Drilling layer

Problem description:

The function of the drilling layer is to show the position and the diameter of the drill holes.If there is missing drilling layer in your

 file, we don't know how to make drill holes on your board.

How to deal with the problem:

1. If you need you any drill holes on your board, please don't forget to add the drilling layer into the zipped packge.

2. If you don't need any drill holes on your board, would bettler add an empty drilling layer into the zipped package. If you don't 

know how to generate an empty drilling layer. You can add a text file that name by'不需要钻孔'as below one into the zipped package.