Years ago I visited an ITT owned factory that made night vision binoculars.
They soldered SMT components (chips and SOICs mostly) onto a thin FR4 PCB.
Then, bent it into a cylinder that fit into the binocular tubes. Somehow,
this configuration was able to pass validation tests for military service.
Everything about it seemed at odds with my experience but it was a proven
process and proven product.

On Tue, Oct 6, 2020 at 10:17 PM Wayne Thayer <[log in to unmask]> wrote:

> Hi Jack-
>
> It is REALLY difficult to damage epoxy/glass laminate by bending. In almost
> all cases, it will be the components: First the large ceramics, then
> leadless parts, then parts with stiff leads....and always the larger the
> part the more susceptible to damage.
>
> Wayne Thayer
>
> On Tue, Oct 6, 2020 at 8:41 AM Bush, Jeffrey D. (US) <
> [log in to unmask]> wrote:
>
> > FEA model should be completed for fatigue to solder joints and devices  -
> > ie ceramics
> >
> > Jeffrey Bush
> > Program Quality Engineering Manager
> > BAE SYSTEMS
> > Electronic Systems Division
> > C4ISR Solutions – Space Systems Group
> > P.O. Box 868
> > Nashua, NH 03061-0868
> > T: (603) 885-8137  |  M: (603) 318.8056   |  E:
> > [log in to unmask]
> > 144 DW Highway, Merrimack, NH 03054  Mail Stop: MER24-116A-A4
> >
> > Important:
> > This email may contain BAE SYSTEMS INCORPORATED Proprietary Information
> > for the sole use of the intended recipient. Any review or distribution by
> > others is strictly prohibited.  If you are not the intended recipient,
> > please contact the sender and delete all copies.
> >
> > -----Original Message-----
> > From: TechNet <[log in to unmask]> On Behalf Of Jack Olson
> > Sent: Tuesday, October 6, 2020 11:13 AM
> > To: [log in to unmask]
> > Subject: [TN] Bending a Board Assembly
> >
> > *** WARNING ***
> > EXTERNAL EMAIL -- This message originates from outside our organization.
> >
> >
> > We are considering a change to a manufacturing process which will save
> > time and money, but will cause extra stress on the completed board
> assembly.
> > Q1) I'm familiar with bow and twist for bare boards, but is there data on
> > flexing a completed assembly? I'm sure it depends on board thickness and
> > material, etc. but is there danger to the  board itself? or does it
> always
> > break a component first?
> > Q2) I'm NOT familiar with stress on components. How can I determine
> > whether we are in danger of damaging components, especially SMDs?
> >
>