I might suggest that if your board size is not the one specified by your
terminal, counterbore the board until it is the right size. Terminals
are designed to fit a specific size. It is up to the designer to
supply a board of that size.
Mike Green
Production Design Engineering
Lockheed Martin Space Systems
Sunnyvale, CA 94089
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Brooks,Bill
Sent: Tuesday, March 29, 2005 9:00 AM
To: [log in to unmask]
Subject: Re: [TN] Solder Terminals
Hi Robert,
Yes... I recall the acceptability of cracks in terminals and eyelets...
Thanks for the reminder. It's been a long time since I have had to deal
with
them. Your last comment on PTH swaging of terminals... I thought they
didn't
allow that in the Mil Specs... there was an issue with damage to the PTH
I
think... We always added multiple vias around any non-plated or plated
mechanical hole that was used for ground and/or mounting or if the board
was under any mechanical compression so as to guarantee that the
continuity
of the pads on top to the planes and pads on the bottom was maintained
by a
via free of mechanical compression... regardless of any single failure
in a
mounting or swaged terminal hole. It was just 'good insurance'.
Do you have the specific spec numbers for those? I'd like to look at
them
again.
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Langston, Robert L [mailto:[log in to unmask]]
Sent: Tuesday, March 29, 2005 3:08 AM
To: [log in to unmask]
Subject: Re: [TN] Solder Terminals
Cracking of the solder terminals is a subject that has been around
forever
and is not confined to any one supplier.
IPC,MIL, and NASA Spec's address this and allow end item terminal cracks
of
a maximum of 3, if they are located at least 90 degrees apart, and none
enter into the barrel of the terminal.
Final swaging in a PTH should allow rotating the terminal with finger
pressure.
Bob
-----Original Message-----
From: Brooks,Bill [mailto:[log in to unmask]]
Sent: Monday, March 28, 2005 1:02 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Terminals
They may have changed materials in the alloy on you...
Check with the manufacturer of the terminals to make sure the alloy has
not
changed. Or if that isn't it, then maybe the plating process is
affecting
the brittleness of the material? Dead soft copper is very malleable and
brass is less malleable. Most of the terminals I have used in
electronics
are tin plated brass with the only exception being copper eyelets back
in
the 1970's.
I assume that you have not changed the hole size in the board and the
board
thickness is the same... The speed with which the material is 'cold
formed'
may also come into play... If you are using automated tooling the stops
on
the swage tool will have something to do with preventing over stretching
the
material to the cracking point. The 'very old' terminals comment you
made
makes me suspect that the materials have changed rather than the process
of
forming them with the Cambion tool. Just a guess. Work with your
supplier
and see if the old batch of terminals came from a different source or
used
different materials.
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
----------------
Hi Technetters:
I would like to know if anybody has experienced difficulties in
flaring
the flange of solder terminals. On J-std-001C 6.2.3 it states that the
angle
of flare shall be between 35 and 120 deg. Some terminals crack even if
they
are flared at 36 deg. Other terminals can be flared at 120 deg and not
crack. I suspect that the plating finish has a lot to do with it.
Regards,
Ramon
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