Altium IPC Footprint Options: Which One Should I Choose for Best DFA and Assembly Yield?
When downloading a Manufacturer Part Number (MPN) directly from Altium Manufacturer Part Search, I often see multiple footprint options available for the same component:
IPC_A
IPC_B
IPC_C
MFG (manufacturer-recommended footprint)
I understand that IPC_A/B/C correspond to different IPC‑7351 density levels, but I am not fully clear on the practical differences from an assembly point of view. Specifically:
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What are the real differences between IPC_A, IPC_B, and IPC_C in terms of pad size, solder volume, and assembly robustness?
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How does the manufacturer (MFG) footprint compare to IPC footprints in practice?
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From a Design for Assembly (DFA) and SMT manufacturing yield perspective, which footprint is generally preferred?
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Is IPC_B usually the safest default, or should the manufacturer footprint always be trusted?
For context, this is for professional SMT assembly (not hobby-level), typically low‑to‑medium volume, with standard reflow processes.
I’d appreciate insights from people with EMS / PCB manufacturing experience on what works best in real production.
2 answers
The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| newbie | (no comment) | Apr 29, 2026 at 08:16 |
I normally use the IPC A footprints because they have the largest pads, and they lend themselves to manual rework. I tend to use 0603 for resistors and capacitors. My boards with IPC A are machine-assembled by two PCBA houses. They didn't complain about the footprints. They didn't complain about yield.
1 comment thread
You didn't say what the specs for the various options are, so unless someone has Altium (which I don't) they can't really answer your question.
Personally, I always make my own footprints. Vetting someone else's footprint to my own standards and preferences wouldn't save any time.
There are different footprints for the same part because there are different standards and criteria that can be applied for each design. These issues include:
- Min trace/space width design rules. If you are using rather wide spacing, then pads under tight parts may need to be made smaller sideways, possibly just to the width of the pin.
- Overall board density. If you're designing a cell phone, then you want to cram everything as close as possible. That might mean making each pad only big enough for the pin.
- Prototyping and debugging. If a board has room and is for debugging, you might want to add an extra 20 mil or so outward from each pin. That makes it easier to hold a scope probe to or temporarily solder a wire to.
- Surface tension balancing. This is important for asymmetrical SMD parts. For example, if you add extra area for heat dissipation to the tab of a TO-220 package, you have to think carefully about how that will pull the part when the solder is liquid, and design the remaining pads accordingly.
- Will you try to route traces between adjacent pins?
- Current-carrying ability.
These criteria vary from design to design, so there is no one right answer. As always, you need to understand the reasons for the various options. When you do, you can design your own solution as needed.
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