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Decimal Precision in Physical Description

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AGONZ67 View Drop Down
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    Posted: 25 May 2012 at 1:21pm
I have noticed in the physical description field most dimensions are two places past the decimal, ie 3.20 x 1.60 x1.40, but there are several that are carried out to three places. This only refers to the description field as the examples shown below. IPC Standard is two places past the decimal point and include trailing zeros

PLCC127P1244X1244X457-28 Plastic Leaded Chip Carrier (PLCC), 1.27mm pitch;square,7 pin X 7 pin,12.445mm L X 12.445mm W X 4.57mm H body

TO254P1054X203-4 Transistor Outline (TO, DPAK),2.54 pitch;;3 pin,10.54mm L X 9.395mm W X 2.03mm Hbody

LEDDFN120X77X40-4 LED, Dual Flat No-Lead (DFN 4 Pins), 0.75mm pitch;4 pin,1.20mm L X 0.775mm W X 0.40mm H body

DIOMELF3515   Diode, Metal Electrode Face (MELF);3.50mm L X 1.525mm Dia
 
RESMELF3515   Resistor, Metal Electrode Face (MELF);3.50mm L X 1.525mm Dia
 
 
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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: 21 Oct 2012 at 2:46pm
If the package is originally a Inch Based part, the millimeter values are sometimes carried out 3 places to the right of the decimal point.
 
Eventually all packages will be metric based parts and this will automatically correct itself.
 
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