SMD Package type selection based on component role

Question

Apologies if this is an obvious question, but as a novice, I wanted to ask - is there a rule of thumb when it comes to selecting a surface mount package type (https://en.wikipedia.org/wiki/List_of_integrated_circuit_packaging_types) based on the role of a component?

E.g. a filtering capacitor on my board's input power track, vs. capacitors used in setting up an external crystal to drive my MCU?

The question stems from this video: https://youtu.be/aVUqaB0IMh4?t=2971 Here, the author makes explicit mention of sizing components, but there's no explanation of any hard design rules.

Thank you in advance for your help!

Answer 1

Smaller packages have lower parasitics, tend to be easier to fit into optimized layouts and introduce smaller impedance discontinuities. Thus they tend to be preferred when high frequencies are of interest.

Larger packages tend to have higher voltage ratings, more stable capacitance (for capacitors) lower series resistance and higher saturation currents (for inductors), and better thermal characteristics. Thus they tend to be preferred for low frequency and higher voltage or power applications.

For applications like smaller digital systems you'll often have one or a few sizes that make sense given the package size of your digital ICs and assembly costs. For example, you'll probably find that a 1206 is awkwardly large for an Arduino bypass capacitor while a 10050 is too expensive to have assembled while being no easier to route than an 0402. Thus you'd probably pick something in between. Similarly for inductors you'll usually find that the range of properties (current, series resistance) you want narrows you down to just a few sizes.