Are you constantly puzzled by your PCBs’ failures, stuck in a frustrating cycle of plating voids, acid traps, and solder bridges? Are you tired of putting your heart and soul into building a masterpiece only to watch it spectacularly crash and burn? Well, worry no more! While repairing PCB failures can be intimidating, it’s easier than you may think with the right tools and knowledge. Repairing a faulty PCB involves standard soldering, component replacement, and reflowing methods. Understanding the risks involved is crucial as taking precautions to avoid damaging the PCB or injuring yourself. So let’s dive into the fascinating world of PCB faults and discover how to troubleshoot them effectively!
PCB Faults
PCB faults refer to issues with a printed circuit board (PCB), such as incorrect component placement, faulty soldering, incorrect circuit design, or physical damage. These errors can result in malfunctions or failures of electronic devices, requiring costly repairs or replacements. Therefore, debugging PCB faults is essential in ensuring electronic products’ quality, reliability, and efficiency and involves identifying and correcting any errors or defects in the PCB design or manufacturing process.
Why do PCBs Fail?
1. Solder Bridges
When you solder two pads on a printed circuit board (PCB), an undesirable electrical connection results. This connection is a solder bridge. Excessive solder on nearby pads or the absence of a solder mask layer between the pads can result in this. The electrical connection that results may result in short circuits and other issues. To prevent solder bridges, PCB designers must ensure that solder mask layers are applied correctly, and that solder mask layers are present between adjacent pads.
2. Acid Traps:
Areas on a PCB called “acidic traps” are prone to catching and keeping corrosive leftovers like acid flux. Acid traps are frequent in recessed regions or tight spaces, such as between components. These corrosive residues can harm the PCB and cause corrosion, resulting in electrical shorts and other issues. Therefore, large open spaces between components and solder mask layers should be helpful when designing PCBs to protect recessed areas from acid traps.
3. Plating Voids:
When a hole in a PCB partially has plating material, we can refer to it as a plating void. This can occur when you improperly carry out the plating procedure or when the hole size needs to be more significant for the plating material to fill. In addition, plating voids can bring on electrical shorts, limited current flow, and other issues. Therefore, PCB designers should ensure that they carry out the plating procedure appropriately and that the size of the holes is compatible with the plating substance to prevent plating voids.
4. Environmental Factors:
Environmental factors like humidity and temperature can significantly affect how reliable PCBs are. Components can expand and compress under the influence of high temperatures, resulting in fractures and other mechanical issues. Electrical shorts and component corrosion are both effects of high humidity. PCB designers should build their boards to resist severe temperatures and humidity levels and employ protective coatings to stop corrosion to avoid these issues.
5. PCB age:
PCBs’ performance might deteriorate over time for several reasons. First, components may become more fragile and shatter more easily. Second, electrical shorts can result from connections that become loose. Third, corrosion in plating might lead to electrical issues. To avoid these issues, PCB designers should make their boards as durable as possible and utilize corrosion-resistant coatings.
Types of faults in PCB
1. Soldering fault
Soldering problems account for the majority of the printed circuit board flaws. Using the tiny components present on a PCB board makes the technical skill of soldering even more challenging. However, we can reduce soldering faults during design phase and the soldering procedure. The following are some typical soldering flaws:
When your solder fails to connect with a given point of contact properly, often the pad, the open joints, also known as “dry joints,” result. As solder may be present making poor or sporadic contact, the open joints may not always result in a circuit failure. The open joints can result from physical bending or movement, the wrong solder temperature, faulty designing or manufacturing processes, impact during usage or transit, and shifting.
2. The temperature fault:
The printed circuit boards’ operation may degrade due to temperature when stored and attached to components. Parts or joints may break or fail due to extreme temperatures or significant temperature variations. Many assume the highest or lowest safe temperature without considering temperature variations during use or storage. Temperature changes can result in expansion and contraction too quickly, leading to the PCB failing before it should.
3. Plating fault
Electricity travels through holes from one given side to the other of the board. During manufacturing, the engineer plates the hole wall. During this, the operator deposits copper in the endplate part to establish electrical conductivity with reference to the top. An incorrect copper deposition will result in plating voids, which leaves the wall areas without copper coating. We can blame this to tainted materials, air bubbles, contamination occurring in the holes, and other related causes. You can stop this by adhering to the manufacturer’s instructions and clean the equipment appropriately as directed.
4. Electromagnetic Compatibility fault
We link electromagnetic compatibility (EMC) and Electromagnetic interference (EMI) to PCB manufacturing process. While the latter phrase refers to the harmful effects of EMC, the former is typically employed in production and transportation of electromagnetic radiation. These problems may result from design faults, but we can quickly resolve them by reducing the ground surface of the board.
5. Non-wetting fault
The PCB finish dramatically affects the reflow of the solder and the amount of wetting that occurs. With a poor finish and a lot of exposed bare board, the solder reflows with more challenges and poorly adheres to the PCB. In addition, a prolonged storage period makes soldering more challenging and increases the risk of non-wetting. In most cases, solderability and plating thickness have a direct correlation. The plating required for optimum solderability may deteriorate over an extended storage period. Therefore, a PCB in storage for about a year or longer may be more susceptible to non-wetting and poor solderability.
Methods of finding fault in PCB board
Visual inspection:
This is the quickest type of examination and most widely applicable method for spotting PCB problems. Therefore, we must visually inspect for any obvious evidence of damage, such as cracks, scratches, or burn marks.
Physical inspections:
You can use a multimeter test the resistance and continuity of various PCB components. It can be helpful to identify any open or short circuits.
X-ray examination:
X-ray inspection is a method for spotting faults that are difficult to see with the unaided eye, like microscopic cracks or hidden solder joints. Using X-rays, the designer can scan the PCB to create an image that is easy to check for defects.
In-Circuit Testing (ICT):
ICT, also known as in-circuit testing, involves inspecting the PCB while it is in use to check for any defects. First, by modeling the PCB’s operation and with specialized testing tools, it looks for any irregularities. Next, put the PCB through its paces during Functional testing: functional testing to ensure that it performs as intended. It is often conducted after completing all other testing and can help identify any performance issues with the board.
Thermal imaging:
This process involves using an infrared camera to identify any hot spots on the PCB. In addition, it might help find any damaged components that are generating an excessive quantity of heat.
The procedure for repairing a faulty PCB
When a PCB fault occurs, repairing it can be a challenging process. However, with the right tools, techniques, and knowledge, it is possible to fix many types of PCB faults. Here is a step-by-step procedure for repairing a faulty PCB:
Step 1: Take out the damaged component or pad
Please remove the damaged or defective components or pads to fix a broken PCB. This step may entail carefully removing the element from the board without harming the nearby circuitry using a soldering iron or desoldering tool. In addition, it might be necessary to carefully scrape away the damaged pad with a sharp instrument or blade if it has any damage.
Step 2: Remove the solder and clean the track.
The next step is to clean the track and remove any extra solder or debris after removing the damaged component or pad. Using a soldering iron or desoldering pump, you can carefully heat and remove the solder. Alternatively, gently clean the region around the track using a fine wire brush or abrasive pad.
Step 3: Cover the track with your copper tape.
Next, cover the damaged track or pad with copper tape once you have cleaned the region. You can remedy this by carefully putting a piece of copper tape over the damaged section after cutting it to size and ensuring it extends the track’s whole length.
Step 4: Solder the joints.
The next step involves soldering the joints to firmly attach the copper tape to the board. To achieve this, carefully apply solder to the joint while heating the soldering iron, not overheating the board or harming any nearby components or tracks.
Step 5: Repair the PCB through-hole.
It would be necessary to return the hole in the PCB to its original size and form if you had placed the damaged component through it. To accomplish this, gently remove any extra solder or debris from the hole using a tiny drill bit or reamer, not harming any nearby tracks or components.
Step 6: Insert and solder your component.
Now, please replace the new component and solder it onto the board after you have repaired the hole. To accomplish this, carefully align the element with the repaired hole and solder the leads or pins to the proper board pads.
Step 7: Remove any extra tape from the mended area.
Removing any extra copper tape from the repaired area after soldering the component into place is crucial. To do this, please use a sharp blade or pair of scissors, careful not to harm any nearby parts or railroad tracks.
Benefits of debugging PCB Faults
- Cost saving
Cost reductions are one of the critical advantages of debugging PCB mistakes. You may save on pricey rework and recalls by spotting and fixing problems early in the design or production process. The cost of replacing or repairing a malfunctioning unit might be high when you put a product with a faulty circuit board on the market. By debugging PCB defects, you can find these problems before manufacturing and resolve them before they become expensive.
- Improve product quality.
Troubleshooting PCB issues might enhance the final product’s overall quality. You can lessen the chance that a product will fail by locating and fixing problems with the PCB design or manufacturing procedure. This strategy can boost client satisfaction and lead to repeat business.
- Improved effectiveness
Debugging enables targeted improvements and efficiencies by identifying particular PCB design or manufacturing issues. As a result, you may decrease the time and resources needed to make PCBs by optimizing the design and manufacturing processes, boosting productivity and profitability.
- Increased reliability
Identifying and fixing circuit board flaws can enhance the final product’s dependability. A faulty circuit board may cause a product to fail, which could be expensive and harm a company’s reputation. Ensuring the circuit board is error-free increases product dependability, lowers the likelihood of failure, and lengthens product life.
- A better understanding of the design
We can better understand the PCB design and manufacturing process through debugging, which helps with design and process optimization. Engineers can pinpoint areas where the design or manufacturing process might be improved by examining issues that arise throughout the debugging phase. This action enables more effective manufacturing techniques and better designs.
Conclusion
It is evident from the above article that PCBs can malfunction in various ways. Several things might cause a defective board, including solder bridges, acid traps, plating gaps, environmental variables, and PCB age. Fortunately, finding and fixing these flaws is possible if you have the necessary equipment and skills. Once you’ve completed all these laborious steps and repaired your damaged PCB, the item should be in working order. With the right equipment, expertise, and understanding, repairing a defective PCB is achievable, even though it may appear difficult. It may take some time and effort, but the sense of accomplishment when the device works again is worth it! With out-of-the-box thinking, anything is possible. Now, let us hope that our PCBs are up to the task!
