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Q&A Via on pad: acceptable or not?

I am designing a PCB with somewhat limited space. To save space, I am placing some vias on component pads. However, I am not sure if this is a good practice in PCB design. As far as I understand, t...

1 answer  ·  posted 2y ago by Mu3‭  ·  last activity 2y ago by Olin Lathrop‭

Question pcb-layout
#2: Post edited by user avatar Mu3‭ · 2021-12-21T10:37:17Z (over 2 years ago)
Added images to illustrate the question.
  • I am designing a PCB with somewhat limited space. To save space, I am placing some vias on component pads. However, I am not sure if this is a good practice in PCB design. As far as I understand, there are certain pros and cons for such designs.
  • **Pros**
  • - Lower impedance for circuits where this matters (RF).
  • - Saves space on the PCB.
  • **Cons**
  • - Wicks solder away if via is not plugged, affects reflow.
  • However, it seems like big PCB houses (e.g. Eurocircuits) will offer plugging/filling of vias, eliminating the wicking concern. This makes the production more costly.
  • If the cost argument is not considered, what is the reason to use or not to use vias on component pads?
  • I am designing a PCB with somewhat limited space. To save space, I am placing some vias on component pads. However, I am not sure if this is a good practice in PCB design. As far as I understand, there are certain pros and cons for such designs.
  • **Pros**
  • - Lower impedance for circuits where this matters (RF).
  • - Saves space on the PCB.
  • **Cons**
  • - Wicks solder away if via is not plugged, affects reflow.
  • My layout contains vias that are directly placed on pads or at least intersect them (see example below, courtesy of Eurocircuits):
  • ![Via intersecting pad](https://electrical.codidact.com/uploads/hgUJYDu9XDPZMAFcDgSnmkt8)
  • ![Via directly on pad](https://electrical.codidact.com/uploads/2xJHXwsbpEDT7GkcRfjpA5er)
  • However, it seems like big PCB houses (e.g. Eurocircuits) will offer plugging/filling of vias, eliminating the wicking concern. This makes the production more costly.
  • If the cost argument is not considered, what is the reason to use or not to use vias on component pads?
#1: Initial revision by user avatar Mu3‭ · 2021-12-21T07:42:08Z (over 2 years ago)
Via on pad: acceptable or not?
I am designing a PCB with somewhat limited space. To save space, I am placing some vias on component pads. However, I am not sure if this is a good practice in PCB design. As far as I understand, there are certain pros and cons for such designs.

**Pros**

 - Lower impedance for circuits where this matters (RF).
 - Saves space on the PCB.

**Cons**

 - Wicks solder away if via is not plugged, affects reflow.

However, it seems like big PCB houses (e.g. Eurocircuits) will offer plugging/filling of vias, eliminating the wicking concern. This makes the production more costly.

If the cost argument is not considered, what is the reason to use or not to use vias on component pads?