Common Mistakes in PCB Design and Assembly

1.PCB Design and Assembly-Cold Solder Joints




One of the common issues that could be resolved with the better calculation of heat dissipation of the PCB. With adequate thermal relief, the assembly would be able to solder components easier to the PCB and significantly reduce manufacturing time. Also, PCB design and assembly PCB designer should be aware of the design spec and amount of current going through thermal relief to avoid a lack of copper trace. PCB design and assembly.


Figure1: Small thermal relief.


In figure 1, the component (a relay in this case) is designed to carry high current (~16 Arms). On trace red, there is thermal relief but not on trace blue. Blue trace would be complicated to solder because the heat would be dissipated through the copper area. PCB design and assembly. Red evidence would be easy to weld but might not have enough copper to carry 16A current. The model has to be careful to place the right amount of copper and ensure the manufacturability of the PCB. A solution is to reduce the radius of thermal relief and apply it to both traces. PCB design and assembly.


2.PCB Design and Assembly-Design for testing (ICT)




To produce a reliable board and maximize production quality, Printed circuit board design and assembly have to include ICT (In-Circuit Testing) capability with 100% coverage. Sometimes during ICT placement, a designer might accidentally create an un-intentional antenna, which could fail EMC testing.


Figure 2: ICT test point.


In figure 2, During ICT placement, the designer accidentally made the ICT trace 2 inches long. Printed circuit board design and assembly. During Radiate immunity testing, it could pick up ~2GHz noise into the system. One of the solutions is to reduce the length of the ICT trace.






PCB designers and assemblies sometimes don’t notice the clearance between components and board edge, which could lead to issue with installing the components on PCB. Printed circuit board design and construction.

Figure 3: Component too close to the PCB edge.


In figure 3, the component is placed too close to the board edge, which results in manual soldering. This could lead to slower manufacturing time increase costs. The solution to this issue would be working closely with PCB manufacture to review the PCB and read their capabilities.  Printed circuit board design and assembly.

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