Chip Component Land Pattern

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Hi all, 
How can I calculate Gmin for chip component (IPC-7351B)? 
I can't get the PCB Footprint Expert result.  

Gmin=Smax-2*JH-SQRT(Cs^2+P^2+F^2), where 
Smax=Smin+Stol(RMS);
Smin=Lmin-2*Tmax;
Cs=Stol(RMS);
Stol(RMS)=SQRT[(Lmax-Lmin)^2+(Tmax-Tmin)^2]
JH=0 (Nominal Density for 0603 chip component)
P - placement tol.; F - fabrication tol.

Is that right?

Thanks in advance

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bakhmat Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 13 Sep 2012 Status: Offline Points: 2	Post Options Post Reply Quote bakhmat Report Post Thanks(0) Quote Reply Topic: Chip Component Land Pattern Posted: 13 Sep 2012 at 7:38am
	Hi all, How can I calculate Gmin for chip component (IPC-7351B)? I can't get the PCB Footprint Expert result. Gmin=Smax-2JH-SQRT(Cs^2+P^2+F^2), where Smax=Smin+Stol(RMS); Smin=Lmin-2Tmax; Cs=Stol(RMS); Stol(RMS)=SQRT[(Lmax-Lmin)^2+(Tmax-Tmin)^2] JH=0 (Nominal Density for 0603 chip component) P - placement tol.; F - fabrication tol. Is that right? Thanks in advance



Nick B Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 02 Jan 2012 Status: Offline Points: 1909	Post Options Post Reply Quote Nick B Report Post Thanks(0) Quote Reply Posted: 17 Sep 2012 at 2:31am
	For those who want to customize library rules to meet manufacturer’s requirements and want to see how it works to create customized Footprint Expert DAT files (personal rules). IPC-7351C Reference Calculator (forum login is required to download)