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A Simple Guide for Printed Circuit Board Repair

Why do printed circuit boards fail?



Can PCB be repaired? How to fix the PCB board? What materials are needed for PCB board repair? Before clarifying these problems, we need to know the reasons for the damage to the printed circuit board.


PCB short circuit 

 

There are many faults caused by PCB. Short circuit is the most common problem in PCB failure. A short circuit can make the PCB not work properly.


1) The most significant cause of the PCB short circuit is improper solder pad design. At this point, the circular pad can be changed to oval, increase the distance between the point and point, to prevent short circuit. While we're at it, it's a good idea to change the shape of the round pad. We can make it an oval. The purpose of this is to increase the distance between the points. That way, there won't be a short circuit.


2) We know that there are a lot of electronic components on the circuit board. The directional design of these electronic components is important. If these electronic components are in the wrong direction, a short circuit is bound to occur. Let's take an example to understand that. Parallel directions of IC pins and tin waves can cause a short circuit on the circuit board. If we encounter this situation, carefully check the orientation of the PCB electronics. IC foot perpendicular to tin wave is the safest design.


3) Now let's discuss the third cause of PCB short circuits. We all know that automatic plug-ins can cause short circuits. That's the crooked foot. We must ensure that the pins do not exceed 2mm. If the pin is too long, the electronics will fall off. Electronic components that fall off the PCB can cause a short circuit. So when we weld electronic components, we make sure that the distance between the solder joint and the circuit is less than 2 mm.


In addition to the three common reasons we mentioned, some reasons can cause a PCB short circuit. For example, the substrate hole is too large; the temperature of the tin furnace is too low; the solderability of the board is poor; the solder mask is invalid, and the board Surface pollution, etc. Engineers can compare the above reasons for eliminating and inspecting the PCB board.

 

PCB open

 
When the trace is broken or the solder is only on the pad and not on the component lead, the PCB will open. In this case, there is no adhesion or connection between the component and the PCB. Like short circuits, these may also occur during the production process or the welding process and other operations. Vibration or stretching of the circuit board, drop, or other mechanical deformation factors will destroy the traces or solder joints of the PCB board. Similarly, chemical or moisture can cause solder or metal parts to wear, which can cause component leads to break.
 

Dark and grainy contacts appear on the PCB board

 
Contact problems on PCB boards are mainly due to: the solder is contaminated, and the oxides mixed in the molten tin are too much; the resulting solder joint structure is too brittle. Be careful not to use solder with low tin content. Otherwise, it will easily cause dark color confusion.
 
Another reason for this problem is the change in the composition of the solder used in the manufacturing process. The most typical is that the solder contains too many impurities, and pure tin needs to be added or replaced. As a result, the stained glass causes physical changes in the fiber buildup, such as separation between layers. But this situation is not due to poor solder joints. The reason is that the substrate is heated too high, so it is necessary to reduce the preheating and soldering temperature or increase the speed of the substrate.
 

PCB solder joints turn golden yellow

 
Under normal circumstances, the solder on the PCB board is silver gray. Occasionally, golden solder joints appear. The main cause of this problem is the high temperature. At this time, it is only necessary to lower the temperature of the tin furnace.
 

Bad boards are also affected by the environment

 
Due to the PCB structure itself, it is easy to cause damage to the PCB when it is in an unfavorable environment. Extreme temperature or temperature fluctuations; excessive humidity; high-intensity vibration, and other conditions are all factors that cause the performance of the board to be reduced or even scrapped. For example, changes in ambient temperature will cause deformation of the board. Therefore, this situation will destroy the solder joints; bend the board's shape, or cause the copper traces on the board to open.
 

On the other hand, moisture in the air can cause oxidation of the metal surface; corrosion, and rust; such as exposed copper traces, solder joints, pads, and component leads. Dirt buildup on the surface of components and circuit boards; dust or debris will also reduce the airflow and cooling of the components; cause PCB overheating and performance degradation. Vibration, dropping, hitting, or bending the PCB will deform it and cause cracks. The high current or overvoltage will cause the PCB board to be broken down; or drive the rapid aging of components and paths.



What materials are necessary for PCB board repair?


Most printed circuit board repairs require the same or improved materials used in the official design.
 
If you are searching for "electronic board repair near me," please contact us. Our PCB repair services and the team can help you reassemble or repair the damaged circuit board to make it close to its original state. There is almost no difference between the previous version and the upgraded version. Of course, this requires many skills and experience, which you will not find outside the experienced professional environment of electronic board repair.
 
An essential part of professional PCB repair services is to ensure that they have the suitable PCB repairing materials and tools to complete the work. Some PCB board repair teams did not provide everything on the property or on-site, and they must wait to receive the necessary materials or tools. This may increase the time required for circuit board repair or reassembly of parts. 
 

It is no secret that many materials used in PCB repair are not environmentally friendly or not conducive to safety. We still have a long way to go, but scientists and cutting-edge teams are studying biodegradable PCBs, which decompose naturally after being discarded.



 How to repair electronic circuit boards?



The electronic circuit board repair is most commonly after thermal and physical damage and excessive voltage to the components. So, how to repair broken circuit boards step by step?

 

First, collect the tools and other materials needed for PCB repairing:

 

  • Sharp knife or flat-head screwdriver or fantastic sandpaper
  • Sticky copper tape
  • Welding gun
  • Hot air gun
  • Scissors or craft knife
  • Pen
  • Cotton swabs and rubbing alcohol
  • Tweezers
  • Paper clip


Then restore the damaged circuit board to normal function according to our PCB rework and repair guide.

 

Step 1: PCB solder pad repair

Remove damaged pads or components. First, fix the PCB to your work surface to avoid moving around while working. It is best to use tape.

 

Step 2: Clean the track and remove the solder.

After repairing solder pads on a circuit board, use a sharp knife to remove the existing solder. If you are not used to using a knife on this relatively delicate part of the operation, you can also use a pointed screwdriver or fine sandpaper. No matter which tool you prefer, the result should be a wholly exposed track, with no existing solder, looking bright and clean.


Step 3: Place the copper tape on the track.

After removing the damaged track and cleaning up the area, it is time to put your sticky copper tape on top of the site you are using. Your tape should overlap the existing track and cover part of the current through the hole and surrounding area.


Step 4: Weld the joints.

It is necessary to carefully solder the joints between the new copper tape and the existing track joints on the repaired PCB. Here are some tips and warnings about this part of the process: The copper strip will melt rapidly at the soldering temperature, so don't start until you are sure you can complete this part of the process in one go. Use as little heat as possible and work deliberately but quickly to reduce the heat applied.


Step 5: Restore PCB vias.

Find a hard tool with a round tip, such as a pen or other simple device. Press down on the area just soldered and rubbed it hard to ensure that the copper tape is firmly attached to the entire pad area. After heating the area, the adhesive should still be sticky. Using this technique, you will determine the hole's location, which you can then pierce with a paperclip or other similar tool.


Step 6: Place and solder your components.

If you have followed these steps so far, you should have a PCB with restored functionality and be ready to receive the selected components.

From here, soldering components should be a familiar process. However, as before, you need to shorten the healing time as much as possible. The new joint you formed between the newly pasted copper tape/pad and the track may be somewhat fragile.


Step 7: Trim the excess tape in the repaired area.

Using scissors or a craft knife, carefully cut the sticky copper tape to the appropriate size to complete the repair. It is important to note that the connector you just repaired may restore functionality to your PCB. But the pads, tracks, and connectors will never be structurally as intact as the original board. Nonetheless, you have taken many things that other people would throw away as trash and given it new life.



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