Rex, this is the BEST answer I've seen for a torque spec . . . problem
is, I'm usually the customer.

However Walt, there are way too many elements to consider for canned
specs, hence you will have a hard time finding one especially for
hardware under 1/4".  Bottom line - all lock washers must be fully
collapsed & the stack-up per IPC-A-610.  If KEP nuts or SEMS screws are
being used then the mfr will have a recommendation.  If threadlocker or
locking inserts are used then snug is good.

If you are using electric or pneumatic drivers, set to lowest possible
setting that will seat the hardware without tightening then go back &
torque - don't confuse driving force with torque.  Also, don't confuse
interference force with torque before proper seating is achieved.

In other words, the torque settings are pretty much product specific.
And as mentioned, if you have a chance to evaluate a field return or a
unit that has been thru environmental qualification you can verify your
spec & adjust (and recall if necessary) as required.

Good luck,
Loa

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Thursday, October 08, 2009 6:55 AM
To: [log in to unmask]
Subject: Re: [TN] torque

In cases like this, where the customer often has a feel for what they
want, we provide them with an indicating torque driver and ask them to
do it up to the tightness they feel appropriate. We then set the spec to
that torque.
Regards
Rex


Technical Manager

Hansatech EMS provides value manufacturing through engineering and
quality

Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
Dorset BH17 0RY
United Kingdom

Tel: +44 (0)1202 338200
Fax: +44 (0)1202 338202
DDI: +44 (0)1202 338222
[log in to unmask]
www.HansatechEMS.com 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Walt Manchin
Sent: 08 October 2009 14:29
To: [log in to unmask]
Subject: [TN] torque

Hello All,

I have been working with customer that wants to attach daughter board to
mother board using standoffs and #6 screw.

We found specifications for torque on certain type of screws, but what
is your experience on the torque required to attach PCB's before causing
damage to the BOARDS AND/OR MATERIALS?

Thanks in advance.

 

 

Walter Manchin

Prototron Circuits Mid Atlantic

610-499-4964 - (office)

610-299-8969 - (cell)

mailto:[log in to unmask]

www.prototron.com <http://www.prototron.com/> 

 

Prototron

 




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