In IPC website there is a search tab. It might help you
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, October 12, 2006 4:03 PM
To: [log in to unmask]
Subject: Re: [TN] Compression Limit on FR4?
I don't know.
That's why I wondered if there was any kind of industry consensus on the
subject.
Jack
On 10/12/06, Ian Hanna <[log in to unmask]> wrote:
>
> 'damage' occurs as soon as you assemble the board...
>
> how much 'damage' is acceptable to your application?
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Thursday, October 12, 2006 3:53 PM
> To: [log in to unmask]
> Subject: Re: [TN] Compression Limit on FR4?
>
> Thank you for responding.
>
> The problem is, someone is asking me about the MAXIMUM before damage
> occurs, so I am quite interested in your statement that it "tends to
> deform the fiberglass over time".
>
> Where can I learn more about that?
> Does any IPC document even mention it?
> I wish there was such a thing as an "IPC index"... any IPC people
> listening?
>
> thanks again, though
> Jack
>
>
> On 10/12/06, Stadem, Richard D. <[log in to unmask]> wrote:
> >
> > Hi, Jack
> > I can tell you that typically the torque setting used for hardware
> > on pwb assemblies is between 1 to 6 in/lbs. More than that tends to
> deform
> > the fiberglass over time. Of course, it all depends on the type of
> board
> > material, layer count, etc.
> > It also depends on the application.
> > Realize that a lot of relaxation occurs during any type of thermal
> > excursion, and the hardware will loosen up. It is always a good idea
> to
> > use a Bellville washer in conjunction with a serrated or star washer
> to
> > continue to hold the torque. It is also a good idea to use Glyptol
> > or some other threadlocker.
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> > Sent: Thursday, October 12, 2006 1:54 PM
> > To: [log in to unmask]
> > Subject: [TN] Compression Limit on FR4?
> >
> > Does anyone know of any guidelines or recommendations that suggest a
> > maximum limit on compressing board material?
> >
> > Can any damage occur by over-torque'n screws, for example?
> >
> > I've never heard anyone discuss that...
> >
> > Jack
>
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