There is not one Gerber file, but a separate one for each layer.
By layers, I also mean solder mask layers, silkscreen layers, and solder paste layers, as well as the electrical layers.
But it is also common to include much of that as text data on the “Drill Layer”. Again, this is just a convention.
It is a bit easier with RS274X, which can have (but rarely does) multiple layers in 1 file.
The most important addition with ‘X’ was embedding the aperture table in the files.
The original Gerber machines shone light through holes in a wheel. Each wheel had 25 “holes”. Each hole might be a circle, rectangle. Gerber file commands are a set of light on/off commands, interweaved with X,Y coordinate pairs. Light would be made to shine through the selected hole and as the arm with the wheel on it moved, an image was traced on a film. The wheel positions were D01 .. D25. And you will see this “Dnn” pattern through the Gerber file.This text represents either the current wheel position, or a new one.
If you had more than 25, then the wheel positions might also include D26.. D50, and so on. One was supposed to change the wheels, ie run the file several times, changing wheels as required. Gerber had a set of standard wheels, and you were supposed to either use these, or you could have a wheel made up for you.
Long, long ago, such analogue film systems went the way of the Dodo.
But until ‘X’ your CAD system had to create a separate aperture table file, which had a way to define what shape D01 was, D02 etc. ‘X’ simplified that by incorporating the aperture table into each Gerber file.
#PCB Design
In the world of printed circuit board design and manufacturing, precision and accuracy are paramount.…
Soldering is a cornerstone technique in electronics assembly, it's used to connect electrical pieces and…
Nowadays, electronic products are both compact and lightweight while performing a variety of functions. This…
As technology continues to advance in the electronics industry, packaging remains one of the key…
Bringing your electronic ideas to life begins with PCB drawing, which is the process of…
Printed Circuit Board design is one of the most significant processes in electronics production. Deciding…