Palladium Dendrite to Tin/Lead Interlayer Interconnection for Multi-Layer Substrates
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Leal, GR: AUTHOR [+3]
Disclosed here is an interlayer electrical connection technique using a palladium dendrite plating, and a stud and cavity layer interconnection technique.
Palladium Dendrite to Tin/Lead Interlayer Interconnection
here is an interlayer electrical connection technique
using a palladium dendrite plating, and a stud and cavity layer
density carrier technology exists in which individual
and testable 1S1P (one signal, one power) layers are laminated into a
single multi-layer structure. To facilitate the interlayer
connection (via), a "stud and cavity" technique with appropriate
joining metals is used to form the actual interconnection.
disclosure teaches the use of palladium dendrites
plated on one of the interconnection surfaces (stud or cavity) and a
Sn/Pb solder alloy plated on the mating interconnection surface. The
preferred embodiment consists of a eutectic tin/lead stud (2 in the
Figure) and a cavity (1) into which are plated palladium dendrites.
The dendrities may also be plated with a flash of gold to further
facilitate joining without the use of a flux. During layer to layer
lamination, the palladium dendrites will penetrate the Sn/Pb deposit
(3). The composite multilayer structure is then heated to a final
lamination temperature in the range of 185 to 240ºC.
As the rising
lamination temperature exceeds the melting point
of the Sn/Pb solder (183ºC) a transient liquid phase consisting
of molten eutectic Sn/Pb forms. This liquid phase dissolves the
mating layer of palladium dendrites (and...