U.S. patent application number 10/969369 was filed with the patent office on 2006-04-20 for flexible land grid array connector.
Invention is credited to Li-Sen Chen, Ping Chuang, Chien-Yu Hsu.
Application Number | 20060084288 10/969369 |
Document ID | / |
Family ID | 36101865 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060084288 |
Kind Code |
A1 |
Chuang; Ping ; et
al. |
April 20, 2006 |
FLEXIBLE LAND GRID ARRAY CONNECTOR
Abstract
An LGA connector is used to interconnect an LGA package and a
printed circuit board. The LGA connector includes an elastomeric
body with a plurality of through-holes. Metal films are formed on
inner walls of through-holes and splay out around the mouths of
their upper and lower openings. The metal films are formed by
vacuum metallization, sputtering, chemical plating, electrical
plating or PVD. The through-holes have a funnel-like shape to
absorb external stresses and redirect the stress to shrink the
through-hole diameters. Moreover, the metal films' elastic
deformation is larger than conventional metal conductive fillers so
as to improve reliability.
Inventors: |
Chuang; Ping; (Taoyuan
Hsien, TW) ; Chen; Li-Sen; (Taoyuan Hsien, TW)
; Hsu; Chien-Yu; (Taoyuan Hsien, TW) |
Correspondence
Address: |
PRO-TECHTOR INTERNATIONAL
20775 Norada Court
Saratoga
CA
95070-3018
US
|
Family ID: |
36101865 |
Appl. No.: |
10/969369 |
Filed: |
October 19, 2004 |
Current U.S.
Class: |
439/66 |
Current CPC
Class: |
H05K 3/4602 20130101;
H05K 3/42 20130101; H05K 3/326 20130101; H05K 2201/09827 20130101;
H01R 12/52 20130101; H05K 2201/0133 20130101; H01R 13/2414
20130101; H05K 2201/10378 20130101; H05K 2201/09509 20130101 |
Class at
Publication: |
439/066 |
International
Class: |
H01R 12/00 20060101
H01R012/00 |
Claims
1. An LGA connector for interconnection between an LGA packaged
integrated circuit and a printed circuit board, said LGA connector
comprising: an elastomeric body, having an upper major surface, and
a lower major surface opposed to said upper major surface; a
plurality of tubular metallic film conductors, each connecting an
upper opening on said upper major surface to an opposed lower
opening on said lower major surface, each of said plurality of
tubular metallic film conductors being formed by metallic
deposition around said upper opening and said opposed lower opening
and onto a surface of an inner wall of a through-hole connecting
said upper opening and said opposed lower opening, each of said
plurality of tubular metallic film conductors being insulated from
one another; and each of said plurality of tubular metallic film
conductors having an axial cross-section which tapers inwardly from
said upper opening to form a funnel-like shape with a central
through-hole; and wherein each of said plurality of tubular
metallic film conductors compress radially inward in reaction to
external stresses exerted against said upper major surface and said
lower major surface; whereby a portion around said upper opening of
each of said plurality of metallic film conductors connects to the
LGA packaged integrated circuit, and a portion around said opposed
lower opening of each of said plurality of metallic film conductors
connects to the printed circuit board.
2. (canceled)
3. The LGA connector of claim 1, wherein said plurality of tubular
metallic film conductors are formed by vacuum metallization,
chemical plating, physical vapor deposition, or sputtering.
4. (canceled)
5. An LGA connector for interconnection between an LGA packaged
integrated circuit and a printed circuit board, said LGA connector
comprising: an elastomeric body, having an upper major surface, and
a lower major surface opposed to said upper major surface; a
plurality of tubular metallic film conductors, each connecting an
upper opening on said upper major surface to an opposed lower
opening on said lower major surface, each of said plurality of
tubular metallic film conductors being formed by metallic
deposition around said upper opening and said opposed lower opening
and onto a surface of an inner wall of a through-hole connecting
said upper opening and said opposed lower opening, and each of said
plurality of tubular metallic film conductors being insulated from
one another; and a polyurethane layer interposed between each of
said plurality of metallic film conductors and the corresponding
surface of said elastomeric body; each of said plurality of tubular
metallic film conductors having an axial cross-section which tapers
inwardly from said upper opening and said opposed lower opening to
form a funnel-like shape with a central through-hole; and wherein
each of said plurality of tubular metallic film conductors compress
radially inward in reaction to external stresses exerted against
said upper major surface and said lower major surface; whereby a
portion around said upper opening of each of said plurality of
metallic film conductors connects to the LGA packaged integrated
circuit, and a portion around said opposed lower opening of each of
said plurality of metallic film conductors connects to the printed
circuit board.
6. (canceled)
7. The LGA connector of claim 5, wherein said plurality of tubular
metallic film conductors are formed by vacuum metallization,
chemical plating, physical vapor deposition, or sputtering.
8. (canceled)
9. (canceled)
10. (canceled)
11. (canceled)
12. (canceled)
Description
BACKGROUND
[0001] 1. Field of Invention
[0002] The present invention relates to a flexible land grid array
connector. More particularly, the present invention relates to a
flexible connector between a land grid array connector and a
printed circuit board.
[0003] 2. Description of Related Art
[0004] Integrated circuits are typically housed within a package,
which is designed to protect the circuit from damage, provide
adequate heat dissipation during operation, and provide electrical
connection between the integrated circuits and the leads of a
printed circuit board. Several conventional package types, such as
land grid array (LGA), pin grid array (PGA), ball grid array (BGA)
and column grid array (CGA), are designed to provide the above
functions.
[0005] The current trend for connector design in the computer field
is to provide both high-density and high-reliability connections
between various major circuit devices of a computer. High
reliability for such connections is essential due to potential end
product failure. As both module size and distance from which solder
connections are located to the center of the module (i.e., the
distance from neutral point, hereafter DNP) continue to increase,
even CGA solder connections can become unreliable, especially due
to thermal fatigue. These same concerns about broken
interconnections also apply to PGA applications when the DNP is too
large. Therefore, what is needed is an interconnection, which is
relatively flexible and capable of accommodating the thermal
mismatch over an expected temperature range that can closely match
the electrical performance and density of a BGA or CGA array.
[0006] One solution is to use an LGA connector. An array of
interconnection elements, known as an interposer, is placed between
two arrays to be connected, and provides the electrical connection
between the contact pins or pads. Since the individual contact
members of an interposer can be made resilient, they can
accommodate a CTE (coefficient of thermal expansion) mismatch
between the module and system board.
[0007] An LGA package is an integrated circuit package having a
plurality of planar metallized areas, called lands, for
interconnection between the leads of the integrated circuit and a
printed circuit board. An LGA can be mounted to a printed circuit
board with connectors, which have been developed to maintain a
solderless connection between an integrated circuit package and a
printed circuit board. As the number of lands is increased, the
pitch between contacts decreases and manufacturing problems
consequently increase.
[0008] For example, the manufacturing method of placing individual
wires into tightly packed through-holes requires tremendous
technological developments. Another example is a metallized polymer
interconnect (MPI) connector. The MPI connector includes a siloxane
core with conductive fillers that is positioned between the LGA
module and the substrate. However, extreme stress relaxation rates
are needed in order to achieve a desired level of durability.
SUMMARY
[0009] It is therefore an objective of the present invention to
provide a flexible LGA connector, so as to provide reliable
electrical connection and enhance its durability.
[0010] In accordance with the foregoing and other objectives of the
present invention, an LGA connector is used to interconnect an LGA
package and a printed circuit board. The LGA connector includes an
elastomeric body with a plurality of through-holes. Metal films are
formed on inner walls of the through-holes and splay out around the
mouths of their upper and lower openings. The metal films are
formed by vacuum metallization, sputtering, chemical plating,
electrical plating or PVD (physical vapor deposition). The
through-holes have a funnel-like shape to absorb external stresses
by redirecting the stress to shrink the diameters of the
through-holes. Moreover, the metal films' elastic deformation is
larger than conventional metal conductive fillers so as to improve
reliability.
[0011] According to another preferred embodiment, a triple-layered
elastomeric body is provided when corresponding contact electrodes
of an LGA package and a printed circuit board are mismatched in
position. An upper elastomeric layer and a lower elastomeric layer
made of rubber exist, which have a plurality of funnel-like
through-holes formed by etching. A metal layer is formed on an
inner wall and around each upper and lower opening of each
through-hole of each layer. An interconnection elastomeric layer
made of rubber exists, which has a plurality of funnel-like
through-holes formed by etching. A metal layer is formed on an
inner wall and around each upper and lower opening of each
through-hole so as to interconnect the metal layer of the upper and
lower elastomeric layer. Thus, the LGA connector in this preferred
embodiment can interconnect an LGA package and a printed circuit
board even when corresponding contact electrodes are mismatched in
position.
[0012] It is to be understood that both the foregoing general
description and the following detailed description are by examples
and are intended to provide further explanation of the invention as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. In the
drawings,
[0014] FIG. 1A illustrates a cross-sectional view of an LGA
connector according to one preferred embodiment of this
invention;
[0015] FIG. 1B illustrates a cross-sectional view of an LGA
connector according to another preferred embodiment of this
invention;
[0016] FIG. 2 illustrates a top cross-sectional view of an LGA
connector's elastomeric body according to one preferred embodiment
of this invention;
[0017] FIG. 3 illustrates a cross-sectional view of an LGA
connector according to yet another preferred embodiment of this
invention; and
[0018] FIG. 4 illustrates a cross-sectional view of an LGA
connector under upper and lower stress according to one preferred
embodiment of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Reference will now be made in detail to the present
preferred embodiments of the invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers are used in the drawings and the description
to refer to the same or like parts.
[0020] In order to overcome the shortcomings of the prior art, the
present invention provides an LGA connector for solderless
connection between an LGA package and a printed circuit board. The
LGA connector is an elastomeric body having a plurality of
through-holes. There is a metal layer on an inner wall and around
each upper and lower opening of each through-hole so as to
interconnect an LGA package and a printed circuit board.
[0021] FIG. 1A illustrates a cross-sectional view of an LGA
connector according to one preferred embodiment of this invention.
The LGA connector includes an elastomeric body 200 made of rubber,
which has a plurality of funnel-like through-holes 202 formed by
etching. A metal layer 204 is formed on an inner wall and around
each upper and lower opening of each through-hole 202. Each metal
layer 204 is insulated from one another. A polyurethane layer 203
is formed by coating between the metal layer 204 and the inner wall
of each through-hole 202 so as to maintain the as-deposited
physical and chemical properties of the metal layers. The
manufacturing method for coating the metal layer 204 can be vacuum
metallization, chemical plating, electrical plating, physical vapor
deposition or sputtering.
[0022] FIG. 1B illustrates a cross-sectional view of an LGA
connector according to another preferred embodiment of this
invention: The LGA connector includes an elastomeric body 200 made
of rubber, which has a plurality of funnel-like through holes 202
formed by etching. A metal layer 204 is formed on an inner wall and
around each upper and lower opening of each through-hole 202. Each
metal layer 204 is insulated from one another. A bump 206 of
elastomeric material is formed around each through-hole 202 so as
to increase contact effect. In practice, a clamp 210 should be
designed on a printed circuit board 106 so as to secure an LGA
package 100 and the LGA connector together. The manufacturing
method for coating the metal layer 204 can be vacuum metallization,
chemical plating, electrical plating, physical vapor deposition or
sputtering. This LGA connector could be employed to interconnect
two printed circuit boards with LGA-type electrodes as well.
[0023] FIG. 2 illustrates a top cross-sectional view of an LGA
connector's elastomeric body according to one preferred embodiment
of this invention. FIG. 2 is taken along the line A-A in FIG. 1A
and illustrates an elastomeric body 200 made of rubber, which has a
plurality of through-holes 202 coated by metal layers 204.
[0024] FIG. 3 illustrates a cross-sectional view of an LGA
connector according to yet another preferred embodiment of this
invention. When corresponding contact electrodes 101a and 105a
mismatch in position (i.e., a contact electrode 101a mismatches its
corresponding contact electrode 105a such that they cannot be
connected by the LGA connector illustrated in FIGS. 1A and 1B),
this preferred embodiment discloses a triple-layered elastomeric
body to resolve this issue. An upper elastomeric layer 200a made of
rubber exists, which has a plurality of funnel-like through-holes
202a formed by etching. A metal layer 204a is formed on an inner
wall and around each upper and lower opening of each through-hole
202a. Each metal layer 204a is insulated from one another. A lower
elastomeric layer 200c made of rubber exists, which has a plurality
of funnel-like through-holes 202c formed by etching. A metal layer
204c is formed on an inner wall and around each upper and lower
opening of each through-hole 202c. An interconnection elastomeric
layer 200b made of rubber exists, which has a plurality of
through-holes 202b formed by etching. A metal layer 204b is formed
on an inner wall and around each upper and lower opening of each
through-hole 202b so as to interconnect the metal layer 204a and
204c. Thus, the LGA connector in this preferred embodiment could
interconnect an LGA package and a printed circuit board even when
corresponding contact electrodes are mismatched in position. This
LGA connector could be employed to interconnect two printed circuit
boards with LGA-type electrodes as well.
[0025] FIG. 4 illustrates a cross-sectional view of an LGA
connector under upper and lower stress according to one preferred
embodiment of this invention. The LGA connector equipped with an
elastomeric body 200 and funnel-like through-holes 202 can
accommodate the thermal mismatch and achieve a desired level of
durability. When the through-holes have a funnel-like design,
pressure, under upper stress 208a and lower stress 208b, can be
absorbed by redirecting the stress to shrink the through-hole
diameters. Moreover, metal layers are more flexible than metal
fillers, such that the electrical connection is more reliable.
[0026] According to the preferred embodiments above, the disclosed
LGA connector equipped with an elastomeric body and funnel-like
through-holes can provide a reliable electrical connection. When
the through-holes have a funnel-like design, pressure from above
and below can be absorbed by shrinking the through-hole diameters.
Moreover, metal layers are more flexible than metal fillers, such
that the electrical connection is more reliable.
[0027] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
present invention cover modifications and variations of this
invention provided they fall within the scope of the following
claims and their equivalents.
* * * * *