Browse Prior Art Database

Localized Electroplating Process

IP.com Disclosure Number: IPCOM000110486D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 58K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+6]

Abstract

Printed circuit board manufacturing is undergoing many changes due to the diverse types of packages that are being surface mounted to a single board. It is not always metallurgically correct to provide a uniform layer of eutectic solder to all the contact pads. Fine pitch components such as TAB packages have very stringent solder thickness requirements while some packages may require a solder hierarchy. MCM having large numbers of I/O may require a field demountable connection scheme that would necessitate a localized Au or Pd plating. The tool described here could be used to address these requirements.

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Localized Electroplating Process

      Printed circuit board manufacturing is undergoing many changes
due to the diverse types of packages that are being surface mounted
to a single board.  It is not always metallurgically correct to
provide a uniform layer of eutectic solder to all the contact pads.
Fine pitch components such as TAB packages have very stringent solder
thickness requirements while some packages may require a solder
hierarchy.  MCM having large numbers of I/O may require a field
demountable connection scheme that would necessitate a localized Au
or Pd plating. The tool described here could be used to address these
requirements.

      A typical plating requirement for a TAB site would necessitate
an Au-plated thickness of 30 - 50 microinches with a fine grain
structure and good adhesion to the underlying Cu pad.  It should be
understood that the metallurgical composition of the plating solution
or the type of I/O pads can be of a number of different recipes and
configurations, respectively.  The LPH (localized plating head) shown
in cross-section is a square with the dimensions to coincide with the
dimensions of the pads to be plated.  The LPH body, the inlet, and
outlet are made of PVC.  At the top of the head is an insulated tang
used to attach the head to an external locating system having X, Y,
and Z movements.  The top of the head, shown here as stainless steel
is the anode which has a post for electrical contact.  The cathode
assembly i...