PCB Gerber

Pcb Gerber

A PCB experience starts from communicating with the board factory for the laminate line width, to the PCB layout, and then to the wiring to determine whether the PCB needs to use any special process. Finally, after the PCB design is completed, the design file needs to be sent to the board factory. Make it a PCB. Of course, we do not directly send PCB design files, such as Allegro's .brd files, to the board factory. Instead, the Gerber (light painting) files are sent to the board factory, so that the PCB can be made. So what are the Gerber files?

Generally, Gerber usually contains the following files:

1. The .art file corresponding to the copper traces of each layer.

2. Silkscreen on the upper and lower surfaces.

3. Soldermask on the upper and lower surfaces.

4. Steel mesh layer (Pastemask).

5. Drill hole file (a .drl file containing the coordinates of all drill holes).

These are actually enough for making a PCB.

First of all, the light drawing file of each layer, this is easy to understand.

To make a PCB, of course, you need to know what the lines of each layer look like in order to do it right. Then the silk screen layer, the PCB finally produced by the board factory, finally needs to be pasted with components, and the pasted components need to have a silk screen number.

For the solder mask layer, green oil will be attached to the surface of the PCB at the end, but where there are pads, the green oil needs to be processed by opening the window. The solder layer is to tell the manufacturer where to open the solder mask.

For the stencil layer, a stencil needs to be made before the PCB is patched to expose the pads that need to be brushed with solder paste, and block the places that do not need to be brushed with solder paste. This is the role of the steel mesh.

This completes the tinning of all pads at once. In the drilling layer, there are almost via holes on the PCB, and the manufacturer needs to know the coordinate position of each hole.

It is customary in engineering to call the first and last layers TOP and BOTTOM instead of L1 and L10.

Open Gerber files are generally opened and viewed in CAM350.

After you send the Gerber to the board factory, the board factory will usually send you an EQ (engineering confirmation) in a day. That is, after checking your Gerber, the board factory may have some questions to confirm with the PCB Layout engineer.

Almost every PCB receives more or less EQ problems.

After the EQ is completed, wait for the PCB to come out. You can paste it next. But the premise is that you have all the materials ready.

Finally, it may be necessary to send a coordinate file of the device to the SMT manufacturer separately for the placement of the placement machine.

The design process of a PCB is basically like this.

The design-related software that may be used in the middle, such as Allegro, Polar, and CAM350, of course, need to accumulate experience in ordinary actual combat, and you will naturally become proficient with more use.

Next, I would like to talk about a foreign language, about the advancement of PCB Layout engineers.

The first stage of the Layout engineer is of course to be proficient in the above design software, and then familiar with the PCB process rules and accumulate certain experience.

If Layout engineers go deeper, it is actually better to develop in the direction of signal integrity (SI).

There is a lot of outsourcing of PCB, including because of work reasons, I have also contacted Layout engineers of many outsourcing companies. In fact, if Layout does not go deep into the SI field, then Layout is indeed a manual job, and the ceiling is actually not high.

Of course, every time I see some Allegro keyboard shortcuts, it is also a visual impact. But as a person with technical pursuits, let's develop towards SI.

As an SI engineer, as well as a hardware engineer in many companies, the basic entry is two books: Eric's Signal Integrity Analysis (I heard that the third edition is out), and Steph's high-speed digital system design. This is equivalent to the red book of TOEFL and IELTS. These two books can be called Sapphire Books, because they have blue covers. After all, the circuit boards and high-speed digital interfaces that are made now are almost all encountered, such as PCIe, USB, Ethernet, and so on. So SI/PI is also becoming more and more important.

Have you ever encountered a situation where a cable is too long, causing the interface to not work? What is the appropriate length of cloth? These are all signal integrity questions to answer.

To tell the truth, now for a domestic hardware engineer, excluding the empirical design accumulation, pure technical theoretical basis, and usually used more, I think the most important basics are: 1. Signal Integrity Theory. 2. Radio frequency theory. 3. Op amp, analog-to-digital, digital-to-analog signal chain technology. 4. High power circuits.