solder fluxes? We have some reliable suggestions for you.

If you need to desolder a critical portion of a printed circuit board, you should go for No-clean solder flux.

Again, Rosin flux offers quick solder wicking. But unlike No-clean solder flux, this braid requires cleaning after desoldering. So, you have to choose the most appropriate solder flux based on your demands.

Avoid Keeping Solder In Extreme Temperature

Extreme temperatures cause severe damage to PCB and its components. So, you should avoid keeping solder flux at high temperatures. It is effective in handling thermal stresses to a large extent.

Using Soldering Tip Similar To The Braid Width

To ensure accuracy in desoldering, you should keep the braid width and soldering iron tips matched. Too small and too large soldering tips cause defects in removing defective parts from the PCB surface.

Desoldering In Printed Circuit Board

Desoldering In Printed Circuit Board

Challenges After PCB Repair

You need to face some inevitable challenges after PCB repair. If you have a clear concept of these complications, you can better prepare to overcome these challenges.

The notable challenges after repairing a circuit board include-

  • Keeping the fixed portion safe from external elements.
  • Cleaning the residual solder flux.
  • Controlling thermal conduction
  • Improving the outlook of the repaired zone on the circuit board.

PCB Repairing For Broken EMI Shield

Have you ever thought of repairing a broken EMI shield?

You need to ensure a proper EMI (Electromagnetic Interference) shield for the circuit board used in your device. But EMI or radiofrequency shields often break due to mechanical, thermal forces. That’s why you have to take an effective way of repairing or reworking EMI shields.

Usually, you can find metal screens and wire mesh in EMI shieldings. These wire meshes are adequate to maintain constant electron flow. You have to ensure a smaller mesh size compared to the EMI wavelength.

Polyimide tapes are primarily invisible to radio frequencies. So, RF or EMI can’t transcend polyimide tapes.

You can use these tapes for repairing EMI shields. Besides, you should apply conductive paints to these tapes to maintain continuity.

EMI Shielding In PCB

EMI Shielding In PCB

The Way Of Connecting Temperature Sensitive PCB Components

Don’t you face difficulties in connecting temperature-sensitive PCB components?

Don’t worry. We have a superb solution for you.

You can apply conductive epoxy materials to connect these components without applying high temperatures. IYou have to mix epoxy materials properly before using them. It takes around 30-60 minutes to create a successful connection.

After completing the connections, it is necessary to wire the components for a while to secure the connections.

Connecting Temperature Sensitive PCB Components

Connecting Temperature Sensitive PCB Components

How Do You Remove Conformal Coating  While Repairing A PCB?

Ensuring a safe conformal coating removal is a challenge while repairing a circuit board. Its process varies concerning the types of conformal coatings you use in PCB.

You can apply three different techniques for the most common PCB conformal coatings like Acrylic, Silicon, Epoxy Resin, Ultra-thin coatings, etc. Let’s see.

Hard Coatings

Parylene and epoxy resin coatings are very hard. These conformal coatings have superior tolerance to chemical and mechanical forces. That’s why you can’t remove these coatings by applying chemicals. Besides, heat causes damage to the circuit board during the repair.

So, what should you do?

Micro-abrasive blasting is the most effective way of removing Parylene and Epoxy resin coatings. In this case, a device blows the harsh particles from the coated surface.

Using micro-abrasive blasting, you need to follow some vital instructions to achieve the best outcome. Such as

  • Cover the repair zone to avoid unwanted removal of necessary components.
  • Select the abrasive medium concerning your PCB components.

Soft Coatings

Urethane, Acrylic, Silicon coatings are comparatively softer than Epoxy resin or Parylene coatings. You don’t need to apply any abrasive medium to remove these conformal coatings.

You can rely on the traditional burning method in this case. But some considerations can save you from additional difficulties after the removal of conformal coatings.

  • Ensure sufficient ventilation while removing the conformal coatings.
  • A through-burning leaves some hard edges in PCB repair services. So, don’t forget to clean these edges before applying the subsequent coating.
  • You should choose a coating remover that offers less toxicity. Some solvents like toluene and xylene can dissolve conformal coatings. But these materials can affect the PCB components connected to the repair area. So, you can use a coating remover pen to avoid such unwanted incidents.
  • Wait for some moments after rubbing and wiping the pen on the resin. Usually, silicone coatings take more time than acrylic coatings.
  • Wear your protective equipment.

Ultra-thin Coatings

Ultra-thin conformal coatings are invisible to a large extent. These coatings get burnt and scrapped when you apply adequate thermal pressure. That’s why you don’t need to think about their removal.

You can find ultra-thin coatings in advanced electronic devices. Their easy removal while repairing makes them compatible with consumer electronic products.

Removal Of Conformal Coating From The PCB Surface When Repair

Removal Of Conformal Coating From The PCB Surface When Repair

Repairing Process Of A Broken PCB Trace

PCB traces get broken due to high electrical and mechanical pressures. This is a widespread problem for the users of electronic appliances and manufacturers. How do you handle a broken trace on a printed circuit board?

The conventional way is to bypass an electrical wire around the broken PCB trace. Bit it is not good-looking. Besides, you need to spend a significant time wiring the fractured trace on the circuit board. That means it is not a  convenient process to repair the PCB trace.

You should use a conductive pen in this case. Usually, conductive pens hold silver and nickel. These materials create a polymer that offers excellent flexibility in redrawing the broken trace on PCB.

Damaged PCB Trace

Damaged PCB Trace

But there are some techniques of using conductive pens on a trace. Such as

  • First, scrape away an exposed zone of the main trace.
  • Clean this area by using isopropyl alcohol. You can also apply a remover pen for this purpose.
  • Then, apply the conductive ink through the pen. Don’t forget to shake the pen properly before using it.
  • Use an overcoat pen when you repair the broken trace.

Check this video to know more about PCB trace repair:

 

 

How Do You Repair A Damaged Pad On A PCB?

Using conductive epoxy is a wonderful way to repair a damaged pad on circuit boards. But how?

First, you need to wash the region you want to repair. You can use Isopropyl alcohol in this case.

Then, apply the mixture of conductive epoxy at the lower part of the damaged pad. You should utilize a plastic pick to make it perfect.

Now, press the pad softly and wait for some time. The used epoxy can cure within this interval. After the complete cure, you can solder the repaired pad.

Pad Repairing On PCB

Pad Repairing On PCB

The Way You Can Repair PCB Crack

You can apply the overcoat epoxy to repair a crack on the PCB. This type of epoxy ensures reliable repair to make the circuit board usable.

Before applying the mixture of overcoat epoxy, you should clean the cracked area. Some plastic picks are practical to use the epoxy to the PCB crack. The pot life and the tack-free time need to be around 20 min and 30 min, respectively, at 25⁰C.

You can cure the cracked circuit board at 100⁰C. For around 10 minutes. It will ensure excellent output. It is required to keep the repaired board for a day at room temperature before using it again.

PCB Crack Repair

PCB Crack Repair

Final Words

This is everything you need to know about “How To repair PCB.” A reliable and cost-effective PCB repair service improves the quality of PCB manufacturing to a large extent. So, you should pay close attention to each factor related to PCB repair.

PCBMay offers safe and hassle-free repair services for various circuit boards. We have skilled engineers and facilities to ensure high-class repairing. Contact us to experience trustworthy repairing services at affordable costs. For more information, stay tuned.

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