U.S. patent application number 10/954959 was filed with the patent office on 2006-03-30 for low melting-point solders, articles made thereby, and processes of making same.
Invention is credited to Melissa A. Baeten, Tiffany A. Byrne, Edward L. Martin, Daewoong Suh.
Application Number | 20060067852 10/954959 |
Document ID | / |
Family ID | 36099341 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060067852 |
Kind Code |
A1 |
Suh; Daewoong ; et
al. |
March 30, 2006 |
Low melting-point solders, articles made thereby, and processes of
making same
Abstract
A composition includes a tin-containing solder with a melting
temperature below about 150.degree. C. The tin-containing solder
includes indium, tin, and bismuth as alloy elements, and optionally
contains a doping material and/or a second-phase dispersiod. A
process includes blending the tin-containing solder under
non-alloying conditions to achieve the discrete dispersion of the
doping material. A process also includes blending the
tin-containing solder with the particulate to achieve the discrete
dispersion of the particulate. The composition is also combined
with a microelectronic device to form a package. The composition is
also combined with a microelectronic device and at least one I/O
functionality to form a computing system.
Inventors: |
Suh; Daewoong; (Phoenix,
AZ) ; Byrne; Tiffany A.; (Chandler, AZ) ;
Baeten; Melissa A.; (Chandler, AZ) ; Martin; Edward
L.; (Chandler, AZ) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH
1600 TCF TOWER
121 SOUTH EIGHT STREET
MINNEAPOLIS
MN
55402
US
|
Family ID: |
36099341 |
Appl. No.: |
10/954959 |
Filed: |
September 29, 2004 |
Current U.S.
Class: |
420/555 ;
257/E21.508; 420/577; 420/589 |
Current CPC
Class: |
H05K 3/3463 20130101;
C22C 32/00 20130101; H01L 2224/32225 20130101; H01L 2924/01033
20130101; H01L 2924/16152 20130101; H01L 24/81 20130101; H01L
2224/16225 20130101; H01L 2224/16225 20130101; H01L 2224/73204
20130101; H01L 2224/73253 20130101; H01L 2224/0555 20130101; H01L
2224/05599 20130101; H01L 2924/00 20130101; H01L 2924/1433
20130101; H01L 2924/01057 20130101; H01L 2924/01005 20130101; H01L
2924/01051 20130101; H01L 2224/0556 20130101; H01L 2224/32225
20130101; H01L 2924/00 20130101; H01L 2224/32225 20130101; H01L
2924/00014 20130101; H01L 2924/01049 20130101; H01L 2924/01077
20130101; H01L 2224/8121 20130101; H01L 2924/00014 20130101; H01L
2924/01029 20130101; H01L 2924/01046 20130101; H01L 2924/01074
20130101; H01L 2224/05568 20130101; H01L 2924/15311 20130101; H01L
2224/48235 20130101; H01L 2924/01078 20130101; H01L 2224/48464
20130101; H01L 2224/16225 20130101; H01L 2224/73253 20130101; H01L
2924/01006 20130101; H01L 2924/01327 20130101; C22C 12/00 20130101;
H01L 2924/01018 20130101; H01L 2224/16237 20130101; H01L 2224/81815
20130101; H01L 2924/01012 20130101; H01L 2924/01027 20130101; H01L
2924/14 20130101; H01L 2924/0103 20130101; H01L 2224/056 20130101;
H01L 2924/16152 20130101; C22C 30/04 20130101; H01L 2224/05573
20130101; H01L 2924/01059 20130101; H01L 2924/01022 20130101; H01L
2224/0554 20130101; H01L 2224/1132 20130101; H01L 2924/01079
20130101; C22C 13/00 20130101; H01L 2224/73204 20130101; H01L
2924/00014 20130101; H01L 2924/01045 20130101; H01L 2924/01072
20130101; H01L 24/11 20130101; H01L 2224/73204 20130101; H01L
2924/00014 20130101; H01L 2924/00014 20130101; H01L 2924/0107
20130101; H01L 2924/15311 20130101; H01L 2224/13099 20130101; H01L
2924/01025 20130101; C22C 28/00 20130101; H01L 2224/056 20130101;
H01L 2924/01047 20130101; H01L 2224/48471 20130101; H01L 2924/0104
20130101; H01L 2924/014 20130101 |
Class at
Publication: |
420/555 ;
420/577; 420/589 |
International
Class: |
C22C 30/04 20060101
C22C030/04; C22C 12/00 20060101 C22C012/00; C22C 28/00 20060101
C22C028/00 |
Claims
1. A composition comprising: indium in a range from about 36% to
about 63%; tin in a range from about 28% to about 48%; and bismuth
in a range from about 2% to about 26%.
2. The composition of claim 1, wherein the composition includes a
solder including: indium in a range of about 41% to about 58%; tin
in a range from about 34% to about 42%; and bismuth in a range from
about 7% to about 19%.
3. The composition of claim 1, wherein the composition includes a
solder including: indium in a range from about 46% to about 53%;
tin in a range from about 37% to about 39%; and bismuth in a range
from about 12% to about 14%.
4. The composition of claim 1, wherein the composition includes a
solder including: about 49% indium; about 38% tin; and about 13%
bismuth.
5. The composition of claim 1, further including: at least one
doping material selected from zinc, titanium, zirconium, hafnium,
yttrium, ytterbium, lanthanum, praseodymium, nickel, palladium,
platinum, cobalt, rhodium, iridium, magnesium, manganese, iron,
copper, silver, gold, and combinations thereof.
6. The composition of claim 1, further including a zinc doping
material in a concentration range from about 0.1% to about 1%.
7. The composition of claim 1, further including doping materials
of at least two selected from zinc, silver, and copper, wherein the
doping materials are present in a combined concentration range from
about 0.1% to about 1%.
8. The composition of claim 1, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, and wherein the particulate has a size in a
range below about 100 nm.
9. The composition of claim 1, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, wherein the particulate has a size in a range
below about 100 nm, and wherein the particulate occupies a volume
in the composition in a range from about 0.1% to about 50%.
10. The composition of claim 1, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, wherein the particulate has a size in a range
below about 100 nm; and wherein the particulate is selected from an
oxide, a carbide, a nitride, an oxynitride, a silicide, a carbon
Fullerene, and combinations thereof.
11. The composition of claim 1, further including: at least one
doping material selected from zinc, titanium, yttrium, ytterbium,
zirconium, nickel, cobalt, lanthanum, magnesium, manganese, iron,
copper, silver, gold, palladium, praseodymium, and combinations
thereof; and a particulate dispersed in the composition, wherein
the solder provides a matrix for the particulate, wherein the
particulate has a size in a range below about 100 nm, and wherein
the particulate occupies a volume in the composition in a range
from about 0.1% to about 50%.
12. A composition comprising: bismuth in a range from about 42% to
about 62%; tin in a range from about 19% to about 42%; and indium
in a range from about 7% to about 28%.
13. The composition of claim 12, wherein the composition includes a
solder including: bismuth in a range from about 46% to about 57%;
tin in a range from about 24% to about 38%; and indium in a range
from about 11% to about 24%.
14. The composition of claim 12, wherein the composition includes a
solder including: bismuth in a range from about 52% to about 54%;
tin in a range from about 29% to about 33%; and indium in a range
from about 15% to about 19%.
15. The composition of claim 12, wherein the composition includes a
solder including: about 52% bismuth; about 31% tin; and about 17%
indium.
16. The composition of claim 12, further including: at least one
doping material selected from zinc, titanium, zirconium, hafnium,
yttrium, ytterbium, lanthanum, praseodymium, nickel, palladium,
platinum, cobalt, rhodium, iridium, magnesium, manganese, iron,
copper, silver, gold, and combinations thereof.
17. The composition of claim 12, further including a zinc doping
material in a concentration range from about 0.1% to about 1%.
18. The composition of claim 12, further including doping materials
of at least two selected from zinc, silver, antimony, and copper,
wherein the doping materials are present in a combined
concentration range from about 0.1% to about 1%.
19. The composition of claim 12, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, and wherein the particulate has a size in a
range below about 100 nm.
20. The composition of claim 12, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, wherein the particulate has a size in a range
below about 100 nm, and wherein the particulate occupies a volume
in the composition in a range from about 0.1% to about 50%.
21. The composition of claim 12, further including: a particulate
dispersed in the composition, wherein the solder provides a matrix
for the particulate, wherein the particulate has a size in a range
below about 100 nm; and wherein the particulate is selected from an
oxide, a carbide, a nitride, an oxynitride, a silicide, a carbon
Fullerene, and combinations thereof.
22. The composition of claim 12, further including: at least one
doping material selected from zinc, titanium, yttrium, ytterbium,
zirconium, nickel, cobalt, lanthanum, magnesium, manganese, iron,
copper, silver, gold, palladium, praseodymium, and combinations
thereof; and a particulate dispersed in the composition, wherein
the composition provides a matrix for the particulate, wherein the
particulate has a size in a range below about 100 nm, and wherein
the particulate occupies a volume in the composition in a range
from about 0.1% to about 50%.
23. A composition comprising: from about 33% to about 67% indium;
from about 32% to about 67% bismuth; and from about 0% to about 20%
tin.
24. The composition of claim 23, wherein the composition includes a
solder including: indium in a range of about 25% to about 33%; tin
in a range from about 0% to about 19%; and bismuth in a range from
about 56% to about 67%.
25. The composition of claim 23, wherein the composition includes a
solder including: indium in a range from about 48% to about 67%;
tin in a range from about 0% to about 20%; and bismuth in a range
from about 32% to about 33%.
26. A composition comprising: from about 52% to about 54% indium;
from about 0% to about 2% zinc; and from about 46% to about 48%
tin.
27. The composition of claim 26, wherein the composition includes a
solder including: indium in a range of about 52.5% to about 53.5%;
zinc in a range from about 0.5% to about 1.5%; and tin in a range
from about 46.5% to about 47.5%.
28. The composition of claim 26, wherein the composition includes a
solder including: about 53% indium; about 1% zinc; and about 47%
tin.
29. A composition comprising: from about 33% to about 67% indium;
from about 32% to about 67% bismuth; and from about 0.1% to about
1% zinc.
30. The composition of claim 29, wherein the composition includes a
solder including: from about 32% to about 33% indium; from about
66% to about 67% bismuth; and from about 0.1% to about 1% zinc.
31. The composition of claim 29, wherein the composition includes a
solder including: from about 33.4% to about 52.2% indium; from
about 47.4% to about 66.3% bismuth; and from about 0.3% to about
0.4% zinc.
32. The composition of claim 29, wherein the composition includes a
solder including: from about 52.2% to about 66.8% indium; from
about 32.7% to about 47.4% bismuth; and from about 0.4% to about
0.5% zinc.
33. The composition of claim 29, wherein the composition includes a
solder including: from about 66% to about 66.8% indium; from about
32.7% to about 34% bismuth; and from about 0.1% to about 0.5%
zinc.
34. A package comprising: a substrate; a solder composition,
selected from: a first solder including: indium in a range from
about 36% to about 63%; tin in a range from about 28% to about 48%;
and bismuth in a range from about 2% to about 26; and the solution,
mixture, and reaction products of the first solder; or a second
solder including: bismuth in a range from about 42% to about 62%;
tin in a range from about 19% to about 42%; indium in a range from
about 7% to about 28%; and the solution, mixture, and reaction
products of the first solder; and a microelectronic device disposed
on the substrate, wherein the microelectronic device is coupled to
the solder.
35. The package of claim 34, wherein the microelectronic device is
a flip-chip die, and wherein the solder is selected from a thermal
interface subsystem, an electrical bump, and combinations
thereof.
36. The package of claim 34, wherein the microelectronic device is
a flip-chip die, and wherein the solder is selected from a first
electrical bump that contacts a die, a second electrical bump that
contacts a board and that is coupled to the die, and combinations
thereof.
37. The package of claim 34, wherein the microelectronic device is
a wire-bond die, and wherein the solder is selected from a
wire-bonding ball, an interconnect, a bump to a board, and
combinations thereof.
38. A computing system comprising: a substrate; a solder
composition, selected from: a first solder including: indium in a
range from about 36% to about 63%; tin in a range from about 28% to
about 48%; bismuth in a range from about 2% to about 26%; and the
solution, mixture, and reaction products of the first solder; or a
second solder including: bismuth in a range from about 42% to about
62%; tin in a range from about 19% to about 42%; indium in a range
from about 7% to about 28%; and the solution, mixture, and reaction
products of the first solder; a microelectronic device disposed on
the substrate; and at least one of an input device and an output
device coupled to the microelectronic device, wherein the solder is
coupled to the microelectronic device.
39. The computing system of claim 38, wherein the computing system
is disposed in one of a computer, a wireless communicator, a
hand-held device, an automobile, a locomotive, an aircraft, a
watercraft, and a spacecraft.
40. The computing system of claim 38, wherein the microelectronic
die is selected from a data storage device, a digital signal
processor, a micro controller, an application specific integrated
circuit, and a microprocessor.
41. A process comprising: assembling a solder with a structure, the
solder including: indium in a range from about 36% to about 63%;
tin in a range from about 28% to about 48%; and bismuth in a range
from about 2% to about 26%.
42. The process of claim 41, before assembling, the process further
including blending the solder with at least one of a second-phase
particulate and a doping material.
43. The process of claim 41, wherein blending the second-phase
particulate includes first milling the second-phase particulate to
a particle size about 100% passing 100 nm, followed by second
kneading the second-phase particulate into the solder.
44. The process of claim 41, wherein blending the second-phase
particulate includes first kneading the second-phase particulate
into the solder.
45. The process of claim 41, before assembling, the process further
including: blending the solder with a doping material; and wherein
assembling the solder with a structure includes in situ alloying of
the doping material during reflow of the solder against the
structure, wherein the structure is selected from a heat sink, a
die, a bump, a wire-bond pad, and combinations thereof.
46. A process comprising: assembling the solder with a structure,
the solder including: indium in a range from about 69% to about
97%; tin in a range from about 28% to about 48%; and bismuth in a
range from about 2% to about 26%.
47. The process of claim 46, before assembling, the process further
including blending the solder with at least one of a second-phase
particulate and a doping material.
48. The process of claim 46, wherein blending the second-phase
particulate includes first milling the second-phase particulate to
a particle size about 100% passing 100 nm, followed by second
kneading the second-phase particulate into the solder.
49. The process of claim 46, wherein blending the second-phase
particulate includes first kneading the second-phase particulate
into the solder.
50. The process of claim 46, before assembling, the process further
including: blending the solder with a doping material; and wherein
assembling the solder with a structure includes in situ alloying of
the doping material during reflow of the solder against the
structure, wherein the structure is selected from a heat sink, a
die, a bump, a wire-bond pad, and combinations thereof.
Description
TECHNICAL FIELD
[0001] Embodiments relate to solder for bonding microelectronic
devices. In particular, an embodiment relates to a solder paste
that includes in situ alloying components that form an alloy during
reflow.
BACKGROUND INFORMATION
[0002] Where a microelectronic device is sensitive to conventional
oven reflow temperatures, which are about 200.degree. to
220.degree. C., reflow of electrical bumps needs to occur at
temperatures less than about 125.degree. C. The operating
temperature range of a microelectronic device, however, can be in
the range from about 50.degree. to about 80.degree. C. Such a
device requires the solder to have a higher liquidus temperature to
reduce thermally accelerated solder joint reliability failure
modes, such as creep and fatigue, that can occur at the ordinary
operating temperature range of the device. Multiple solder bump
reflows and burn-in testing can make solder joint failure and
device failure more likely.
[0003] Conventional solders are susceptible to thermally
accelerated solder joint reliability failures such as creep and
fatigue. One board mounting process with conventional solders
requires at least two solder bump reflows. They include a ball
attach first reflow and a board attach second reflow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] In order to understand the manner in which embodiments are
obtained, a more particular description of various embodiments
briefly described above will be rendered by reference to the
appended drawings. These drawings depict embodiments that are not
necessarily drawn to scale and are not to be considered to be
limiting in scope. Some embodiments will be described and explained
with additional specificity and detail through the use of the
accompanying drawings in which:
[0005] FIG. 1 is cross-section of a composition according to an
embodiment;
[0006] FIG. 2 is a process flow depiction of a solder paste mixture
according to an embodiment;
[0007] FIG. 3 is a cross-section of a chip package according to an
embodiment;
[0008] FIG. 4 is a cross-section of a flip-chip package according
to an embodiment;
[0009] FIG. 5 is a cross-section elevation of a wire-bond chip
according to an embodiment;
[0010] FIG. 6 is a process flow diagram according to an embodiment;
and
[0011] FIG. 7 is a depiction of a computing system according to an
embodiment.
DETAILED DESCRIPTION
[0012] The following description includes terms, such as upper,
lower, first, second, etc., that are used for descriptive purposes
only and are not to be construed as limiting. The embodiments of a
device or article described herein can be manufactured, used, or
shipped in a number of positions and orientations. The terms "die"
and "processor" generally refer to the physical object that is the
basic workpiece that is transformed by various process operations
into the desired integrated circuit device. A die is usually
singulated from a wafer, and wafers may be made of semiconducting,
non-semiconducting, or combinations of semiconducting and
non-semiconducting materials.
[0013] A board is typically a resin-impregnated fiberglass
structure that acts as a mounting substrate for the die. A board
can be prepared with a bond pad, also referred to as a bond finger,
that is flush with the board, or the bond pad can be set upon the
board surface. As depicted in this disclosure, a bond pad is not
limited to being flush or setting upon the surface only because it
is illustrated as such, unless it is explicitly stated in the
text.
[0014] Reference will now be made to the drawings wherein like
structures may be provided with like reference designations. In
order to show the structures of embodiments most clearly, the
drawings included herein are diagrammatic representations of
inventive articles. Thus, the actual appearance of the fabricated
structures, for example in a photomicrograph, may appear different
while still incorporating the essential structures of embodiments.
Moreover, the drawings show only the structures necessary to
understand the embodiments. Additional structures known in the art
have not been included to maintain the clarity of the drawings.
[0015] FIG. 1 is cross-section of a composition 100 according to an
embodiment. In an embodiment, the composition 100 includes a
tin-containing solder 102. In an embodiment, the composition 100
includes a zinc-containing solder 102. The composition 100 has
modifications in some embodiments, however, that make it a
compound. In an embodiment, the solder 102 is a monophasic
composition.
[0016] Various low melting-point solders are disclosed according to
several embodiments. Table 1 provides a summary of example
embodiment solders. TABLE-US-00001 TABLE 1 Low Melting-Point Solder
Embodiment Examples Example Sn, % In, % Bi, % Zn, % 1 42-19 0-25
58-56 0 1A 19 25 56 0 1B 42 0 58 0 1C 29-32 11-15 57 0 2 48-20
52-48 0-32 0 2A 42-26 52-48 10-22 0 2B 36-32 51-49 14-18 0 3 0-19
33-25 67-56 0 3A 5-14 31-27 64-59 0 3B 8-11 30-28 62-61 0 4 0-20
67-48 33-32 0 4A 5-15 62-53 33-32 0 4B 8-12 59-56 33-32 0 5 48-46
52-54 0 0-2 5A 47 53 0 1 6 0 32-33 66-67 0-1 6A 0 32.5 66.5 1 7 0
33.4-52.2 66.3-47.4 0.3-0.4 7A 0 38-48 60-50 0.3-0.4 8 0 52.2-66.8
47.4-32.7 0.4-0.5 8A 0 58-60 45-37 0.4-0.5 9 0 66-66.8 32.7-34
0-0.5 9A 0 66.8 32.7 0.5
[0017] In an embodiment, an indium-tin-bismuth first solder 102 is
prepared. In this embodiment, the indium-tin-bismuth first solder
102 includes indium as a major component. In an embodiment, the
indium-tin-bismuth first solder 102 includes indium in a range of
about 36% to about 63% indium. A tin component is present in a
range from about 28% to about 48% tin. The bismuth is present in a
range from about 2% to about 26%.
[0018] In an embodiment, the indium-tin-bismuth first solder 102
includes indium in a range of about 41% to about 58% indium, the
tin component is present in a range from about 34% to about 42%,
and the bismuth component is present in a range from about 7% to
about 19%. In an embodiment, the first solder 102 includes indium
in a range of about 46% to about 53% indium, the tin component is
present in a range from about 37% to about 39%, and the bismuth
component is present in a range from about 12% to about 14%. In an
embodiment, the first solder 102 includes about 49% indium, about
38% tin, and about 13% bismuth.
[0019] In an embodiment, the indium-tin-bismuth first solder 102 is
prepared with at least one doping material. The at least one doping
material is added to give the indium-tin-bismuth first solder 102
selected properties. In an embodiment, the indium-tin-bismuth first
solder 102 is doped with about 1% or less of the at least one
doping material. In an embodiment, the indium-tin-bismuth first
solder 102 is doped with about 0.5% or less of the at least one
doping material. In an embodiment, the indium-tin-bismuth first
solder 102 is doped with about 0.1% or less of the at least one
doping material.
[0020] In an embodiment, the at least one doping material includes
zinc. In an embodiment, the at least one doping material is
selected from titanium, zirconium, hafnium, and combinations
thereof. In an embodiment, the at least one doping material is
selected from yttrium, ytterbium, lanthanum, praseodymium, and
combinations thereof. In an embodiment, the at least one doping
material is selected from nickel, palladium, platinum, and
combinations thereof. In an embodiment, the at least one doping
material is selected from cobalt, rhodium, iridium, and
combinations thereof. In an embodiment, the at least one doping
material is selected from magnesium, manganese, iron and
combinations thereof. In an embodiment, the at least one doping
material is selected from copper, silver, gold, and combinations
thereof.
[0021] In an embodiment, the at least one doping material includes
zinc alone. In an embodiment, the at least one doping material
includes silver alone. In an embodiment, the at least one doping
material includes copper alone. Where the at least one doping
material is present, the above-given concentrations of the first
solders are adjustable proportionally by recalculating the
percentages.
[0022] In an embodiment, the at least one doping material includes
any two of zinc, silver, or copper. In an embodiment, the at least
one doping material includes zinc and silver. In an embodiment, the
at least one doping material includes zinc and silver with zinc as
the major doping material. In an embodiment, the at least one
doping material includes zinc and silver with silver as the major
doping material.
[0023] In an embodiment, the at least one doping material includes
zinc and copper. In an embodiment, the at least one doping material
includes zinc and copper with zinc as the major doping material. In
an embodiment, the at least one doping material includes zinc and
copper with copper as the major doping material.
[0024] In an embodiment, the at least one doping material includes
silver and copper. In an embodiment, the at least one doping
material includes silver and copper with silver as the major doping
material. In an embodiment, the at least one doping material
includes silver and copper silver with copper as the major doping
material.
[0025] In an embodiment, the at least one doping material includes
all three doping materials of silver, copper, and zinc. In an
embodiment, the at least one doping material includes all three
doping materials with zinc as the majority doping material. In an
embodiment, the at least one doping material includes all three
doping materials with zinc as the majority doping material, and
copper as the minority doping material. In an embodiment, the at
least one doping material includes all three doping materials with
zinc as the majority doping material, and silver as the minority
doping material.
[0026] In an embodiment, the at least one doping material includes
all three doping materials with zinc as the plurality doping
material and copper as the minority doping material. In an
embodiment, the at least one doping material includes all three
doping materials with zinc as the plurality doping material and
silver as the minority doping material.
[0027] By review of this disclosure, it will become apparent to one
of ordinary skill in the art that combinations of zinc, silver, and
copper are also preparable as doping materials in the
indium-tin-bismuth solders, wherein silver is the doping material
with the greatest presence, and zinc and copper are alternatively
present with one of them in a lowest concentration. Similarly, the
majority or plurality doping material may be complemented by equal
concentrations of the two minority doping materials.
[0028] In an embodiment, the at least one doping material is
supplied to the composition 100 by providing an atomized doping
material in a particle size from about 0.1 micrometer (.mu.m) to
about 100 .mu.m. The atomized doping material is blended into the
composition 100 by mechanical alloying. In an embodiment, the
mechanical alloying describes the blending action, but the atomized
doping material is not substantially alloyed, but it is
interstitial in the matrix of the first solder 110.
[0029] FIG. 2 is a process flow depiction of a solder paste mixture
according to an embodiment. The process flow is depicted against a
temperature-versus-time graphic to illustrate the state of the
solder paste during processing. According to a process embodiment,
the graphic ordinate depicts a room temperature of 20.degree. C., a
first ramp temperature of about 100.degree. C., a flux activation
temperature of about 120.degree. C., a solder in situ alloying
temperature of about 140.degree. C., and a cooled solder
temperature of 20.degree. C. The abscissa depicts process time in
arbitrary units.
[0030] In an embodiment, a process unit 200 includes a substrate
210 and a solder paste brick 212. Within the solder paste brick 212
is a solder paste matrix 216, which includes a solder mixture. In
an embodiment, the solder mixture includes any solder as set forth
in this disclosure.
[0031] The solder paste brick 212 also includes a discrete
dispersion of the doping material according to any of the
embodiments set forth in this disclosure. The doping material 220
is depicted within the solder paste brick 212 as four discrete
particles for the purposes of illustration.
[0032] During processing, the solder paste brick 212 is heated
during a ramp-up stage from room temperature to about 100.degree.
C. During further heating, the solder paste flux begins to
activate. According to an embodiment, the process unit 201 is
depicted as relating to the temperature of about 100.degree. C. At
about this temperature, the flux in the solder paste brick 213
begins to activate. The solder paste brick 213 is arbitrarily
depicted with softening corners during flux activation. The solder
paste matrix 217 is changing chemically during this process as the
flux is activating and the solder mixture begins to soften.
According to an embodiment, the discrete dispersion of the doping
material 221 is not changed to the same degree as the solder
mixture.
[0033] According to an embodiment, the process unit 202 is depicted
as relating to the temperatures from about 120.degree. C. to about
140.degree. C. during the heating portion of the reflow process. At
about this temperature range, the flux in the solder paste brick
214 has activated and the solder mixture in the solder paste matrix
218 is melted. The solder paste brick 214 is depicted arbitrarily
with a substantially rounded profile. Additionally, the doping
material 222 is depicted as enlarging while intermingling within
the solder matrix 218 during the in situ alloying of the doping
material 221 into the solder mixture.
[0034] According to an embodiment, the process unit 203 is depicted
as relating to the temperatures from about 140.degree. C. to about
20.degree. C. during cool-down of the unit. At about this
temperature range, the flux in the solder bump 215 has been
substantially driven from the matrix 219. The solder bump 215 is
depicted arbitrarily with a substantially rounded profile.
Additionally, the doping material is depicted as substantially
dispersed and alloyed into the matrix 219.
[0035] In an embodiment, preparation of the solder paste brick 212
is carried out by a non-alloying blending of components of the
solder paste matrix 216. In an embodiment, the blending process is
carried out in a conventional kneading device.
[0036] In an embodiment, during blending of the composition of the
solder mixture, the paste including flux, and the doping material,
no significant mechanical or chemical alloying occurs between the
solder mixture and the doping material.
[0037] As depicted in FIG. 2, after the doping material powder
particles are discretely dispersed into the solder paste, the
solder paste is printed via an automated stencil print process and
takes the form of the brick 212. As set forth herein, flux in the
solder paste reacts chemically at increasing temperatures to
release acids that reduce metal-oxides that are present. As the
temperature reaches and surpasses the liquidus temperature of the
solder mixture, the powder particles of the doping material(s) in
the solder paste liquefy and alloy in situ. As depicted with the
process unit 202, the matrix 218 coalesces and takes the form of a
hemisphere. Simultaneously, the matrix 218 reacts chemically with
under-bump metallization in the substrate 210 to form a metallic
bond. Additionally, the doping material powder diffuses into the
molten solder, although the liquidus temperature of the doping
material powder may not be reached. Upon cooling, the solder bump
215 solidifies at a temperature that is higher than the liquidus
temperature of the tin-containing solder that is depicted as part
of the solder paste brick 212.
[0038] According to an embodiment, were the solder bump 215 to be
reheated, the in situ-formed solder alloy would liquefy at a higher
temperature than it did upon its first reflow, due to a change in
composition from the in situ alloying process.
[0039] Reference is again made to FIG. 1. Prior to the in situ
alloying process, if it is used according to an embodiment, a
particulate can be dispersion-filled into the solder 100.
[0040] In an embodiment, the first solder 102 includes a first
particulate 104 that is dispersed within the matrix of the first
solder 102. The first particulate 104 is a second-phase component
in the solder 102 that adds selected properties to the alloy. In an
embodiment, the particulate occupies a volume in the composition in
a range from about 0.1% to about 50%.
[0041] In an embodiment, the first particulate 104 is an inorganic
dielectric material such as an oxide. Various oxides can be used
for the inorganic dielectric material, such as alumina, thoria,
titania (whether rutile or anatase), urania, zirconia, ceria, and
combinations thereof. In an embodiment, the first particulate 104
is a carbide material such as tungsten carbide. In an embodiment,
the first particulate 104 is a carbon-based structure such as
graphite, a Fullerene, and combinations thereof. In an embodiment,
the first particulate 104 is an intermetallic dispersion material
such as Cu.sub.6Sn.sub.5, Cu.sub.3Sn, Ni.sub.3Sn.sub.4, or the
like, other intermetallics, and combinations thereof. In an
embodiment, the first particulate 104 is a silicide material that
approaches the coefficient of thermal expansion (CTE) of silicon,
such as titanium silicide. In an embodiment, the first particulate
104 is a material selected from at least two of the
above-enumerated materials or the like. In an embodiment, the first
particulate 104 is a material selected from at least three of the
above-enumerated materials or the like. In an embodiment, the first
particulate 104 is a material selected from at least four of the
above-enumerated materials or the like. In an embodiment, the first
particulate 104 is a material selected from all of the
above-enumerated materials or the like.
[0042] In an embodiment, preparation of the first particulate 104
is carried out by milling the first particulate 104 to a size
distribution that is submicron. In an embodiment, the first
particulate 104 has a size distribution that is 100% passing about
100 nanometer (nm). Milling of the first particulate 104 can be
carried out in a high-energy ball mill such as a Fritsch
Pulverisette 7, made by Fritsch, GmbH of Rudolstadt, Germany, and
which can be obtained from Gilson Co. of Worthington, Ohio. Other
milling equipment can be obtained to obtain submicron, and about
100 nm particulates.
[0043] In an embodiment, the first particulate 104 is milled in a
tungsten carbide (WC) environment such as in a planetary ball mill
that includes WC grinding balls as well as a WC vial. In a
non-limiting example, graphite is milled under about 300 kPa Argon
atmosphere, to form a nanoporous structure of a Fullerene. In a
non-limiting example, alumina (Al.sub.2O.sub.3) is milled under
about 300 kPa Argon atmosphere, to form a 100% passing 100 nm
distribution.
[0044] FIG. 1 also illustrates the presence of two particulates
according to an embodiment. In an embodiment, the first particulate
104 is an inorganic dielectric, and a second particulate 106 is
present in a second morphology such as a fiber or a shattered
structure. In an embodiment, the second particulate 106 includes a
Fullerene that has an elongated structure. In an embodiment, the
particulate material is selected from at least two of the
above-enumerated materials or the like. In an embodiment, the
particulate material is selected from at least three of the
above-enumerated materials or the like. In an embodiment, the
particulate material is a material selected from at least four of
the above-enumerated materials or the like. In an embodiment, the
particulate material is a material selected from all of the
above-enumerated materials or the like.
[0045] Although FIG. 1 illustrates the distribution of at least the
first particulate 102 as discretely isolated in the matrix of the
tin alloy 102, in an embodiment, the first particulate 104 is
present as a reticulated structure. In an embodiment where the
first particulate 104 is a Fullerene, it is similarly a reticulated
structure that is dispersed in the matrix of the tin alloy 102, and
therefore is substantially touching neighboring particulates.
[0046] After preparation of at least one particulate such as the
first particulate 104, the first particulate 104 (and the second
particulate 106 if present) is blended into the matrix of the
solder 102. In an embodiment, blending of the particulate(s) is
carried out according to known technique, such that agglomeration
of the particulate(s) is minimized. Such techniques can include
conventional mechanical alloying equipment.
[0047] Although the shapes for the first particulate 104 and the
second particulate 106 are respectively depicted as round and
irregular, these shapes are depicted to distinguish the two
particulate types.
[0048] FIG. 1 also illustrates the presence of two particulates
according to an embodiment. In an embodiment, the first particulate
104 is a second-phase dispersiod as set forth above, and the second
particulate 106 is the doping material prior to in situ alloying as
set forth above.
[0049] Reference is again made to FIG. 1. In an embodiment, a
bismuth-tin-indium second solder 102 includes bismuth as a major
component. In an embodiment, the bismuth-tin-indium second solder
102 includes bismuth in a range of about 42% to about 62% bismuth.
The tin component is present in a range from about 19% to about 42%
tin. The bismuth-tin-indium second solder 102 also includes indium.
The indium is present in a range from about 7% to about 28%.
[0050] In an embodiment, the bismuth-tin-indium second solder 102
includes bismuth in a range from about 46% to about 57% bismuth,
the tin component is present in a range from about 24% to about
38%, and the indium component is present in a range from about 11%
to about 24%. In an embodiment, the bismuth-tin-indium second
solder 102 includes bismuth in a range of about 52% to about 54%
bismuth, the tin component is present in a range from about 29% to
about 33%, and the indium component is present in a range from
about 15% to about 19%. In an embodiment, the bismuth-tin-indium
second solder 102 includes about 52% bismuth, about 31% tin, and
about 17% indium.
[0051] In an embodiment, the bismuth-tin-indium second solder 102
is prepared with at least one doping material. The at least one
doping material is added to give the bismuth-tin-indium second
solder 102 selected properties. In an embodiment, the
bismuth-tin-indium second solder 102 is doped with about 1% or less
of the at least one doping material. In an embodiment, the
bismuth-tin-indium second solder 102 is doped with about 0.5% or
less of the at least one doping material. In an embodiment, the
bismuth-tin-indium second solder 102 is doped with about 0.1% or
less of the at least one doping material.
[0052] In an embodiment, the at least one doping material for the
bismuth-tin-indium second solder 102 includes silver alone. In an
embodiment, the at least one doping material includes antimony
alone. In an embodiment, the at least one doping material includes
copper alone. Where the at least one doping material is present,
the above-given concentrations of the bismuth-tin-indium second
solder 102 are adjustable proportionally by recalculating
percentages.
[0053] In an embodiment, the at least one doping material includes
any two of silver, antimony, or copper. In an embodiment, the at
least one doping material includes silver and antimony. In an
embodiment, the at least one doping material includes silver and
antimony with silver as the major doping material. In an
embodiment, the at least one doping material includes silver and
antimony with antimony as the major doping material.
[0054] In an embodiment, the at least one doping material includes
silver and copper. In an embodiment, the at least one doping
material includes silver and copper with silver as the major doping
material. In an embodiment, the at least one doping material
includes silver and copper with copper as the major doping
material.
[0055] In an embodiment, the at least one doping material includes
antimony and copper. In an embodiment, the at least one doping
material includes antimony and copper with antimony as the major
doping material. In an embodiment, the at least one doping material
includes antimony and copper antimony with copper as the major
doping material.
[0056] In an embodiment, the at least one doping material includes
all three above-mentioned doping materials. In an embodiment, the
at least one doping material includes all three doping materials
with silver as the majority doping material. In an embodiment, the
at least one doping material includes all three doping materials
with silver as the majority doping material, and copper as the
minority doping material. In an embodiment, the at least one doping
material includes all three doping materials with silver as the
majority doping material, and antimony as the minority doping
material.
[0057] In an embodiment, the at least one doping material includes
all three doping materials with silver as the plurality doping
material and copper as the minority doping material. In an
embodiment, the at least one doping material includes all three
doping materials with silver as the plurality doping material and
antimony as the minority doping material.
[0058] By review of this disclosure, it will become apparent to one
of ordinary skill in the art that combinations of silver, antimony,
and copper are also preparable as doping materials in the
bismuth-tin-indium solders, wherein antimony is the doping material
with the greatest presence, and silver and copper are alternatively
present with one of them in a lowest concentration. Similarly, the
majority or plurality doping material may be complemented by equal
concentrations of the two minority doping materials.
[0059] In an embodiment, the second solder 102 includes any first
particulate 104 that is set forth in this disclosure. In an
embodiment, the second solder 102 includes any combination of a
first particulate 104 and a second particulate 106 that is set
forth in this disclosure.
[0060] In an embodiment, the at least one doping material can be
added prior to effecting the dispersion of the particulate if it is
present. In an embodiment, the at least one doping material can be
mechanically blended into the second solder 102 for in situ
alloying as set forth and illustrated in FIG. 2. In an embodiment,
neither the particulate nor the doping material is present in the
second solder 102.
[0061] FIG. 3 is a cross-section of a chip package 300 according to
an embodiment. The chip package 300 includes a die 320 with an
active surface 322 and a backside surface 324. In an embodiment,
the chip package 300 includes an interface subsystem 326 that is a
solder according to any embodiment set forth in this
disclosure.
[0062] The die 320 is connected to a thermal management device. In
an embodiment, the thermal management device is an integrated heat
spreader (IHS) 328 that is disposed above the backside surface 324
of the die 320. The interface subsystem 326, in the form of a
thermal interface material (TIM) is disposed between the backside
surface 324 of the die 320 and the IHS 328.
[0063] In an embodiment, the IHS 328 is attached to a mounting
substrate 330 with a lip portion 332 of the IHS 328. In an
embodiment, the mounting substrate 330 is a printed circuit board
(PCB), such as a main board, a motherboard, a mezzanine board, an
expansion card, or another mounting substrate with a specific
application.
[0064] In an embodiment, the thermal management device is a heat
sink without a lip structure, such as a simple planar heat sink. In
an embodiment, the thermal management device includes a heat pipe
configuration.
[0065] In an embodiment, the solder such as the solder 100 in FIG.
1 is the main structure of a series of electrical bumps 334. The
electrical bumps 334 are composed of a solder according to any
embodiment set forth in this disclosure. The electrical bumps 334
are each mounted on a series of bond pads 336. The electrical bumps
334 make contact with the active surface 322 of the die 320. By
contrast, the interface subsystem 326 makes thermal contact with
the backside surface 324 of the die 320. A bond-line thickness
(BLT) 338 is depicted. The BLT 338 is the thickness of the
interface subsystem 326. In an embodiment, the BLT 338 is in a
range from about 100 .ANG. to about 1,000 microns.
[0066] FIG. 4 is a cross-section of a flip-chip package 400
according to an embodiment. A die 440, and a substrate 442 onto
which it is mounted, are further mated with a board 444. The die
440 is coupled to the substrate 442 by a plurality of first bumps,
one of which is illustrated with the reference numeral 446. In an
embodiment, the first bumps 446 are composed of a solder according
to any embodiment set forth in this disclosure. The substrate 442
is coupled to the board 444 by a plurality of second bumps, one of
which is illustrated with the reference numeral 448. In an
embodiment, the second bumps 448 are composed of a solder according
to any embodiment set forth in this disclosure.
[0067] FIG. 5 is a cross-section elevation of a wire-bond package
500 according to an embodiment. The wire-bond package 500 includes
a die 550 including an active surface 552 and a backside surface
554. The die 550 is disposed on a mounting substrate 556, which in
turn is disposed on a board 558. Electrical coupling of the die 550
to the board 558 is done through a via 560. The die 550 is first
coupled to the mounting substrate 556 by a bond wire 562 that
connects to a wire-bond pad 564, and that is also assisted by a
wire-bonding ball 566. In an embodiment, the wire-bond pad 564 is
reverse wire bonded to the die 550 by first attaching the bond wire
562 at the wire-bonding ball 566, and second attaching the bond
wire 562 to the die 550.
[0068] In an embodiment, the via 560 is filled with an interconnect
568. In an embodiment, the via 560 is not filled, as depicted in
FIG. 1, and the electrical path relies substantially upon a via
liner 566.
[0069] FIG. 5 also depicts electrical coupling of the die 550 to
the board 558. The die 550 is coupled to a bump 570, which in an
embodiment, is at least partially disposed in the via 560. The bump
570 can be any electrical connection such as a solder ball. In an
embodiment, an interconnect 568 is disposed in the via 560.
[0070] According to an embodiment, the vertical profile of the
entire package is lower due to the bump 570 being at least
partially embedded in the mounting substrate 556. In an embodiment,
the board 558 is a motherboard, a mezzanine board, an expansion
card, or others. In an embodiment, the board 558 is a penultimate
casing for a wireless handheld such as a wireless telephone.
[0071] It can be appreciated that any one or more of the
interconnect 564, the wire-bonding ball 566, and the bump 570 is a
solder according to any of the solder embodiments set forth in this
disclosure.
[0072] FIG. 6 is a process flow diagram 600 according to an
embodiment.
[0073] At 610, the process includes providing a solder according to
any of the embodiments set forth in this disclosure. In an
embodiment, the process flow terminates at 610.
[0074] At 620, a process further includes blending the solder with
a doping material. By way of non-limiting example the first solder
102 or the second solder 102 is blended with any of the doping
materials set forth in this disclosure. In an embodiment, blending
includes pre-alloying. In an embodiment, blending includes
non-alloying blending to achieve a discrete presence of the doping
material until further processing such as by in situ alloying. In
an embodiment, the process flow terminates at 620. In an
embodiment, the process flow originates and terminates at 620.
[0075] At 630, the process flow includes blending the solder with a
second-phase particulate. By way of non-limiting example, the
second-phase particulate is the first particulate 104 and/or the
second particulate 106 according to any of the embodiments set
forth in this disclosure. In an embodiment, the process flow
terminates at 630. In an embodiment, the process flow originates
and terminates at 630.
[0076] In an embodiment the process flow includes both process 620
and 630.
[0077] At 640, the process flow includes printing the solder on a
substrate. By way of non-limiting example, the interface subsystem
326 in FIG. 3 is printed on the substrate, being the die 320 or the
IHS 328. In an embodiment, the process flow terminates at 640. In
an embodiment, the process flow originates and terminates at
640.
[0078] At 642, the process flow includes assembling a mounting
substrate with a die. By way of non-limiting example, the die 440
in FIG. 4, the die 440 and the substrate 442 are assembled. Further
by way of non-limiting example, the die 440 and the board 444 are
assembled as illustrated. In an embodiment, the process flow
terminates at 642. In an embodiment, the process flow originates
and terminates at 642.
[0079] At 650, the solder is reflowed. By way of non-limiting
example, the wire-bonding ball 566 in FIG. 5 is reflowed during
wirebonding thereof. Further by way of non-limiting example, the
bump 568 is reflowed. Further by way of non-limiting example, where
the solder is blended but not pre-alloyed with the doping material,
the doping material alloys in situ with the solder. In an
embodiment, the process flow terminates at 650. In an embodiment,
the process flow originates and terminates at 650.
[0080] At 660, the process flow includes cooling the solder.
[0081] FIG. 7 is a depiction of a computing system according to an
embodiment. The computing system 700 includes a solder bump and/or
an interface subsystem such as any of the solders set forth in this
disclosure. Hereinafter, where the computing system 700 refers to a
microelectronic device that is coupled to a solder, it is
understood to include any of the solders set forth in this
disclosure. One or more of the foregoing embodiments of the solder
may be utilized in a computing system, such as a computing system
700 of FIG. 7. Similarly, the computing system can include a die, a
solder, a solder TIM, and a heat sink according to any of the
article embodiments set forth in this disclosure.
[0082] In an embodiment, the computing system 700 includes at least
one processor which is enclosed in a package 710, a data storage
system 712, at least one input device such as keyboard 714, and at
least one output device such as monitor 716, for example. The
computing system 700 includes a processor that processes data
signals, and may include, for example, a microprocessor, available
from Intel Corporation. In addition to the keyboard 714, the
computing system 700 can include another user input device such as
a mouse 718, for example. Similarly depending upon the complexity
and type of system, the computing system 700 can include a board
720 for mounting at least one of the microelectronic device package
710, the data storage system 712, or other components.
[0083] For purposes of this disclosure, a computing system 700
embodying components in accordance with the claimed subject matter
may include any system that utilizes a microelectronic device
system, which may include for example, a solder embodiment that is
coupled to data storage such as dynamic random access memory
(DRAM), polymer memory, flash memory, and phase-change memory. In
this embodiment, the solder embodiment is coupled to any
combination of these functionalities by being coupled to an
input-output device. In an embodiment, however, the solder
embodiment set forth in this disclosure is coupled to any of these
functionalities. For an example embodiment, data storage includes
an embedded DRAM cache on a substrate that is coupled to a solder
embodiment. Additionally in an embodiment, the solder embodiment is
part of the system with a solder embodiment that is coupled to the
data storage of the DRAM cache. Additionally in an embodiment, a
solder embodiment is coupled to the data storage 712.
[0084] In an embodiment, the computing system 700 can also include
a solder embodiment that is coupled to a digital signal processor
(DSP), a micro controller, an application specific integrated
circuit (ASIC), or a microprocessor. In this embodiment, the solder
embodiment is coupled to any combination of these functionalities
by being coupled to a motherboard or the like. For an example
embodiment, a DSP is part of a chipset that may include a
stand-alone die processor (in package 710) and the DSP as separate
parts of the chipset. In this embodiment, a solder embodiment is
coupled to the DSP, and a separate solder embodiment may be present
that is coupled to the processor in package 710. Additionally in an
embodiment, a solder embodiment is coupled to a DSP that is mounted
on the same board 720 as the package 710.
[0085] It can now be appreciated that embodiments set forth in this
disclosure can be applied to devices and apparatuses other than a
traditional computer. For example, a die can be packaged with an
embodiment of the solder embodiment, and placed in a portable
device such as a wireless communicator or a hand-held device such
as a personal data assistant and the like. Another example is a
solder embodiment that can be packaged as an embodiment and placed
in a vehicle such as an automobile, a locomotive, a watercraft, an
aircraft, or a spacecraft.
[0086] The Abstract is provided to comply with 37 C.F.R.
.sctn.1.72(b) requiring an Abstract that will allow the reader to
quickly ascertain the nature and gist of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims.
[0087] In the foregoing Detailed Description, various features are
grouped together in a single embodiment for the purpose of
streamlining the disclosure. This method of disclosure is not to be
interpreted as reflecting an intention that the claimed embodiments
of the invention require more features than are expressly recited
in each claim. Rather, as the following claims reflect, inventive
subject matter lies in less than all features of a single disclosed
embodiment. Thus the following claims are hereby incorporated into
the Detailed Description, with each claim standing on its own as a
separate preferred embodiment.
[0088] It will be readily understood to those skilled in the art
that various other changes in the details, material, and
arrangements of the parts and method stages which have been
described and illustrated in order to explain the nature of this
invention may be made without departing from the principles and
scope of the invention as expressed in the subjoined claims.
* * * * *