How to choose standard parts

Community PCB Design
1

I am new to smt and somewhat amateur at designing my own pcb for fabrication.

I want standard parts/sizes in Eagle that will make my life easier. For instance, capacitors, resistors, and transistors. Which library part/size for smt do people use?

Also, when it comes to digikey, I usually find the options overwhelming… What are standard ways to filter down to get reasonable price and normal choices for parts?

Thank you so much.

2

I don’t know what the optimal way to do it is, but I generally just use 0603 resistors and capacitors when I can. Sometimes 0402 if I need to pack it more tightly or the price is significantly different. For selecting an actual part, I filter for my requirements, perhaps filter for the better of some criteria that aren’t hard requirements, and sort by price. I’ll then choose the “best” part out of the first tier of price - often there will be one or two parts that have better tolerance or voltage limits than the rest, at the same price.

3

Thanks, should I be concerned if I choose a 0402 that placing by hand is hard. Also, I saw in a post that some manufacturers don’t do 0402, have you ever seen an issue with that? Perhaps an older post that no longer applies?

I guess I just need to get the hang of this and determine my constraints better. I just learned that for capacitors MLCC is probably a cheap and good way to go for capacitors though, so I am picking up a few tricks.

Thanks.

4

You’re welcome. I haven’t found hand-placing 0402 parts any more difficult than 0603 parts; both need a relatively steady hand and tweezers, and a magnifying light helps a lot. If you’re speaking of PCB manufacturers, I don’t see why they wouldn’t; 0402 pads are around 24mils. I have no experience with assemblers, though, having only done small run PCBs for myself.