U.S. patent application number 11/215884 was filed with the patent office on 2005-12-29 for electronic device package.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Fuller, Jason L., Hall, Frank L., Jiang, Tongbi.
Application Number | 20050287706 11/215884 |
Document ID | / |
Family ID | 31977198 |
Filed Date | 2005-12-29 |
United States Patent
Application |
20050287706 |
Kind Code |
A1 |
Fuller, Jason L. ; et
al. |
December 29, 2005 |
Electronic device package
Abstract
An electronic device package is described that includes a
non-metal die attached adhesive. The die attach is positioned in
discrete positions on a surface to which the die will be fixed. The
die is placed on the discrete die attach. The die attach, in an
embodiment, is an epoxy resin or other material that is cured.
After curing, the die is electrically connected to an external
circuit. The volume between the die and surface is filled with an
underfill. In an embodiment, underfill cross-links with the die
attach.
Inventors: |
Fuller, Jason L.; (Meridian,
ID) ; Hall, Frank L.; (Boise, ID) ; Jiang,
Tongbi; (Boise, ID) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH
1600 TCF TOWER
121 SOUTH EIGHT STREET
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Micron Technology, Inc.
|
Family ID: |
31977198 |
Appl. No.: |
11/215884 |
Filed: |
August 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11215884 |
Aug 31, 2005 |
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10929610 |
Aug 30, 2004 |
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10929610 |
Aug 30, 2004 |
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10233262 |
Aug 29, 2002 |
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Current U.S.
Class: |
438/108 ;
257/E21.503; 257/E21.505; 257/E21.705; 257/E23.004; 257/E23.024;
257/E23.069; 257/E25.013; 438/118 |
Current CPC
Class: |
H01L 2224/2919 20130101;
H01L 2225/06586 20130101; H01L 2924/00014 20130101; H01L 2924/01039
20130101; H01L 25/50 20130101; H01L 2224/73265 20130101; H01L
2224/8314 20130101; H01L 2924/01047 20130101; H01L 24/83 20130101;
H01L 2224/73257 20130101; H01L 2224/8385 20130101; H01L 2924/09701
20130101; H01L 2924/12044 20130101; H01L 2224/73215 20130101; H01L
2224/0401 20130101; H01L 2924/01013 20130101; H01L 2224/48463
20130101; H01L 2224/83192 20130101; H01L 23/49816 20130101; H01L
24/29 20130101; H01L 2924/01029 20130101; H01L 2924/014 20130101;
H01L 24/85 20130101; H01L 2224/73215 20130101; H01L 2224/73265
20130101; H01L 2924/01014 20130101; H01L 2924/07802 20130101; H01L
2924/12044 20130101; H01L 2225/06555 20130101; H01L 2924/15311
20130101; H01L 2924/181 20130101; H01L 2224/48227 20130101; H01L
2924/01087 20130101; H01L 2924/0665 20130101; H01L 2924/181
20130101; H01L 2924/00014 20130101; H01L 2224/16 20130101; H01L
2924/15311 20130101; H01L 2924/19041 20130101; H01L 2224/48091
20130101; H01L 2224/32145 20130101; H01L 2224/73203 20130101; H01L
2225/06582 20130101; H01L 2924/00014 20130101; H01L 25/0657
20130101; H01L 2924/01005 20130101; H01L 2224/83192 20130101; H01L
2924/01015 20130101; H01L 2924/15311 20130101; H01L 2924/01079
20130101; H01L 2224/32225 20130101; H01L 23/4951 20130101; H01L
23/3128 20130101; H01L 2924/19043 20130101; H01L 2224/2919
20130101; H01L 2225/06575 20130101; H01L 2924/0665 20130101; H01L
2924/01006 20130101; H01L 2224/48091 20130101; H01L 2224/83194
20130101; H01L 24/32 20130101; H01L 2924/01027 20130101; H01L
2224/4824 20130101; H01L 23/13 20130101; H01L 2224/92247 20130101;
H01L 2224/06136 20130101; H01L 2224/4824 20130101; H01L 2225/0651
20130101; H01L 2224/85 20130101; H01L 2924/01033 20130101; H01L
2924/19042 20130101; H01L 2924/01032 20130101; H01L 2224/06135
20130101; H01L 2924/01082 20130101; H01L 24/48 20130101; H01L 24/27
20130101; H01L 2224/73265 20130101; H01L 2224/92247 20130101; H01L
2225/06517 20130101; H01L 2924/14 20130101; H01L 2224/73204
20130101; H01L 2224/73265 20130101; H01L 2224/92247 20130101; H01L
2924/0105 20130101; H01L 2924/15311 20130101; H01L 24/73 20130101;
H01L 21/563 20130101; H01L 2224/73265 20130101; H01L 2224/32225
20130101; H01L 2224/48227 20130101; H01L 2224/48227 20130101; H01L
2224/48227 20130101; H01L 2224/32225 20130101; H01L 2224/73265
20130101; H01L 2924/00 20130101; H01L 2924/00 20130101; H01L
2224/32225 20130101; H01L 2924/0665 20130101; H01L 2924/00012
20130101; H01L 2224/48227 20130101; H01L 2924/00 20130101; H01L
2224/48227 20130101; H01L 2224/32145 20130101; H01L 2924/00
20130101; H01L 2224/73265 20130101; H01L 2924/00012 20130101; H01L
2924/00 20130101; H01L 2224/48227 20130101; H01L 2924/00 20130101;
H01L 2224/32225 20130101; H01L 2224/32225 20130101; H01L 2224/4824
20130101; H01L 2224/32145 20130101; H01L 2224/73265 20130101; H01L
2924/00012 20130101; H01L 2224/32225 20130101; H01L 2224/48227
20130101; H01L 2224/4824 20130101; H01L 2224/73215 20130101; H01L
2224/32145 20130101; H01L 2224/48463 20130101; H01L 2224/32225
20130101; H01L 2224/4824 20130101; H01L 2924/00 20130101; H01L
2924/00 20130101; H01L 2924/00012 20130101; H01L 2224/45099
20130101; H01L 2224/73265 20130101; H01L 2224/32225 20130101; H01L
2224/48227 20130101; H01L 2924/00 20130101; H01L 2924/00012
20130101; H01L 2224/48227 20130101; H01L 2224/78 20130101; H01L
2924/00 20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
438/108 ;
438/118 |
International
Class: |
H01L 021/44; H01L
021/48 |
Claims
What is claimed is:
1. A method for attaching a die to a substrate, comprising: placing
a plurality of adhesive bumps on the substrate; placing the die on
the adhesive bumps; and curing the adhesive bumps.
2. The method of claim 1, wherein placing the adhesive bumps
includes placing an epoxy resin on the substrate.
3. The method of claim 2, wherein placing the epoxy resin includes
placing a material including formed from 1,6-Bis(2,3-epoxypropoxy)
naphthalene; methyl hexahydrophthalic anhydride; silica; and carbon
black on the substrate.
4. The method of claim 1, wherein curing the adhesive bumps
includes fixing the die to the substrate.
5. The method of claim 4, wherein placing the die on the adhesive
bumps occurs before curing the adhesive bumps.
6. The method of claim 4, wherein placing the adhesive bumps
includes placing adhesive bumps on both sides of a slot in the
substrate.
7. A method for attaching a die to a substrate, comprising: placing
a plurality of adhesive bumps on the substrate; placing the die on
the adhesive bumps; curing the adhesive bumps; and filling a gap
between the substrate and die with an underfill material.
8. The method of claim 7, wherein filling the gap includes filling
the gap with an epoxy resin.
9. The method of claim 7, wherein placing adhesive bumps includes
placing an epoxy resin on the substrate.
10. The method of claim 9, wherein placing the epoxy resin includes
depositing the epoxy resin in discrete units on the substrate.
11. The method of claim 10, wherein depositing the epoxy resin
includes covering less than 25% of the surface area of the
substrate with epoxy resin.
12. The method of claim 7, wherein placing the die includes
contacting the adhesive bumps to less than 30% of the surface area
of the die.
13. The method of claim 7, wherein placing the die includes
contacting the adhesive bumps to less than 50% of the surface area
of the die.
14. The method of claim 7, wherein curing the adhesive bumps occurs
before filling the gap.
15. The method of claim 7, wherein filling the gap includes
depositing underfill on the substrate before placing the die on the
adhesive bumps.
16. A method for attaching a die to a substrate, comprising:
placing a plurality of adhesive bumps on the substrate; placing the
die on the adhesive bumps; curing the adhesive bumps; filling a gap
between the substrate and die with an underfill material; and
cross-linking the underfill material to the adhesive bumps.
17. The method of claim 16, wherein cross-linking includes
providing a continuous cured epoxy layer between the die and the
substrate.
18. The method of claim 16, wherein placing a plurality of adhesive
bumps includes placing an epoxy resin on the substrate.
19. The method of claim 16, wherein filling a gap includes
underfilling the die with an epoxy resin.
20. The method of claim 19, wherein underfilling the die includes
filling the void between the die and substrate by capillary
action.
21. The method of claim 16, wherein placing adhesive bumps includes
placing a material that includes 1,6-Bis(2,3-epoxypropoxy)
naphthalene; methyl hexahydrophthalic anhydride; silica; and carbon
black on the substrate.
22. A method for attaching a die to a substrate, comprising:
placing a plurality of adhesive bumps on the substrate; placing the
die on the adhesive bumps; filling a gap between the substrate and
die with an underfill material; and cross-linking the underfill
material to the adhesive bumps.
23. The method of claim 22, wherein cross-linking includes
providing a continuous cured epoxy layer between the die and the
substrate.
24. The method of claim 22, wherein placing a plurality of adhesive
bumps includes placing an epoxy resin on the substrate.
25. The method of claim 22, wherein filling a gap includes
underfilling the die with an epoxy resin.
26. The method of claim 25, wherein cross-linking includes cross
linking the epoxy resin adhesive bumps with the epoxy resin
underfill.
27. The method of claim 26, wherein underfilling the die includes
filling the void between the die and substrate by capillary
action.
28. The method of claim 27, wherein placing adhesive bumps includes
placing a material that includes 1,6-Bis(2,3-epoxypropoxy)
naphthalene; methyl hexahydrophthalic anhydride; silica; and carbon
black on the substrate.
29. A method for attaching a die to a substrate, comprising:
placing a plurality of adhesive bumps on the substrate; placing the
die on the adhesive bumps; electrically connecting the die to the
substrate; filling a gap between the substrate and die with an
underfill material; and cross-linking the underfill material to the
adhesive bumps.
30. The method of claim 29, wherein electrically connecting
includes wire bonding the die to the substrate.
31. The method of claim 30, wherein electrically connecting
includes extending a wire bond through a clot in the substrate.
32. The method of claim 29, wherein placing the die on the adhesive
bumps includes curing the adhesive bumps.
33. The method of claim 29, wherein placing the adhesive bumps on
the substrate includes placing a high viscosity epoxy resin on the
substrate.
34. The method of claim 29, wherein placing the die on the adhesive
bumps includes holding the die spaced from the substrate.
35. A method for attaching a die to a substrate, comprising:
placing a plurality of adhesive bumps on the substrate; placing the
die on the adhesive bumps; curing the adhesive bumps; electrically
connecting the die to the substrate; filling a gap between the
substrate and die with an underfill material; cross-linking the
underfill material to the adhesive bumps; and encapsulating the die
in a molding material.
36. The method of claim 34, wherein the substrate is further
connected to a further substrate.
Description
[0001] This application is a Divisional of U.S. application Ser.
No. 10/929,610 filed on Aug. 30, 2004, which is a Divisional of
U.S. application Ser. No. 10/233,262, filed Aug. 29, 2002. These
applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to packaging, and more particularly
to packaging electronic devices.
BACKGROUND OF THE INVENTION
[0003] Electronic devices, such as integrated circuit dice, are
packaged using a variety of materials. For example, plastics,
ceramics, and glasses are used as substrates and die carriers,
while adhesives and polymers are used to attach dice to substrates
or other die carriers. Patent Application Publication No. U.S.
2002/0025602A1 describes a microelectronic assembly with a
pre-disposed fill material and associated method of manufacture and
is hereby incorporated by reference. This publication describes
attaching a microelectronic die to a substrate using solder balls
that fix to solder ball pads to form solder joints. Thus, a metal
is used to connect the die and substrate. Underfill fills the void
between the die and substrate adjacent the solder balls. Underfill
improves the structural integrity of a die/substrate assembly. For
example, underfill reduces the effects of global thermal expansion
mismatch between the die and substrate. That is, underfill reduces
the stress and strain on the solder joints. Underfill further
protects the chip from moisture, ionic contaminants, and mechanical
stresses such as twist, pull, shear, and shock/vibration.
Accordingly, the bond between the die and substrate includes at
least two materials.
[0004] U.S. Pat. No. 5,679,977 and U.S. Pat. No. 5,852,326 teach
that attaching a die to a substrate using a material having a low
Young's modulus produces fewer package failures than attaching a
die to a substrate using a material having a high Young's modulus,
and that improved packaging reliability is obtained by selecting a
die attachment material having a very low Young's modulus.
[0005] U.S. Pat. No. 6,426,564 describes a system for attaching a
plurality of solder balls to an electronic device that includes a
heat-resistant tape having a first side comprising a plurality of
recesses. The first side of the tape may form an adhesive surface.
The recesses are located for registration with a plurality of
connection points on the electronic device. The recesses are each
adapted to receive and retain a solder ball therein. After placing
a solder ball within two or more of the recesses, the first side of
the tape may be adhered to the electronic device with the solder
balls retained therein. Heating of the solder balls causes them to
reflow and adhere to the connection points. After cooling, the tape
may be removed, wherein the solder balls remain bonded to the
connection points, forming a Ball Grid Array (BGA).
SUMMARY OF THE INVENTION
[0006] The above mentioned problems with electronic device packages
and other problems are addressed by the present invention and will
be understood by reading and studying the following specification.
An electronic device package is described that includes a die
attachment material that is adapted to attach a die to a
substrate.
[0007] The subject matter of the present application provides, in
an embodiment, an electronic package including a substrate and a
plurality of adhesive bumps on the substrate. A die is received on
the adhesive bumps. The adhesive bumps fix the die to the
substrate. The plurality of adhesive bumps stand upright from a
surface of the substrate and separate the die from the substrate.
In an embodiment, the plurality of adhesive bumps includes a high
viscosity adhesive material. In an embodiment, the plurality of
adhesive bumps includes an epoxy resin. In an embodiment, the
plurality of adhesive bumps contact a small fraction of the die
surface area.
[0008] The subject matter of the present invention provides, in an
embodiment, a substrate, a plurality of adhesive bumps on the
substrate, and a die on the plurality of adhesive bumps and spaced
from the substrate. An underfill material in positioned in the
space between the substrate and the die. In an embodiment, the
underfill material includes a epoxy encapsulant. In an embodiment,
the underfill material has a lower viscosity than the plurality of
adhesive bumps. In an embodiment, the underfill material includes a
Young's modulus that is an order of magnitude greater than the
Young's modulus of the plurality of adhesive bumps. In an
embodiment, the underfill material cross-links to the plurality of
adhesive bumps. In an embodiment, the underfill material connects
to the plurality of adhesive bumps to form a continuous material
layer between the substrate and the die. In an embodiment, the
underfill material includes 1,6-Bis(2,3-epoxypropoxy) naphthalene;
methyl hexahydrophthalic anhydride; silica; and carbon black.
[0009] The present subject matter invention also provides, in
embodiments, methods of fabricating an electronic package as
described above. In an embodiment, the method includes placing a
plurality of adhesive bumps on the substrate, placing the die on
the adhesive bumps, and curing the adhesive bumps. In an
embodiment, placing the die on the adhesive bumps occurs before
curing the adhesive bumps. In an embodiment, the method includes
filling a gap between the substrate and die with an underfill
material. In an embodiment, the method includes placing the epoxy
resin includes depositing the epoxy resin in discrete units on the
substrate. In an embodiment, depositing the epoxy resin includes
covering less than 25% of the surface area of the substrate with
epoxy resin. In an embodiment, the method includes cross-linking
the underfill material to the adhesive bumps. In an embodiment, the
method includes electrically connecting the die to the substrate.
In an embodiment, the method includes encapsulating the die in a
molding material.
[0010] These and other embodiments, aspects, advantages, and
features of the present invention will be set forth in part in the
description which follows, and in part will become apparent to
those skilled in the art by reference to the following description
of the invention and referenced drawings or by practice of the
invention. The aspects, advantages, and features of the invention
are realized and attained by means of the instrumentalities,
procedures, and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is a cross-sectional view of an electronic package
according to the present invention;
[0012] FIG. 1B is a cross-sectional view of an electronic package
according to the present invention;
[0013] FIG. 1C is a cross-sectional view of an electronic package
according to the present invention;
[0014] FIG. 1D is a cross-sectional view of an electronic package
according to the present invention;
[0015] FIG. 1E is a cross-sectional view of an electronic package
according to the present invention;
[0016] FIG. 1F is a plan of an electronic package according to the
present invention;
[0017] FIG. 2A is cross sectional view another embodiment of an
electronic package of the present invention;
[0018] FIG. 2B is cross sectional view another embodiment of an
electronic package of the present invention;
[0019] FIG. 2C is cross sectional view another embodiment of an
electronic package of the present invention;
[0020] FIG. 3 is a block diagram of one embodiment of an electronic
system including a die packaged according to the present invention;
and
[0021] FIG. 4 is a further embodiment of an electronic package
according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] In the following detailed description of the embodiments,
reference is made to the accompanying drawings which form a part
hereof, and in which is shown by way of illustration specific
embodiments in which the inventions may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention, and it is to be
understood that other embodiments may be utilized and that process,
electrical or mechanical changes may be made without departing from
the scope of the present invention. The following detailed
description is, therefore, not to be taken in a limiting sense, and
the scope of the present invention is defined only by the appended
claims and their equivalents.
[0023] FIG. 1A shows an embodiment of electronic package 100 during
fabrication according to the present invention. Electronic package
100 includes a substrate 101 that is adapted to support a die and
has an upper surface 102 and a lower surface 103. A slot 104 is
positioned in the substrate 101 and extends from upper surface 102
to lower surface 103. A plurality of adhesive bumps 105 are
patterned on substrate upper surface 102. Adhesive bumps 105 are
volumes of adhesive material that stand upraised from substrate
upper surface 102. Adhesive bumps 105 are adapted to fix a die to
the substrate. At least one bump 105 is deposited on both sides of
slot 104. In an embodiment, at least two bumps 105 are positioned
on each side of slot 104. In an embodiment, bump(s) 105 are pillars
or columns that are upright from the substrate upper surface.
[0024] In the present invention, substrate 101 is not limited to a
particular material or a particular structure. Substrate 101, in an
embodiment, is fabricated from a flexible material. Substrate 101,
in an embodiment, is fabricated from an inflexible (rigid)
material. In an embodiment, substrate 101 is fabricated from a
chemically inert material. Exemplary embodiments of substrates
suitable for use in connection with the present invention include
single metal layer substrates, multi-metal layer substrates,
printed circuit board (PCB) substrates, such as organic, glass
fiber reinforced and ceramic substrates, and flexible substrates.
Other exemplary embodiments of substrates suitable for use in
connection with the present invention include multilayer
substrates, such as multilayer BT epoxy substrates having signal,
power, and ground layers.
[0025] Adhesive bumps 105 are formed of an epoxy resin. In an
embodiment, adhesive bumps 105 are formed from a high viscosity
material. In an embodiment, adhesive bumps 105 have a viscosity of
greater than about 100,000 cps (at room temp, using 5 rpm spindle
speed). In an embodiment, adhesive bumps 105 have a viscosity of
greater than about 250,000 cps. In an embodiment, the viscosity is
in the range of 100,000-500,000 cps (at room temp, using 5 rpm
spindle speed). The thixotropic index (defined as viscosity at 0.5
rpm divided by viscosity at 5 rpm) is greater than about 4. In an
embodiment, the thixotropic index is in range of 4-7. Examples of
epoxy resins include those epoxy resins formed from
1,6-Bis(2,3-epoxypropoxy) naphthalene; methyl hexahydrophthalic
anhydride; silica; and carbon black. The adhesive bumps 105 are die
attach material that provide a structure for mechanically securing
die 110 to substrate 101. Preferably, die attach material, e.g.,
adhesive bumps 105, maintains contact with both die 110 and
substrate 101 during and after further processing of the package
100. One example of further processing is a solder reflow process,
which in one embodiment occurs at between about 200 degrees
Centigrade and about 280 degrees Centigrade. To maintain contact
with die 110, die attach material 105 should not peel away from the
surface of substrate 110 and should not deform during the solder
reflow process. According to the present invention, a die attach
material having a high Young's modulus provides a more reliable
structure than a die attach material having a low Young's modulus.
According to the present invention, die attach material 105 having
a high Young's modulus provides a more reliable structure than a
die attach material having a low Young's modulus. In an embodiment,
die attach material 105 has a low coefficient of thermal expansion.
For example, in one embodiment, die attach material 209 has a
.alpha..sub.2 of less than about 400 (four-hundred) ppm (parts per
million)/.degree. C. .alpha..sub.2 is defined as coefficient of
thermal expansion at temperature above T.sub.g, the glassy
transition temperature. Materials that are suitable for use in
connection with the present invention include epoxy resins.
[0026] As used herein, "epoxy resin" refers to a polymeric resin
with terminal epoxy groups. The epoxy resin is typically formed
from oxiranes. The oxiranes employed to form the epoxy resin, via a
polymerization reaction, can be the same or different. When the
oxirane monomers are different, the resulting epoxy resin will be a
copolymer. As used herein, a "copolymer" is a mixed polymer or
heteropolymer formed when two or more unlike monomers (e.g., the
oxirane monomers) are polymerized together. Concise Chemical and
Technical Dictionary; 4th Ed.; Chemical Publishing Co., Inc., NY,
N.Y. (1986), p. 336.
[0027] In one embodiment of the present invention, each of the
oxirane monomers are identical. In another embodiment of the
present invention, all of the oxirane monomers are not identical
(i.e., the epoxy polymer is an epoxy copolymer). In such an
embodiment, the number of different oxirane monomers can be from 2
to about 1,000, from 2 to about 100, or from 2 to about 10.
[0028] In one specific embodiment of the present invention, the
epoxy resin can be a mixture of two or more epoxy resins, as
defined above. The mixture can include 2 to about 100 epoxy resins,
2 to about 50 epoxy resins, or 2 to about 10 epoxy resins.
[0029] As used herein, an "oxirane" refers to a cyclic organic
compound having an oxygen atom bonded to two other atoms,
preferably carbon. Suitable oxiranes are disclosed, e.g., in
Concise Chemical and Technical Dictionary; 4th Ed.; Chemical
Publishing Co., Inc., NY, N.Y. (1986); Aldrich Catalog Handbook of
Fine Chemicals, Milwaukee, Wis. (1999); the disclosures of which
are incorporated by reference herein.
[0030] As used herein, "epoxy" refers to a diradical of an
oxirane.
[0031] A specific oxirane employed to form the epoxy resin can be a
compound of formula (I): 1
[0032] wherein
[0033] each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is
independently hydrogen, halo, trifluoromethyl, cyano, hydroxy,
nitro, (C.sub.1-C.sub.24)alkyl, (C.sub.2-C.sub.24)alkenyl,
(C.sub.2-C.sub.24)alkynyl, (C.sub.3-C.sub.8)cycloalkyl,
(C.sub.1-C.sub.24)alkyl (C.sub.3-C.sub.8)cycloalkyl,
(C.sub.6-C.sub.10)aryl, (C.sub.6-C.sub.10)heteroaryl,
(C.sub.1-C.sub.24)alkyl (C.sub.6-C.sub.10)aryl,
(C.sub.1-C.sub.24)alkyl (C.sub.6-C.sub.10)heteroaryl,
(C.sub.6-C.sub.10)aryl (C.sub.1-C.sub.24)alkyl,
(C.sub.6-C.sub.10)heteroaryl (C.sub.1-C.sub.24)alkyl, or
(C.sub.3-C.sub.8)cycloalkyl (C.sub.1-C.sub.24)alkyl;
[0034] wherein any alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or
heteroaryl can optionally be substituted with one or more (e.g., 1,
2, 3, or 4) (C.sub.1-C.sub.24)alkoxy, epoxy
(C.sub.1-C.sub.24)alkyl, epoxy (C.sub.1-C.sub.24)alkoxy, halo,
trifluoromethyl, cyano, hydroxy, nitro, C(.dbd.O)OR.sub.6, wherein
R.sub.6 is hydrogen or (C.sub.1-C.sub.24)alkyl- , or
NR.sub.7R.sub.8, wherein each R.sub.7 and R.sub.8 are independently
hydrogen or (C.sub.1-C.sub.24)alkyl; and
[0035] wherein any alkyl, alkenyl, or alkynyl is optionally
interrupted with one or more (e.g., 1, 2, 3, or 4) oxo, thio,
sulfonyl, or sulfinyl;
[0036] or a suitable salt thereof.
[0037] Specifically, R.sub.4 can be aryl oxy
(C.sub.1-C.sub.24)alkyl, wherein the aryl is substituted with epoxy
(C.sub.1-C.sub.24)alkoxy.
[0038] More specifically, R.sub.1 can be 2
[0039] Specifically, R.sub.2 can be hydrogen.
[0040] Specifically, R.sub.3 can be hydrogen.
[0041] Specifically, R.sub.4 can be hydrogen.
[0042] A specific oxirane employed to form the epoxy resin can be
oxirane 2,2'-(1,6-naphthalenediylbis(oxymethylene))bis- or
1,6-Bis(2,3-epoxypropoxy) naphthalene, having a CAS Registry Number
of 27610-48-6, and is shown below: 3
[0043] In one specific embodiment of the present invention, the
epoxy resin can be formed from one or more oxiranes. It is
appreciated that those of skill in the art understand the reaction
conditions in which oxiranes can be polymerized to form epoxy
resins. See, e.g., J. March, Advanced Organic Chemistry, Reactions,
Mechanisms and Structure, (2nd Ed.), McGraw Hill: New York, 1977;
F. Carey and R. Sundberg, Advanced Organic Chemistry, Part B:
Reactions and Synthesis, (2nd Ed.), Plenum: New York, 1977; and
references cited therein; which are incorporated by reference
herein. For example, the one or more oxiranes can be polymerized
under basic or acidic conditions.
[0044] The polymerization of the one or more oxiranes to form the
epoxy resin can include materials or compounds that will impart
desirable properties to the epoxy resin (e.g., a solidifier) or
that will catalyze the polymerization process. For example,
bisphenol A, bisphenol F, methyl hexahydrophthalic anhydride,
silica, carbon black, and/or CTBN can be employed in the
polymerization process.
[0045] The number of monomers in the epoxy resin that is formed
from the oxirane can range from 2 to about 1,000,000; from 2 to
about 100,000; from 2 to about 50,000 or 2 to about 10,000.
[0046] The epoxy resin can be formed (i.e., cured) at room
temperature. Alternatively, the epoxy resin can be formed (i.e.,
cured) at an elevated temperature, an elevated pressure, or a
combination thereof. Additionally, the epoxy resin can be formed
(i.e., cured) via the use of radiant energy (e.g., UV, electron
beam, microwave, beta radiation, gamma radiation, neutron beam,
proton beam, infra red, etc.).
[0047] As used herein, "elevated temperature" refers to any
temperature above room temperature, 77.degree. F. (25.degree. C.).
Typically, the elevated temperature can be above about 100.degree.
C. (212.degree. F.), above about 150.degree. C. (302.degree. F.),
above about 200.degree. C. (392.degree. F.), or up to about
250.degree. C. (482.degree. F.). Specifically, the elevated
temperature can be about 77.degree. F. (25.degree. C.) to about
315.degree. C. (599.degree. F.), about 100.degree. C. (212.degree.
F.) to about 315.degree. C. (599.degree. F.), about 77.degree. F.
(25.degree. C.) to about 218.degree. C. (425.degree. F.), about
100.degree. C. (212.degree. F.) to about 218.degree. C.
(425.degree. F.), or about 175.degree. C. (374.degree. F.) to about
218.degree. C. (425.degree. F.).
[0048] As used herein, "elevated pressure" refers to any pressure
above standard pressure, 1 atm. (14.7 psi). Typically, the elevated
pressure can be up to about 5.0 atm (73.5 psi), up to about 10.0
atm (146.9 psi), or up to about 20.0 atm (293.9 psi). Specifically,
the elevated pressure can be about 1 atm. (14.7 psi) to about 5.0
atm (73.5 psi).
[0049] FIG. 1B shows an embodiment of electronic package 100 during
fabrication according to the present invention. A die 110 is placed
on the top of adhesive bumps 105 such that a void 112 is formed
between opposed surfaces of die 110 and substrate 101. The adhesive
bumps 105 have a high viscosity and thus support the die 110
without substantially deforming. That is, the adhesive bumps are
viscous enough to support the weight of die 110 without
substantially spreading. In an embodiment, adhesive bumps 105 are
upright supports that are formed from a material used as a dam for
liquid encapsulation materials Void 112 is a gap between the
opposed surfaces of the die that is generally equal in height to
the height of the adhesive bumps 105. Substrate 101 provides a base
for mounting die 110.
[0050] In an embodiment, die 110 is fabricated from a
semiconductor, such as silicon, germanium, or gallium arsenide. In
an embodiment of the present invention, die 110 includes one or
more processor circuits, such as a reduced instruction set
processor or a complex instruction set processor. In an embodiment,
die 110 includes one or more communication circuits, such as a
transmitter, receiver, or transceiver. In an embodiment, die 110
includes one or more memory circuits or cells, such as dynamic
random access memory circuits or cells, or static random access
memory circuits or cells. Each of the circuits, cells, processors,
communication devices or other complex systems fabricated on die
110 are, in an embodiment, fabricated from passive and active
integrated circuit devices, such as resistors, capacitors,
inductors, transistors, and diodes. Die 110 is thus adapted to
compute or store electronic data. Die 110 further includes
input/output terminals to import or export electrical signals. Wire
bonds 115 are attached at one end to an I/O terminal of die 110 and
at another end to a terminal on substrate 101. In an embodiment, at
least one terminal is a bond pad. The wire bonds 115 are adapted to
electrically couple conductors of the die 110 to electrical
conductors of substrate 101. In an embodiment, electrical
conductors of the die include integrated circuits. In an
embodiment, electrical conductors of the substrate 101 include
traces and conducting lines. The die, in embodiments of the present
invention, includes silicon-on-sapphire (SOS) technology,
silicon-on-insulator (SOI) technology, thin film transistor (TFT)
technology, doped and undoped semiconductors, epitaxial layers of a
silicon supported by a base semiconductor structure, as well as
other semiconductor structures well known to one skilled in the
art.
[0051] The adhesive bumps 105 are cured to fix the die 110 to the
substrate 101. Adhesive bumps 115 are adapted to fix die 110 to
substrate 101 during the wire bonding steps, e.g., fixing one end
of bond wire 115 to a die contact and fixing a second end of bond
wire 115 to a substrate contact. In an embodiment, curing includes
heating the assembly 100 to harden the adhesive material of bumps
105. In an embodiment, curing includes waiting a period of time for
the polyermization of the epoxy components. The curing process is a
chemical reaction in which the epoxide groups in epoxy resin react
with a curing agent (hardener) to form a highly crosslinked,
three-dimensional network. In order to convert epoxy resins into a
hard, infusible, and rigid material, it is necessary to cure the
resin with hardener. Epoxy resins cure quickly and easily at
practically any temperature from 5-150 degrees Celsius depending on
the choice of curing agent. The curing of the adhesive bumps 105
provides a structurally secure assembly of the die 110 to substrate
101. In an embodiment, assembly 100 does not have structural metal
interconnects between the die 110 and the substrate 101. That is,
there are no solder connection between the die 110 and substrate
101. In an embodiment, assembly 100 includes both solder (not
shown) and adhesive bump 105 connections.
[0052] FIG. 1C shows an embodiment of electronic package 100 during
fabrication according to the present invention. An underfill
material 120, which is adapted to introduced into void 112 between
die 110 and substrate 101, connects the die and the substrate. In
an embodiment, a bead of flowable epoxy underfill material 120 is
positioned on the substrate 101 along two edges of the die 110. As
shown in FIG. 1C, the bead of underfill material 120 extends along
the right side and back side of the die on the substrate. Underfill
material 120 is heated until it flows and fills the void 112 by
capillary action. However, the underfill is not heated to such a
temperature that the underfill will cure before it flow into gap
112. In an embodiment, the underfill and assembly 100 is heated to
a temperature in a range of about 40 degrees Celsius to about 90
degrees Celsius. The underfill 120 includes an epoxy resin.
Underfill material 120 accordingly protects connections from oxides
and other contaminants. Further, underfill material 120 increases
the rate at which heat is transferred away from the die 110. The
underfill material 120 also increases the mechanical strength of
the connection between the die 110 and the substrate 120 to keep
the package 100 intact during environmental temperature changes,
despite the fact that die 110, the solder balls (not shown), if
any, and substrate 120 generally have different coefficients of
thermal expansion. The underfill material 120 has a lower viscosity
than the adhesive bumps 105. In an embodiment, underfill material
120 has a viscosity of about 2,800 mPa s at 25 degrees Celsius.
[0053] FIG. 1D shows an embodiment of electronic package 100 during
fabrication according to the present invention. Underfill material
120 has flowed into gap 112 between die 110 and substrate 101.
Underfill material 120 substantially fills gap 112 and contacts the
lower die surface and the upper substrate surface. Underfill 120
further contacts adhesive bumps 105. In an embodiment, adhesive
bumps 105 and underfill 120 cross-link. Cross-linking forms an
essentially homogenous material filling the gap between the die and
the substrate. In an embodiment, the die adhesive and underfill
form a continuous layer between the die and substrate.
[0054] FIG. 1E shows an embodiment of electronic package 100 during
fabrication according to the present invention. A mold compound 130
encases the die 110, bonding wires 115 and die attach compound such
as die adhesive bumps 105 and underfill 120. The mold compound 130
protects the die and its connection from the environment.
[0055] Board 140 provides a base for mounting substrate 101. In
addition, board 140 can provide a base for mounting additional
substrates (not shown). Board 140 is not limited to being
fabricated from a particular material. In an embodiment, board 140
is fabricated from an inert material that has a coefficient of
thermal expansion about equal to the coefficient of thermal
expansion of substrate 101. In one embodiment, board 140 is
fabricated from a ceramic. In an alternate embodiment, board 140 is
fabricated from a glass-epoxy resin. In still another embodiment,
board 140 is fabricated from FR-4. Board 140 may include any number
of conductive layers separated by a non-conductive material, such
as a dielectric. In one embodiment, board 140 includes a single
conductive layer formed on a dielectric base, such as a layer
comprising copper or a copper alloy formed on FR-4.
[0056] One or more solder balls 142 mechanically and electrically
connect the substrate to board 140. Solder balls 142 are preferably
fabricated from a conductive material. In one embodiment, the
conductive material is a metal or metal alloy. Metals and metal
alloys used in exemplary embodiments of the present invention
include aluminum, copper, tin, gold, silver, lead, and alloys of
aluminum, copper, tin, gold, silver, or lead. Each of the one or
more solder balls 142 has a solder reflow temperature. The solder
reflow temperature is the temperature at which each of the one or
more solder balls 142 makes a sustainable electrical connection to
pads (not shown) on substrate 101 and the electrical connection
sites (not shown) on board 140. A sustainable electrical connection
is a connection for which small stresses and vibrations at the
electrical connection do not interfere electrical conduction at the
connection. In one embodiment of the present invention, the solder
reflow temperature is between about 183 degrees Centigrade and 280
degrees Centigrade.
[0057] FIG. 1F shows a plan view of the package 100 according to an
embodiment of the present invention. Package 100 includes a
substrate 101, a board-on-chip slot 104, and a plurality of
adhesive bumps 105 on the substrate top surface. A die 110 is fixed
on the adhesive bumps to the substrate 101. The board-on-chip slot
104 is at least partially covered by the die 110.
[0058] FIG. 2A shows a cross-sectional view of another embodiment
of an electronic package 100A according to the invention. Another
method for depositing underfill material 120A is a "no-flow"
process. The adhesive bumps 105 are formed on the substrate as
described herein. A no-flow underfill dispenser 200 places no-flow
underfill directly on the substrate upper surface 102 and in
contact with the adhesive bumps 105. In an embodiment, the
substrate upper surface 102 and adhesive bumps 105 are dipped in a
no flow underfill bath as described in Patent Application
Publication No. U.S. 2002/0025602A1, hereby incorporated by
reference. The underfill material 120A has a lower viscosity than
the adhesive bumps 105.
[0059] FIG. 2B shows a cross-sectional view of the electronic
package 100A. Die 110 is placed on the adhesive bumps 105 and
underfill material 120A. The adhesive bumps 105 support the die
105. Underfill material 120A substantially fills the entire void
112. The underfill material 120A and adhesive bumps 120A are cured.
In an embodiment, the adhesive bumps 105 cross-link to the
underfill material 120A.
[0060] FIG. 2C shows a cross-sectional view of electronic package
100A according to the present invention. Electronic package 100A is
similar to the embodiment described above. Package 100A includes
substrate 105, die 110, one or more solder balls 142 for
electronically coupling substrate 105 to board 140, a plurality of
adhesive bumps 105, a die attach material 120A, and molding
compound 130. Bonding wires 115 electrically couple a top surface
113 of die 110 to a top surface 102 of substrate 105. Bonding wires
115 extend outwardly along the peripheral edges of the die 110. Die
attach material 120A attaches die 110 to the first surface 102 of
substrate 105. The die attach material 120A includes materials
described above with reference to FIGS. 1A-1F in embodiments of the
invention. Electronic package 100A, which includes die attachment
material 120A, has the same attachment characteristics as
electronic package 100 shown in FIGS. 1A-1F in embodiments of the
invention.
[0061] FIG. 3 is a block diagram of a computer system 300 according
to the present invention. System 300 includes a processor 305 and
memory board assembly 310. Memory board assembly 310 includes a
memory array 315, address circuitry 320, and read/write (command
and control) circuitry 330. Address circuitry 320, in an
embodiment, includes a row decoder 321 and a column decoder 322. An
address bus 335 couples processor 305 to memory board assembly 310
and is adapted to deliver memory signals to address circuitry 320.
A data bus 340 connects processor 305 to memory board assembly and
is adapted to deliver and receive (i.e., bidirectional) data
signals to and from the memory board assembly 310. A command and
control bus 345 further connects the processor 305 to the memory
board assembly 310 and is adapted to deliver command and control
signals to command and control circuitry of 330. In one embodiment,
the processor 305 is packaged as die 110 in an electronic package
as described herein. In another embodiment, the processor and
memory are packaged as die 110 in electronic package as described
herein. In still another embodiment, the memory array 315 is
packaged as die 203 in an electronic package as described herein.
Processor 305, through address bus 335, data bus 340, and control
bus 345 communicates with memory board assembly 310. In a read
operation initiated by processor 305, address information, data
information, and control information are provided to memory board
assembly 310 through busses 335, 340, and 345. This information is
decoded by addressing circuitry 320, including a row decoder and a
column decoder, and read circuitry 330. Successful completion of
the read operation results in information from memory array 315
being communicated to processor 305 over data bus 340.
[0062] FIG. 4 shows another embodiment of the present invention
that includes a stacked die assembly 400 mounted to substrate 101.
Assembly 400 includes a plurality of die 110A and 110B that are
fixed together according to the teachings of the present invention.
At least one of the die 10A and 10B includes adhesive bumps 105
formed thereon. The adhesive bumps 105 fix the adjacent dies
together with an underfill 120 material filling the gap between the
die 10A and 10B. The present invention further includes stacking a
plurality of dies using adhesive bumps 105 between at least two
adjacent dies. In an embodiment, an underfill material fills the
gap between at least two adjacent dies. In an embodiment, the stack
of die include electrical connections between at least two of the
stacked die. The present subject matter further includes a
plurality of die that are stacked together and at least one of the
stacked die is fixed to the substrate according to the teachings
herein. The die, in an embodiment, are connected together using
solder connections. The die, in an embodiment, are connected
together using an underfill material. In an embodiment, the stacked
die are mechanically and electrically connected together. In an
embodiment, at least one of the stacked die is electrically
connected to the substrate.
CONCLUSION
[0063] An electronic device package has been described. In an
embodiment, the electronic device package includes a non-metal
support attaching the die to and above the substrate. The die
support is a die adhesive An underfill material fills the space
between the die and substrate. The underfill material includes
non-metal materials. Thus, the space between the die and substrate
is filled with similar materials, i.e., the support and the
underfill. In an embodiment, the support material is an epoxy
resin. In an embodiment, the epoxy resin has a high viscosity. This
allows the epoxy resin to hold its shape with the die supported
thereon. The application of the die adhesive is flexible as to its
amount, location, and bond line thickness (the thickness between
the die and substrate). Moreover, the die adhesive support and
underfill material cross-link such that the material intermediate
the die and substrate is essentially homogenous. This eliminates
potential unwanted interaction between dissimilar materials.
Further, the use of the die adhesive supports and underfill allows
the use of a high modulus underfill. For example, the underfill has
a modulus that is 100 times the modulus of the die adhesive
material. The higher modulus improves the reliability of the
assembly. Still further, the use of non-metal material for both the
die support and underfill is believed to be more inexpensive than
conventional technologies.
[0064] The present invention provides advantages over convention
tape adhesive technologies for attaching a die to a substrate. The
present invention does not require the expensive tooling costs
associated tape adhesive technologies.
[0065] It will be appreciated that in some embodiments of the
invention, the fabrication steps recited herein are performed in
the order recited in the attached claims and in the written
description.
[0066] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement which is calculated to achieve the
same purpose may be substituted for the specific embodiment shown.
This application is intended to cover any adaptations or variations
of the present invention. Therefore, it is intended that this
invention be limited only by the claims and the equivalents
thereof.
* * * * *