Note
As WARG has shifted to A365 (in 2022) a lot of our practices have changed since this document was authored in 2021. As our WARG EE leads have gained more knowledge (and diffused it into our members) we have also refined many of our techniques. In the future we are hoping to have more formalized designed standards which should completely replace this document. This document will live on as at least a relic of an era for the time being.
Introduction
Component Sourcing and Library Management Guide for https://github.com/UWARG/hardware primarily intended for new members of the WARG Electrical subteam as it doesn’t dive into advanced topics.
This writing assumes you have completed the Electrical bootcamp and have a basic understanding of how to use Altium Designer. If you do not, resolve that before proceeding and interacting with our github!
Currently a WIP
Github! This guide does not go into specifics so please ask others as you are learning.
Github Repository & How to use it with Altium and Discord
...
Next, we prefer components that are cheap! For common components I’ve listed typical price ranges below, but for other components just be sure you’re going with the cheapest option that still meets the required specifications.
Below I will outline a few requirements for common components, but for other uncommon components just be sure that the package is easily hand solderable and be sure to ask someone else if you are unsure.
Capacitors
For capacitors we prefer Murata due to their nice capacitor simulation tool, https://ds.murata.co.jp/simsurfing/index.html?lcid=en-us , that show us how the components will behave through graphs and whatnot. They have most components in stock, but if they lack something, Kemet is our backup. There is a reason for this, probably previous good experiences with these companies, but I’m unsure of the specifics. If you want to deviate from these, check with a lead.
...
For making the capacitor symbol, assuming you’re grabbing an 0603/0805/1206 package, just copy paste the generic symbol and fill in the parameters with information from the datasheet. These must be filled in perfectly as failure to do so will mess up the bill of materials (“BOM”). The footprints are already made for these packages as well so this should go pretty quick.
Headers
Resistors
Other non-standard components
Symbol Making
parameters
can copy for common packages of common components
Pins can (and should for aesthetic state) go in any position you want as long as the number and name are correct according to the part datasheet.
Naming scheme, blend in
For the drawing itself you can copy from other libraries as long as it is clean
Footprint Making
Correct pin numbers, no need for top overlay except for dot on pin one on components in which pin1 is important.
Can copy from other components or other libraries, make it clean, must be perfect, download 3d body from digikey or make sure it is 100% the exact component, then use the 3d body to ensure your pins are in the correct positionI like to go with Molex because they’re pretty standard and have a lot of stuff, but manufacturer is not picky with headers. This is the only component in which we use Through Hole, do not source surface mount headers.
For power connectors we like screw terminals and for general purpose we use male pins. Other more unique headers are acceptable for other applications so just be sure you know what your doing.
Mating pitch is critical for male pin headers so stick with 2.54mm as a standard and positions and rows options vary depending on requirements.
Resistors
I don’t think we have a preferred supplier here, but I tend to use Yageo.
Resistance is picky with resistors so be sure to check exactly what you need. For tolerance, +-1% is fine for most applications and are widely available.
For the package follow the same rules as with capacitors. Prefer 0603 with 0805 as a backup if you cannot find what you need.
Symbol Making
For standard components copy paste the generic component with the proper package, fill in the parameter values and you’re good to go! For things like headers, you can copy paste a header, add or subtract positions, then update the parameters. The parameters are extremely important for making our BOM look proper.
For components that aren’t already in our libraries you can find one in another library with a nice symbol and copy paste the symbol over. We want our symbols to be extremely clean so I do not recommend drawing things yourself.
For symbols for pretty much anything you can position the pins wherever you want. For microcontrollers we highly recommend you arrange the pins in a way that makes logical sense as this will make your schematic sheet look far nicer. Be sure each pin is named correctly and the designator number matches perfectly with the footprint. This is because the schematic symbol pin numbers will sync up with the footprint pad numbers when in the PCB designing stage and if they aren’t named properly you will end up connecting things to the wrong pads even though your schematic may look correct.
For pin and symbol naming scheme look at other similar components and follow the pattern, blend in!
Additionally, checkout this guide https://resources.altium.com/p/guidelines-creating-useful-schematic-symbols.
When you create a symbol be sure to fill in the parameters. Order of parameters is irrelevant, but naming has to be exactly perfect for the BOM! For every component no matter what include “Manufacturer Part Number 1” and “Manufacturer 1” in addition to the supplier parameters which Altium fills in for you. For which other parameters to include check similar components.
Footprint Making
For the footprint of common components you can reuse the exact same footprint for multiple components. For things like headers it is easy to just add or subtract positions from other similar header footprints just be sure to check the datasheet to be sure the spacing is correct. If you are making your own footprint be sure to check the datasheet and use some basic geometry to determine the exact spacing. I would highly recommend using the footprint wizard as is outlined in the bootcamp for creating unique components as it makes it very easy to extract the values from the datasheet and drop them straight into Altium.
Additionally, feel free to copy from other libraries as long as it is clean. One difference from the bootcamp is that we do not include the top overlay lines, though don’t forget to make pin 1! For 3d bodies Digikey often has links to the .stp file at the bottom of the items page, but if they don’t check for the Ultralibrarian link as that will give you a 3d body as well. Finally, you can google the package to find a 3d body, but be sure it is the correct package as outlined in the datasheet. Be sure you line up the 3d body perfectly and then check in 3d that everything lines up perfectly to ensure you spaced the pads properly and everything looks correct!
In Conclusion
This is meant as an introduction and I’m sure I’ve forgotten things. Please ask questions!