Browse Prior Art Database

Breakaway Leadframe Surface Mount Pad-on-Pad Connector

IP.com Disclosure Number: IPCOM000117746D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 113K

Publishing Venue

IBM

Related People

Gaio, D: AUTHOR [+3]

Abstract

Disclosed is a connector component comprised of a plurality of pad-on-pad contact elements attached to a removable metal leadframe. Also included in the description embodiment are preferred fabrication methods, connector-to-carrier attach methods and carrier-to-carrier interconnection approaches to be used with the pad-on-pad interconnection design.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Breakaway Leadframe Surface Mount Pad-on-Pad Connector

      Disclosed is a connector component comprised of a plurality of
pad-on-pad contact elements attached to a removable metal leadframe.
Also included in the description embodiment are preferred fabrication
methods, connector-to-carrier attach methods and carrier-to-carrier
interconnection approaches to be used with the pad-on-pad
interconnection design.

      A low-cost, Surface Mount Technology (SMT) component made
from punched or etched sheet metal leadframe stock such as alloy 42,
phosphor bronze, copper (Cu), or beryllium-copper (Be-Cu) alloy,
plated or coated with tin-lead (Sn-Pb), pure Sn, or a combination of
nickel (Ni) underplating with hard gold (Au) overplate or Au flashed
palladium (Pd) or Pd-Ni plating is used to provide hard, raised
pad-on-pad interconnections to electrically join independent circuit
carriers together.  Schematics that illustrate the key features of
both the circuit carrier interconnection approach and the pad-on-pad
surface mount component used for the carrier-to-carrier
interconnection are shown in Figs. 1 and 2.

      In Fig. 1, three basic elements are shown.  Elements (A)
are textured pads that remain from initial SMT connector component
placement and attach.  The pad elements (A) provide raised contact
points to interconnect circuit carriers (B) and (C).  Pad-on-pad
component (A) is punched from sheet metal stock and is coated
accordingly with a specified thickness of one or more metal plating
or coating layers described above.  The metal stock used for the
punched component is preferably 0.005 inch 0.020 inch thick.

      The SMT pad-on-pad component (Fig. 2) is initially placed into
solder paste printed on the corresponding interconnect pads of either
carrier (B) or (C).  The connector placement operation is performed
during standard placement of other solderable SMT components which
may be required on the carrier(s).  A metallurgical bond of the SMT
pad-on-pad connector component to the carrier is established by
exposing the carrier to a typical solder reflow operation, followed
by subsequent cleaning if desired or necessary.  In Fig. 1, it is
seen that solder joints (D) that provide metallurgical bonding are
depicted for carrier element (C).  When Sn based coatings are present
on connector pad elements (A) soldered to carrier element (C),
corresponding pad interconnection locations on carrier (B) should
preferably possess a coating of plated or reflowed solder that can
range in thickness from less than .001" i...