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| Reply To: | TechNet E-Mail Forum. |
| Date: | Mon, 21 Apr 2003 09:16:37 -0700 |
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Don,
This is the explanation of the formulas:
For the Aspect ratio= Aperture Width/Stencil Thickness
For instance on a 20 mil pitch QFP with stencil design as follows: width
equals 10, length 75 mil apertures and thickness of 6 mils, the aperture
ratio would be 1.67
this aperture would be OK since the ratio is above the 1.5
Area Ratio= Area of the aperture wall/Area of the aperture =
(Length*Width)/(Thickness*2(Length+Width))
Example for the same component above, the result is .74
Hope the information is useful...
Jorge Rodriguez
Process Engineer
Varian Electronics Manufacturing
615 South River Drive
Tempe, AZ 85281
E-mail: [log in to unmask]
-----Original Message-----
From: Don_well [mailto:[log in to unmask]]
Sent: Sunday, April 20, 2003 11:27 PM
To: [log in to unmask]
Subject: [SP: 39%] [TN] Aspect Ratio&Area Ratio Defines
Hi all
In IPC7525 specification.'Aspect Ratio'and 'Area Ratio'defines like below:
Aspect Ratio¡ê3/41.5, Area Ratio¡ê3/40.66
My question is how to get the actual data? I mean the 1.5 & 0.66...
B.regards
Feng.Xu
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