The final step that you need to do creating the pads for your footprint is to make sure that they have appropriate 'names' -- specifically, that the pad names match the pin/pad numbers in the datasheet.
This is important because later on we will need to connect these 'pads' to our schematic symbol, and if we don't have the right names for our pads you can easily end up connecting something improperly and you'll either have a useless PCB or some potentially nasty and time consuming rework to do when it does arrive!
A few extra minutes double-checking every pad and part of your footprint can save you hours or debugging and rework later, and more than a little bit of money on PCBs!
If you followed the advice in the previous pages, you 'created' the pads in the same order that they are listed in the datasheet, counter-clockwise starting with pad 1 in the upper-left-hand corner, and they should have the right numbers associated with them.
Just in case, though, you should always double-check your pin names before proceeding since this is an easy mistake to avoid, but one with significant consequence if we mess something up here.
Verifying/Changing Pad Names
To view or modify the pad name, you can select the 'name
' tool in the left-hand toolbar, shown highlighted in yellow below:
Just select this tool, then click on any pad and it's name will be displayed, and you can update it if necessary.
Alternatively, you can also right-click on the pad and select 'Name' from the popup menu:
A Note on Default Pad Names
By default Eagle will assign pad names like P$1
, etc., incrementing the number by one each time. This is perfectly normal for Eagle users, and what you will see in most footpints.
It's also acceptable to rename the pads to '1', '2', '3', though, instead of 'P$1', 'P$2, 'P$3'. The advantage is that this clutters up the schematics less, but it's purely a cosmetic change.
Any other change in names except to correct the pin numbers should be avoided unless you are very confident that you know what you are doing!
Be sure to following the pin numbers in the datasheet exactly, since this is what you will use to connect the pins later, and this is what anyone looking and your footprints will expect to see! Anything else is just asking for easily avoidable problems.
The pin names below are what you should have before proceeding, since this matches the pin names in the datasheet. If you don't get the same names, go back and correct them before continuing on to the next steps.
If you've made it this far, you actually have a fully functional package that you can connect up to any schematic symbol, and place it on your board.
Go ahead, pat yourself on the back! You've done the bare minimum of sizing and placing a set of appropriately named pads, and organizing them in a single package, which is the main requirement to move on to the next stage, creating a symbol for your schematic.
That said ... you'll thank yourself later for putting a bit of extra effort into things now. Accurate footprints are about more than a few pads and proper names.