PCB Gerber File

PCB Gerber File: What You Need to Know concerning PCB Manufacturing

Everyone enjoys the art of well-fabricated and well-assembled printed circuit boards, at times, unknowingly or knowingly. However, the bottom line encompasses the fact that PCBs form a critical aspect and operational soundness of electronics. But the fabrication process often relies on the design of the PCB, whose details get communicated through the PCB Gerber file. It becomes a pivotal aspect in ensuring the successful capture and actualization of the PCB design.

 

A PCB Gerber File

Electronic manufacturing service companies and contract manufacturers often take printed circuit board designs into the quality and reliable PCBs. However, for such ECMs to carry out the processes successfully, they need the raw materials (electronic components, materials, etc.). Most importantly, however, they need the design guidelines that come in the PCB Gerber file format.

A PCB Gerber file represents an open ASCII vector formatted file and comprises information on all the physical circuit board layers of the PCB design. Aspects like the circuit board copper traces, pads, vias, silkscreen, and solder mask images get represented by a draw or flash code. Further, such objects get defined using multiple vector coordinates. In short, the PCB Gerber file becomes pivotal for PCB manufacturers in translating the design details into the corporeal properties of the circuit board.

Therefore, it becomes essential for the PCB engineer or designer to get all the design details in their Gerber files right. The information has to prove accurate, easily understandable, and according to the laid-down standards. In most instances, the Gerber files get generated by PCB design software suites. However, the process of the Gerber file generation varies with the CAD tool. Presently, popular PCB design file generation happens using the RS-274X file format (Gerber file). It supersedes obsolete formats like the R-274-D Gerber format. Additionally, the Gerber data can have file extensions such as .gbr or .gb when it comes in a text file. In such instances, assigning a distinctive file name becomes unnecessary.

 

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The Deployment of PCB Gerber Files in Electronics Manufacturing

The current technology used in printed circuit board manufacturing has evolved, similar to electronic circuit boards over the years. For instance, vector photo-plotters have previously gotten deployed in creating the tooling film for use in printed circuit board manufacturing. It deployed a concentrated light, which gets conducted via an aperture or opening to expose the film. After that, it forms the flashes besides drawing every trace and pad.

Before, the number and set of apertures proved minimal, and therefore, designers had to develop creative ways of restricting their lines and features. The vector machines have gotten phased out with newer types that deploy the raster laser in exposing the film.  However, larger film pieces with plenty of line drawing could take longer periods using the photo-plotter. It has now become possible to reduce the time to minutes when using the laser plotter.

The history of the Gerber file traces back to the requirements of the first vector photo-plotter. It became vital for the plotter to receive instructions. As a result, the Gerber file had minimal plotter configuration details besides the X/Y coordinates. After that, the drawing or flash command would get deployed to select the aperture position to utilize. Nonetheless, the Gerber data possesses enhanced functionality accrued over the years and includes extra configuration information. It includes an aperture and macro definitions.

Current Gerber Deployment Status

The current laser plotters deploy similar Gerber information, though the previous aperture restrictions on vector plotters prove obsolete. It converts the coordinates of the Gerber into the raster file, whose information instructs the “what” and “where” of film creation. For instance, the definition of the aperture tends to convey the sizes and thickness of the pads and traces. Similarly, the drawings command outlines the positions of the polygon fills, lines, or flashes—the laser function by sweeping across the film and exposing the image in real-time.

However, as times change, the Gerber files also continue changing. Most circuit board manufacturers have realized the need to deploy laser and thus carry out laser imaging to create copper PCB images. It bypasses the film stage through direct printing. Fresh database formats have come to the fore in creating printed circuit board images besides more smart design data like net connectivity data.  It is, however, prudent to admit that the current Gerber file will perhaps remain the same for a while. Therefore, understanding what it entails and its role in manufacturing printed circuit boards can go a long way.

 

Generating PCB Gerber Files for Your PCB Design

PCB Gerber files become more prominent upon the finalization of the PCB design where generation of the design commences. However, the process of achieving this can vary based on the circuit board design software utilized. For instance, older tools tend to take more steps when setting up and generating the files. On the other hand, current tools such as CAD packages and their simplification make the process easier.

Traditionally, the Gerber files generated come as single files for every circuit board’s physical layer. Therefore, a circuit board design with six layers containing four signal layers and a layer each for ground and power will have six files. Further, generating or creating a distinct Gerber file for both the bottom and top solder mask layers becomes pivotal. The bottom and top layers of the silkscreen also (whenever required) have to get printed. However, it depends on whether the design needs paste and silkscreen on either side of the board.

What’s more? Some manufacturers can ask for extra Gerber files, especially assembly and fabrication information or board outlines. But such requests only apply to distinctive design configurations.

It also becomes pivotal to configure your Gerber file creator before creating the files to ensure the formats, standards, and units get set up in a design consistent with your manufacturer’s standards.  Another crucial file, while proving a separate file type from the Gerber file, entails the drill file (NC). It becomes instrumental in directing the drilling equipment on the spots to drill during the fabrication process. The file is similar to the Gerber formatted file regarding the vector data, drill size details, and spots.

 

Design Software Suites Used in Generating PCB Gerber Files

Advancements in the circuit board types and the need to achieve miniaturization have necessitated Gerber files’ emergence and subsequent importance. Currently, most PCB contract manufacturers have the latest equipment or machinery and technology that can read specific standard PCB file types. Therefore, it becomes futile to develop an incredible design, but one that your manufacturer’s machines cannot interpret and fabricate.

Gerber file format is a universally acceptable file format of printed circuit boards that almost all top electronic contract manufacturers can work with. It got developed by Gerber, a company, with the format proving capable of detailing the board images, including solder mask, conductor layers, and legend layers.

Most printed circuit boards get designed in specialized CAD (computer-aided design) or EDA (electronic design automation) systems. Both systems generate circuit board data dependent on the type of fabrication. It becomes difficult for the PCB contract manufacturer to comprehend all the relevant PCB design information without enclosing a Gerber formatted file. It contains reference information that ensures fabrication and assembly that proves true-to-type to the design.

PCB Gerber files describe all the PCB image requirements and apply to both the bare board and the PCBA (printed circuit board assembly) process. For instance, PCB fabrication of the bare board calls for the typical photo-plotter besides other manufacturing machines that need image data. It includes legend printers, automated optical inspection (AOI) equipment, etc. On the other hand, the assembly requires a stencil layer sheet within the Gerber file to point out spots for component location. It becomes critical for surface-mount and through-hole technologies or approaches.

 

Software Design Options

The generation of PCB Gerber files can happen through the deployment of various PCB design software suites. Some of the most popular include the EAGLE, Altium, and Cadence, among other types of design software.  Each type of design software suite utilizes distinct steps of generating the Gerber formatted files. Understanding one or more of these design software suites becomes integral in ensuring reliable and timely PCB delivery from the manufacturer. Some of these PCB design software include the following.

 

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Altium Designer

It is an incredible printed circuit board design suite that possesses over thirty-five years of constant enhancements. It is instrumental for PCB engineers and designers in generating Gerber files. Altium Designer provides a unified design setting making it popular among many designers. It comes full of features for editing schematics, besides including powerful collaborative capabilities. The package also has an incredible set of rich schematic capture tools that quickly develop, edit, simulate, besides documenting the schematics.

Gerber Generation Steps

The first step involves opening your PCB file with the Altium Designer suite. You then click on the file “fabrication output” and Gerber file. It will open the Gerber setup window with five options for setting the corresponding considerations in the Gerber files. The parameters entail layers, general, apertures, advanced, and the drilling drawing.

  • General Button. It becomes crucial to determine two parameters under this in Format and Unit. The “Unit” has either “Millimetres” or “Inches,” while the “Format” has three options of 2:3, 2:4, and 2:5.
  • It is vital to determine the mirror and the plot under the layers.
  • Drill Drawing. Not a lot happens at this stage or tab
  • It becomes essential to select the right aperture option, for instance, the embedded aperture RS274X.
  • Advanced
  • Set the parameters as default for the film size to avoid errors by using smaller dimensions. Selecting minus and setting them at 0.005mil becomes critical for the aperture matching tolerances. Additionally, choose the separate-file-per-layer from the “Batch Mode.” However, the preferences of the engineer or designer should influence the trailing/leading zeroes, spot on the film, besides the plotter type. It is also prudent to consider the recommendation of optimizing the change location.
  • Click the Ok button upon setting all of the preferences recommended above.

 

Essential Attributes of Altium Designer
  • Design review, which is instrumental in capturing design discussions via contextual commenting
  • The electronic collaboration feature allows collaborative work with other engineers from across the world.
  • Customer interaction that keeps everyone updated besides the capability of sharing work-in-progress and design images
  • Manufacturer collaboration where you can share assembly and fabrication details or data within the browser
  • MCAD collaboration allows for synchronized bi-directional sharing that does not use any file medium. It also provides native collaboration through SOLIDWORKS.
  • The remote working feature that allows for the design and Gerber file generation on the go

 

Cadence (Allegro)

It is an instrumental PCB design software tool that can allow you to design, plot, and view Gerber files in an innovative and constraint-driven setting. As such, you enjoy the Gerber generation ability with the tool and allow real-time and visual feedback. It also permits for quick analysis of the design process of the layout. Other benefits include simplicity of routing complex and simple routes of whatever density, collaborative or team design, among other benefits.

Gerber Generation Process

The first step entails opening the PCB layout in Cadence or Allegro before clicking on “manufacture,” then “artwork.” The control form will appear in which you should incorporate the board outline. To accomplish this, right-click the “TOP” folder before selecting the “Add Manual.” After that, determining the film name ensues before clicking on “board selection” in the subclass selection and then the “outline.”

Once you finish selecting the different aspects suggested, click on the “select all” with the layer’s output. It will generate the Gerber files upon the selection of the “create artwork” button.

Leading Attributes of Cadence
  • Real-time constraints allow for the easy setup of design rules besides visually verifying that the distinct needs get met.
  • In-design analysis or analysis-driven design
  • High frequency and high-speed designs have vital signals that require management earlier on. Because of this, real-time checks (analysis) help in identifying and resolving signal length conflicts.
  • Complex routing. It becomes possible to route complicated and dense boards and gets aided by real-time visual cues.
  • DFM or design for manufacture feature. The feature allows for real-time checks during the manufacturing process for DFT, DFF, and DFA in identifying potential challenges. Such checks help in avoiding costly re-spins capable of derailing the project’s timelines.
  • It comes as an integral feature that allows the packaging of complex technologies within small areas using HDI technology.

 

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EAGLE

It is a popular EDA (electronic design automation) software suite for generating PCB Gerber files after the design process completes. Designers can seamlessly link schematic diagrams, PCB routing, component placement, and extensive library content. It has over 40 years of constant improvements and thus offers unrivaled dependability and an enhanced capacity. Further, it offers numerous attributes in the printed circuit board design and subsequent Gerber file generation.

The advantages that come from using the EAGLE PCB design suite entail the affordability and access of the software (both individual, small, and medium-sized entities). Since it comes in two categories, the Cad Softs option proves better than the original one.

PCB Gerber File Generation Process

The first step entails opening the PCB layout in the EAGLE software suite before clicking on “file” and “CAM processor.” It then springs the popup dialog window where you have to go to “file,” “open,” and “job.” Opening the design file in a fresh window then ensues. It becomes pivotal to define the Gerber file on aspects like older side, component side, silkscreen CMP, border, paste CMP, Silkscreen SOL, etc.  Immediately, the parameters get set, and the buttons are determined, then clicking the “process job” completes the generation of the Gerber files.

EAGLE’s Attributes
  • It possesses the schematic editor with a SPICE simulator, electronic rule checking, and modular design blocks.
  • The presence of the PCB layout editor allows for real-time synchronization of the design, shove and push routing, and intuitive alignment tools. The editor also possesses a new routing engine, obstacle avoidance routing, and RDC or design rule checking.
  • The printed circuit board library content has managed virtual or online libraries, complete components, and three-dimensional PCB models.
  • The online printed circuit board community with particulars like one-click make, ULPs (user language programs), and fusion 360 integration come in handy when designing, generating PCB Gerber files, and sharing the design particulars.

 

Attributes to Consider in Submitting a PCB Gerber File

Almost every contract manufacturer or EMC appreciates the submitted Gerber file to come prepared a certain way. Besides preparing each layer as a distinct Gerber file (silkscreen, solder mask, etc.), submitting the file in the popular 274-x format is prudent. However, preparing it as 274-d in case your software cannot output it in the 274-x Gerber format becomes necessary. It is also crucial to set the image’s position on the lower-left corner of the film. The same applies to the board outline for solder mask images or drill drawings.

 

Drill Drawing or Fabrication Print

Submitting a drill drawing or fabrication print together with the design package proves an incredible idea. However, the format needs to come as a Gerber file, though it should entail a board outline, graphical representation of the hole positions, besides appropriate fabrication notes. In submitting your fabrication notes, always limit the volume of the notes for every board and avoid the lure of cutting and pasting notes from prior designs. It helps avoid enclosing notes that may prove inapplicable to the specific PCB design, which proves confusing.

An excellent way of ensuring that the confusion gets limited entails referencing the IPC-6012 standard. It stipulates all the industry-approved requirements necessary for the appearance and performance of the typical rigid board. Consequently, it becomes simpler for the PCB manufacturer to reference the IPC specs you have detailed and build it to type (according to the design anticipation). It removes the vagueness that accompanies detailed description and their subsequent openness to interpretation.

 

NC Drill File

It represents an important file that needs to get submitted together with the PCB Gerber file. It has to come in the Excellon format, ideally the 2.4 trailing format. Non-plated and plated hole files also should become available to the ECM. Whenever a different file has to get created for the non-plated holes, always ensure that holes do not get consideration in the process of FreeDFM analysis.

 

Read.me Text File

It becomes pivotal to enclose a “read.me” text file containing information like the list of each file name, complete with a concise description of its particulars. It also includes the list of all the non-Gerber specifications of the job, especially when not enclosed in the fabrication print (fab. print). Finally, it should also have your contact details, including your evening phone number.

Documentation of PCB Gerber Files

The documentation stage becomes critical for designers and engineers as well. Therefore, once you’ve generated the PCB Gerber file, document them among other crucial accompanying files. It should also involve the NC Drill and other pivotal manufacturing files. Documentation helps the contract manufacturer build the printed circuit board to type or according to your design expectations.

Assemble and fabrication drawings, test data, pick and place details, the schematic netlists, and the readme file creation become necessary in finalizing the process. For this reason, always choose a top-quality contract manufacturer like RayMing PCB and Assembly and work with them in understanding the details required from you for top PCB fabrication results.

A top company will always guide you on the Gerber file format type, other acceptable format types, and crucial aspects to adhere to when generating these types of PCB file formats for your PCB fabrication and assembly needs.

 

Final Remarks

The PCB Gerber file generation cannot happen without understanding the ins and outs of the different printed circuit board design software. Additionally, a Gerber PCB design software also needs the engineer to know the various aspects of design, fabrication, and assembly of electronic circuit boards to offer valuable design details that contract manufacturers can understand. PCB Gerber files will always prove vital in actualizing your PCB designs as a printed circuit board engineer or enthusiast. Therefore, as you factor in the various considerations like picking a top contract manufacturer, the diverse aspects of PCB design, among fabrication and assembly, never forget to acquaint yourself with PCB Gerber files and how to generate them.

 

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