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No Option For Pad Round-off In V2021 Edition?

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Tom H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 8:36am
The Land Pattern Naming Convention must have 3 places because of the way it was designed and created. 

XX.XX for the values. 2 places to the left of the decimal point and 2 places to the right of the decimal point. 

I guess you didn't understand 2 X 2 Decimal Place Accuracy like you set in the Console Options. 

Was this the problem that wasn't really a problem? 

When you select Decimal Place Accuracy to 2 min and 3 max, it still produces the same footprint name because that is the standard naming convention. 

i.e.: you can't change the naming convention regardless of your Decimal Place Accuracy because the naming convention is a standard XX.XX for now according to IPC-7351. 

Note: all leading zero's "0" are dropped and ending zero's are not.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Quist Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 11:07am
Ah, no I was not referring to the Naming Convention but rather to the actual pad dimensions presented under Footprint -> Manufacturer's Dimensions.
I got the impression that no matter what decimal accuracy I put in I got three decimal places on the dimensions but now I can't reproduce the behaviour so it was probably user induced...
I see in our fpx library that we have a different number of decimal places on the pads for different components. That might have been whats fooled me.

Can you please comment on the subtitle "Manufacturer's Dimensions". Who is Manufacturer referring to, component manufacturer or PCB manufacturer? I find it a bit confusing.
Wouldn't it be better to call it something like "Pad dimensions" and the checkbox something like "Use custom dimensions" or similar?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 11:42am
The Manufacturer reference is the Component Manufacturer, not the fabrication or assembly shops. 

The current pad stack and footprint naming conventions are intentionally created in 0.01 mm increments because if you added one more place to accommodate 0.001 accuracy, the footprint name would be too long for most CAD tools. 

Right now, the character limit for a footprint name is 40 characters. If you added one more number to each value the footprint name would be 47+ characters. 

Body Length X Width X Height X Lead Width X Length X Thermal Tab Width X Length 

Same with Pad Stack names. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Quist Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 12:34pm
I agree, 0.01 mm is good for naming no matter what the physical accuracy is. I even seriously doubt that there is any practical benefit with going below 0.01 accuracy. Normal trace tolerance in an etch proces is probably around 0.05 mm and might be tweaked down to 0.02 mm.

Regarding "Manufacturer's Dimension": If I open a part in Footprint Expert and would like to see the size of the pads calculated by Footprint Expert the only way I know to do it is to go to the "Manufacturers Dimensions" section and look there. However, this is not the manufacturers dimensions but rather the dimensions calculated by Footprint Expert. 

I don't think the naming is intuitive.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 1:20pm
The pad stack naming convention used in Footprint Expert is available for free download on www.pcblibraries.com/downloads

In Footprint Expert you can double click (or single click + RMB > Properties) any pad and the program will open the pad Properties. 



If you select the Pas Stack name, it will open the Pad Stack Manager. 



The values are grayed out for any Calculator footprint because if you edit it, PCB Libraries, Inc. or IPC cannot be responsible for any typos. 

But you can visually see the pad length and width and corner radius too. 

I can look at any pad stack name and tell you the length, width and corner radius. 

You can control the corner radius in Options > Pad Stack Rules > SMD Corner Rounding > Corner Size Limit 

The default is 0.25 but many users change that value to 0.10 or 0.05. 

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