In this passage, we are going to tell you everything about common failures of PCB assembly. How to prevent them? Check an read for more information below.
Failure 1: PCB Crack or Bend
Printed circuit board assembly (PCBA) may crack or bend because of high mechanical or physical stress. For instance, a rigid PCBA may fail if you put it to repeated vibrations or thermal shock. Also, even the flex PCBAs can crack if you apply a bending strength more than its capability.
Before using the PCBs in the assembly process, make sure to prebake it and keep it in humidity-controlled cupboards. Will remove any water content in the bare PCB, which may cause shocks at the later stages of assembly.
Failure 2: There is Apparent Polarity in the Components of the Assembled PCB
You may forget to mention the contradictions of the parts while designing the PCB layout. If the ingredients’ opposition is not apparent on the printed circuit board assembly, it can cause issues of reverse polarity. For instance, if you connect a battery with reversed poles, it can damage the battery and the electrical parts. The printed circuit board assembly may also fail, and electrical shock may occur.
You can either use a diode or a Schottky diode to mitigate the impacts of the reverse polarity. If you connect a diode in series with the battery, the circuit will shut off in the opposite polarity case. It will prevent any significant damage to the printed circuit board assembly.
Failure 3: Solder Joint Fracture
The difference in PCB’s thermal coefficients and the electronic components may cause fracturing of the solder joint. The printed circuit board assembly may fail if you put it in an environment with repeated high or low temperatures. Another reason could be manual soldering, which makes solder more prone to heat stresses.
It would help if you used specialized automatic machines for the soldering of the electronics components. You should not just put a small whisker of solder as it would eventually break due to vibrations. Therefore, make sure that the PCB has undergone visual inspection before sending it for the assembly process.
Failure 4: The Printed Circuit Board Corrosion
Since the flux residues are used in this process, the printed circuit board assembly may corrode. The solder flux is obligatory for making sure secure connections of electrical components. However, it can also cause their corrosion once it comes in contact.
The solder flux consists of organic acids such as citric or adipic acids. PCB assemblers should make sure that they eliminate any excess flux from the surface of PCB. In this way, there will be no flux left to destroy the metal contact. It touches on its way. If the PCB assemblers are using reflow soldering machines, they should remember to rinse off any extra flux.
Failure 5: The Component is Burned or Burned out (short circuit)
During the printed circuit board assembly operation, short courses can damage both the PCB and the electronic components. It can be due to undetected solder bridges, moisture, or unexpected occurrences like high current spikes. The short circuits cause sudden and abrupt damage to the components. It may also cause a fire break out and damage to electrical equipment.
Perform visual inspection for checking the short circuits on the PCB surface. For inner layers, electrical testing works best for printed circuit board assembly. This test will mainly inspect for any short or open circuits. Further, you may also compare the readings obtained with the ones obtained from probe tests.
Also, while designing the PCB layout, the PCB assembler must accurately align every layer. This way, they will be able to work in tandem and avoid any short circuits. You may also reduce the thickness of the PCB stencil to decrease the solder paste deposition.