In every field and industry, standards are the key to the evolution of any product, service, or device. Standards promote uniformity and efficiency, which typically correlate with higher quality and lower overall production costs.
For example, in the field of PCBA, standards are consistently evolving. However, adherence to newer standards is not always immediate. There are times in which companies do not wish to make drastic changes, even when it is in the interest of greater efficiency, accuracy, cost-effectiveness.
One important change that a company can (and should) make is in the way its designers transfer their design data to their contract manufacturers (CMs). There is significant debate about which PCBA transfer method is the best, and currently, Digital Product Model Exchange (IPC-DPMX) or IPC-2581, Gerber X2, and ODB++ are at the top of this list. All of them are more than adequate in handling the demands necessary to convey a designer's design data to the appropriate CM, but which one is best for your company?
The Gerber File Format
It can be challenging to pinpoint the exact number of design file formats accessible to PCB manufacturers and designers in today's market. However, the fact remains that most PCB manufacturers utilize either Gerber or ODB++. The following statement coincides with a written statement in The PCB Design Magazine that, as of 2016, 90% of the world's PCB manufacturing utilizes Gerber.
Within the PCB industry, Gerber is the defacto standard for design-to-fabrication data transfer with regards to PCB manufacturing. Furthermore, Gerber is a numerical control (NC) format and the design of Gerber Systems Corp. Moreover, its original design function was to drive vector photo-plotters for the PCB industry in 1980. It is a subset of the Electronic Industries Association RS-274-D specification, which is a format to drive mechanical NC machines in a variety of industries.
However, in today's market, Gerber's evolution gives way to Gerber X2. Before this iteration, RS-274X or extended Gerber (Gerber X1) was released in September 1998. Gerber X1 is a human-readable ASCII format that consists of a stream of commands generating an ordered flow of graphics objects. These graphics objects can be negative or positive. Furthermore, when superimposed in the correct order, they create a final image.
The Gerber X2 File Format
A Gerber X2 file contains the entire description of a PCB layer image without the necessity of any external file data. It incorporates all of the necessary imaging operators for a PCB image while affording the definition of every aperture shape. Moreover, Gerber X2 provides specifications of planes and pads without the requirement of vector-fill or paint as in the Standard Gerber.
Note: Some applications still use painting, but it typically presents problems for the users of those files.
With the February 2014 release of Gerber X2, the file format adds additional metadata to images. Attributes now allow the addition of metadata to a Gerber file. The attributes are like labels that provide information related to image files or the features within them. The following are examples of metadata Gerber X2 conveys through attributes:
- Pad function: For example, is the flash an SMD pad, a fiducial, or a via pad?
- File function: For example, is the file the bottom copper layer or the top solder mask?
- What part the file represents: Is it an array, a single PCB, or a test coupon?
The ODB++ File Format
Although Gerber maintains a firm grip on the PCB manufacturing world, there are obvious weak points in its armor, and some in the industry feel that it is time for Gerber to retire altogether. Gerber’s weaknesses include being more complex, less user-friendly, and proprietary.
ODB++ is an alternative option that is becoming increasingly popular due to its more straightforward and user-friendly format. Being non-proprietary is another advantage of using ODB++ because it allows users the ability to use any tool to flexibly create ODB++ files. The culmination of these features affords users the option of using the tools they prefer to generate ODB++.
In summary, ODB++ uses a hierarchy of files and folders to store its data file structure. This feature allows designers to transfer their design data to their CMs with common OS commands that also preserve the hierarchy structure by grouping all the data into a single compressed file.
The IPC-DPMX (IPC-2581) File Format
If observing these different file formats from a zoomed-out chronological view, it is a little easier to see which file format is the best. Gerber, of course, comes with the longest history. Though ODB++ is not as rich in terms of history, the fact that it became so popular so quickly speaks volumes about the industry’s demands for change. The need for improvements in data transfer methods is evident since PCB developers are gravitating towards newer standards that are more in tune with the future of the industry.
The newest standard, IPC-2581 (DPMX), is gaining tremendous traction in the field of PCBA manufacturing. Digital Product Model Exchange (IPC-DPMX) is similar to ODB++ in terms of its functionality. However, it takes the lead over the two predecessors due to its open and neutral features.
In general, IPC-DPMX is a universal standard for PCB assembly and manufacturing description data and transfer methodology. The development of this standard takes place in 2004 (IPC). The sole purpose of this standard is to transmit information between PCB designers and manufacturing (CM) or assembly facilities. Furthermore, IPC-DPMX affords companies superior quality, manufacturability, consistency, and reliability in virtually every step of the manufacturing process. Overall, IPC-DPMX is considered the open, neutral, global standard for efficient PCB design data transfer.
Is IPC-DPMX the Better Transfer Method?
So, is IPC-DPMX the better transfer method? Well, there is no right or wrong answer because it’s primarily a matter of which file format best fits your design needs. To summarize:
- The most widely used file format.
- It is a simple two-dimensional artwork that indicates where the manufacturing equipment will place solder mask, silkscreen, or copper.
- A Gerber file has no idea about net connectivity, component libraries, or design rules.
- It requires far more files to convey an equal amount of data compared to the other formats. For example, if you have a two-layer board and each side has Gerber files for solder mask, silkscreen, and copper, you will require six Gerber files.
- ODB++ stores its data in a hierarchy of files and file folders.
- Designers can transfer their data with common OS commands that retain the hierarchy structure that combines data into one file (compressed).
- It allows designers and manufacturers to transfer more than just the standard layer artwork and drill data.
- It has a unique file structure that allows for large amounts of additional data to be included in a single file. These files contain a bill of materials, material stack-up, dimension and fabrication data, and as well as component placement.
- It can be accessed through most PCB design programs.
IPC-2581: Digital Product Model Exchange (DPMX)
- IPC-2581 is a universal standard method for transferring data between a PCB designer and an assembler or manufacturer.
- Provides guidelines for nearly every step of the flow process, thus ensuring superior quality, reliability, consistency, and manufacturability in electronics assembly.
- Stores all data in a single file, thus mitigating the chances of errors.
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, we are able to use all of the top PCB transfer options. For maximal accuracy, completeness, and openness, we recommend the IPC-2581 (DPMX) format. However, regardless of the specific format you choose, we are committed to delivering high-quality boards with short turnaround times.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on Digital Product Model Exchange (DPMX) or want to learn which data transfer method might best fits your company’s needs, contact us.