• Gerber/ODB++ Files :

  This is the most widely used file for PCB manufacturing. Gerber file is a set of files used to create different layers of the printed circuit board to be used for production. Each layer requires a separate Gerber image file.

• Top solder mask

• Bottom solder mask

• Top silkscreen

• Bottom silkscreen

• Drilled holes

• One for each copper layer

• NC drill

• Centroid File:

  The centroid file, also known as a pick and place or XY data, is used for quick programming of PCB assembly. This file contains the information about the orientation and position of all surface mount parts including reference designator, X and Y position, rotation and side of the board. Most times, CAD tools automatically generate centroid file, while some don’t. In such cases, you may need to modify the file and then create the centroid file.

• Bill of Materials (BOM):

  BOM plays a crucial role in the PCB assembly. It contains the list of components, raw materials, assemblies and sub-assemblies that need to be precisely assembled on the PCB. A PCB manufacturer depends on the BOM information to build a product. Thus, it has to be highly precise and suitably detailed. BOM should be in a digital format or preferably in an excel format and comprises the following information:

• Reference designator

• Quantity

• Component description such as material requirement, power rating, value, etc.

• Precise manufacturer part number

• Case/package type

• Manufacturer

• Assembly Drawings:

  Being an integral part of PCB design and fabrication, these offer an assembly machine operator with enough information to check whether the rotation of each assembled part or component is correct or not. The file is usually in .jpg or. Pdf format. The file is created by exporting an image file of the silkscreen layer of the board.

• NC Drill File:

  The NC drill file acts as a secondary file that needs to be sent to the PCB manufacturer along with the Gerber file. This will determine the position and size of the drill holes on the board. In some cases, NC drill file being referred to as an Excellon the file, which is based on routing and drilling machines.

• ReadMe text File:

  This file contains the following information that can be helpful for PCB assembly:

• List of non-Gerber specs

• List of each file name

• Contact information

All the above-discussed files are important to assemble printed circuit boards. This information not only helps to better understand PCB assembly needs but also rectify mistaken part placements.