Choosing SMD components

[Hussein.aljawazri]

Hello everyone,
Hello Philip,

I wanted to ask about the right way to start designing the schematic. If I need for example 1K ohm resistor, should I search from the beginning the right ohmic value, SMD size, etc.... and pick one that is available by a distributor? for ex. from Altium manufacturer search engine. or should I choose first only the component with the right SMD size and save the rest of the work (ohmic value, manufacturer, ...) till the end while creating BOM? Because I saw in Phils Libraries that there are resistance, capacitance,.. symbols defined only by their size (e.g. 0603) and nothing else. This means that we need later to match this component to an existing one by a distributor while creating BOM?

Note: I am working with Altium

Thanks in Advanced

[qdrives]

It is a personal preference.
The question is asked often. I personally define everything up front.

[robertferanec]

and save the rest of the work (ohmic value, manufacturer, ...) till the end while creating BOM?

- this only "saves" work for very small hobby projects

For professional designs, the right way to do it is to have individual components for each part number.

Why? Biggest problems are BOMs (Bill of materials). Don't forget, in companies you don't create BOM only once. You may have several variants of the board (the same board but different components fitted), you may have several versions (similar boards or new board revisions with fixes), you can go back to the board after year(s) and need to re-generate BOM or a different engineer may go back to your project and generate BOM. All these additional changes in BOMs will be a LOT of work in future and if not done properly it will increate risk of fitting wrong components and costing a lot of money to fixing that mistake. So, process of generating BOM has to be as automatic as possible - and it is only possible if you don't do any manual changes in generated BOMs.

+ once you create a proper component with all the information (e.g. part number), you don't have to search for its part number in future anymore nor correcting all the future BOMs where this component is used