Parametric CAD for footprints - Page 1
Forum section: electronics / general

author: jmw
author_rank: Frequent Contributor
timestamp: September 28, 2018, 11:29:26 pm
content: Does any software package out there have parametric modeling for footprints? By this I mean you can directly enter constraints on distances and sizes of primitives and let the software do the work of doing the math to satisfy those constraints. This is a pretty powerful part of 2D MCAD programs where a sketch can be almost completely determined by the solution of constraints instead of being freehanded. OTOH whenever I have to do weird footprints in Altium I have whip out a calculator and figure out the x-y coordinates of pads and it's a pain.If I could type in the clearance and distance measurements right off the datasheet from something like this I could do these footprints in a couple of minutes.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: September 28, 2018, 11:36:21 pm
content: Yes tons. Recommend trying fusion360; is free for hobby and small business

author: jmw
author_rank: Frequent Contributor
timestamp: September 28, 2018, 11:45:12 pm
content: Yes! I've used F360 and the prompt for this post was my thought, "Why isn't doing footprints as easy as sketches in F360?" But F360 can just get the shape, once you have it, you've got to tie pads to net names which needs some integration in the EDA program.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 28, 2018, 11:59:54 pm
content: Eagle and F360 are slowly becoming integrated, which is great.However - pad design is done inside of Eagle and it sucks beyond comprehension. I am admittedly spoiled with the past 20+ years using Solidworks for parametric design....but Eagle is particularly bad in this area. F360 is only useful to design the 3D part and associate it with the part in Eagle.In general - I use Ultra Librarian, SnapEDA for schematic symbols and pads. Sometimes they are passable but almost always provide a better starting point than a blank sheet. Some parts, I just duplicate and modify something similar from my own library to avoid starting from scratch.For some parts that do not conform to any standard - like connectors, switches, inductors, etc....you need a pen, paper, and a hand calculator. The ultimate fail IMHO to need those to make a simple pad layout.

author: Rerouter
author_rank: Super Contributor
timestamp: September 29, 2018, 12:18:59 am
content: Kicad has been able to do this using "Freecad" for some time, either a dimensioned drawing, or from the manufacturer step model directly.https://forum.kicad.info/t/kicad-stepup-the-sketcher-for-footprint-generation/9582/19

author: electrolust
author_rank: Unknown
timestamp: September 29, 2018, 03:33:08 pm
content: huh, isn't this extremely common?IPC wizard in altium, PCBL Library Expert. With PCBL you don't even have to enter the data, you can buy the footprint data for $1 or something per part if you want.

author: jmw
author_rank: Frequent Contributor
timestamp: September 29, 2018, 04:22:36 pm
content: Quote from: electrolust on September 29, 2018, 03:33:08 pmNot really. I've used both satisfactorily for common patterns, but it's back to a pen, pad, and calculator if you go off the reservation like with that MOSFET footprint above.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 29, 2018, 05:19:59 pm
content: Just last night, I got the update for Eagle and they now have a pattern tool that can be used to create footprints - it is a huge boost!It can be used to define a pad, the spacing, qty, etc and makes your pad pattern. Still no parametric tools for odd shapes, but this is at least a step in the right direction.

author: maginnovision
author_rank: Super Contributor
timestamp: September 30, 2018, 03:02:10 am
content: Yea my biggest pet peeve with eagle is the lousy pads. My god let me do it how I want. The pattern tool is good though other than that.

author: voltsandjolts
author_rank: Unknown
timestamp: September 30, 2018, 01:49:01 pm
content: https://www.pcblibraries.com/The free version (called PRO btw) is quite good (even makes nice STEP models) but doesn't save your entries, need to enter all package info again if altering footprint sometime later.Paid version lets you alter a parameter and rebuild your whole library, nice. 1KUSD IIRC.