Guideline

Advanced Techniques for Salvaging and Repairing Damaged PCB Boards

Fix PCB Board

Printed Circuit Boards serve as a base in most electronics and can be used both as a physical support piece and as a wiring area for various electronic products. They are either made up of fiberglass or some composite materials such as composite epoxy. Since PCBs are so sensitive and fragile, they often get damaged, and it becomes a headache to repair them. Here are some techniques for anyone who wants to know how to repair PCB.

Troubleshooting Causes of PCB Damage

Only people with ample theoretical knowledge and analytical skills can do the troubleshooting and fault analysis of a damaged PCB. These skills can be enhanced through frequent testing and investigation. The very first step in repairing a PCB is troubleshooting the cause behind its damage. In this way, it is sophisticated on how to fix PCB board. Some common troubleshooting techniques are as follows:

  • Visual Inspection

This technique involves human senses to detect any errors in the circuit. Visual inspection includes checking for loose connections, carbon on either an IC socket or connectors, burned components, broken tracks, missing components, etc. It is important to identify the reasons behind the overheating of the components before replacing them. For example, when a fuse blows, it should be replaced with a fuse having the right current and voltage rating instead of a jumper wire to avoid safety hazards. Visual inspection may be a good choice for those who want to know how to repair PCB.

  • Physical Check

Physical check is done on a powered PCB to test the circuit’s functionality when it operates properly for a while, but later it fails due to a heated IC or other problems. This technique is useful to identify the source of defect behind overheated or broken components. Additionally, some specialized freezing sprays are used to freeze components or ICs in the beginning. If the circuit begins to operate the moment after it is sprayed, the IC or the heated component is likely the cause of the circuit failure. However, before replacing these items, it is better to examine the chilly ICs or components, as the current flow causes all of them to release heat. It is also useful to use a multimeter to look for any broken tracks in the circuit in case of a cold component or an IC.

Also read: Essential Steps for Using a Multimeter to Test Your PCB Board

  • Separate Component Testing

This technique involves separate testing of the components such as resistor, capacitor, inductor, diode, transistor, MOSFET thyristor, etc. A multimeter or LCR meter is used to check all these components. In case of satisfactory results, it is better to conduct PCB trials on a dependable system before moving toward the next step.

  • Testing Integrated Circuits (ICs)

It is better to use an IC tester for all testable ICs as manual testing cannot always be performed for some types of ICs, including logic gates, Op-amps, multiplexers, etc. If an IC is found to be defective, it should be replaced carefully as hot air, or an overheated soldering station may damage the internal layer track or the pad, hindering us from repairing the boards.

Repairing Damaged PCB Boards

Techniques for Fixing a Defective PCB

Following are some easy methods for someone who wants to know how to fix PCB.

1. Soldering

Soldering is used to join two metal parts using a chemical material called solder paste. It is commonly used to fix petty issues such as broken tracks on the PCBs. For instance, in this case, the first step would be to uncover the damaged area and introduce a new metal wire or any desired component. Then, the metal wire and the broken track are joined together through soldering. This enables the current to flow again through the circuit.

2. Replacing Components

This technique is used when a defective component has to be replaced. It is necessary to identify the defective components before replacing them. Once all such components are identified, they are then removed with the help of a soldering iron and replaced with a functional one. It is commonly used for devices with damaged capacitors, resistors, transistors, etc.

3. PCB Rework

This technique is primarily used when the surface mount components on a PCB are not functioning properly. It is executed by using tools such as rework stations and specialized soldering irons. However, it often needs an expert’s help as it is comparatively difficult to perform individually or by someone who does not have the required expertise. Additionally, it is best used to treat problems in electronic devices such as PC mother boards, phones, TVs, etc.

The Complete Process of PCB Repair

Before you can even think about how to repair PCB board, you must have all the items such as a knife or a screwdriver, copper tape, a soldering gun & a hot air gun, a pair of scissors, a pen and a paper clip, a cotton swab, rubbing alcohol, and a tweezer. Following is a step-by-step process for someone who wants to know how to repair PCB.

  • The first step involves using an oscilloscope to check signal strengths and waveforms at various points to test the functionality of the circuit across the board. Additionally, a burned area or a nonfunctional component highlights that the component needs to be replaced or rejoined to the board.
  • Next, use a tape to fix the PCB to your work area.
  • In case a component is not functioning properly, replace it with the help of a hot air gun. Hold the gun to the faulty component no more than 6 inches and continue applying heat until it is ready to be taken out with a pair of tweezers.
  • Remove the damaged PCB pad carefully with a knife in such a way that it does not affect the rest of the components on the board.
  • Use a knife or a screwdriver to remove the solder that is left on the board after the pad has been removed.
  • Once you have removed the defective pad and cleaned off the area, place copper tape on the top of the area that you are on in such a way that it overlaps with the existing track, through-hole, and area surrounding it.
  • The next step is to solder the joints where the copper tape joins the existing track. However, in doing so, make sure that you can finish this process in one go, along with using as little heat as possible.
  • Take a pen and press it against the area that you just soldered, and ensure that the copper tape is properly attached to the pad area. By doing so, you can identify the through hole and pierce it with a paper clip.
  • By following all the above steps till now, you will have a fully functional PCB. Now you can solder the components of your choice over it but keep the heat as low as possible.
  • In the end, power up the PCB and look out for any issues before using a multimeter to measure the voltage or connectivity across the circuit. Conduct extensive tests as well to ensure that the PCB has been repaired successfully.

Also read: The Beginner’s Guide to Soldering PCB Boards: Essential Tools and Techniques

Cases in which PCBs are Irreparable

Typically, when we say how to repair PCB board, it indicates that the PCB board can be repaired. However, printed circuit boards inevitably break and become defective at some point. Thus, it is better to replace the damaged PCB with a new one in such a case. Additionally, experts also believe that the maximum service life of a PCB is 5 years, and it is better to buy a new one after that.

Some situations in which the defective PCBs cannot be repaired are when:

  • PCBs are burned
  • Copper gets exposed
  • The pads are lifted
  • Some components have already been replaced several times before

Conclusion

Everyone should have a basic knowledge of how to fix a PCB board so that they can fix it themselves upon encountering such a situation. However, it requires a certain level of skills to repair a damaged PCB along with accurate hand-eye coordination and a lot of patience. Thus, repairing a PCB can only be mastered by practicing frequently. Additionally, it is important to maintain PCBs regularly as neglecting their repair can lead to equipment failure, lost time, increased costs, etc.

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