Hi Phil - our board modification (i.e. cuts & jumpers) type of stuff is
covered by a couple of procedures so they are not included in the "3"
number since they are reviewed and any possible impact on integrity is
assessed. I was talking about the removal of components in production/test
as part of a product flow. Say a BGA isn't working so they would be allowed
to "rework" it 3X before having to pull together a process/design group
review.
Dave
On Wed, Mar 28, 2018 at 1:41 PM, Nutting, Phil <[log in to unmask]>
wrote:
> Our reworks are not to a single location, but rather various cuts, jumpers
> and component changes. Some due to design issues of the existing board,
> change in operating points or obsolescence of the existing parts.
>
> Only three reworks? Geesh, we surpassed that ages ago.
>
> Having a magic number is easier for some folks to wrap their head around.
> I'll pass along your suggestions.
>
> Thanks,
>
> Phil
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Wednesday, March 28, 2018 2:07 PM
> To: [log in to unmask]
> Subject: Re: [TN] when is there too much rework on a circuit board
>
> 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/>
> > >
> > >
> > > [Excelitas R_emailsig]
> > >
> > >
> > > Please consider the environment before printing this e-mail.
> > > ________________________________
> > > This email message and any attachments are confidential and
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> > to
> > > Excelitas Technologies Corp. If you are not the intended recipient
> > > of
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> > > message, please inform the sender by replying to this email or
> > > sending a message to the sender and destroy the message and any
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> > >
> >
> >
> >
> > --
> > Bhanu Sood
> > Tel: (202) 468-8449
> >
>
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