With this in mind, I like to start by picking the via size that will be used throughout most of the board. Via type and layer count: As we’ll see below, the layer count will also contribute to pad size once the layer count exceeds 8 layers under IPC-2221.Reliability: Larger lands will be more reliable, and as we’ll see, that is the entire point of this article… The IPC standards have plenty to say about this and will determine whether a given drill hit produces a defect in a via pad.Note that this doesn’t also require a large via. Therefore, if you’re using a large trace width, such as a large controlled impedance trace, you’ll want a larger pad size. Trace width: It’s generally accepted that the pad size should be somewhat larger than the via size.Larger vias will then require larger pad sizes. Manufacturing cost: Opting for a larger via is going to carry lower manufacturing costs, as I’ve discussed in an older article on cost estimates.When selecting an appropriate land size for a via, there are a few places to start looking: PCB Via and Pad Size BasicsĮvery via should have a landing pad on the surface layers where traces can make an electrical connection the question is how large the via pad needs to be.

This is one area where it’s difficult to find concrete answers beyond just an answer to “what is an annular ring?” We’ll look at the answer and how it relates to two important IPC standards in this article. Under the IPC standards, lands for vias are related to the layer count, via hole size, and plating thickness, and the land should be sized so that the annular ring produced during production is sufficiently large. The pad size you choose for your design relates to another important design aspect that is found during manufacturing, known as annular rings. However, there are some important sizing guidelines to follow when matching pad and via sizes, and this match is an important element of DFM and reliability. Obviously, these two points are related all vias have (or should have) a landing pad that supports the via and provides a place to route traces into a via pad. One of these design aspects is the match between PCB via size and pad size. There are some aspects of PCB design and layout that seem deceptively simple, and yet they have a complex answer that is related to many important aspects of manufacturing.

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