U.S. patent application number 10/994695 was filed with the patent office on 2005-03-24 for connection components with anistropic conductive material interconnector.
Invention is credited to Lagattuta Tostado, Paula, Light, David, Warner, Michael.
Application Number | 20050064626 10/994695 |
Document ID | / |
Family ID | 26836939 |
Filed Date | 2005-03-24 |
United States Patent
Application |
20050064626 |
Kind Code |
A1 |
Light, David ; et
al. |
March 24, 2005 |
Connection components with anistropic conductive material
interconnector
Abstract
A connection component for a microelectronic element includes a
body of dielectric material having opposing first and second
surfaces. A plurality of elongated leads extend through the body
between the first and second surfaces. The leads have a first end
accessible at the first surface and a second end accessible at the
second surface. A layer of anisotropic conductive material overlies
the first ends and the first surface of the body for electrical
connection of the leads to a microelectronic element.
Inventors: |
Light, David; (Los Gatos,
CA) ; Lagattuta Tostado, Paula; (San Jose, CA)
; Warner, Michael; (San Jose, CA) |
Correspondence
Address: |
LERNER DAVID, LITENBERG, KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Family ID: |
26836939 |
Appl. No.: |
10/994695 |
Filed: |
November 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10994695 |
Nov 22, 2004 |
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10139169 |
May 6, 2002 |
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6825552 |
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60289718 |
May 9, 2001 |
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Current U.S.
Class: |
438/106 ;
257/E23.067; 257/E23.069; 438/118 |
Current CPC
Class: |
H01R 13/2414 20130101;
H01L 2924/00 20130101; H01L 2924/0002 20130101; H01L 23/49827
20130101; H01L 2924/0002 20130101; H01L 2924/15311 20130101; H01L
23/49816 20130101; H01R 43/007 20130101 |
Class at
Publication: |
438/106 ;
438/118 |
International
Class: |
H01L 021/44; H01L
021/48; H01L 023/34 |
Claims
1. A method of making a connection component for a microelectronic
element, said method comprising providing a body of dielectric
material having opposing first and second surfaces and a plurality
of elongated leads extending therethrough between said first and
second surfaces, said leads having a first end accessible at said
first surface and a second end accessible at said second surface,
and providing a layer of anisotropic conductive material overlying
said first ends and said first surface of said body for electrical
connection to a microelectronic element.
2. The method of claim 1, wherein said dielectric material is
flexible.
3. The method of claim 1, wherein said dielectric material is
rigid.
4. The method of claim 1, further including forming said plurality
of leads whereby said first and second ends are offset from each
other.
5. The method of claim 1, wherein said anisotropic conductive
material is provided in the form of a paste.
6. The method of claim 1, wherein said anisotropic conductive
material is provided in the form of a preformed sheet.
7. The method of claim 1, wherein said anisotropic conductive
material is an adhesive material.
8. The method of claim 1, further including providing said layer of
said anisotropic conductive material on said first surface of said
body.
9. The method of claim 8, further including providing said layer of
said anisotropic conductive material on said second surface of said
body.
10. The method of claim 1, further including forming a plurality of
contacts on said first surface in electrical contact with said
first ends of said leads.
11. The method of claim 10, further including providing a layer of
dielectric material on said second surface of said body.
12. The method of claim 11, further including providing a plurality
of conductors extending through said layer of dielectric material
in electrical contact with said second ends of said leads.
13. The method of claim 12, wherein said plurality of conductors
comprise lined vias.
14. A method of making a microelectronic package, said method
comprising: providing a first microelectronic element having a
front face including a plurality of first contact terminals,
forming a body of dielectric material having opposing first and
second surfaces and a plurality of elongated leads extending
therethrough between said first and second surfaces, said leads
having a first end accessible at said first surface and a second
end accessible at said second surface, arranging said first surface
of said body opposing said front face of said first microelectronic
element, providing a layer of anisotropic conductive material
between said front face of said microelectronic element and said
first surface of said body, and adhering said first microelectronic
element to said body whereby said anisotropic conductive material
provides electrical continuity between said plurality of contact
terminals and said leads.
15. The method of claim 14, further including forming a plurality
of contacts on said first surface in electrical contact with said
first ends of said leads, said plurality of contacts arranged in
alignment with said plurality of contact terminals.
16. The method of claim 14, wherein said anisotropic conductive
material is an adhesive material.
17. The method of claim 14, wherein said dielectric material is
flexible.
18. The method of claim 14, wherein said dielectric material is
rigid.
19. The method of claim 14, further including forming said
plurality of leads whereby said first and second ends are offset
from each other.
20. The method of claim 14, wherein said anisotropic conductive
material is provided in the form of a paste.
21. The method of claim 14, wherein said anisotropic conductive
material is provided in the form of a preformed sheet.
22. The method of claim 14, wherein said layer of anisotropic
conductive material is applied to said first surface of said
body.
23. The method of claim 14, wherein said layer of anisotropic
conductive material is applied to said front face of said first
microelectronic element.
24. The method of claim 14, wherein said anisotropic conductive
material is further applied to said second surface of said
body.
25. The method of claim 14, further including providing a layer of
dielectric material on said second surface of said body.
26. The method of claim 25, further including providing a plurality
of conductors extending through said layer of dielectric material
in electrical contact with said second ends of said leads.
27. The method of claim 14, wherein said layer of anisotropic
conductive material is rigid.
28. The method of claim 14, wherein said first microelectronic
element comprises a semiconductor chip.
29. The method of claim 14, further including a second
microelectronic element disposed on said second surface of said
body.
30. The method of claim 29, wherein said second microelectronic
element includes a plurality of second contact terminals connected
to said second ends of said leads.
31. The method of claim 30, further including a layer of
anisotropic conductive material on said second surface for
electrically connecting said second ends of said leads to said
plurality of second contact terminals.
32. The method of claim 14, further including a plurality of
contacts integrally formed as a portion of said first ends of said
leads adjacent said first surface.
33. A connector component for a microelectronic element made in
accordance with the method of claim 1.
34. A microelectronic package made in accordance with the method of
claim 14.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 10/139,169, filed May 6, 2002, which
application claims the benefit of the filing date of U.S.
Provisional Patent Application No. 60/289,718, filed May 9, 2001,
the disclosure of which is hereby incorporated herein by reference
in its entirety. The present application is commonly assigned and
copending with Ser. No. 10/205,635 which has a filing date of Jul.
25, 2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates in general to the field of
microelectronic element mounting and connection, and more
particularly, to connection components and semiconductor chip
packages using anisotropic conductive adhesive material
interconnection and to assembly methods therefor.
[0003] Microelectronic elements such as semiconductor chips are
connected to external circuitry, such as the circuitry of a
supporting substrate or circuit panel, through electrical contacts
on the front face of the chip. Various processes for making these
interconnections use prefabricated arrays of leads or discrete
wires. For example, in tape automated bonding processes, a
dielectric supporting tape such as a thin film of polyimide,
includes an array of metallic leads on one surface of the
dielectric film. The metallic leads are aligned with the contacts
on the front face of the chip. The dielectric film is juxtaposed
with the chip so that the leads extend over the front or contact
bearing surface on the chip. The leads are then bonded to the
contacts of the chip, as by ultrasonic or thermocompression
bonding. The terminals on the dielectric film may then be connected
to external circuitry for electrically interconnecting the chip and
the external circuitry.
[0004] The evolution of the semiconductor art in recent years has
created a continued demand for semiconductor chip packages having
progressively greater numbers of contacts and leads in a given
amount of space. An individual chip may require hundreds or even
thousands of contacts, all within the area of the front face of the
chip. Certain complex semiconductor chips currently being used have
contacts spaced apart from one another at extremely small
center-to-center distances. With such closely-spaced contacts the
leads connected to the chip contacts must be extremely fine
structures, typically having a smaller bonded surface than the
contacts onto which they are bonded so that the adjacent leads do
not electrically short.
[0005] In the bonding process of some assembly methods, the bonding
region of each lead is engaged by a bonding tool which bears on the
top surface of the lead in the bonding region and forces the lead
downwardly into engagement with the contact. Energy supplied
through the bonding tool causes the bonding metal to join with the
contact. Typically, the leads are bonded to the chip contacts with
the bonding tool using heat, force, ultrasonic energy, or a
combination of two or more thereof, for a given time period. If
incorrect force, heat and/or ultrasonic energy is used, the bond
between the leads and the contacts may be too weak to withstand
thermal cycling stresses during operation of the chip (heating and
cooling cycles during operation). Also, the bonding tool may create
areas of the lead which are prone to early fatigue during thermal
cycling because of excessive non-uniform deformation in the bonding
region, typically causing early breaks in the lead at the point the
lead bends up from the chip surface.
[0006] In various microelectronic devices, it is also desirable to
provide a connection between two components, which can accommodate
relative movement between the components. For example, where a
semiconductor chip is mounted to a circuit board, thermal expansion
and contraction of the chip and circuit board can cause the
contacts on the chip to move relative to the corresponding
electrically conductive features of the circuit board. This can
occur during service and can also occur during manufacturing
operations as, for example, during soldering operations on the
circuit board.
[0007] As illustrated in U.S. Pat. No. 5,518,964 ("the '964
patent"), the disclosure of which is incorporated herein by
reference, movable interconnections between elements such as a
semiconductor chip and another element can be provided by first
connecting leads between the elements and then moving the elements
away from one another through a preselected displacement so as to
bend the leads. For example, a connection component may incorporate
a dielectric body and leads extending along a bottom surface of the
dielectric body. The leads may have first or fixed ends permanently
attached to the dielectric element and connected to electrically
conductive features such as terminals, traces or the like on the
dielectric body. The leads may also have second ends releasably
attached to the dielectric body. The dielectric body, with the
leads thereon, may be juxtaposed with the chip and the second ends
of the leads may be bonded to contacts on the chip.
[0008] Following bonding, the dielectric body and chip are moved
away from one another, thereby bending the leads towards a
vertically extensive disposition. During or after movement, a
curable material such as a liquid composition may be introduced
between the elements. This may be cured to form a compliant
dielectric layer such as an elastomer or gel surrounding the leads.
The resulting packaged semiconductor chip has terminals on the
dielectric body connection component which are electrically
connected to the contacts on the chip but which can move relative
to the chip to compensate for thermal effects. The packaged chip
may be mounted to a circuit board by solder-bonding the terminals
to conductive features on the circuit board. Relative movement
between the circuit board and the chip due to thermal effects is
taken up in the moveable interconnection provided by the leads and
the compliant layer.
[0009] There is further disclosed in the '964 patent a connector
for use in making connections between two other microelectronic
elements which is fabricated by a generally similar thus far
described process. For example, in one embodiment a dielectric body
having terminals and leads as discussed above is connected to
terminal structures on a temporary sheet. The temporary sheet and
dielectric body are moved away from one another so as to bend the
leads, and a liquid material is introduced around the leads and
cured to form a compliant layer between the temporary sheet and the
dielectric body. The temporary sheet is then removed, leaving the
tip ends of the terminal structures projecting from a surface of
the compliant layer. Such a component may be used, for example, by
engaging it between two other components. For example, the terminal
structures may be engaged with a semiconductor chip, whereas the
terminals on the dielectric body may be engaged with a circuit
panel or other microelectronic component. Variation of the above
described structures are disclosed in U.S. Pat. No. 6,117,694 ("the
'694 patent") the disclosure of which is incorporated herein by
reference.
[0010] In copending U.S. patent application Ser. No. 09/237,072,
filed Jan. 25, 1999 and entitled "Compliant Semiconductor Package
With Anisotropic Conductive Material Interconnects and Methods
Therefor" ("the '072 application"), the disclosure of which is
incorporated herein by reference, there is described a
microelectronic package including a first microelectronic element
having a front face including a plurality of contacts and a second
microelectronic element including terminals accessible at a surface
thereof and a plurality of flexible leads. Each of the flexible
leads have a terminal end connected to one of the terminals and a
tip end opposite the terminal end. Each flexible lead extends away
from the second microelectronic element and is electrically
interconnected with the plurality of contacts of the first
microelectronic element. An anisotropic conductive material is
interposed between each of the tip ends of the flexible leads and
the contact associated therewith.
[0011] There is further described in the 1072 Application a method
of making a microelectronic package which includes providing a
first microelectronic element having a front face including a
plurality of contacts. An anisotropic conductive material is
provided over each one of the plurality of contacts. A second
microelectronic element is provided having terminals accessible at
a surface thereof and including a plurality of flexible leads. Each
of the leads has a terminal end attached to one of the terminals
and a tip end offset from the terminal end. The first and second
microelectronic elements are juxtaposed with one another. The tip
ends of the flexible leads and the contacts are electrically
interconnected so that the flexible leads extend away from the
second microelectronic element with the anisotropic conductive
material interposed between the tip ends and the contacts.
[0012] Akagawa, U.S. Pat. No. 5,677,576 discloses a semiconductor
package including a semiconductor chip having one surface provided
with an insulating passivation film having openings exposing
aluminum contact pads formed on the surface of the semiconductor
chip in a predetermined pattern. An anisotropic conductive sheet is
formed over the passivation film and the contact pads. The
anisotropic conductive sheet is formed of a resin containing
conductive fillers such as metallic powders whereby the application
of pressure to the film results in electrical conductivity in the
pressed direction due to the continuity of the conductive fillers
caused by the pressure. The metallic powders may be, for example,
metallic particles in the nature of resin particles coated with
nickel plated layers or the like or metallic particles such as of
gold, nickel or the like.
[0013] Electrical conductive circuit patterns are formed in a
predetermined arrangement on the exposed surface of the anisotropic
conductive sheet. The circuit patterns are formed by adhering a
metallic foil, such as a copper foil to the anisotropic conductive
sheet and etching the foil in conformity with the predetermined
circuit patterns. A photoresist film is deposited over the
anisotropic conductive sheet and the circuit patterns. The
photoresist film is provided with openings in the nature of via
holes for receiving conductive bumps to provide external
termination to the circuit patterns. By compressing the anisotropic
conductive sheet in the region overlying the contact pads,
electrical continuity to the circuit patterns is provided.
[0014] Tang, et al., U.S. Pat. No. 5,749,997 discloses another
semiconductor device using an anisotropic conductive sheet. The
device includes a semiconductor chip supporting on its major
surface a plurality of composite bumps. The bumps are formed of a
polymer body such as polyamic acid polyimide covered by a
conductive metal coating such as a composite of chrome/gold or
nickel/gold. An anisotropic conductive sheet is compressed over the
composite bumps and the surface of the semiconductor chip. A
dielectric layer having leads formed thereon such as in the
conventional tape automated bonding process is arranged overlying
the surface of the anisotropic conductive sheet. The leads may be
fully supported by the dielectric sheet, or have portions extending
within a window formed within the sheet. In either event, the
dielectric sheet is arranged with the leads having one end
overlying each of the composite bumps. Upon compression of the
anisotropic conductive sheet, the conductive particles therein will
make electrical contact with the leads and the conductive metal
coating on the composite bumps.
[0015] Chillara, U.S. Pat. No. 5,627,405 discloses an anisotropic
conductive sheet adhered to the surface of an integrated circuit
semiconductor chip which includes a plurality of input/output
terminals. The anisotropic conductive sheet is used to electrically
couple the semiconductor chip directly to terminals on a printed
circuit board, to leads of a lead frame, to traces on various
substrate structures and the like.
[0016] Notwithstanding the foregoing known use of an anisotropic
conductive sheet, there is still the need for improvements in
microelectronic packages and methods of manufacturing same. In
particular, there is the need for improvements in microelectronic
packages which eliminate metal-to-metal bonding which is known to
require the use of high temperature/pressures during
thermocompression or thermosonic bonding. There is further the need
for providing improved methods for making such microelectronic
packages which will minimize deformation of the flexible leads
thereby minimizing the potential for fatigue problems. Still
further, there is the need for such microelectronic packages and
methods for manufacturing same which provide for the use of narrow
flexible leads which enables the obtaining of very fine pitches so
as to accommodate more leads in a given space.
SUMMARY OF THE INVENTION
[0017] In accordance with one embodiment of the present invention
there is described a connection component for a microelectronic
element, the component comprising a body of dielectric material
having opposing first and second surfaces, a plurality of elongated
leads extending through the body between the first and second
surfaces, the leads having a first end accessible at the first
surface and a second end accessible at the second surface, and a
layer of anisotropic conductive material overlying the first ends
and the first surface of the body for electrical connection of the
leads to a microelectronic element.
[0018] The aforesaid connection component wherein the dielectric
material is flexible or rigid, wherein the first and second ends of
the leads are offset from each other, and further including a
plurality of contacts on the first surface in electrical contact
with the first ends of the leads, wherein the plurality of contacts
are formed from a portion of the first ends of the leads.
[0019] The anisotropic conductive material can be provided in the
form of a paste or a preformed sheet, provided on the first surface
of the body as an adhesive material.
[0020] The aforesaid connection component further including a layer
of dielectric material on the second surface of the body, further
including a plurality of conductors extending through the layer of
dielectric material in electrical contact with the second ends of
the leads, wherein the plurality of conductors comprise lined
vias.
[0021] The aforesaid connection component wherein the layer of
anisotropic conductive material is provided on the first surface of
the body and the first ends of the leads, wherein the layer of
anisotropic conductive material is provided on the second surface
of the body and the second ends of the leads, and wherein the first
ends are horizontally displaced from the second ends.
[0022] In accordance with another embodiment of the present
invention there is described a connection component for a
microelectronic element having a plurality of contact terminals
arranged in an array, the component comprising a body of polymer
material having opposing planar first and second surfaces, a
plurality of elongated leads extending through the body between the
first and second surfaces, the leads having a first end accessible
at the first surface and a second end accessible at the second
surface, a plurality of contacts on the first surface in electrical
contact with the first ends of the leads, the plurality of contacts
arranged in an array corresponding to the array of the plurality of
contact terminal pads on the microelectronic element, and a layer
of anisotropic conductive material overlying the first surface of
the body and the plurality of contacts.
[0023] The aforesaid connection component further includes a layer
of dielectric material on the second surface of the body and
includes a plurality of conductors extending through the layer of
dielectric material in electrical contact with the second ends of
the leads, wherein the layer of anisotropic conductive material is
provided on the first surface of the body and the layer of the
anisotropic conductive material is further provided on the second
surface of the body.
[0024] In accordance with another embodiment of the present
invention there is described a microelectronic package comprising,
a first microelectronic element having a front face including a
plurality of contact terminals, a connector comprising a body of
dielectric material having opposing first and second surfaces, the
first surface facing the front face of the microelectronic element,
a plurality of elongated leads extending through the body between
the first and second surfaces, the leads having a first end
accessible at the first surface and a second end accessible at the
second surface, the first ends of the leads facing in alignment
with the plurality of contact terminals on the first
microelectronic element, and a layer of anisotropic conductive
material between the front face of the microelectronic element and
the first surface of the body, the anisotropic conductive material
providing electrical continuity between the plurality of contact
terminals and the leads.
[0025] The aforesaid microelectronic package further includes a
plurality of contacts on the first surface in electrical contact
with the first ends of the leads, wherein the dielectric material
is flexible or rigid and the anisotropic conductive material is an
adhesive material.
[0026] The aforesaid microelectronic package wherein the first and
second ends of the leads are offset from each other and further
including a plurality of contacts formed from a portion of the
first ends of the leads, wherein the anisotropic conductive
material is provided in the form of a paste or a preformed
sheet.
[0027] The aforesaid microelectronic package wherein the layer of
the anisotropic conductive material is provided on the first
surface of the body and the first ends of the leads, and wherein
the layer of the anisotropic conductive material is provided on the
second surface of the body and the second ends of the leads and
further including a layer of dielectric material on the first
surface of the body, wherein the plurality of vias extend through
the layer of dielectric material in electrical contact with the
second ends of the leads.
[0028] The aforesaid microelectronic wherein the layer of
anisotropic conductive material is provided on the front face of
the first microelectronic element, wherein the first
microelectronic element comprises a semiconductor chip, further
including a second microelectronic element disposed on the second
surface of the body, and wherein the second microelectronic element
includes a plurality of second contact terminals connected to the
second ends of the leads.
[0029] The aforesaid microelectronic package further comprising a
second layer of anisotropic conductive material between the second
microelectronic element and the second surface of the body, the
second layer of anisotropic conductive material providing
electrical continuity between the second contact terminals and the
second ends, wherein the plurality of contact terminals are
arranged in an array and the first ends of the leads are arranged
in a corresponding array.
[0030] In accordance with another embodiment of the present
invention there is described a method of making a connection
component for a microelectronic element, the method comprising
providing a body of dielectric material having opposing first and
second surfaces and a plurality of elongated leads extending
therethrough between the first and second surfaces, the leads
having a first end accessible at the first surface and a second end
accessible at the second surface, and providing a layer of
anisotropic conductive material overlying the first ends and the
first surface of the body for electrical connection to a
microelectronic element.
[0031] The aforesaid method wherein the dielectric material is
flexible or rigid and further includes forming the plurality of
leads whereby the first and second ends are offset from each
other.
[0032] The aforesaid method further including providing the layer
of the anisotropic conductive material on the first surface of the
body, further including providing the layer of the anisotropic
conductive material on the second surface of the body, further
including forming a plurality of contacts on the first surface in
electrical contact with the first ends of the leads, further
including providing a layer of dielectric material on the second
surface of the body, further including providing a plurality of
conductors extending through the layer of dielectric material in
electrical contact with the second ends of the leads, and wherein
the plurality of conductors comprise lined vias.
[0033] In accordance with another embodiment of the present
invention there is described a method of making a microelectronic
package, the method comprising providing a first microelectronic
element having a front face including a plurality of first contact
terminals, forming a body of dielectric material having opposing
first and second surfaces and a plurality of elongated leads
extending therethrough between the first and second surfaces, the
leads having a first end accessible at the first surface and a
second end accessible at the second surface, arranging the first
surface of the body opposing the front face of the first
microelectronic element, providing a layer of anisotropic
conductive material between the front face of the microelectronic
element and the first surface of the body, and adhering the first
microelectronic element to the body whereby the anisotropic
conductive material provides electrical continuity between the
plurality of contact terminals and the leads.
[0034] The aforesaid method further including forming a plurality
of contacts on the first surface in electrical contact with the
first ends of the leads, the plurality of contacts arranged in
alignment with the plurality of contact terminals, further
including forming the plurality of leads whereby the first and
second ends are offset from each other, wherein the layer of
anisotropic conductive material is applied to the first surface of
the body, wherein the layer of anisotropic conductive material is
applied to the front face of the first microelectronic element.
[0035] The aforesaid method wherein the anisotropic conductive
material is further applied to the second surface of the body,
further including providing a layer of dielectric material on the
second surface of the body, further including providing a plurality
of conductors extending through the layer of dielectric material in
electrical contact with the second ends of the leads.
[0036] The aforesaid method further including a second
microelectronic element disposed on the second surface of the body,
wherein the second microelectronic element includes a plurality of
second contact terminals connected to the second ends of the leads,
further including a layer of anisotropic conductive material on the
second surface for electrically connecting the second ends of the
leads to the plurality of second contact terminals, and further
including a plurality of contacts integrally formed as a portion of
the first ends of the leads adjacent the first surface. In
accordance with another embodiment of the present invention there
is described a connector for a microelectronic element, the
connector comprising a body of dielectric material having opposing
first and second surfaces, a plurality of elongated leads extending
through the body between the first and second surfaces, the leads
having a first end at the first surface and a second end at the
second surface, and a layer of anisotropic conductive material
overlying the first surface and the first ends of such leads.
[0037] The aforesaid connector wherein the anisotropic conductive
material is applied on the first surface and wherein the
anisotropic conductive material is provided in the form of a
preformed sheet.
[0038] In accordance with another embodiment of the present
invention there is described a microelectronic package comprising,
a first microelectronic element having a front face including a
plurality of first contact terminals, a printed circuit board
having a front face including a plurality of second contact
terminals, a connector comprising a body of dielectric material
having opposing first and second surfaces, the first surface facing
the front face of the microelectronic element, a plurality of
elongated leads extending through the body between the first and
second surfaces, the leads having a first end accessible at the
first surface and a second end accessible at the second surface,
the first ends of the leads facing in alignment with the plurality
of contact terminals on the first microelectronic element, and a
first layer of anisotropic conductive material between the front
face of the microelectronic element and the first surface of the
body, the anisotropic conductive material providing electrical
continuity between the plurality of contact terminals and the
leads, and the plurality of second contact terminals electrically
connected to the second ends of the leads.
[0039] The aforesaid microelectronic package further includes a
second layer of anisotropic conductive material provided between
the front face of the printed circuit board and the second surface
of the body, the anisotropic conductive material providing
electrical continuity between the plurality of second contact
terminals and the leads.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] The above description, as well as further objects, features
and advantages of the present invention will be more fully
understood with reference to the following detailed description of
connection components with anisotropic conductive material
interconnection, when taken in conjunction with the accompanying
drawings, wherein:
[0041] FIG. 1 is a front elevational view of a connector
constructed in accordance with one embodiment of the present
invention;
[0042] FIG. 2 is a front elevational view of the connector shown in
FIG. 1 in assembled relationship with a semiconductor chip using a
layer of anisotropic conductive material;
[0043] FIG. 3 is a front elevational view of a connector
constructed in accordance with another embodiment of the, present
invention;
[0044] FIG. 4 is a front elevational view of the connector shown in
FIG. 3 in assembled relationship with a semiconductor chip using a
layer of anisotropic conductive material;
[0045] FIGS. 5-10 are sequential front elevational views showing
the steps in the process of making the connector shown in FIG.
3;
[0046] FIG. 11 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention and in assembled relationship with a semiconductor chip
using a layer of anisotropic conductive material;
[0047] FIG. 12 is a front elevational view of a connector
constructed in accordance with one embodiment of the present
invention in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material;
[0048] FIG. 13 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention and in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material;
[0049] FIG. 14 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material;
[0050] FIG. 15 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material;
[0051] FIG. 16 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material; and
[0052] FIG. 17 is a front elevational view of a connector
constructed in accordance with another embodiment of the present
invention in assembled relationship with first and second
microelectronic elements using at least one layer of an anisotropic
conductive material;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0053] In describing the preferred embodiments of the subject
matter illustrated and to be described with respect to the
drawings, specific terminology will be resorted to for the sake of
clarity. However, the invention is not intended to be limited to
the specific terms so selected, and is to be understood that each
specific term includes all technical equivalence which operate in a
similar manner to accomplish a similar purpose.
[0054] Referring now to the drawings, wherein like reference
numerals represent like elements, there is shown in FIG. 1 a
connector or connection component constructed in accordance with
one embodiment of the present invention and generally designated by
reference numeral 100. The connector 100 can be used to provide
electrical connection between two microelectronic components, for
example, a semiconductor chip, printed circuit board, circuit panel
or other microelectronic device. Where the connector 100 is
constructed from flexible or compliant materials, the connector can
accommodate relative movement between the connected microelectronic
components resulting from their thermal expansion and
contraction.
[0055] The connector 100 is generally constructed from a body 102
of dielectric material having a generally planar first surface 104
and an opposing spaced apart generally planar second surface 106. A
plurality of electrically conductive elongated leads extend through
the body 102 between the first and second surfaces 104, 106. The
leads 108 are provided with first ends 110 generally accessible at
the first surface 104 and second ends 112 generally accessible at
the second surface 106. The first and second ends of leads 108, in
accordance with one embodiment, are offset from each other in
horizontal direction, as shown in FIG. 1, to form an S-shaped
profile. However, the leads may have other shaped profiles such as
straight where the first and second ends 110, 112 are arranged
generally overlying each other in collinear alignment such as
disclosed in certain embodiments of the '964 patent. The first and
second ends 110, 112 of the leads 108 can be arranged in various
patterns and matrices which may be the same or different as will be
understood from the further description of the present
invention.
[0056] Referring now to FIG. 2, there is disclosed a
microelectronic package 114 formed by electrically connecting a
connector 100 to a microelectronic element such as a semiconductor
chip 116. The semiconductor chip 116 has an exposed face 118 which
includes a plurality of contact terminals 120 arranged in a
predetermined array. The second ends 112 of the leads 108 are
arranged in a corresponding array to the contact terminals 120. The
second ends 112 form contacts for electrical connection to the
contact terminals 120 of the semiconductor chip 116.
[0057] The connector 100 is adhered to the semiconductor chip 116
to provide electrical continuity between the contact terminals 120
and leads 108 by a layer of anisotropic conductive material 122
which in accordance with the preferred embodiment has adhesive
properties. The material 122 in describing the following example
will therefore be designated for illustration purposes as adhesive
122. The anisotropic conductive adhesive can be provided in the
form of a paste or a preformed sheet. In this regard, the layer of
anisotropic conductive adhesive 122 may be deposited onto the first
surface 104 of the body 102 or the exposed face 118 of the
semiconductor chip 116. As the anisotropic conductive adhesive 122
is electrically conductive only in the vertical direction, i.e.,
between the contact terminals 120 and first ends 110 of the leads
108, it is not required that the adhesive be stenciled in a pattern
only over the contact terminals. In this regard, the anisotropic
conductive adhesive 122, whether in paste or preformed sheet form,
is generally applied over the entire first surface 104 of the
connector 100 or the corresponding exposed face 118 of the
semiconductor chip 116. The microelectronic package 114 can be
electrically mounted to another microelectronic element such as a
circuit panel by, for example, solder balls 124 which are
attachable in electrical continuity to the second ends 112 of the
leads 108 at the second surface 106 of the connector 100 or, for
example, another layer of anisotropic conductive adhesive (not
shown) at the second surface.
[0058] As shown in FIG. 2, the connector 100 is adhered to a
semiconductor chip 116 by the adhesive properties of the
anisotropic conductive material 122 in accordance with the
preferred embodiment. However, it is not required that the
anisotropic conductive material 122 have adhesive properties. In
this regard, the periphery of the mating surfaces of the
semiconductor chip 116 and connector 100 can be provided with an
adhesive layer, such as a non-conductive adhesive, as well as at
other locations which do not interfere with the conductive path
between the ends of the leads 108 and contact terminals 120 on the
semiconductor chip 116. In addition, other techniques can be used,
for example, mechanical clamping, encapsulation of the connector
100 and semiconductor chip 116, and the like.
[0059] Referring to FIGS. 3 and 4, there is disclosed another
embodiment of a connector 100 and microelectronic package 114 in
accordance with the preferred embodiment of the present invention.
As shown in FIG. 3, the connector 100 is formed with a plurality of
individual electrically conductive contacts 126. The contacts 126
are formed in the first surface 104 of the body 102 in alignment
with the first ends 110 of the leads 108. As will be described
hereinafter, the first ends 110 of the leads 108 are attached to
the contacts 126 to provide electrical continuity.
[0060] In other features, the connectors shown in FIGS. 1 and 3 are
generally of similar construction. The contacts 126 are
electrically connected to the contact terminals 120 of the
semiconductor chip 116 using the anisotropic conductive adhesive
122 as thus far described with respect to the microelectronic
package 114 in FIG. 2. It can therefore be appreciated that
connectors 100 and microelectronic packages 114 can be constructed
either with or without separate contacts 126.
[0061] Turning now to FIGS. 5-10, there will be described a method
of making a connector 100 in accordance with the preferred
embodiment of the present invention. A planar substrate 128 which
functions as a mandrill is provided with a generally planar surface
130. The substrate 128 can be formed from a variety of rigid
materials such as borosilicate glass, aluminum and the like. A
layer of releasable adhesive 132, such as, for example a heat or UV
releasable adhesive, is applied over the surface 130 of the
substrate 128. A sacrificial sheet of an electrically conductive
material 134, such as aluminum foil, is laminated onto the adhesive
layer 132. It being contemplated that other materials for the
sacrificial layer 134 such as chrome, nickel, alloys or
combinations thereof, or other electrically conductive metals which
are capable of being selectively etched with respect to the metal
of the copper layer 136, can be provided on the adhesive layer 132.
By any suitable means, a copper layer 136 is formed on the aluminum
layer 134. The copper layer 136 may be formed by known processes
such as lamination, sputtering or electroless plating followed by
electroplating.
[0062] The exposed copper layer 136 is circuitized to form the
desired features of the connector 100 such as leads 108, circuit
traces, bonding pads, solder ball pads and the like. In this
regard, the first ends 110 of the leads 108 can function as bonding
pads while the second ends 112 of the leads can function as solder
ball pads. The first ends 110 of the leads 108 can be arranged in
an array corresponding to the array of the contact terminals 120 on
the semiconductor chip 116. In one embodiment, the first ends 110
can be arranged in an area array, i.e., an array of features
arranged in a substantially regular pattern with a substantially
uniform density of features throughout the horizontal extent of the
pattern. Similarly, the second ends 112 of the leads 108 can be
arranged in an array corresponding to the array of the contact
terminals of the microelectronic element to which the second ends
are to be electrically attached via the solder balls 124. The leads
108, as well as the other circuit features can be formed from the
copper layer 136, by way of one example only, by conventional
photographic processes. It is to be understood that the leads 108
may be fabricated from essentially any conductive material, but
most typically being formed from conductive metals such as copper,
copper alloys, gold, gold alloys and composites including layers of
these metals. The leads 108 are made peelable from the aluminum
layer 134 using any one of a number of conventional processes as to
be described hereinafter.
[0063] A fusible metal such as a tin/lead alloy is selectively
plated onto the first ends 110 of the leads 108 to form a plurality
of conductive contacts 138. If desired, the contacts 138 may be
overplated with a non-oxidizable metal layer, for example, gold.
The contacts 138 are bonded to a temporary support 140 such as a
sheet of solder-wettable metal such as copper, copper alloys and
the like. The resulting structure, as shown in FIG. 7, is subject
to vertical expansion through, for example, separation of vacuum
platens or pressurized injection of an elastomeric encapsulant.
[0064] Further in this regard, the temporary support 140 and the
substrate 128 are moved vertically away from one another through a
predetermined displacement, and horizontally relative to one
another, so that the first end 112 of the lead 108 moves
horizontally toward and vertically away from the first end 110 of
the lead. To this end, the temporary support 140 may be engaged
with a lower platen while the substrate 128 may be engaged with an
upper platen. The engagement may be maintained by applying a vacuum
through each of the platens to hold the substrate 128 and temporary
support 140 firmly in engagement with the platens as the platens
are moved away from one another. The relative movement of the lead
ends 110, 112 bend the main portion of the lead 108. Continued
vertical and horizontal movement of the temporary support 140 and
substrate 128 causes the lead 108 to buckle and form a generally
S-shaped configuration as shown in FIG. 8. Horizontal movement is
preferred, but optional, as you can still produce the S-shape of
the leads if one starts with the leads 108 which are curved in the
horizontal plane before the vertical displacement.
[0065] During or after movement of the temporary support 140 from
the substrate 128, a flowable material such as a liquid composition
142 capable of curing to form a compliant dielectric material such
as a gel or an elastomer is injected between the temporary support
140 and aluminum layer 134. For example, the curable liquid
composition 142 may be a silicone or epoxy composition which forms
a compliant flexible body. On the other hand, it is also
contemplated that the curable liquid composition 142 may be in the
nature of a rigid polymer material if desired. If the liquid
composition 142 is injected during the movement step, the pressure
of the flowable composition will help to force the temporary
support 140 and substrate 128 away from each other, either with or
without assistance from the platens. The liquid composition 142 is
then cured to form a compliant dielectric layer having a first
surface 144 formed in contact with the temporary support 140 and a
second surface 146 formed in contact with the sacrificial aluminum
layer 134.
[0066] As shown in FIG. 9, the temporary support 140 is removed by,
for example, reflowing the fusible metal forming the contacts 138.
The temporary support 140 may be removed by other techniques such
as ablation, plasma or wet chemical etching. However, the latter
methods will require that the temporary support 140 be constructed
of a material whose etchant will not attack the remaining structure
of the connector 100, such as the contacts 138, leads 108, etc. The
resulting structure as shown in FIG. 9 is further released from the
temporary support 128 by heating or application of UV radiation to
release the adhesive layer 132.
[0067] The sacrificial aluminum layer 134 is etched away using a
suitable etchant, leaving the second ends 112 forming solder ball
pads 148 exposed on the second surface 106. Conductive metal such
as copper, copper gold alloy and the like may be plated onto the
exposed surface of the solder ball pads 148 if desired to enhance
bonding of the solder balls 124. Residual fusible material on the
contacts 138 can be etched away when etching the aluminum
sacrificial layer 134 using a suitable etchant such as hydrochloric
acid. The resulting connector 100 is illustrated in FIG. 3 as
previously described. It is to be understood that the contacts 138
are not an essential component of the connector 100. In this
regard, the contacts 138 may be omitted during the manufacturing
process to produce the connector 100 as shown in FIG. 1. In this
regard, the first ends 110 of the leads 108 adjacent the first
surface 104 of the body 102 will function as contacts for joining
with the contact terminals 120 of the semiconductor chip 116. The
first ends 110 of the leads 108 can be joined to the temporary
support 140 by stenciling fusible material thereon, and later
removing same by chemical etching.
[0068] The anisotropic conductive adhesive 122 is provided as a
continuous preformed sheet or layer in the form of a paste which is
provided over substantially all of the contacts 126, 138 and
exposed first surface of the body 102. The anisotropic conductive
adhesive 122 can alternatively be applied over exposed face 118 of
the semiconductor chip 116. The anisotropic conductive adhesive 122
is preferably a polymeric resin having a matrix of conductive
particles therein, such as the conductive particles as shown in
FIG. 2. The anisotropic conductive adhesive 122, need not be
flexible and/or compliant such as preferred with respect to the
composition 142 forming the body 102. In this regard, the
anisotropic conductive adhesive 122 may be formed in the nature of
a rigid layer.
[0069] By the application of pressure, the anisotropic conductive
adhesive 122 becomes conductive in the pressed direction due to the
continuity of the conductive material, for example, the metallic
powders, caused by the pressure. The conductive particles may
include metallic powders such as nickel or gold. The metallic
powders may also be, for example, metallic particles consisting of
resin particles coated with Ni-plated layers or the like, or solid
metallic particles consisting of gold, nickel or the like. The
particles may, for example, be in the size range of from about 3 to
15 microns, preferably as solid balls of nickel or gold. One
suitable anisotropic conductive material includes the material sold
under the tradename "FC-262B" by the Hitachi Chemical Company. The
exact composition and characteristics of the FC-262B anisotropic
conductive material are set forth in more detail in the chemical
data sheet for the FC-262B material, which is incorporated herein
by reference.
[0070] There are a number of advantages associated with using an
anisotropic conductive adhesive 122 for electrically connecting the
flexible leads 108 and chip contacts 120. First, there is no
metal-to-metal ("intermetallic") bonding requiring the use of high
temperatures/pressures during thermocompression or thermosonic
bonding. In addition, when using an anisotropic conductive adhesive
122 to attach the leads 108 to the contacts 120, lower temperatures
and pressures will be required to make the connections. The lower
temperatures and pressures will minimize stresses on the connector
100 which, in turn, will minimize the potential for the fatigue
related problems. Another benefit of bonding at lower temperatures
and pressures is that finer flexible leads 108 may be used which
will enable even finer pitches to be obtained (i.e., more leads in
the same space).
[0071] Referring now to FIG. 11, there is shown a modified form of
the connector 100 in accordance with another embodiment of the
present invention. The connector 160 includes a layer 162 generally
in the nature of a single layer of dielectric material such as a
polyimide. Although the layer 162 is illustrated as including only
a single layer of dielectric material, it should be appreciated
that it can include other features such as multiple dielectric
layers, electrically conductive traces extending in horizontal
directions along the surfaces of the body or within the body,
electrically conductive ground planes or power planes also
extending in a horizontal direction on a surface of the body within
the body, as well as electrically conductive vias connecting these
features with one another. In this regard, a plurality of vias 164,
lined with an electrically conductive material, such as copper,
extend through the layer 162 into electrical connection with the
leads 108.
[0072] It is contemplated that the first and second ends 110, 112
of the leads 108 can be redistributed on the first and second
surfaces 104, 106 of the connector 100, 160. Redistribution can be
achieved, by way of example, using conductive traces which extend
to the desired location for redistributing the pattern or matrix of
the first and second ends of the leads 108. The conductive traces
(not shown) can be preformed on the dielectric body 102 using
conventional techniques, for example, a patterned photomask
followed by conductive metal deposition, e.g., sputtering, followed
by electroless and/or electroplating. Thus, the solder balls 124 as
shown in FIG. 11 can be at any location desired so as to mate with
conductive terminals on a microelectronic element such as a printed
circuit board or other semiconductor chip and the like. The
conductive traces can be electrically connected to the vias.
[0073] The connector 160 can be made in accordance with the methods
as thus far described, wherein the dielectric layer 162 is used in
place of the sacrificial aluminum layer 134. In addition, the
dielectric layer 162 may be applied to the second surface 106 of
the body 102 after manufacture, as well as being an integral part
of the manufacturing processes as disclosed in the '694 patent, the
disclosure of which is incorporated herein by reference.
[0074] As previously described, the leads 108 are made peelable
from the sacrificial aluminum layer 134 or dielectric layer 162
using a variety of techniques. For example, prior to the expansion
step, i.e., between FIGS. 7 and 8, the sacrificial aluminum layer
134 can be subjected to a selective etchant process by exposing
portions of the aluminum layer to a liquid etch solution which
attacks the layer so as to undercut the leads 108 and remove the
sacrificial aluminum layer from beneath the etch resistant leads at
all locations except at their second ends 112. At the second ends
112, most, but not all of the sacrificial aluminum layer is
removed. This method of forming peelable leads is further disclosed
in the '964 patent which is incorporated herein by reference. Other
methods for forming peelable leads which can be used in practicing
the present invention are disclosed in commonly assigned U.S. Pat.
No. 5,763,941, entitled, "Connection Component With Releasable
Leads"; U.S. patent application Ser. No. 09/549,638 entitled,
"Components With Releasable Leads", filed on Apr. 14, 2000; U.S.
patent application Ser. No. 09/200,100 entitled "Connection
Component With Peelable Leads", filed on Nov. 25, 1998; and U.S.
patent application Ser. No. 09/566,273 entitled "Components With
Releasable Leads", filed on May 5, 2000, the disclosures of which
are incorporated herein by reference.
[0075] Referring to FIG. 12, there is shown a microelectronic
package generally designated by reference numeral 170. The
microelectronic package 170 is provided with a pair of
microelectronic elements 172, 174. As previously noted, the
microelectronic elements 172, 174 may include, for example,
semiconductor chips, printed circuit boards, circuit panels, other
microelectronic devices and the like. The microelectronic element
172 is electrically connected to the leads 108 using a layer of
conductive anisotropic material 122 preferably having adhesive
properties. The face of the microelectronic element 172 can be
provided with a plurality of contact terminals (not shown) arranged
in the appropriate matrix or array.
[0076] A second microelectronic element 174 is similarly
electrically mounted for electrical connection to the leads 108 on
the other surface of the connector 100 using a layer of anisotropic
conductive material 122. Solder balls 124 may be provided in
contact with the ends of the leads 108 which are exposed on either
side of the microelectronic element 174. It is preferred that the
height of the solder balls 124 be larger than the combined height
of the anisotropic conductive material 122 and microelectronic
element 174. This enables the microelectronic package 170 to be
bonded to another microelectronic element such as a printed circuit
board via the solder balls 124.
[0077] Referring to FIG. 13, there is disclosed a microelectronic
package 176 constructed in accordance with another embodiment of
the present invention. In this regard, the ends of the leads 108
are redistributed to allow the microelectronic element 174 to be
wire bonded via the conductive wires 178. The microelectronic
element 174 and surrounding bond wires 178 are encapsulated by, for
example, overmolding with a polymer material, which may be rigid or
flexible. Preferably, the encapsulant is a dielectric material.
[0078] Turning to FIG. 14, there is disclosed another embodiment of
a microelectronic package 182. The microelectronic element 172 is
in the nature of a bump chip having a plurality of contact
terminals 184. The contact terminals 184 are in electrical
continuity with the free ends of the leads 108 via the anisotropic
conductive material 122. The microelectronic element 174 via the
anisotropic conductive material 122 is in electrical continuity
with redistributed leads on the surface of a flexible polyimide
layer 185. The polyimide layer 185 is provided with a plurality of
plated through vias 164 for electrical connection to the ends of
the leads 108. The solder balls 124 are in direct electrical
connection to the vias 164 which provide continuity to the ends of
the leads 104.
[0079] Referring to FIG. 15, there is shown another embodiment of a
microelectronic package 186. The package 186 is provided with a
dielectric polyimide layer 185 which is rigid and extends beyond
the periphery of the connector 100, and may include a plurality of
plated through vias 164. The resulting package is encapsulated with
an encapsulant 188 similar to the encapsulant 180 as previously
described. The larger dielectric layer 185 allows for the
arrangement of a greater number of solder balls 124 for
interconnection to another microelectronic element.
[0080] Turning to FIG. 16, there is shown a microelectronic package
190 constructed in accordance with another embodiment of the
present invention. The microelectronic element 174 is connected to
the connector 100 via a second connector 192 comprising a plurality
of leads 194 embedded in a compliant layer 196. The leads 194 may
be in alignment with for direct electrical connection to the ends
of the leads 108 as shown in the left hand portion of the connector
192. As also shown, the ends of the leads 108 may be redistributed
for connection to the ends of the leads 194 as shown in the right
hand portion of the connector 192. The second connector 192 can be
constructed in a similar manner as connector 100. However, it is to
be understood that other methods of forming the connector 192 can
be used. In addition, a layer of anisotropic conductive material
may be sandwiched between the first and second connectors 100,
192.
[0081] Turning to FIG. 17, there is shown a microelectronic package
196 constructed in accordance with another embodiment of the
present invention. As shown, the microelectronic element 174 is in
the nature of a bump chip or flip chip having a plurality of
conductive bumps 198 thereon. The ends of the leads 108 on the
surface of the connector 100 may be redistributed if necessary into
an array corresponding to an array of the bumps 198
[0082] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
application of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *