OPEN DISCUSSION: How do you ensure that your PCB design is ready for assembly? Do you run DFA checks?

When it comes to PCB design, ensuring it’s ready for assembly is crucial to avoid costly rework and delays. Isn’t that right?

:point_right: How do you ensure that your design is assembly-ready?
:point_right: Do you run DFA (Design for Assembly) checks? What tools or processes do you rely on?

Sierra would love to hear your insights, experiences, and best practices. Share your thoughts and join the conversation!

I learned the hard way that component placement can make or break PCBA. One time I didn’t leave enough clearance around a tall connector and it became a soldering nightmare. Now I double check all my placements and make sure everything is assembly friendly before sending it off.

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With modern PCBs incorporating high-density components and leadless packages, relying solely on manual checks is not feasible. The sheer number of solder joints and connections in an average PCB is overwhelming. Implementing DFA checks through software tools can automate the verification process, ensuring that every aspect of the design is optimized for assembly, significantly reducing the risk of errors.

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DFA checks have saved my skin more times than I can count. I remember once catching a tiny trace that was way too close to a pad. total solder short waiting to happen. If I hadn’t run that check production would have been a mess. Lesson learned: run the checks and run them early.

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Assembly readiness is the key. Here’s my usual workflow:

  • Start by choosing components with assembly in mind. This includes considering package types, lead styles, and availability.
  • Run DRCs frequently throughout the design process to catch any violations related to spacing, clearances, and other manufacturing constraints.
  • Use the built-in DFA tools in my EDA software to check for things like component placement issues, silkscreen errors, and manufacturability problems.
  • Even with automated checks, I always do a thorough manual review of the board layout. Also pay close attention to component orientation, spacing around connectors, and the overall layout aesthetics.
  • Send my preliminary design files to my assembly house early on for a DFM review. Their feedback is invaluable in identifying potential issues and preventing costly rework later.
  • Plan for panelization early in the design process to ensure efficient board utilization and manufacturability.
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An important point that seems simple, but can become complex with the DFA tools integrated into EDA software to check things like component placement issues is that you need to know how to properly adjust their parameters according to the manufacturability capabilities of your assembly house based on the equipment they have, especially for soldering, which are not all the same!

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We once ran into solder paste stencil gasketing issues due to thick silkscreen overlapping fine-pitch pads. To fix this, we added silkscreen keep-out regions within component footprints to prevent ink from encroaching on pads. This small adjustment drastically improved stencil alignment and soldering quality, especially for tiny components. After that experience, we never skip DFA checks—they’ve become a crucial step in our process to catch these kinds of issues early.

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Test points are crucial for post-assembly testing, yet they are often overlooked in the design phase. Poorly placed test points can lead to accessibility issues, making automated or manual testing difficult and increasing the risk of quality control challenges. To avoid this, test points should be planned early and checked as part of DFA/DFM reviews. Ensure they are not obstructed by components or enclosures and follow industry standards for size and spacing to maintain compatibility with automated test equipment.

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Design for assembly goes beyond component placement. Consider the entire manufacturing workflow. Ensure there are adequate fiducials for automated assembly alignment, and think about how the board will be gripped by pick-and-place machines. Fragile components may need added protection in high-handling areas. Plan panelization carefully to prevent issues during board separation. Additionally, microvias can trap air, leading to defects during reflow, so their placement should be carefully managed.

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