1. Circuit board short circuit: For thistype of problem, one of the common faults that directly cause the circuit boardto work, the biggest reason is that the PCB short circuit is the incorrectdesign of the pad. At this time, the circular pad can become an oval shape.Shape, increase the distance between points to prevent short circuits. Improperdesign of the direction of the PCB proofing components will also cause thecircuit board to short-circuit and fail to work. If the pin of the SOIC isparallel to the tin wave, it is easy to cause a short circuit accident. In thiscase, the direction of the part can be modified to be perpendicular to the tinwave. The PCB may also be short-circuited, that is, automatic plug-in bending.Since the IPC stipulates that the length of the wire is less than 2mm, when thebending angle is too large, this part may drop, so it is easy to cause a shortcircuit, and the welding point needs to be greater than 2mm offline.
2. PCB solder joints become golden yellow:Generally speaking, the solder of PCB circuit board is silver-gray, butoccasionally there are golden solder joints. The main reason for this problemis that the temperature is too high, only need to reduce the temperature of thetin furnace.
3. Black and granular contacts on thecircuit board: The dark or small particle contacts on the PCB are mainly due tosolder contamination and excessive oxides in the tin, which form an overlyfragile solder joint structure. Care must be taken not to confuse the darkcolor and low tin content caused by the use of solder. Another reason for thisproblem is that the composition of the solder itself used in the manufacturingprocess has changed, and the impurity content is too high. It is necessary toadd pure tin or replace the solder. The tinted glass acts as a physical changein the fiber layer, such as the separation between the layers. However, thissituation is not a bad solder joint. The reason is that the substrate heatingis too high, and it is necessary to reduce the preheating and solderingtemperature or increase the substrate travel speed.
4. PCB components are loose or misaligned:During the reflow soldering process, small parts may float on the molten solderand eventually fall off from the target solder joints. Possible reasons for thedisplacement or tilt include the vibration or rebound of the components on thesoldered PCB due to insufficient circuit board support, reflow oven settings,solder paste problems, and human error.
5. Open circuit board: When the trace isbroken or the solder is only on the pad and not on the component lead, an opencircuit will occur. In this case, there is no glue or connection between thecomponent and the PCB. Just like short circuits, these can also occur duringproduction or during welding and other operations. Shaking or stretching thecircuit board, dropping the circuit board or other mechanical deformationfactors can damage the circuit board or solder joints. In addition, chemicalsor moisture can cause the solder or metal parts to wear, causing componentwires to break.
6. Welding problems: The following are someof the problems caused by poor welding: the solder joints are disturbed: thesolder moves due to external interference before solidification. This issimilar to a cold solder joint, but for different reasons, it can be correctedby reheating, and the solder joint is cooled without external interference.Cold welding: This happens when the solder cannot melt properly, resulting inrough surfaces and unreliable connections. Cold solder joints can also occurbecause excessive solder will prevent complete melting. The solution is toreheat the joint and remove the excess solder. Solder bridge: This situationoccurs when the solder crosses and physically connects the two leads together.These may cause accidental connections and short circuits, and when the currentis too high, it may cause the components to burn out or the wires to burn out.The pads, pins or lead are not wet enough. Too much or too little solder. Landsraised due to overheating or rough soldering.
7. The badness of the PCB board is alsoaffected by the environment: due to the structure of the PCB itself, when it isin an unfavorable environment, it is easy to cause damage to the circuit board.Extreme temperature or temperature changes, other conditions such as highhumidity and high-intensity vibration are the factors that lead to reducedcircuit board performance or even scrap. For example, changes in ambienttemperature can cause circuit boards to deform. This can damage the solderjoints, bend the shape of the circuit board, or may also cause the copper wireson the circuit board to break. On the other hand, moisture in the air can causeoxidation, corrosion and rust on metal surfaces, such as exposed copper traces,solder joints, pads and component leads. Dirt, debris or debris thataccumulates on the surface of components and circuit boards can also reduce airflow and component cooling, which can lead to PCB overheating and performancedegradation. The vibration, drop, impact or bending of the PCB will cause thePCB to deform and cause cracks, while high current or overvoltage can causedamage to the PCB or cause rapid aging of components and paths.
8. Human error: Most defects in PCBmanufacturing are caused by human error. In most cases, wrong productionprocesses, incorrect component placement and unprofessional manufacturingspecifications result in up to 64% avoidable. A product defect has occurred.
1. Circuit board short circuit: For thistype of problem, one of the common faults that directly cause the circuit boardto work, the biggest reason is that the PCB short circuit is the incorrectdesign of the pad. At this time, the circular pad can become an oval shape.Shape, increase the distance between points to prevent short circuits. Improperdesign of the direction of the PCB proofing components will also cause thecircuit board to short-circuit and fail to work. If the pin of the SOIC isparallel to the tin wave, it is easy to cause a short circuit accident. In thiscase, the direction of the part can be modified to be perpendicular to the tinwave. The PCB may also be short-circuited, that is, automatic plug-in bending.Since the IPC stipulates that the length of the wire is less than 2mm, when thebending angle is too large, this part may drop, so it is easy to cause a shortcircuit, and the welding point needs to be greater than 2mm offline.
2. PCB solder joints become golden yellow:Generally speaking, the solder of PCB circuit board is silver-gray, butoccasionally there are golden solder joints. The main reason for this problemis that the temperature is too high, only need to reduce the temperature of thetin furnace.
3. Black and granular contacts on thecircuit board: The dark or small particle contacts on the PCB are mainly due tosolder contamination and excessive oxides in the tin, which form an overlyfragile solder joint structure. Care must be taken not to confuse the darkcolor and low tin content caused by the use of solder. Another reason for thisproblem is that the composition of the solder itself used in the manufacturingprocess has changed, and the impurity content is too high. It is necessary toadd pure tin or replace the solder. The tinted glass acts as a physical changein the fiber layer, such as the separation between the layers. However, thissituation is not a bad solder joint. The reason is that the substrate heatingis too high, and it is necessary to reduce the preheating and solderingtemperature or increase the substrate travel speed.
4. PCB components are loose or misaligned:During the reflow soldering process, small parts may float on the molten solderand eventually fall off from the target solder joints. Possible reasons for thedisplacement or tilt include the vibration or rebound of the components on thesoldered PCB due to insufficient circuit board support, reflow oven settings,solder paste problems, and human error.
5. Open circuit board: When the trace isbroken or the solder is only on the pad and not on the component lead, an opencircuit will occur. In this case, there is no glue or connection between thecomponent and the PCB. Just like short circuits, these can also occur duringproduction or during welding and other operations. Shaking or stretching thecircuit board, dropping the circuit board or other mechanical deformationfactors can damage the circuit board or solder joints. In addition, chemicalsor moisture can cause the solder or metal parts to wear, causing componentwires to break.
6. Welding problems: The following are someof the problems caused by poor welding: the solder joints are disturbed: thesolder moves due to external interference before solidification. This issimilar to a cold solder joint, but for different reasons, it can be correctedby reheating, and the solder joint is cooled without external interference.Cold welding: This happens when the solder cannot melt properly, resulting inrough surfaces and unreliable connections. Cold solder joints can also occurbecause excessive solder will prevent complete melting. The solution is toreheat the joint and remove the excess solder. Solder bridge: This situationoccurs when the solder crosses and physically connects the two leads together.These may cause accidental connections and short circuits, and when the currentis too high, it may cause the components to burn out or the wires to burn out.The pads, pins or lead are not wet enough. Too much or too little solder. Landsraised due to overheating or rough soldering.
7. The badness of the PCB board is alsoaffected by the environment: due to the structure of the PCB itself, when it isin an unfavorable environment, it is easy to cause damage to the circuit board.Extreme temperature or temperature changes, other conditions such as highhumidity and high-intensity vibration are the factors that lead to reducedcircuit board performance or even scrap. For example, changes in ambienttemperature can cause circuit boards to deform. This can damage the solderjoints, bend the shape of the circuit board, or may also cause the copper wireson the circuit board to break. On the other hand, moisture in the air can causeoxidation, corrosion and rust on metal surfaces, such as exposed copper traces,solder joints, pads and component leads. Dirt, debris or debris thataccumulates on the surface of components and circuit boards can also reduce airflow and component cooling, which can lead to PCB overheating and performancedegradation. The vibration, drop, impact or bending of the PCB will cause thePCB to deform and cause cracks, while high current or overvoltage can causedamage to the PCB or cause rapid aging of components and paths.
8. Human error: Most defects in PCBmanufacturing are caused by human error. In most cases, wrong productionprocesses, incorrect component placement and unprofessional manufacturingspecifications result in up to 64% avoidable. A product defect has occurred.