Hi Guy,

Funny you should mention that, because it was the kind of thing we were
working on in Tulsa just before I was laid off and came to Allentown to
work for you. It was a helmet mounted monocular sight for Apache helicopter
pilots called IHADSS.  The small thin PCB's were formed in a fixture in a
oven and allowed to cool, then the components were hand soldered. Not sure
why flex wasn't used, but that's what the customer wanted.

Steve


On Sun, Oct 11, 2020, 5:28 AM Guy Ramsey <[log in to unmask]> wrote:

> 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?
> > >
> >
>

-- 



This email and any attachments are only 
for use by the intended 
recipient(s) and may contain legally privileged,
 confidential, proprietary 
or otherwise private information. Any 
unauthorized use, reproduction, 
dissemination, distribution or other 
disclosure of the contents of this 
e-mail or its attachments is strictly
 prohibited. If you have received 
this email in error, please notify the
 sender immediately and delete the 
original.