Although some companies choose to outsource design data to engineers, the problems of getting a workable PCB out the door can be difficult to predict and lead to costly mistakes. The first part of this two-part series will reveal some of the unexpected expenses associated with outsourcing your PCB design data, as well as some options for how you can deal with them.
Problem 1: Design Defects
Usually, when you send a PCB to a fabricator, that fabricator’s engineers will examine your design to ensure that it will emerge from the manufacturing process in workable shape. However, with outsourced board designs, time-consuming and costly problems can still arise. To an engineer designing a 2-inch circuit board on a 15-inch screen, the space between traces can easily appear vast–until it is printed, allowing barely enough space for a human hair! Another problem is that layers can sometimes be mislabeled, placing surface-mount attachments on a board’s inner layers.
When design data is outsourced to a fabricator, these errors can become extremely costly as a result of slowing down the design process and stalling production while you wait for your prototype to travel back and forth between you and the fabricator. No solution will be completely foolproof, but one way of confronting these problems is rapid in-house prototyping, as evidenced by the wide acceptance of 3D printing by mechanical design engineers to construct a model.
Through using rapid in-house prototyping, when they arise, unforeseen problems can be quickly addressed, and another print run can be done as soon as problems have been identified. This eliminates lag time in a development schedule, allowing you to fix any mistakes with a quick revision. The same prototyping benefits that 3D printing provides to mechanical designers are also available to the PCB design engineer.
Problem 2: Returns Are Not a Top Priority
Once your PCB is finished by an outsourced fabricator (containing errors or not), it’s sent back to you–out of a fabricator’s hands and mind–until a problem is discovered. Then, after spending all the time necessary to address a problem, your PCB might be sent to the bottom of the fabricator’s production queue. After all, why worry about your project when the sale has already been made?
By contrast, rapid in-house prototyping reduces both the time and expense of identifying errors, while also assuring that they will be addressed much more quickly, possibly even on the same day. In-house prototyping also ensures that the priority given to projects is assigned by you, not a third party fabricator.
Problem 3: Problems With Routing Automation
Although PCB CAD and other layout software used to design PCBs are widely available, engineers are often provided with little or no training regarding how to lay out a board to ensure manufacturability. This can lead to problems in certain situations, most notably producing incorrect solder masks (more about this in part two,) but also failing to take board shape into account if a board is of an unconventional design. Without rapid in-house prototyping, these problems can start the loop of sending a board back to be printed, requiring waiting even longer for a revision.
If you have in-house prototyping capabilities, however, these problems are easily addressed by quickly getting a design off the screen and into your hands, resolving any issues from the layout software, and getting the specifics for your project dialed in, so that the specs will be perfect.
Problem 4: The Generation of the Board Design File
These days computers are less bound by memory constraints than ever before, with even laptops holding many gigabytes of memory. This means that it isn’t only the physical elements of outsourcing your design data that can cause unforeseen problems, but problems can also arise when transferring your board design file to a fabricator. The problem is that these files are just too large to transfer easily to a fabricator, and any over-sized file can slow the process of manufacturing your boards.
Some online board houses boast speedy turn around times, but the amount of time that they can save is highly debatable. Each “quick-turn” online house has its proprietary design software for submitting files, each with its own limitations, and what their estimates don’t take into account is the time you’ll spend learning what those limitations are or, in some cases, even altering your design to meet them. It would be much quicker and more reliable to conduct your own in-house, rapid prototyping, which would allow you to keep an eye on your file size, as well as to quickly and cheaply address any issues that might arise in terms of dealing with your design file.
These are just a few of the issues that can result from outsourcing design data.