Before becoming an engineer, I spent quite a bit of time trying to work on products designed by others. This included automobiles, appliances, and electronic devices. The most frustrating thing about repair work is when routine jobs or preventive maintenance tasks are tremendously complicated or hard to do. Things that have to be done often should be the easiest to get to and perform. When this is not the case, it is obvious that the designer gave little if any thought to the fact that someone would have to perform these supposedly routine tasks in the future. The consequences of this type of ”oversight” can be significant and result in excessive downtime, reduced production, and perhaps lost revenue.
Rework station for BGAs
Even graver than failing to consider routine maintenance and repairs is to not consider manufacturing during design. Doing so can negatively impact board functionality and manufacturability. Redesigns, PCB rework, extensive turnaround times, and unnecessary manufacturing costs can all result from this type of omission. Therefore, it is imperative that you consider how your design choices impact the manufacturing of your board. Let’s review board design and devise a set of PCB design steps that illuminate areas where it is essential to consider the manufacturing implications.
How Your PCB Design Steps Impact Manufacturing
Taking an idea or set of performance objectives and creating a design from which it can be physically manifested is no simple task. It takes years of experience to become a good PCB designer and even then there are always new components, design tools, and technologies. Thus, board design is a career-long learning experience. One aspect that should be understood as early as possible is the need for synchronization between design specifications and PCB manufacturing.
Understanding how design decisions impact PCB manufacturing will not only make you a better designer, but also help you create a more effective development process. Although your board’s manufacture should be a source of reference throughout your design process, below is a list of PCB design steps that will aid your contract manufacturer (CM) in building your boards.
PCB Design Step 1: Select the minimum number of unique components
Choose like components whenever possible. This is better for the pick-n-place process. It is also helpful to use like-sized packages for multiple components.
PCB Design Step 2: Use SMDs and minimize through-hole components
SMDs and through-hole components require different soldering methods with the process being longer for through-hole.
PCB Design Step 3: Do not overload nets
Nets on the schematic with large numbers of component connections translate into wide traces or heavy copper weights on your layout. This can present issues for layer and overall board size.
PCB Design Step 4: Follow CM clearance guidelines
One, if not the main reason for ensuring sufficient clearance between board elements is for solder masking. This is an essential fabrication task that protects your board and aids in isolating electrical connections that must be soldered during PCBA.
PCB Design Step 5: Avoid board edge connectors, if possible
Just like elsewhere in your PCB layout, board edge clearance is important. There is a tendency (and sometimes a necessity) to place connectors near or over the board edge. However, doing so requires good panelization design and consultation with your CM.
PCB Design Step 6: Use adequate, but minimum number of layers for stackup
PCB Design Step 7: Use least complex via routing
As most of your designs are likely to be multilayer, how to best route your vias is a major design and manufacturing issue. The most important rule of thumb for manufacturing is the least complex the better.
PCB Design Step 8: Perform DFM checks often
Probably, the most important single thing you can do during design is to perform frequent DFM checks on your circuit. However, the constraints should be based on your CM’s rules and guidelines.
PCB Design Step 9: Perform thermal analysis and PDN check
It is also important for you to simulate your board and analyze its thermal response and PDN. Excess temperatures on your board from components or power distribution can be problematic, especially for soldering during PCB assembly.
PCB Design Step 10: Ensure manufacturing file package is complete and accurate
Last, but not least, you should make sure that your design specifications and all pertinent data, information, and graphics are included in your design file(s).
|Tempo‘s Custom PCB Manufacturing Service
It is essential that you incorporate PCB design steps that are intended to support the process of your board’s manufacture. Not doing so, is setting yourself up for redesign, long turnarounds and perhaps unnecessary costs. At Tempo Automation, the industry leader in fast, high-quality PCB prototyping and low volume production, we will work with you from day one to ensure your boards incorporate the desired design intent and are manufacturable.
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 PCB design steps that will aid in your board manufacture, contact us.