How PCB Design Decisions Can Affect Manufacturing

PCB design is driven by performance requirements. Grounding, thermal management, signal integrity, routing density, and reliability all influence board layout. 

Those decisions also affect how the finished board is manufactured. 

A useful example is via placement. Modern CAD and electronic design automation (EDA) software can automate parts of the process, including the placement of additional vias across available areas of a board. This can be useful for achieving design objectives, but it can also introduce manufacturing considerations that are not immediately visible during layout. 

Understanding those considerations early can help designers and manufacturers find an efficient way to achieve the required performance. 

EVERY VIA HAS A MANUFACTURING REQUIREMENT

Vias are an essential part of many PCB designs. They provide electrical connections between layers and can also support thermal transfer and grounding. 

From a design perspective, extra vias can offer a straightforward way to meet these requirements. 

From a manufacturing perspective, every via also represents a drilling operation. 

When a design contains tens of thousands of vias, those operations quickly become significant. Extra holes increase drilling time, raise the number of drill hits required during production, and can increase drill tool usage. 

This does not mean that a high via count is inherently a problem. Some designs require large numbers of vias to meet their electrical or thermal requirements. 

The important consideration is whether the number and arrangement of vias are appropriate for the performance the board needs to achieve. 

AUTOMATION CAN CHANGE THE MANUFACTURING PROFILE OF A DESIGN 

Automated features within CAD/EDA software help engineers develop PCBs more efficiently. 

For example, software can automatically populate available areas with vias to support grounding or thermal performance. Once a rule has been applied, the software can quickly generate many additional features across the board. 

That can be useful during design, but the resulting manufacturing requirements still need to be considered. 

A pattern that takes very little time to generate in software may require significantly more machine time when the board enters production. 

This is one reason manufacturing input can be useful during PCB design. The manufacturer can assess whether the team can produce the design and how efficiently production can run. 

DESIGN FOR MANUFACTURE IS ABOUT FINDING THE RIGHT BALANCE 

Design for Manufacture (DFM) brings manufacturing considerations into the engineering process. 

DFM does not simplify a PCB at the expense of its performance. It helps engineers understand what the design must achieve and identify the most efficient way to manufacture it. 

For example, if a board requires vias for grounding and thermal transfer, engineers should ask how many vias they need to achieve the intended result and how their placement affects manufacturing. 

That discussion can help teams reduce unnecessary manufacturing operations while maintaining the board's electrical and thermal requirements. 

The same principle applies across many areas of PCB design. 

SMALL DESIGN DECISIONS CAN HAVE A LARGE PRODUCTION IMPACT  

Via count is one example, but designers and manufacturers need to consider the manufacturing implications of many different features, including: 

• Hole sizes and aspect ratios 
• Track and spacing requirements 
• Layer count 
• Copper thickness 
• Microvia structures 
• Material selection 
• Tolerances 
• Surface finishes 
• Panelisation 

Each feature can influence the processes, tooling, machine time, or inspection needed to manufacture the board. 

In some cases, these requirements are essential to the design. In others, there may be alternative approaches that achieve the same objective with less manufacturing complexity. 

Early discussion helps designers and manufacturers identify these alternatives before the design becomes difficult or costly to change. 

WHY EARLY MANUFACTURING INPUT MATTERS 

Design teams do not need to wait until a PCB is ready for production before considering manufacturing requirements. 

Bringing the manufacturer into the conversation earlier gives the design team an opportunity to understand how particular decisions will translate into manufacturing processes. 

For engineers, this provides another perspective on the design. For manufacturers, it creates an opportunity to identify potential production challenges before they become changes later in the process. 

It also creates a shared understanding of the priorities for the board: what performance is essential, which features support that performance, and where there may be opportunities to simplify production without changing the specification. 

DESIGN AND MANUFACTURING WORK BEST TOGETHER 

Modern PCB design tools give engineers more control and automation than ever before. They can quickly generate complex layouts and apply rules consistently across a board. 

The manufacturing process still has to deal with every feature that appears in that layout. 

Understanding that connection is an important part of designing PCBs for production. 

Good DFM does not ask engineers to design around manufacturing limitations. It gives them better information about the manufacturing consequences of their decisions, so they can consider electrical, thermal, mechanical, and production requirements together. 

At Exception PCB, our engineers work with customers to review designs and identify manufacturing considerations before production begins. 

If you are developing a PCB and want to understand how design decisions could affect its manufacture, speak to our engineering team about your next project.