1. The overlapped pads will obviously lead to overlapped vias, during the PCB fabrication process, vias may hurt or break if it is repeated drilled;
Miss-use of layers
1. Some useless traces may be connected on some layers, for example, only top layer, inner layer 1, inner layer
2. bottom layer are required for four-layer design, but some designers may accidently put a fifth layer inside;
3. For Protel software, it would be unacceptable to draw the trace with board layer, and mark the layers with board layer, this may lead to short circuit and cause defective designs;
4. Some designers may make some strange designs, for example, the component side is accidently put in the bottom layer, and put solder side on the top one.
1. The silkscreen may overlapped with SMD pads, and this is very inconvenient for electronic test and component soldering;
Vias diameter for single-sided pads
1. Drilling is normally not required for single-sided pads, it would better to specify if required.The via diameter should be set as zero. For if there is any data created, the via drawing appears on the design and thus causing issue;
Fill the pads
Because the flower pads on plane and ground layers are mirrored in the design, all the related traces are isolated. And be careful of the isolated traces in case of any short circuit.
1. For a single-sided boards, if the layer names are incorrect ,the finished boards may mirrored completely;
Too much filled area
1. It is not a good idea to fill the pads too much or use thin trace to fill the area;
2 .We may miss data with this design, or lead to incomplete trace data;
3. The excessive filling area will make it more difficult to deal with the design data .
The pads on SMD is too short
Narrow space for net trace