Hi Inge,
In some cases the drilled hole diameter is critical to the success of the
press fit connection. The manufacturer of the press fit component may
specify the drilled hole size along with the plated hole size and plated
hole size tolerance for a given component. In the case of some small
(finished hole size 0.022") compliant pins I had to work with, the hole size
prior to plating was more important than the finished hole size when looking
at the required insertion force. It is now our policy to call out the
drilled hole size on the fab drawing along with the finished hole size and
finished hole size tolerance for holes that will receive press fit
components whenever the manufacturer recommends a drilled hole size.
As far as board finish goes, I have seen similar results when working with
Sn/Pb and gold as a general rule. One other thing to consider is the finish
of the component. While pressing pin with a Sn/Pb finish into a board I
haven't noticed much difference in insertion force with varied board
finishes. I have however noticed that pressing a gold finished lead into a
gold finished board requires a significantly higher force. That however has
not caused us to change the hole size on the board, yet.
Either way, I recommend you work closely with the manufacturer of the
component that you want to press while defining your board characteristics.
Regardless of which manufacturer I have dealt with (Amp, EPT, Teradyne, FCI,
etc...), I have received the right information to make that part work on a
given board.
I hope this helps...
Valquirio N. Carvalho
Mfg. Engineer
Teradyne, Inc.
P.S. I don't work in the connector division of Teradyne. I work in the
board assembly end of things.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Inge Schildermans
Sent: Tuesday, October 30, 2001 5:03 AM
To: [log in to unmask]
Subject: [TN] Press-fit hole dimensions
Hi all,
I was looking for an international standard which describes the tolerances
on the dimensions of press-fit holes, since we had some troubles in
production. I did not found anything in IPC, but I did in IEC-60352-6.
In this standard they did not make a difference between Sn-Pb finish and
electroplated or immersion finish. I think this is strange since Sn/Pb has
better smearing properties than the other finishes, and therefore can have
other tolerances on the finishes
hole diameter. In the table they also make a difference between the
diameter prior to plating and after plating. Can anyone tell me if it is
necessary to define the drill diameter? In my opinion, the copper thickness
in the hole and the finished hole
diameter are the only parameters which are of importance. Another strange
thing is that comparing the different hole diameters, the difference between
the drilled and finished hole is not always the same.
Can someone help me out of this?
Thanks,
Inge, Alcatel
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