Hi team! I agree with Bhanu, having a fixed number requires established
processes and material sets to be safe and even then, there is risk. Our
current procedures allow for 3 reworks before a process/design team
consultation/review is required.

Dave Hillman
Rockwell Collins
[log in to unmask]

On Wed, Mar 28, 2018 at 1:03 PM, Bhanu Sood <[log in to unmask]> wrote:

> Rework or scrap? the risk is usually assessed by weighing in the laminate
> type (PI, FR-4, flex etc), design, board stack-up, components in vicinity
> of rework site and time/temperature required for each rework (including
> preheat).
>
>
> Any guidelines regarding the number of allowable reworks are going to be
> specific to a design/material combination, tricky to extrapolate that
> guidance into a standard…rework risk assessment needs to analyze all
> factors and be better understood with solid research.  Most companies say a
> site can be reworked 2 or 3 times (assuming high Td/Tg PI...$$$).
>
>
>
> On Wed, Mar 28, 2018 at 1:40 PM, Nutting, Phil <[log in to unmask]
> >
> wrote:
>
> > Respected colleagues,
> >
> > I was just asked a question to which I could not put a number.
> >
> > In the case of needing to fix a circuit board "right now" to fill the
> > income stream there should be a logical point at which the reworks have
> > become too extensive for production boards beyond the "right now" need
> and
> > the board should be revised to eliminate the reworks.
> >
> > Is there an IPC or MIL standard that suggests a limit on the number of or
> > amount of rework allowed on a circuit board before it should be revised?
> >
> >
> > Phil Nutting  |  HVP Senior Development Engineer   |  Excelitas
> > Technologies Corp
> >
> > Lab: +1 978.224.4332   |  Office: +1 978.224.4152
> > 35 Congress St, Salem, MA  01970 USA
> > [log in to unmask]<mailto:[log in to unmask]>
> > www.excelitas.com<http://www.excelitas.com/>
> >
> >
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>
>
> --
> Bhanu Sood
> Tel: (202) 468-8449
>