You’re finally finished with your latest printed circuit board design. It was a tough nut to crack, but at last, it is placed and routed the way you want it. It passed all of its final design rule checks, and you’ve gotten everyone’s signoff on the design reviews. It’s time to celebrate, but before you do, you need to create the manufacturing output files and get the job sent off to the contract manufacturer.
You probably have some company standards on how PCB documentation should be created, and what file formats should be used. The problem is, it’s been a while since those standards were written, and everything changes over time. You’re using different CMs these days for manufacturing, and your design tools have changed and evolved over time as well. So here you are, ready to go, and yet you are faced with a very important question: Are you giving the right PCB assembly file format to your CM?
What Is the Best PCB Assembly File Format for a CM?
In general, PCB contract manufacturers prefer receiving the entire PCB CAD design database from their customers over other manufacturing file formats. With the entire database, the CM can extract and work with the information in a way that best fits their needs for fabrication and assembly. They also can get immediate answers to specific design questions without having to come back to you, which can save a lot of time and confusion.
The type of data file formats preferred by CMs for manufacturing is also task-specific. Depending on what your CM is doing for you, they may need additional or alternate information. In the case of a full system prototype build, there will be additional build instructions, a bill of materials (BOM), and other assembly-related documentation required.
If I Am Not Able to Supply a CAD Database, What Can I Do Instead?
If a PCB design CAD database is not available, most CMs will still work with traditional manufacturing output files. The minimum files your CM will need are as follows:
- Gerber files: Gerber file format 274-X is most common, but most CMs will work with other versions of Gerber as well.
- NC drill files: The Excellon format is standard for drill files.
- Schematic: A PDF of the schematic is the easiest format for a CM to work with.
- IPC netlist: This will be used to create the programming for testing your board.
- BOM: This is best delivered as an Excel file and should list all components used in your design.
- Fabrication drawings: These drawings can be in PDF format and need to include dimensions, board stack-up, and other critical data.
- Assembly drawings: These drawings can also be in PDF format and need to include part placement locations with reference designators and expanded views for specific assembly details.
If you are not able to provide a full database, these files should provide enough information in most circumstances. There are times, however, when additional data may be required for unique builds. Also, additional questions may arise if the supplied data does not adequately communicate everything the CM needs to know.
What Potential Problems Could CMs Have Without Complete Data?
If the CM is missing critical information to build a PCBA, and you’re unable to provide it, the CM will need to create the data manually. For instance, missing IPC netlist data can be created manually from the Gerbers. If the CM makes changes to a prototype build but doesn’t have a database to update with the changes, they will create a schematic database from the PDF first and link it to the Gerber data to make their changes.
Whether the CM is creating missing files from other data or recreating a database to update with design changes, it can be a labor-intensive operation. Additionally, it will involve a lot of interactive support from your engineering team. This is essential, however, to ensure that nothing has been missed and that critical information has been verified so the final PCBA will meet your expectations.
Can Your CM Work With the Data You Provide?
In the end, your contract manufacturer should be able to work with a variety of data, depending on what you are able to provide to them. As we stated earlier, CMs would prefer to have a PCB CAD database, but if that isn’t possible, there are plenty of alternatives. A quality CM will work with what you can provide to ensure your PCBA is built to your expectations and beyond.
At VSE, we have the resources to work with most, if not all, PCB CAD design databases. If you aren’t able to provide us with a database, however, we have years of experience working with the other file formats listed above. We also have a fully staffed engineering department who can work with you to perfect your design, and we have a proven history of partnering with our customers’ engineering teams to ensure the PCBAs we build are of the highest quality.
If you are looking for a CM with a long tradition of working together with its customers, look no further than VSE. We pride ourselves on our care and attention to detail to ensure that each PCB assembly is built to the highest standards in the industry. Contact us today to learn more about partnering with us for your next project.