PCB Libraries Forum : Chip Cap Naming https://www.PCBLibraries.com/forum/ Mon, 06 Apr 2026 23:36:07 +0000 Tue, 28 May 2013 12:29:58 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=949 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Chip Cap Naming : I believe that comes from an...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3583.html#3583 Author: SteveASmith
Subject: 949
Posted: 28 May 2013 at 12:29pm

I believe that comes from an old engineering rule that if an even number is followed by a 5 then you don't round up.  I have also seen this in other technical disciplines.]]> Tue, 28 May 2013 12:29:58 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3583.html#3583 <![CDATA[Chip Cap Naming : I will bring this issue up at...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3582.html#3582 Author: Tom H
Subject: 949
Posted: 28 May 2013 at 12:23pm

I will bring this issue up at our next IPC standards meeting scheduled for June 3.
 
Thanks for the info.
 
]]> Tue, 28 May 2013 12:23:37 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3582.html#3582 <![CDATA[Chip Cap Naming : But, the Standards do round if...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3581.html#3581 Author: JZsori
Subject: 949
Posted: 28 May 2013 at 12:16pm

But, the Standards do round if 5.59 becomes 56.  To me, I would start rounding up at 6 so that, in this case, 5.59 would become 56.  No argument on the vendor dim - 5.59 should have been 5.6, esp when they show a tolerance of +/-0.25.]]> Tue, 28 May 2013 12:16:47 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3581.html#3581 <![CDATA[Chip Cap Naming : Where do you start rounding?...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3580.html#3580 Author: Tom H
Subject: 949
Posted: 28 May 2013 at 12:12pm

Where do you start rounding? 7, 8 or 9? The Standards don't round and the component manufacturer's should not have 5.99 mm as a value it should be 6.00 mm
 
]]> Tue, 28 May 2013 12:12:08 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3580.html#3580 <![CDATA[Chip Cap Naming : I can see where that might sense...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3579.html#3579 Author: JZsori
Subject: 949
Posted: 28 May 2013 at 12:09pm

I can see where that might sense if you're sitting in the middle.  But when you are within 0.01 why would they want it rounded down?
 
Interestingly enough the question was posed to me by a client when I created that footprint for him.
]]> Tue, 28 May 2013 12:09:59 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3579.html#3579 <![CDATA[Chip Cap Naming : For the Land Pattern (Footprint)...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3578.html#3578 Author: Tom H
Subject: 949
Posted: 28 May 2013 at 12:02pm

For the Land Pattern (Footprint) Name, the standards do not round-off, they drop numbers.
 
Example: EIA 1206 = 0.125" X 0.062"
One would think that you would round up 0.125" to 0.13 but they don't.
 
A better example is the 0805 or metric 2012 is 2.0 mm X 1.25 mm. One would think that 1.25 mm should be rounded up to 13 to create a 2013, but they don't, they just drop the 3rd number.
 
]]> Tue, 28 May 2013 12:02:10 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3578.html#3578 <![CDATA[Chip Cap Naming : Using 2012.53 to create a footprint...]]> https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3577.html#3577 Author: JZsori
Subject: 949
Posted: 28 May 2013 at 11:17am

Using 2012.53 to create a footprint for a Vishay VJ2225 series cap.  The dimensions I used from the datasheet are 5.59 X 6.35 L(D) /W(E).  But the tool gives me a 5563 name.  Shouldn't this be 5663?]]> Tue, 28 May 2013 11:17:24 +0000 https://www.PCBLibraries.com/forum/chip-cap-naming_topic949_post3577.html#3577