Via in Pad Guidelines
Vias — many people would place them the simplest aspects of a PCB design, but in the world of PCB Fabrication and PCB Assembly, no element can be neglected, and even the simplest of things can get complicated. A prime example of this fact is the case of vias placed within pads for SMT Assembly, which is commonly known as “Via in Pad” design. Via in Pad is a complex process that many manufacturers simply cannot accommodate, but Bittele Electronics is here to help. Our state of the art fabrication and assembly technology, along with our flexible PCB Assembly Process allows us to offer Via in Pad assembly without any risk of compromising the high standard of quality we always provide to our clients.The first question to ask about Via in Pad is why you might want it in your design, if it can cause so much complication? There are in fact a few cases where this technology does make more sense than any other alternative:
- Spacing concerns for HDI PCBs, or with very fine pitch or high-pin-count BGAs
- Grounding for High-Speed PCB parts in High-Frequency PCB designs
- Improved heat dissipation in thermally sensitive High Power PCB designs

This action can create all sorts of trouble for PCB Assembly, such as Joint Voiding and Cold Solder Defects, or uneven planar surfaces in SMT pads, which are particularly troublesome for BGA Assembly.
The first DFM / DFA advice for those considering Via in Pad is to consider whether or not it is absolutely necessary in your project. Most of the time, other alternatives such as the widely used Dog-Bone Fanout will be more economically viable, even if it means a slight increase to the size of your board.
If other methods just won’t do, then our general advice is to keep the number of Via in Pad instances to a minimum, make the vias themselves as small in diameter as possible, and use Blind Vias to reduce the overall capillary action.
Next, we’ll take a closer look at Via in Pad in specific cases. We’ll talk about how Bittele handles these cases, and when to expect an impact on your PCB Fabrication Quote.
Via in Pad for BGAs and Other Small Pads
For SMT pads with a surface area equal to or less than 0.8 x 0.8 mm, the risk of assembly defects due to Via in Pad capillary action is very high. This is generally true for any BGA, uBGA, POP, LGA, CSP, and other complex package types beyond QFP and QFN (see the following section). Our first advice here is to avoid this type of Via in Pad entirely, if at all possible, as it will unavoidably complicate your project’s assembly. Designing Blind Vias rather than through-hole in these positions can also avoid Via in Pad concerns. Still, if size constraints of your board or component don’t leave any other choice, we can help.
This process takes quite a bit of additional effort, especially for PCB designs that incorporate a large number of vias in smaller SMT pads. If your project requires this sort of special attention, you should expect an additional 3-4 days of lead time, and a price increase of roughly 20 – 30 percent, compared to the same board without Via in Pad filling requirements. The specific lead time and cost impact of Via in Pad is project specific, so be sure to talk to one of Bittele’s PCB Customer Service Experts for a more definite estimate of your specific project.
Via in Pad for QFN Thermal Dissipation and Other Large Pads
Thermal pads, especially in QFN Packages, are probably the most common instance of Via in Pad being recommended by part manufacturers. In these cases, the Via in Pad technology is used to improve thermal conductivity away from the part to help with cooling. These pads are normally connected directly to the ground plane of the PCB since it has a relatively large surface area, allowing for considerable heat sinking away from your critical components.
Via in Pad is so commonly recommended in these sorts of parts, that many standard footprint libraries in CAD software include options for QFN and QFP parts that incorporate thermal vias. The image on the right shows one such footprint.

Will Your Vias Cause Trouble?
At this point, you might be wondering if the vias in your design will result in any additional cost or lead time. For a quick summary of the conditions mentioned above, you can refer to the handy flowchart included below.
Related Articles:
- Difference Between Via Tenting and Via in Pad
- Via in Pad PCB
- Manufacturing Considerations for Via on Pad PCB Designs
- Via in Pads and BGA
- Non-Conductive Via Filling (NCVF) and Its Advantages
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