Source vs. Output




In the design of printed circuit boards, there is a lot of documentation that gets generated. All too often, we give too much information to the board and assembly houses, and yet, do not have the document later on to make modifications!! How can this be?

If we look at the overall anatomy of any project that uses a software tool, there are actually two types of files that are created. The first type is known as ‘source files.’ These are the files that are saved in the default format of the tool being used. For example, if I am going to save a Microsoft Word document, the default is .docx. We can make changes to this file all day long and the program will interact with the .docx file.

The second type is known as ‘output files.’ These files are produced as a result of running a function or process within the tool. Though these files could be altered or changed, such changes never make their way back to the source. They are representations of the source files. To keep with the example above, if I create a PDF of a Word document, I am creating a representation of my original document. In this example, I create it to provide a read only document for others to reference. The PDF is not what I would use to make changes in the future. I would still use the .docx which is the source file.

Therefore, producing an output file is always done with some purpose. In the PCB design flow, we have to produce output files that the fabrication and assembly houses can use to program and set up their equipment. They need the information in industry accepted formats. Knowing the difference between source files and the output files in PCB design is half the battle. The other half is making sure that you have completely archived the project. As we at Nine Dot Connects have seen, there are two very real scenarios to consider:

  • The employee of long ago – In many situations, the employee who created the design has left. When they left, they may have never moved the source files from their hard drive which may now be long gone. Or, they moved the information to a shared drive that is so packed with directories and subdirectories, it will take a major effort to locate it. Keep in mind, this is assuming that the designer used viable file names to search for. This also relies on people who remember this project. If this is a design that came from a merger or acquisition, there may not be any tribal knowledge of this design to tell its story. On top of all of this, there is the assumption that they used a tool that is still available in the company’s software offerings.
  • The unscrupulous service bureau – When using a service bureau to design, some bureaus may only provide the output files for manufacturing to the customer who hired them. The customer who knows little about PCB design and its documentation may not realize that they do not have full control over their IP. Why do some service bureaus do this? Simple - it holds you hostage. Need a new change, you will need to go to them. We at Nine Dot Connects deplore this form of service engagement. But, it happens. All too often, the company parts ways with the service bureau not realizing that they also parted ways with their IP. Or, the service bureau closes shop. Either way, the source files are lost.

In the end, your IP is in the source files. Output files can always be regenerated from the source files. Make sure that these source files are kept in a safe place and that the complete file set is in the company’s procession.