Design Tips for Lowering Costs of Fab and Assembly

Estimated reading time: 2 minutes

This is the million-dollar question of every project: How can I cut the cost of the PCB? 

There are about a thousand answers to this question. I may be exaggerating a little bit, but not much, especially when you consider that there are about 42¹⁸ different ways a PCB could fail. That’s a lot, but fortunately you really need to have a significant combination of these failures before it makes the boards unusable.

That said, there are a few simple guidelines that everyone can follow to reduce costs. I talk about them in my IPC CID and CID+ courses. Designers, fabricators, and assemblers talk about them in a variety of articles. Some professionals who have published some great articles on cost-saving strategies include Tara Dunn, Happy Holden, Chris Church, Kella Knack, Judy Warner, Julie Ellis, Lars Wallin, and many, many others.

It’s not as simple as saying, “Just cut down the layer count” or “Just use smaller parts and traces.” Here’s another: “Just use standard FR-4 material.” Then there’s, “Just don’t use blind and buried vias.”

These will certainly work if you make them happen, but they are not always the go-to answers on how to reduce costs. I’ve actually reduced the cost of some boards by doing the opposite of what you would normally think you should do. Here are some examples:

• Adding layers: This cut the cost of the board because I could increase the size and spacing of the traces. I was able to add an extra GND layer for shielding and better electrical performance. I had less fallout, less bow and twist, and easier manufacturing; thus, I cut the final costs.
• Using larger components: When only one component on the board had pin spacing less than 0.5 mm, it didn’t save any space at all. This part needed a special paste mask and we had to have extra spacing for the masking. Replacing it with a larger package saved us space on the board and cost less in manufacturing.
• Using higher-temp materials: This helped the board to withstand the stresses of manufacturing. It cut down on stress failures and fallout, thus cutting the overall costs.
• Using blind and through-vias: This improved breakout from fine-pitch parts. It wasn’t as expensive as using blind, buried, and through-vias; it improved power connectivity, and saved space on the board.
• Split one board into two boards: I modularized high-power, larger-pitch circuits and low-power, small-pitch circuits. The electrical requirements for these are different and become cost-adders for manufacturing when combined. Creating two boards, one with thick copper and larger features, the other with thin copper and smaller features, allowed each to be easily created at less overall cost.

So, here’s my take on how to reduce your costs:

Planning Ahead

This is one of the most important jobs of the program manager (PM). You’d be surprised how many DFM issues start with the PM. So, how does the PM influence the costs?

To read this entire article, which appeared in the August 2022 issue of Design007 Magazine, click here.