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libraries of schematic symbols and layout footprints

see also Making your own symbols #symbols , and making your own footprints #footprint .

where to get symbols for your schematic -- where to get footprints for your layout

Vounteers have donated footprints at .

Brian Guralnick has generously donated a library with both "schematic components" and "PCB footprints" ("land patterns") at [FIXME: has moved elsewhere ?] and "all schematic discrete components are optimized for the schematic capture display. They are super compact. The pcb foot prints are also space optimized." ``Except for double diodes, discrete component pinouts are B,S,E, G,S,D, A,K instead of pin numbers for matching footprints within your own footprint libraries.''

Protel keeps putting updated parts libraries on its web site: Protel Libraries /* was */ and /* was */ and /* was */ .

a free library of footprints and symbols (which they call ``decals''): (is this compatible with Protel ?)

Q: What's the quickest way to print a page that lists *all* the footprints of a pcb library ? Looking at a page full of footprints at once is much faster than scrolling through the library looking at one at a time. (Especially with several pcb libraries full of parts).

A: "Geoff Harland" on 2001-05-24 08:39:28 PM writes: (lightly edited by the FAQ maintainer):

  1. Create a new blank Pcb file.
  2. Open the pcb footprint library file (``.lib'') you're interested in, and look at one of the footprints.
  3. With the Design Manager panel on, select the "Browse PCBLib" Tab while you have the Pcb Library file concerned currently selected.
  4. Using the left mouse button, click on the *first* footprint listed in the Design Manager panel.
  5. While holding a Shift key down, (left mouse button) click on the *last* footprint listed in the Design Manager panel. *All* of the footprints listed in the Design Manager panel should now be in a highlighted state.
  6. While the cusor is located over the area listing these footprints, right-mouse click, then select "Copy" from the resulting popup menu.
  7. Switch to the (blank) Pcb file, then do ``Edit | Paste'' and click in the PCB area. One copy of each of the footprints will then be pasted into the Pcb file. Now all the components are in a pile where you clicked.
  8. Select the components (perhaps with "Select | All").
  9. From the Component Placement toolbar, select the ``Arrange selected components within defined area'' icon. (If you let the mouse pointer rest on any icon for a couple of seconds, a short line of text pops up explaining that icon.) Click in the PCB area 2 or more times to space out the components.
  10. [optional] Add a string to the Drill Drawing layer, with a caption of .LEGEND (this is a Special String), and preferably place this in the lower left hand corner of the Pcb file.
  11. [optional] Run a process to set the Comment field of each component within a Pcb file equal to its Footprint (string). Geoff Harland wrote a PcbAddon Server to do this.

There's several different things you can do at this point.

Q: Which footprint should I use ?

A: Unlike through-hole components, there is no One True Footprint for a SMT part.

My understanding is that IPC footprints are (were ?) optimized for (c) wave soldering, so many people use smaller footprints that work fine for their process (a) or (b).

There is a (free) online land pad calculator from IPC, .

Bugs in the Protel footprint library (Have these been fixed already ?)

symbols for schematic: schematic library design tips

(schematic library design tips for making new symbols.)

If you want a symbol that's not already in the schematic symbol libraries , then you must make it yourself in your own library.

When designing a new schematic symbol, Ian Wilson says: "don't use hidden pins ... ever. The are not logical or intuitive and new users consistently have problems with them."

There seem to be 2 kinds of schematic symbols:

When making a new shematic symbols, it helps to

(The pin "numbers" on the schematic symbol must match up with corresponding "numbers" on the PWB footprint. The pin "names" on the schematic are just for documentation.)

Bug: The "update schematic" button really ought to (1) take the version of the part in memory (which you have just edited) and save it to disk, *then* (2) use the version on disk to update open schematics.

But at the moment, it only does step (2).

Workaround: Always ``press the "file save" button before you press the "update schematic" button.'' -- "Graeme Zimmer" on 2001-04-04 05:38:42 PM

Q: How do I copy a schematic symbol from some other library to my own personal schematic symbol library ?

A: After I right-click on the name of the component (in the left pane of the symbol editor), I choose "copy". No more clicks needed. Then I switch to my own personal libraries, right-click in that left pane, and choose "paste". Don't have to click again here either. In the schematic symbol editor, there's no way to do that from the menu options -- you *must* do it with the right-click thing. I wish for a ``Edit | Copy Component'' and a ``Edit | Paste Component''. Unfortunately, the ``Tools | Copy Component...'' does *not* do the right thing. Then rename it.

Footprint Library design tips

If the footprint you want isn't already in the libraries , then you'll have to make your own footprint.

If you're lucky, you don't need to create your own footprint library. Most boards can be built out of components that fit the standard footprint libraries.


If you create a new library, please please please embed a description of the library -- your name, email address, web page, the date it was created, the date of this revision, etc. Create an extra dummy component named "__about" with a bunch of "top overlay" silkscreen strings that list this text information ("metadata"). If you use the ".ddb" format, put a simple text file "readme.txt" in each ".ddb" database with this information.

When making a new footprint, it helps to

Editing footprints:

footprint design tips: [FIXME: should I move "component footprint design" to its own page, ?]

Common footprints people design:

custom pad shape

Q1a: How do I make a custom pad shape ? (I need something other than the simple pads shapes built-in to Protel: "circle", "rectangle", "oval", and "octagon")

A1: Build the custom pad shape out of several overlapping pads on the top layer (and optionally a through-hole pad on the multilayer). Assign them all the same reference designator.

A2: For even more flexibility, build the custom pad shape out of overlapping fills on *both* the top paste mask layer *and* the top copper layer. Place a small simple pad touching those fills. (Either a surface-mount pad on the top layer or through-hole pad on the multilayer).

Q1b: I tried that, but when I placed that footprint on my PWB, it lights up bright green with lots of DRC errors.

A1b: run "Design | Netlist Manager | Menu | Update Free Primitives From Component Pads" and run another DRC check.

"virtual short" ("star ground")

One under-appreciated ``component'' is the ``virtual short'', also known as a ``star point'' which can be used as a ``star ground''. (However, many people point out that one solid unsplit ground plane is better than a "star ground". )

unsorted used to point to a couple of CAD libraries ... have they moved elsewhere?

Protel users FAQ




in page
the links:
don't work!


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