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]
> >
> >
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>
>
> --
> Bhanu Sood
> Tel: (202) 468-8449
>
|
