The Top 3 DFM Problems That Affect Every PCB Design

October 11, 2016 Carsten Kindler

top-dfm-problems

 

As a PCB Designer you have to manage a variety of different requirements and expectations. And through all of these requirements, you also need to factor in DFM (Design for Manufacturability). Learn about the top 3 DFM problems that affect every PCB design and how to avoid them.

As a PCB Designer you have to manage a variety of different requirements and expectations. There are electrical, functional, and mechanical aspects to consider. In addition, the PCB layout has to be produced in a timely manner, with the best possible quality, at the lowest possible cost. And through all of these requirements, you also need to factor in DFM (Design for Manufacturability). It’s a big part of the PCB design process, and one which can frequently cause problems if not done properly. Let’s look at the 3 DFM problems that affect every design.

#1 - Even Connection of Component Pads

For SMD components with sizes 0402, 0201, or less, it’s important that pads have a uniform connection. This will help them avoid tombstoning--i.e. components partially or completely lifting off the board during reflow. It’s also important to maintain uniform connections with BGA pads in order to assure reliable soldering results. The test procedure to guarantee this is complicated and costly, often involving X-rays.

 

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creating-uniform-connection-between-smd-component-pads

Creating a Uniform Connection Between SMD Component Pads

 

#2 - Vias in SMD Pads

It’s a commonly shared bit of PCB design wisdom that you should avoid via in pad at all costs. When soldering, the via hole can lead to a weak soldering joint, which can ultimately damage the circuit. However, via in pad does have a place in PCB design, and can be particularly helpful with issues like heat management.

 

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Via in Pad Example that Can Lead to Weak Soldering Joints

 

#3 - Even Copper Distribution on Copper Layers

The process of creating a copper image on an individual board layer is dependant on many factors. If the copper is removed from one area, it can be difficult to keep a single track standing. Because of this it is recommended to keep the copper distribution even as much as possible.

 

evenly-distributed-copper
Evenly Distributing Copper on a PCB Layer
 

 

Avoiding All DFM Problems in Your Design

The three DFM problems described above are just a small list of all the potential mishaps that can happens in your manufacturing process. By managing the requirements from your manufacturer during your PCB design software, you can ensure that your board will be created right the first time. Download a free white paper to learn about even more DFM problems that can affect every PCB design.

About the Author

Carsten Kindler

Carsten currently serves as a Field Application Engineer at Altium and is responsible for providing technical assistance to Corporate Strategic Account Managers, Sales Managers, Resellers, and Application Engineers. He is also in charge on establishing and managing technical relationships with clients, partners and industry leader. Carsten is certified in IPC CID+, and has been focused in the EDA industry for more than 10 years.

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