Admin, January 12,2024
A Complete Guide On Printed Circuit Board Repair
Printed Circuit Board Repair
The printed circuit board repair is not just re-soldering, instead, you have to cut the traces, add jumpers, drill out vias, connect new components, and much more. The repair work should ensure that a faulty board will re-function as original by making certain changes and additions. However, sometimes it would be better to buy new parts instead of repairing them.
You must understand that PCBs have different types of damage so their repair depends on the damage. Like, a burnt circuit board is hard to repair compared to the damage caused by a short circuit. In other words, you can repair some PCBs, whereas some damages are hard to correct.
Almost all electronic devices have printed circuit boards be they small or large. A PCB provides the current to help a device function. The mechanical strength of an electronic device comes through a PCB as it connects various components that carry the current. These components include capacitors, batteries, LEDs, resistors, transistors, etc.
To understand the printed circuit board repair, you must know the types of the boards. A PCB is either one-sided having one copper layer or two-sided with two layers of copper or it can have many layers. A multi-layered PCB is hard to repair though it has many benefits.
Testing And Diagnosing a Damaged PCB
A printed circuit board is essential for an electronic device that cannot function without it. Hence, you must detect the PCB faults for repair or replacement.
When it comes to PCB repair, you must first check its manual or schematic to detect all its components. If any component is damaged you can’t repair it so get a new one.
Experts use signal generators to detect the shorts in the conductors or traces. When two conductors and their routes connect, it results in a short trace. It could have happened due to wrong soldering or damaged solder leading to open circuits.
You can also use an oscilloscope to test the signal waveform. It helps the PCB designers to detect changes in signals to figure out poor function. You can get the necessary data on an oscilloscope while testing a circuit board.
The design of a circuit board also impacts its functionality. A PCB with poor design can fail and even the repair can’t restore its function. So, better get a new and well-designed PCB.
There is also a need for printed circuit board repair due to a broken circuit or trace issue. It is either due to extra impact or vibrations or exposure to the fluids.
The main function of soldering is to join the components with the PCB. Solder joints get damaged due to vibration, high heat, or any environmental changes.
Some circuit boards have high-tech components known as ball grid arrays. Most modern devices have BGA and their fault can result in weak or no signals.
Sometimes PCB gets old or its parts fail to function, so repairing them would be useless. So, you should immediately replace such boards.
Reasons Behind a Faulty PCB
The failure of printed circuit boards happens due to different reasons, as described below.
Plating Issues: You can see the copper plating in a circuit board which can turn into a void when copper strips away. The void also has moisture that affects the current, interrupting the circuit board’s function.
Board Edges with Copper: This happens when copper moves toward the edges of the PCB. It can affect soldering due to a lack of space for the material, resulting in poor joints. In other words, the components don’t connect well on the board.
No Solder Mask: It happens when the solder material can’t stick to the pad due to poor coverage.
Heat Voids: Sometimes engineers can’t manage the soldering heat while PCB testing or assembling. These thermal cavities create pressure, damaging the board and creating cracks. The circuit board can stop functioning if you don’t solve the issue on time.
Copper or Silvers Breakage: The breakage of solder masks or copper can cause its embedding like it gets stuck into a hole or embedded in the pad. Hence, the pads on the other sides of the traces get short.
Acid Trapping: Sometimes too little or too high solder can cause traps for acids. It often happens due to poor PCB manufacturing. So, the printed circuit board repair becomes mandatory.
Physical damage: A PCB may lead to wear and tear if it falls due to an accident. Physical damage can also happen if you put some load or stress on the device having a circuit board. Such boards may or may not be repairable.
Electric Surges: If the electricity or current is not in balance, it may damage the PCB traces. Experts recommend switching off your device during an electric surge.
Poor Design: A PCB with a poor design can fail and even the repair can’t restore its function. So, better get a new and well-designed PCB. It is easy to diagnose a bad design as such a board fails again and again or gets multiple issues when used for longer. Sometimes the circuit board is good but the manufacturer uses low-quality components which affect the function of the device.
Trace issues: Trace is a conductive path on a circuit board with copper or silver plating. You can detect it with the naked eye or through deep scanning. It is easy to detect broken copper or silver due to their brightness. You can resolve it by re-balling or re-soldering which can restore the current.
PCB Repairing Tools
You will need special tools for a printed circuit board repair, including kits like pad repair epoxy, and gold re-plating kits. These kits come with a hot air gun, soldering iron, tweezers, copper braid, alcohol swabs, solders, and so on. Moreover, you may need different repair materials.
Essential Repair Materials
Copper and silver are common materials for trace repair. Some manufacturers also use gold for re-plating or re-soldering.
How To Repair a Circuit Board
The process of a printed circuit board repair involves many steps, such as:
- First, you have to put the circuit board on the work table, fastening it. After that, you can remove its components like capacitors, transistors, LEDs, etc.
- Cleaning the padded area with an alcohol swab.Removing excess tape from the repaired board.
- The hot air gun should be at least 6 inches above the broken part.
- Carefully pull out the repairable parts with tweezers.
- Heat the soldering iron up to the desired temperature.
- Cover the pad with copper and apply heat through the tip of the soldering iron.
- Aligning the pads on the PCB according to the new parts to ensure the right direction before making joints.
- In the end joining all the pads and leads through iron or reinstalling components. As well as recreating through holes.
The above repair process is suitable for most types of damage. Avoid repairing a PCB that comes up with warnings because repairing it can be dangerous.
Printed circuit board repair cost depends on the nature of the damage, however, it may range between $50 and $150. The cost of a capacitor can be $20 or less and you can solder it within an hour. However, the repair time varies, depending on the component. Some other repairs can take 20 to 30 minutes.
Before repairing, the designer should consider a new PCB’s cost which varies according to its size and structure. Repair can become costly in the case of a faulty processor, memory chips, etc.
It would be good to repair a device immediately when its PCB stops working. Especially, in the case of life-saving devices like medical equipment. Whereas you can replace other kinds of devices having less critical functions.
Sometimes the cost of new parts becomes high due to shortage. Whereas sometimes you have to customize the parts so their manufacturing takes time.
Frequently Asked Questions
1. Can I Repair a Printed Circuit Board?
Yes, you can repair a circuit board, however, it depends on different factors. Some PCBs are not repairable or they have multiple failures.
2. When Should I Repair a Printed Circuit Board?
You should repair a PCB if it has no visible fault affecting its components.
3. When You Should Not Repair a Printed Circuit Board?
You should not repair a circuit board in the case of broken traces or vias. Likewise, the broken components need replacement as they are hard to repair.
4. How Costly is PCB Repair?
The repair cost of a circuit board depends on the nature of the damage. Generally, it ranges between $50 and $150.
5. What are PCB Repair Tools?
The tools include the hot air gun, soldering iron, tweezers, copper braid, alcohol swabs, solders, and different repair materials.
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