Seven common errors in Gerber files
date：2019-02-27 15:01:00
Seven common errors in Gerber files
PCB manufacturing is not a simple process. It has many separate components to manage and process. The lack of a component can delay the entire production of the PCB and may even cost you money. One of the most important components is the Gerber file, which basically describes the PCB layout, layers, design, solder mask, etc. Gerber files help PCB manufacturing. Here, we'll discuss seven common mistakes about Gerber files that may delay your PCB production and how you can avoid them.
1: Missing aperture list:
The aperture list contains a description of the shape and size of the tool used to create the pads and tracks. Gerber files should contain a single list of apertures for all layers, not separate. It is best not to modify the aperture list of the software output. When using the 274X format, the aperture list is included in the Gerber file. If you use the 274D format, remember that the layout package also outputs a list of apertures. Some extensions include .rep, .apt, and .apr. The .274D file requires manual input of the aperture definition.
2: Missing Excellon drilling file:
Excellon drilling files are used to drive CNC drilling and milling machines in PCB manufacturing. They determine where the size of the hole is. Tool information can also be specified in the drill file or specified separately. Both gold and non-plated holes are included in one drill file. It should be in ASCII (odd/none) format and should have 2.4 trailing zero suppression, imperial units, no steps or repetitions.
3: Missing tool list:
The tool list is basically used in conjunction with Excellon drill files. Drilling a file specifies where the hole is placed, while the tool list specifies which tool to use. As mentioned earlier, you can embed a list of tools in an Excellon drill file or send it separately. If you use the list of tools available on the production drawing, it is likely to increase the likelihood of errors. Keep in mind that if your layout software outputs Excellon drill files, it will also output a list of tools with extensions including .tol and .rep.
4: Missing Gerber files:
Yes, this is also a common mistake. Gerber files are the most important part of PCB manufacturing, and without them you can't make PCBs. Your Gerber file can be in 274X or 274D format, while English units are preferred. Some manufacturers can also convert your files from other formats to the Gerber format. To do this, you should check the company's requirements before placing an order.
5: Insufficient ring:
The annular ring is the area surrounding the through hole in the pad. The width of the annular ring is important because a suitable annular width length means good electrical conductivity between the pad and the hole. For example, a .030" hole with a .020" hole will have a .005 "annular ring width. For manufacturing, we typically use the smallest .005" annular ring for the via or at least .007" for the component hole In order to maintain proper copper spacing, you should set up enough annular rings in the layout software.
6: Copper trace width / spacing is insufficient:
The copper pitch is the minimum spacing or air gap between two adjacent copper features, and the trace width is the minimum width of the copper trace. You should keep the minimum .005 "trace width/pitch. The layout package usually checks it as a DFM (manufacturability design). You should always set enough trace width and spacing in the layout software.
7: Insufficient internal clearance:
The internal gap is the minimum distance from the edge of the hole to any surrounding unbonded inner copper layer. Providing sufficient internal clearance helps ensure that the drill does not cause any shorting of the inner copper layer. This is important for both coated and uncoated holes. The preferred internal clearance is 0.015 inches and the minimum internal clearance should not be less than .010 inches.
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