For press-fit pins, the drilled (raw) hole size is as critical, if
not more critical than the finished holes size.

When the pin expands in the hole, it cuts into the copper and stops
expanding once it hits the hole wall. The location of the wall is
what determines a good or poor connection, as there is NO solder in
the hole to make the contact between the barrel and the pin.

Whenever using press-fit components, the finished and the drilled
(raw) hole size both need to be called out on the fabrication drawing.
This is information is always the same as what the component manufacturer
has called out.

Also, press-fit padstacks should not have thermals, but be full plane
contacts. Thermals are only need to keep heat from discipating during
soldering. Press-fit pins are never solder, therefore should always
be direct plane contacts.

Hope this helped.

Karen Anne Cardwell, CID
email: [log in to unmask]
phone:408-559-5672 fax:408-377-6148
pager: 877-881-7105
pager_email: [log in to unmask]

-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Cannone Giuseppe
Sent: Thursday, August 31, 2000 3:19 AM
To: [log in to unmask]
Subject: [DC] Press-fit holes


Hi all,

we have a backpanel where we use a 68 pins micropress-fit connector (AMP
786555-7). We require a 0.7 +/- 0.025 mm raw hole and a 0.6 +/- 0.05 mm
finished hole.
Because of the board thickness (6.5 mm), our supplier has many problems in
keeping finished hole tolerances. Do you think that increase to 0.75 the raw
hole requirement may be a good solution?



Thank You in advance

Regards

Giuseppe Cannone

SiemenS
Information and Communication Networks S.p.A.
Address: S.S.17  Loc. Boschetto - 67100 L'Aquila (Italy)
Phone: +39 862 335517
Fax:      +39 862 335812
E-mail:  [log in to unmask]