This is not a press fit pin in this case. The hole dia. is .076 ±.003 with
a .150 dia. pad the part is a .072±.002 shaft with a .093 shoulder. We
expect .0008 to .001" of copper in the hole, if there is more than this and
as long as the vendor knows what his process will return for wall thickness
and adjusts his start drill accordingly its not a problem for us.

Again my question:

What would be the proper specification to check to when after inserting a
gold pin into a Plated through hole the pad is lifted due to stress of the
assembly method. We were using an arbor press to insert the pin and the
material is Glassteel's MC-3. I have looked at IPC-A610 and find no
reference to this situation there. How will this defect effect long term
reliability of the soldered connection. I'm worried about the knee of the
PTH cracking due to the pad lifting.


----------
> From: [log in to unmask]
> To: [log in to unmask]
> Subject: Re: [TN] Spec ref for lifted pad after assy
> Date: Thursday, November 12, 1998 1:29 PM
> 
> Steve,
> 
> Can't help on which spec to look for, but wish to make you aware of
another
> issue. The sizing of the hole is extremely important. However, letting
the
> fabricator know that you are pressing pins into the holes and whichones
are
> more important. 
> 
> Some fabricators will allow a little more room in their over-drill and
plate a
> little extra copper in the hole to make sure that the plated barrel is
very
> ductile and will not fail under normal circumstances. Usually they will
shoot
> for 0.0012 in. in the hole instead of 0.001 in. The philospohy is that no
one
> will complain about extra copper in the hole as long as the component
lead
> fits in the hole. Unfortunately with this copper thickness, the bight of
the
> corner of the pin does not clear the coppper plating, as it should do.
> Subsequently the falt of the pin presses on the plated wall and lifts the
> surface land.
> 
> I have seen the insertion process competely push out the barrel of a hole
> including lifting the lands. 
> 
> When you design the hole size and tolerance, you generally assume that
there
> will be no more than 0.001 in. in the hole. Here the fabricator is trying
to
> be a good guy and it bites you in the end.
> 
> I hope this helps a little for the future.
> 
> Regards,
> 
> Gary

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