Re: Eagle Parts Library for QRP projects?


Dave NZ1J
 

Hi Curt,
 
Like you, I prefer to have enough copper on the board to be able to work with it easily.
 
For something like a DIP package, the lead spacing is 0.100"  The drilled holes are about 0.040"  That leaves 0.060" of fiberglass between the holes.  If 0.020" annular rings are used around each hole, that leaves 0.020" of space between the rings.
 
As you say, modern manufacturing uses pretty tight tolerances.  To pass a trace between those DIP pads, things need to be squeezed a bit.  I think the standard libraries may allow room for that trace as the default.  Though it is some extra work for us, customizing the rings to be larger where possible makes for a board that is more tolerant of some rework.  We can also use oblong pads that leave room for the trace, but provide more copper where there isn't an issue.
 
I also choose wide traces wherever possible.  Sometimes the default is 0.012" or even narrower.
 
I'm sorry that I don't know of any libraries that will do what we want.  Please let us all know what you find.
 
73,
Dave NZ1J


---------- Original Message ----------
From: "Curt via Groups.Io" <rhulett1@...>
To: main@4SQRP.groups.io
Subject: [4SQRP] Eagle Parts Library for QRP projects?
Date: Tue, 16 Apr 2019 08:16:37 -0700

At age 71, decided to attempt learning how to design a PCB for fabrication by the numerous available shops.  Selected Eagle, using the free version at least for starting, managed to draw a schematic and produce a board design for a simple crystal transmitter using parts from the numerous available libraries.  Managed to build one "device" in a personal "library".  When the fabricated board arrived, unfortunately the parts pads weren't as large as I wanted, and the device I had built was larger than would have liked.  The board is likely usable, but nothing would care to share.

So, back to the drawing board.

I think the defaults in the program aren't what an amateur should use, but am not sure what the defaults should be.  For example, default design rules for pad around hole has a minimum of 10 mils and maximum of 20 mils.  What should they be?   

I think the parts vendor libraries are voluminous and targeted toward commercially designed PCBs.

With the many  PCBs designed and fabricated for QRP projects, there are libraries already populated with parts appropriately scaled for the parts that we use with QRP projects.   I have looked unsuccessfully for such a library.  I could build my own of course, but not sure of the value reinventing that wheel.

Is there a resource for QRP PCB design rules and library?  Or is every hobbyist rolling their own?

73, Curt KB5JO



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