Bev,

For the Telcordia document, the sample groups are defined in table 13-3 in 
my copy and a description of the sample groups follows that table.

For the J-STD-004 B version, EVERY SIR value for processed samples must 
maintain above 100 megohms.  Keep in mind that the J-STD-004 B version is 
now calling out the new SIR method 2.6.3.7, which is continuous monitoring 
(every 20 minutes). The old 2.6.3.3 method had only five measurement sets 
taken and only two counted towards passing the test (96 and 168 hours). 
With the new method more measurements are taken and require more data 
evaluation.  That said, the IPC SIR TG has agreed that when method 2.6.3.7 
is used a 24-hour grace period should be given before any data starts to 
count due to the boards acclimating to the test conditions.  The same 
comments have also been made by flux TG about a 24-hour grace period.   I 
always give a 24-hour grace period when performing per J-STD-004, unless I 
don't see any sort of recovery in the SIR results after 24-hours.  If they 
maintain below the pass limit after 24-hours, then I spend the time visually 
inspecting for a root cause.

I hope this helps you.

Best Regards,

Joe Russeau



----- Original Message ----- 
From: "Bev Christian" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October 14, 2010 2:29 PM
Subject: [TN] Interpretation of SIR Requirements


> TechNetters,
> In GR-78-CORE, Issue 1, 1997, SIR Test Procedure 13.1.3.2 R13-6 [808], it 
> states (capitalization mine) "The average insulation resistance (megohms), 
> for EACH SAMPLE GROUP, taken at 24 hours and again at 4 days, shall be 
> greater than the minimum specified in table 13-4.
>
> In IPC J-STD-004B, 3.4.1.4.1 Reporting SIR Test Results, the first 
> criteria for passing the SIR test is: "All SIR measurements on all test 
> patterns shall exceed the 100 Mohm requirements."
>
> My questions are as follows:
> 1) In the Telecordia document, what constitutes a "sample group"? One comb 
> pattern? All the comb patterns on one coupon?  All the coupons being used 
> to test one material?
> 2) For the IPC method does the criteria apply to the readings at the end 
> of the test? First and last? At every measurement?  The document seems 
> vague to me.
>
> Bev
> RIM
>
>
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