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This is my first question here and I am new to board level digital design(I have years of experience on programming development boards though).

So here is my question, what are the differences between different footprint surface mount RLC components? To be more clear, i quote some data from Wikipedia article below

For resistors it seems like only power rating is different for different footprints.

For example does it make any difference to use a 0402 or 0805 footprint 50ohm resistor as terminating resistor? Or as long as given spec data is same, does it matter to use a 0402 or 0805 470nF ceramic capacitor as decoupling capacitor? Why I ask this? Because I am designing an FPGA board using some reference designs and I plan to make board assembly at home :) I want to use bigger components as a beginner.

0402 (1005 metric): 1.0 mm × 0.5 mm (0.039 in × 0.020 in). Typical power rating for resistors = 0.1 or 0.062 watt

0603 (1608 metric): 1.6 mm × 0.8 mm (0.063 in × 0.031 in). Typical power rating for resistors = 0.1 watt

0805 (2012 metric): 2.0 mm × 1.25 mm (0.079 in × 0.049 in). Typical power rating for resistors = 0.125 watt

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  • \$\begingroup\$ You say "as long as given spec data is same" but then you ask if the specifications are different. If you look carefully you will find that the details specifications are different. \$\endgroup\$ – Joe Hass Jan 6 '14 at 11:42
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Power rating on resistors is the primary difference but also maximum voltage rating can be lower on smaller packages. For capacitors, the maximum voltage rating will be lower on smaller packages and it is likely that the dielectric type will be "worse" for the same value in smaller packages. A "worse" dielectric means higher losses and/or capacitance drift with temperature.

For inductors, the effective series resistance will likely be higher on smaller packages but this can be traded-off by the inductor supplier using a higher permeability magnetic material - the downside being that it won't be very good in higher frequency applications. Also, smaller package inductors will, for the same inductance value as a bigger package, use thinner wires and thinner insulation on the wires and this can lead to lower voltage capability and lower self-resonant frequency due to the winding capacitance being higher.

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    \$\begingroup\$ There are few other parameters that change with package: Parasitic capacitance for resistors and inductors is reduced. generally, cost is reduced due to reduced amount of material, amount per reel is increased, a reel of 0402 contains between 8K and 10K pcs where as a reel of 0603 contains between 3000 and 5000 pcs which makes assembly cheaper. \$\endgroup\$ – Lior Bilia Jan 6 '14 at 10:17
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0402 (and smaller) parts require special heads on a pick and place machine, so assembly houses usually charge more if you use them on your design. If you're going to assemble your design by hand, you'll hate yourself if you use 0402. If you are soldering by hand, 0603 is managable, but 0805 would be best.

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