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Plating Jig for Galvanic Metal Deposition on Pin Grid Arrays

IP.com Disclosure Number: IPCOM000117555D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Boecker, JW: AUTHOR

Abstract

This article describes the galvanic deposition of Nickel and Gold with a defect free shank surface of the pins which is a product requirement for most Pin Grid Arrays (PGAs). The specially designed jig is feasible for mass production.

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This is the abbreviated version, containing approximately 52% of the total text.

Plating Jig for Galvanic Metal Deposition on Pin Grid Arrays

      This article describes the galvanic deposition of Nickel and
Gold with a defect free shank surface of the pins which is a product
requirement for most Pin Grid Arrays (PGAs).  The specially designed
jig is feasible for mass production.

      To prevent corrosion, the connecting pins and the wirebond pads
have to be coated with Nickel and Gold.  Plating of both is carried
out in electroless baths due to the hazard that for galvanic
deposition electrical contact has to be made to all areas to be
plated.  Whereas electroless Nickel is a well established process
with long time experience, electroless Gold plating is quite new and
not easy to handle.  Autocatalytic Gold baths are based on the high
alkaline Okynaka type with dimethylaminoborane as a reducing agent.

      Electroplating is not only easier to accomplish but also
cheaper and faster technique.  However, electroplating needs
electrical contact points for current supply with the result that at
the contact areas itself no metal is deposited.  These undesired
defects may lead to corrosion.

      The benefit of electroplating is that Nickel and Gold can be
plated wet in wet with one fixturing as far as all pins are
electrically connected with the wirebond pads via the brick.  Then
electroplating can be carried out without any sealing of electrical
contact points.  Therefore, a special fixture was designed and built
up.  Electrical contact is made via the pins with very tiny contact
areas of about 30 ym diameter at the pin heads.

      As can be seen in the Figure, electrical contact to the pins is
carried out by crown studs (2), where the design of the crown is made
in a way that...