Hi, I am a beginner with NRF chips, just wanted to know that Can I use different package size for Capacitors/Inductors like 603 instead of 402?
Thanks.
Hi, I am a beginner with NRF chips, just wanted to know that Can I use different package size for Capacitors/Inductors like 603 instead of 402?
Thanks.
You need to use components that have similar electrical characteristics.
So assuming the two devices have the same value for L or C as the design dictates, then:
For caps the dielectric type (ie, cog, npo, x5r, etc.) influences the temperature characteristics. So generally it is a good idea to choose the same dielectric.
For both caps and inductors the SRF (self resonant frequency) is the frequency at which the device achieves self resonance. A cap goes to very low impedance since the parasitic structure is generalized as a series resonant circuit whereas an inductor goes to very high impedance since it is a parallel resonant structure. Generally it is safe to choose a device with a higher frequency SRF.
For power inductors average current handling is important and is based on the heating capability of the inductor due to internal resistive losses. You want the same or higher current handling.
Also for power inductors the saturation current is extremely important. This is the point at which the inductors field strength stops increasing linearly with current. Essentially it stops acting as an ideal inductor and can really mess up a dc/dc converter if the saturation current is too low. So choose one with same or higher value as specified.
Finally for RF devices the package size is often chosen to complement the microstrip width. This gives the most predictable result of ideal value and impedance vs. what you get when you put it on the board. Also, as package length changes the phase relationship between input and output will change and this will change the values required for an RF match.
So can you swap them out? Sure! Just make sure all of the above stuff is true.
By the way, I assume you are looking to switch to 0603 since they are easier to hand solder. You should be careful of hand soldering chip parts. The soldering iron builds up huge thermal stresses across the part and it is not uncommon for the end cap to fracture as a result. This fracture is next to impossible to see, even under a microscope and can make for a debugging nightmare.
For all the logic and power a straight out swap of 0603 for 0402 is probably fine as most 0603 have slight better overall characteristics.
For RF it is a bit more complicated as the bigger package size will force you to change the layout and this will change the phase of where the part is on the board as I noted above.
If you are going to be doing this type of work long term, I really advise you get a hot air rework gun and a microscope so that you can place SMD components without a soldering iron.
Good quality hot air rework equipment can be bought for as little as $125 USD and a good quality boom mounted stereoscopic microscope start at about $500.
When working with RF, 0402 are better from an package size inductance and capacitance. 0402 are recommended in most RF designs as a measure to reduce noise from feeding back into your system.