The X and Y location values are measured to the ten thousandth of an inch (0.000). Even the reverse side of the board uses the lower left corner as the origin’s reference point. The board's origin is defined as the (0, 0) value and is located at the lower left corner of the board from a top point of view.

The location is measured from the origin to the component's center. Location Location: the X and Y Locations refer to the values that identify the horizontal and vertical location of a PCB component with respect to the board's origin. PCB fabricators and assemblers often call the top and reverse sides the component side and solder side, respectively. Layer Layer refers to the top side or reverse side of the PCB or the side where the components are placed. It will correspond to your bill of materials and PCB markup.

RefDes RefDes stands for reference designator.

A Centroid file consists of the following information: A Centroid file contains all the positional parameters such that the machine knows where to place a component and in what orientation on a PCB. To place surface mounted parts on PCBs via automated equipment, it is necessary to create a Centroid file to program the equipment.

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