PCB Circuit Board Repair | How to Repair Circuit Boards?

How to Repair Circuit Boards?

To repair circuit boards, start by diagnosing the issue, which may involve damaged components or traces. Use a soldering gun to replace faulty parts, and clean the board with alcohol. For physical damage, techniques like rebelling or resoldering copper traces can be applied. PCB cracks or broken traces require copper tape and precise soldering. Ensure proper safety measures like anti-static straps and protective gear, and use tools like multimeters to check for continuity. More technical tasks may need professional services. For detailed steps, continue reading below.

Is it Worth Fixing a PCB Board?

The primary reason for fixing a PCB board is cost-saving. Replacing a circuit board is costly. Repairing a PCB also saves time, reducing downtime for delivery of a new board. Circuit boards are repairable, much like circuits with wires and breadboards. The repair process builds experience and confidence in electronics. Additionally, solving an electronics issue, including PCB repairs, offers satisfaction.

Why Do Printed Circuit Boards Fail?

Printed circuit boards (PCBs) fail due to various factors such as physical damage, poor design, manufacturing defects, environmental stress (like moisture or heat), electrical overloads, and aging of components. Issues like broken traces, faulty solder joints, or damaged components can cause malfunctions. Additionally, improper handling or exposure to static discharge can degrade sensitive parts.

Physical Damage

Physical damage is the most common cause of PCB failure. It can result from issues with soldered components or external devices applying pressure. Dropping the PCB or hitting it with an object can cause damage. Bending, flexing, or stretching the board may also apply enough force to harm it.

A broken PCB

Disassembly errors can also lead to damage when improperly handling the board. If the PCB breaks or shatters, repairs may not be possible. However, if the damage is less severe, remanufacturing the PCB is an option. This involves melting broken sections, reballing copper traces, and resoldering or replacing damaged components.

Component Failure/Faulty Components

Component failure is common in PCBs but doesn’t compromise the board’s physical structure. Parts like resistors, capacitors, microprocessors, and diodes can fail due to aging, overheating, or shorting. These components may also become loose or detached from the board. Fortunately, such issues are easy to fix by replacing or resoldering the faulty parts.

A short-circuited electronic component on a PCB

If the circuit tracks become nonconductive due to voltage sags, overheating, or aging, the repair requires more technical skill. Tools like multimeters are essential for testing conductivity in the board and its components.

Damaged or short-circuited parts are often easy to spot, as they show visible signs like burns, cracks, or breaks. Loose components are also easy to detect. For faulty traces, however, testing tools are necessary to pinpoint the issue.

Trace Damage

The copper or silver conductive materials in circuit boards can experience damage due to these reasons.

• Power surges
• Wear (aging)
• Overheating
• Shorting
• Metal dust contamination
• Lightning strikes

Burned PCB traces

Since traces act as the "wires" of the circuit, any damage will prevent power from reaching components. Trace damage is often visible, especially with thicker tracks, where signs like discoloration or breaks are easy to spot. Shiny metals also make it easier to identify issues.

However, with thinner traces, voltage tests or multimeters may be required to check for continuity. Repairing trace damage involves reballing or resoldering the affected areas with the appropriate materials once identified.

Poor Design

Some engineers or designers may cut corners during design or manufacturing, leading to poor PCB designs that don't meet proper standards. These faults could be due to errors or intentional cost-cutting. Such boards often fail within days or months of use, and even after repairs, they will continue to malfunction.

The best solution is to replace the board, as repairs are temporary, costly, and ultimately a waste of money. When getting a new PCB, choose a designer or manufacturer that adheres to proper quality standards.

Power Failure

Power failures typically result from damaged components or traces. A broken conductive track may disrupt the power supply to certain components or sections of the circuit. Alternatively, a faulty component may block the flow of electrical signals.

A circuit board after water damage

The issue requires a voltage meter to diagnose electrical problems accurately. The repair process may involve component replacement, resoldering, or reballing depending on the nature of the damage.

What Does PCB Repair and Remanufacturing Consist of?

As stated earlier, the board repair process depends on the extent and type of damage.

But with all repairs, you must adhere to ICO and IPC standards, ensuring the product reconstruction follows the required protocols.

For instance, here’s what you need for the following repairs.

How to Repair PCB Caused by Physical Damage?

Repairing a physically damaged PCB requires rebuilding the baseboard, which involves working with substrate materials like FR4. You may also need to disassemble parts of the board, making soldering skills essential. The process can be complex and often requires expert knowledge, depending on the severity of the damage.

How to Repair Component Failure/Faulty Components?

You will need soldering/desoldering skills, Ball-Grid-Array rework skills, and a steady hand to operate the soldering gun.

The ideal person should have lots of experience with a soldering iron to ensure the following.

• Components seat properly
• Solder spreads on the pads evenly
• Proper wetting to form sturdy joints

A technician using a soldering iron

How Do You Repair a Broken Trace on a PCB?

The most common method is to bypass the damaged section using a wire. First, identify the damaged area and scrape about 2mm on either side to expose the copper. Ensure a proper path is created to avoid EMI issues. Clean the area with flux, peel the wire, dip the ends in flux, and surface mount them to the exposed track. Finally, apply a conformal coating to protect the repair.

PCB Internals Repairs

Internal repairs are highly technical because they need electrical, mechanical, and engineering skills to fix.

If you lack this knowledge, we recommend employing PCB repair services.

What Materials Are Necessary for PCB Repairs?

Depending on the repair, you might need the following materials.

• Silver or copper for repairing/reseating the conductive surfaces
• Substrate materials (fiberglass, epoxy, FR4, metal, phenolic resin, etc.)
• Gold for surface finishing (electroplating or immersion)

How To Troubleshoot a Circuit Board

Map the PCB

PCBs have different components and sections, so the first step is to map out where everything is on the layout.

If you have the design documents, it will be easier to figure it out. You should distinguish sections like the power supply, filters, chokes, voltage dividers, etc.

A PCB is placed against its schematic for easy mapping

Do a Visual Inspection

Visually check the surface components on the board to find if there are any hot spots, cold joints, arcing, tombstoning, excessive solder on joints, cracks on the board, missing or lifted pads, or any other unusual occurrences.

Do a Comparative Analysis

If you can access a good, working version of the same board, use it to compare with this faulty circuit.

A comparative analysis is like an extension of the visual inspection step because it requires you to place the two boards side-by-side and then identify any errors, misplacements, or missing parts.

Take it up a notch by checking the input and output readings of both boards using a multimeter. They should be the same. If not, you’ll have narrowed it down to a specific section or component.

Isolate the Defective Components

If you’ve identified a faulty section or haven’t found any, you should go through each component to test its electrical performance.

You need to have the specifications of each part to determine if the multimeter reading matches the datasheet and PCB design requirements.

Alternatively, you can do a nodal analysis on each component to measure the V/I response.

Nodes, branches, and circuit elements in a circuit

Test or Replace the Chips

Integrated circuits are not that expensive nowadays, so you can test or replace them. Identify the chip’s markings and specifications first then test it using an oscilloscope or logic analyzer. Check the component’s orientation, as well, and verify that all the solder joints are in order. Remember to also evaluate the heat sink and thermal pads. You can do a direct replacement to avoid this testing hassle because it is an easier troubleshooting option.

Check the Power Supply

A faulty power supply can affect the performance of all components because they might be getting more or less juice than what they need. Use a multimeter to measure the rail voltages, which can indicate if there is a short or open circuit if the reading is zero.

Identify the Hotspot

Faulty connections or components usually create a hotspot when power flows through them. You can inject power into the board and feel the heat levels after some time or use a thermal camera to observe the circuit. The latter is better because it is less likely to cause electrical accidents.

Do a Signal Probe

If you know the waveforms and expected values of all the test points, you can use a wave-capturing device, such as an oscilloscope, to analyze the PCB for errors like low voltages.

Necessary Safety Measures When Repairing PCBs

Wear Protective Gear

Harmful compounds or metals, like hot, molten solder, can splutter when making these repairs, so you must wear protective gear to protect your eyes, hands, and nose (to avoid breathing in harmful elements).

A technician wearing protective glasses when repairing a PCB

Eliminate Electrostatic Discharge

Electrostatic discharge

is common when handling electronics, and it can damage sensitive components. To eliminate static before it causes electrical faults, use anti-static wrist straps ESD-safe mats, and ground your workstation.

Discharge the Electronic Components

Capacitors and components in the power supply section can hold the charge even after you disconnect the board from its power source. These can cause harmful static or even spark you a little. The shock can be more intense if the board has an internal supplementary battery, so remember to remove this component, as well.

Operate in a Clean Environment

Your hands or the working surface can have corrosive compounds like salts and water that will damage the board, especially around the edges. So remember to clean your workstation and use electronics-safe hand sanitizer to clean your hands. You can wear gloves but some people prefer bare hands.

Step-by-Step Guide to Repairing Circuit Boards

After identifying the damaged area or components, follow these steps to complete the repairs.

What Repair Tools and Materials Do You Need?

You will need at least the following tools.

• Hot air gun
• Soldering gun
• Copper foil
• Tweezers
• Sharp knife
• Scissors
• Sandpaper
• Adhesive copper tape
• Paper clip
• Rubbing alcohol
• Cotton swabs
• Pen

A soldering gun

Remove the Damaged Pad/Sections

Hot air melts the solder, so use the hot air gun to heat the damaged area.

Keep the nozzle about ¼ to ½ inches away from the surface and heat for 30 seconds.

After that, use the tweezers to lift the component from the copper pad or thru-hole.

If stuck, continue applying heat for 15-20 seconds until the solder melts.

But be careful not to overheat the area. However, you can still fix this issue. If heat damages the pad, remove it using a knife.

And don’t force the copper pad out because you can damage the conductive track.

We recommend sanding down the surface to remove debris or excess solder and restore the shiny look.

Clean the Track and Remove the Unwanted Solder

Cleaning the track ensures the new pad or component creates a solid connection. The process involves:

• Rubbing the alcohol-soaked cotton swab on the track
• Use the craft knife to remove the remaining damaged parts
• Marking the cut track end using a pen to know where to position the new pad/component

A bottle of rubbing alcohol

Place Copper Tape Over the Track

With a clean track, place the copper tape above it to help create a solid connection with the new pad or component.

Ensure the adhesive tape is slightly longer than the track, but the ends should flush with the PCB edges.

Solder the Joints

Next, solder the joints where the copper tape attaches to the existing track. And try to solder in one go.

Keep in mind copper melts quickly at the high soldering temperature.

So only start the process when you can finish soldering in one go.

Copper tape

Also, apply a small solder quantity on the pads, then use the soldering gun to heat the solder until it melts.

After that, use the gun tip to hold the copper tape in place until the solder cools and solidifies.

Solder Components

The next step is to solder the component on the copper tape. But if it is a through-hole component, you must rebuild this hole.

You can identify the hole by pressing down on the soldered area using a pen or object with a rounded edge.

Since the adhesive is still tacky, you’ll be able to find the thru-hole point.

Pierce it using a paper clip and expand the hole to be the same diameter as the component’s lead.

A thru-hole component undergoing soldering

Insert the component, flip the board, then solder the lead using the soldering gun.

Trim the Excess Copper Tape

Use the scissors or knife to cut the excess tape from the repair area.

Ensure you don’t slice the tracks or pads in this process.

What Are Common Electronic Board Repair Applications?

• Home applications: smart home, alarm, HVAC, and lawn irrigation systems
• Lab equipment: analytical equipment and measurement & testing devices
• Office applications: networking devices, phones, security equipment, and printers
• Manufacturing equipment: pumps, motors, sensors, control devices, etc.

PCB Board Repair: Can All PCBs Be Repaired?

No. Boards with poor design/build quality are not worth repairing. And it might be impossible to repair completely shattered PCBs.

In such cases, it is economically viable to get a new PCB.

A broken PCB with electrical connections on both sides

PCB Repair FAQs

How Do You Repair a Damaged Pad on a PCB?

The simplest and quickest repair is to use a copper tape or copper foil patch, which repairs the outer layers and requires minimal tools.

How Do You Repair Breaks in EMI or RF Shielding?

You can apply fast-drying silver-filled polymer or conductive paint, which will dry in minutes to patch the shield. But ensure to maintain or not block the whole pattern.

How Do You Repair a PCB Crack or Open Area of the Solder Resist on a PCB?

It depends on where the crack is and how bad it is. If the crack cuts across a copper trace and is too extensive, you’ll have to glue the pieces back together and then repair the broken trace(s) using the steps explained earlier.

But if it doesn't cut across copper traces, such as on the edge, glue the pieces, and you’ll be good to go.

What Is the Best Glue for PCB Repair?

The best glue for PCB repair and electronics in general is epoxy, but you can also use UV-curing acrylics.

What Wire Should I Use for Trace Repair?

You should use enameled wire, an insulated conductor, the same as what you should use to repair electromagnet or transformer coil wire cuts.

This enamel coating comes off easily when you apply heat using the solder gun, leaving the copper core exposed.

So remember to apply the conformal coating to protect the wire from oxidation and corrosion.

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