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Anodic Cleaning for Direct Electroplating Thru-Holes

IP.com Disclosure Number: IPCOM000103432D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 72K

Publishing Venue

IBM

Related People

Chen, PC: AUTHOR [+2]

Abstract

Many aqueous Tin/Palladium colloidal wet seeding processes are used for dielectric and plated thru-hole metallization in a variety of epoxy/glass and polymer applications. Such processes typically use an organic linking agent which bonds to both the dielectric and exposed metallic substrate surfaces and in turn bonds to the Tin/Palladium colloid; effectively bonding the Tin/Palladium to the exposed metal and dielectric surfaces. The colloid is then used as a catalytic surface for the deposition of electroless metals. A preferred method utilizes the conductive nature of this colloid to support direct dielectric metallization by an electrolytic plating technique.

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Anodic Cleaning for Direct Electroplating Thru-Holes

      Many aqueous Tin/Palladium colloidal wet seeding processes are
used for dielectric and plated thru-hole metallization in a variety
of epoxy/glass and polymer applications.  Such processes typically
use an organic linking agent which bonds to both the dielectric and
exposed metallic substrate surfaces and in turn bonds to the
Tin/Palladium colloid; effectively bonding the Tin/Palladium to the
exposed metal and dielectric surfaces.  The colloid is then used as a
catalytic surface for the deposition of electroless metals. A
preferred method utilizes the conductive nature of this colloid to
support direct dielectric metallization by an electrolytic plating
technique.  For this method to be successful, removal of the organic
linking agent and Tin/Palladium colloid from the exposed metallic
surfaces must be accomplished prior to electroplating.  This removal
is typically achieved by wet chemical etching.  In the most common
case where the substrate metallurgy is Cu, the use of chloride
containing etchants often result in the formation of cuprous chloride
surface contaminates which, in turn, give rise to poor electroplated
film quality.  The use of more strongly oxidizing etchants can result
in the oxidation of Palladium, rendering it non-conductive.  The
following discloses a method whereby anodic cleaning of the substrate
metallurgy following organic and Tin/Palladium apply may be
accomplished without the formation of insoluble surface c...