Chip Resistors in the Base Library


#1

In case someone is interested: We’re discussing the best way to add chip resistors (and later capacitors) to the standard library for about three weeks now: https://github.com/LibrePCB-Libraries/LibrePCB_Base.lplib/pull/15

It’s quite a tricky issue, because on one side we want to have packages that match actual products, but on the other hand that would result in thousands of combinations.

The current approach (see this comment by @ubruhin) that we’re targeting is to create generic packages at IPC density levels A and B, together with generic resistor devices, so you’d add a “R-330” to your project, not a “Yageo AC1206JR-07330RL”. This will work for most cases, since usually (especially for prototypes) you’re not interested in which exact resistor is used, as long as the resistance and shape is correct.

For the cases where you’re designing for mass production, you’ll want the smallest possible footprints (density level C) and should probably use footprints that are made exactly according to the manufacturer specifications (unfortunately not all dimensions of chip resistors are standardized).

So currently we’ll probably add a standard set of generic resistors to the base library, and later manufacturer-specific versions to manufacturer-specific libraries.

If you have any comment on that, please let us know :slight_smile:


#2

That sounds good to me. I’m not sure I’ve ever seen an open source PCB specify a particular part number for a passive. I’ve always just designed assuming it’s going to be assembled with whatever is on hand that meets spec.

Eagle come with tons of libraries for specific parts, and I rarely use even a single one of them. They just clutter up the menu for the most part, because you can’t include every part everyone might ever want.

Trying to keep up with all the thousands of manufacturers, and figure out what’s actually useful to include, seems like it would overwhelm a small project.

I really like Sparkfun’s Eagle library. A lot of their footprints work just fine with junk from eBay, or with proper parts from Digikey, so they’re often my starting point when I think “Hey, I need to put an inductor on this board”. That’s the kind of thing I’d like to see in the base library.

If I really want some industrial switch, LibrePCB makes it ridiculously easy to make footprints.

Otherwise, I’d rather have that one 2.54mm grid spaced slide switch that eBay sells for $3/40 of them, or the 10x10 inductor that I don’t know the actual standard for, but appears to be everywhere, or that one barrel jack footprint that Sparkfun has that seems to work with all the cheap clones.