Hi Hillel -
     
The definition in JSTD-003: **par. 4.2.4.5.2 - Accept/Reject Critirion. "A 
minimum of 95% of each of the surface being tested...** is for each surface pad!
There have been numerous discussions within the 003 committee that the 95% 
minimum should be even more restrictive with the rationale being who would want 
to assemble boards that each pad was 5% dewet. Board fabricators are very 
capable of meeting the 95% and routinely hit 100% wettable. Many folks use the 
5% dewett as a trend yardstick to assess how their board fabricators are 
controlling their processes. The JSTD 003 specification does contain previsions 
that the user and fabricator can agree to use a different minimum if they can 
reach agreement.


Dave Hillman
JSTD003 co-chairman
[log in to unmask]




______________________________ Reply Separator _________________________________
Subject: STD: IPC-6012 - Dewetting Definition
Author:  [log in to unmask] at ccmgw1
Date:    6/17/97 8:51 PM


IPC par. 3.5.4.4.b define classes of dewetting.
     
The questin is if the percentage is related to each unit of soldering (i.e. 
5% of each soldering pad) or the 5% is a total of the dewetted solder area.
     
Similar definition is also in ANSI/J-STD-003 par. 4.2.4.5.2 - Accept/Reject 
Critirion. "A minimum of 95% of each of the surface being tested..." refer 
to each individual inspected pad or the total pads area being inspected?
     
In the first case 100% of the pads will be soldered, in the second case 5% 
of the pads might have soldering problems.
     
What is your interpretation?  
Hillel Dzigan - Quality Manager
Eltek Ltd.
Phone +972-3-939-5022, Fax +972-3-930-9581 
P.O. Box 159, Petach-Tikva 49101, ISRAEL
     
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