Martin Dooner * <[log in to unmask]> wrote:
>I am looking for any mention in any of the Stds (IPC or Mil) for the
>number of heat cycles allowed per joint for rework purposes.
>
>I know most companies have either three or five allowable heat cycles.
>
>Also has anyone done any reliability analysis on the number of BGAs that
>you can rework on a single PCA.
>Is there any industry standard for this?
>
>All assistance appreciated
>
>Regards
>
>Moss D

Hi Moss,
 
The JEDEC STD-J20 requires that the package be subjected to three cycles of
soldering before being tested for its moisture resistance rating. 

You can be satisfied that if you have observed the "out-of-bag" time 
limitation for the package (whether leadframe type or BGA type), then you can
safely solder thc component a total of three times. This means the initial
soldering cycle, followed by two cycles of rework. 
 
Of course, if you bake out the board at 125 Deg C for 24 hours you can 
start all over again - at least as far as moisture resistance is concerned. 
  
Hope this helps, 
  
Tom

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