We always to use this formula to calculate the percentage of the twist of
the bare PCB, both formulas are right, as states in section 5.2.4, if it is
not possible to get the 3 corners of the sample to touch the surface plate
by constraining only one corner, the referee method should be used which is
in section 5.3, so the 2 formulas are both right only used in different
situation, you should know which method fit you.

 

WINNING

 

 

-----邮件原件-----
发件人: TechNet [mailto:[log in to unmask]] 代表 Victor Hernandez
发送时间: 2009年8月1日 0:15
收件人: [log in to unmask]
主题: [TN] IPC-TM-650 2.4.22

 

Fellow TechNetters:

 

   I need assistance/clarification on the above stated Test Method.

What is the difference in the two following section of the stated

document.  Section:  5.2.7  and 5.3.6?

In the first section I clearly understand the "D" to the Diagonal

designator measurement.  The second use the "L" designator which appears

to be the Length.   Is this formula correct?   Both formula appear to be

used to calculate the percentage of twist.   I am confused.

 

 

Victor,

 

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