DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Arguments
RE: the rejection of claim(s) under 35 USC 103, Applicant’s request for reconsideration of the finality of the rejection of the last Office action is persuasive and, therefore, the finality of that action is withdrawn. However, further search and consideration prompted the new grounds of rejection presented herein.
Claim Rejections - 35 USC § 112 (a)
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-11 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
MPEP 2164.01(a) states in order to determine compliance with the enablement requirement of 35 U.S.C. 112(a), the Federal Circuit developed a framework of factors in In re Wands, 858 F.2d 731, 737, 8 USPQ2d 1400, 1404 (Fed. Cir. 1988), referred to as the Wands factors to assess whether any necessary experimentation required by the specification is "reasonable" or is "undue." Consistent with Amgen Inc. et al. v. Sanofi et al., 598 U.S. 594, 2023 USPQ2d 602 (2023), the Wands factors continue to provide a framework for assessing enablement in a utility application or patent, regardless of technology area. See Guidelines for Assessing Enablement in Utility Applications and Patents in View of the Supreme Court Decision in Amgen Inc. et al. v. Sanofi et al., 89 FR 1563 (January 10, 2024). These factors include, but are not limited to:
(A) The breadth of the claims;
(B) The nature of the invention;
(C) The state of the prior art;
(D) The level of one of ordinary skill;
(E) The level of predictability in the art;
(F) The amount of direction provided by the inventor;
(G) The existence of working examples; and
(H) The quantity of experimentation needed to make or use the invention based on the content of the disclosure.
RE: Factor A above, the breadth of claims 1-11 covers a semiconductor package including a plurality of first thermal conductive layers and a plurality of second thermal conductive layers, wherein the first thermal conductive layers include a first thermal interface material, wherein the second thermal conductive layers include a second thermal interface material, wherein a thermal conductivity of the second thermal interface material is greater than a thermal conductivity of the first thermal interface material, wherein a stiffness of the first thermal interface material is greater than a stiffness of the second thermal interface material, and wherein the first thermal interface material and the second thermal interface material each include a filler and a resin. The claims broadly cover any type of resin. Claims 1-2, 4-11 cover any type of filler. Claim 3 covers aluminum oxide or aluminum nitride as the filler.
RE: Factor B above, the nature of the invention relates to the different thermal conductivities and different stiffnesses in the first and second thermal interface materials which are controlled by the amount of fillers in resin.
RE: Factor C above, the state of the prior art:
US 20240286391 A1 (“Arihara”) discloses stiffness may be evaluated, for example, by a storage elastic modulus, [0039]. US20150116946 A1 (“Katase”) discloses stiffness is known as Young’s modulus, [0035]. US 20210272935 A1 (“Wang”) also discloses Generally, materials with higher Young's modulus (lower strain for a stress σ) is stiffer than a material with lower Young's modules (higher strain for the same σ). Other measures may also be used to represent stiffness of a material, such as storage modulus, which also accounts for dynamic performance of the material, [0016].
Wong et al., “Thermal Conductivity, Elastic Modulus, and Coefficient of Thermal Expansion of Polymer Composites Filled with Ceramic Particles for Electronic Packaging” School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, 1999 (“Wong”) measured thermal conductivities and elastic moduli of epoxy resins filled with ceramic fillers such as alumina, see abstract. Alumina is aluminum oxide (see the definition for “alumina” by Merriam-Webster). The material for the epoxy resin and fillers are discussed in the Materials sub-section on pg. 3398.
Wong FIG. 4 on pg. 3400 shows the thermal conductivity of the resin composition increases with alumina filler content. Wong FIG. 12 on pg. 3402 shows the storage modulus increases with alumina filler content from 0%vol to 50%vol alumina.
Accordingly, one of ordinary skill in the art would have understood that, in order to make the invention of claim 1, the first interface material would have a larger filler amount than that of the second interface material in order to achieve a greater stiffness as represented by the storage modulus. However, in doing so, the first interface material would have a larger thermal conductivity than that of the second interface material, contrary to the limitation of claim 1 “wherein a thermal conductivity of the second thermal interface material is greater than a thermal conductivity of the first thermal interface material.” Accordingly, one of ordinary skill in the art would not have been enabled to make the invention of claim 1 at least based on Wong and in view of the instant specification as discussed hereafter in other Wand’s Factors.
In claim 2, the second thermal interface material has a greater amount of the filler which results in the second thermal conductivity having a larger thermal conductivity as in claim 1. However, claim 2 still shares the problem of claim 1 in that based on Wong, one of ordinary skill in the art would have understood that in order to make the first interface material have a larger stiffness, the first interface material would have the greater amount of filler instead, contrary to claim 1.
McGrath et al., “Investigation of the thermal, mechanical, and fracture properties of alumina-epoxy composites,” Polymer 49 (2008) 999e1014, (“McGrath”) measured elastic moduli of epoxy resins filled with alumina, see abstract.
McGrath FIG. 5 on pg. 1004 shows the storage modulus increases with alumina filler content for all resin compositions from 0%vol to 50%vol alumina.
Accordingly, McGrath supports the findings of Wong in that the stiffness as represented by the storage modulus increases with filler content.
Tilbrook et al., “On the mechanical properties of alumina–epoxy composites with an interpenetrating network structure,” Materials Science and Engineering A 393 (2005) 170–178, 2005, (“Tilbrook”) discloses alumina-epoxy composite compositions, see abstract.
Tilbrook FIGs. 5-6 on pg. 174 show Young’s modulus increases with alumina filler content from just below 50%vol to around 100%vol.
Accordingly, Tilbrook supports the findings of Wong even with Young’s modulus being used to represent stiffness.
Moloney et al., “The fracture of particulate-filled epoxide resins,” Journal of Materials Science 18 (1983), (“Moloney”) discloses epoxide resins filled with alumina, see abstract.
Moloney FIG. 9 on pg. 213 shows Young’s modulus increases with alumina volume fraction from below 0.2 to around 0.5. The volume fractions 0.2 and 0.5 correspond to 20%vol and 50%vol, respectively.
Accordingly, Moloney supports the findings of Wong even with Young’s modulus being used to represent stiffness.
Claim 4 includes wherein an amount of the filler in the first thermal interface material is in a range of 20 vol % to 50 vol %, and an amount of the filler in the second thermal interface material is in a range of 80 vol % to 97 vol %.
Claim 5 includes an amount of the filler in the first thermal interface material is in a range of 20 vol % to 50 vol %, and an amount of the filler in the second thermal interface material is in a range of 90 vol % to 92 vol %.
The ranges claimed in claims 4, 5 are included in Wong, McGrath, Tilbrook, and Moloney. The claims require the second thermal interface material to have a greater amount of the filler which results in the second thermal conductivity having a larger thermal conductivity as in claim 1. However, in view of McGrath, Tilbrook, and Moloney, one of ordinary skill in the art would have understood that in order to make the first interface material have a larger stiffness as required by claim 1, the first interface material would have the greater amount of filler instead, contrary to claim 1.
US20230012350A1 (“Huang”) discloses the underfill element 106 can be relatively compliant for relieving thermal stress, such as by having a Young's modulus lower than about 15 GPa, and the molding layer 108 can have a higher thermal conductivity for heat dissipation, such as by having a coefficient of thermal expansion (CTE) lower than about 25×10−6. For example, the underfill element 106 can have a higher CTE than the molding layer 108, and the molding layer 108 can have a higher Young's modulus than the underfill element 106. In a specific example, the underfill element 106 has a CTE of 1.73×10−5 and a Young's modulus of 12 GPa, and the molding layer 108 has a CTE of 1.1×10−5 and a Young's modulus of 21 Gpa. This can be achieved by the molding layer 108 having a higher filler content than the underfill element 106, [0027].
Huang discloses The underfill element 106 may be made of or include an insulating material such as an underfill material. The underfill material may include an epoxy, a resin, a filler material, a stress release agent (SRA), an adhesion promoter, another suitable material, or a combination thereof, [0021]. Huang discloses the molding layer 108 is made of or includes an insulating material such as a molding material. The molding material may include a polymer material, such as an epoxy-based resin with fillers dispersed therein, [0024].
Accordingly, Huang further supports Wong in that a higher filler content is associated with a higher Young’s modulus.
RE: Factor D above, the level of one of ordinary skill in the art is a person with a undergraduate degree or graduate degree in electrical engineering or in materials science.
RE: Factor E above, the art is considered to be unpredictable since parameters such as stiffness and thermal conductivity are based on the composition as a whole.
For example, US 20210296190 A1 (“Nakamata”) discloses the coefficient of linear thermal expansion α.sub.1 and the Young's modulus E.sub.1 of the first sealing layer 21 alone as well as the coefficient of linear thermal expansion α.sub.2 and the Young's modulus E.sub.2 of the second sealing layer 22 alone are determined by the composition of components forming each sealing layer. Each of the first sealing layer 21 and the second sealing layer 22 preferably contains a thermosetting resin base material and an inorganic filler, and may be a cured thermosetting resin product obtained by curing a thermosetting resin composition which may optionally contain a curing agent, a curing accelerator, or an additive. Hereinafter, thermosetting resin base materials, inorganic fillers, curing agents, curing accelerators, and additives usable in common for the first sealing layer 21 and the second sealing layer 22 and properties that the components contained in each of the first sealing layer 21 and the second sealing layer 22 have to satisfy will be described, [0062].
Nakamata further discloses The inorganic filler may be a metal oxide or a metal nitride, includes, for example, fused silica, silica (silicon oxide), alumina, aluminum hydroxide, titania, zirconia, aluminum nitride, talc, clay, mica, glass fiber, and the like, but is not limited to these. These inorganic fillers make it possible to enhance the thermal conductivity of the cured product (sealing layer) and reduce the coefficient of thermal expansion. One of these inorganic fillers may be used alone, or two or more of them may be mixed and used. These inorganic fillers may be microfillers or may be nanofillers. Two or more inorganic fillers having different particle sizes and/or types may be mixed and used, [0068].
Accordingly, a resin composition may have multiple ingredients including a curing agent, a curing accelerator, or an additive, and these would change the thermal conductivity and stiffness of the resulting composition. Accordingly, one of ordinary skill in the art would understand that the thermal conductivity and stiffness of a resin composition could not be determined without knowing if the resin composition contains a curing agent, a curing accelerator, or an additive; in such cases, one of ordinary skill in the art would require the identification and amount of the curing agent, a curing accelerator, or an additive used. One of ordinary skill in the art would further require identification of the base resin material.
US 20150325457 A1 (“Kim”) discloses The underfill resin may include an epoxy resin, a curing agent, a curing accelerator, an inorganic filler, and combinations thereof. The epoxy resin may include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a naphthalene type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac epoxy resin, and the like, and combinations thereof. An amine-based curing agent and an imidazole-based curing accelerator may be used as the curing agent and the curing accelerator, respectively, [0097].
Accordingly, even within one category of resin, epoxy resin, there are different types of resins. One of ordinary skill in the art would understand that different base epoxy resins would result in different thermal conductivities and different stiffnesses for the resulting resin composition, and further, not all resins are epoxy resins.
US20020037138A1 (“Kaneko”) discloses the underfill resin comprises an elastomer resin, polyimide resin, epoxy resin, silicone resin, urethane resin, acrylic resin, fluorine resin, polyolefine resin, or any other polymer resin, [0047].
Accordingly, there are different categories of resins, and one of ordinary skill in the art would understand that base resins in different categories would result in different thermal conductivities and different stiffnesses for the resulting resin composition.
Xu et al., “Thermal Conductivity of Polymers and Their Nanocomposites,” Adv. Mater. 2018, 30, 1705544, (“Xu”) discloses although bulk polymers are well-known thermal insulators, their thermal conductivity can be enhanced by two to three orders of magnitude due to chain realignment under strain or stretching.[32] For polymer-based nanocomposites, the experimental thermal conductivity results are less than the theoretical calculations due to the unpredictable large ITR between inorganic fillers and the polymer matrix, see last paragraph in righthand column on pg. 1 to first paragraph in lefthand column column on pg. 2.
Accordingly, the thermal conductivity in a resin/polymer composition is considered unpredictable due to the unpredictable interaction of the resin and inorganic fillers.
Further, Applicant, in arguing against US20150252217A1 (“Czubarow”) (in the response dated March 17, 2026), stated the relationship between composition (e.g., material and filler%), thermal conductivity, and stiffness in filler compositions is complex and unpredictable (see bottom of pg. 9), further supporting the assertion that the art is unpredictable.
At least for the above reasons, the art is considered to be unpredictable as a resin composition can include multiple ingredients, each affecting the thermal conductivity and stiffness for the resulting composition. Even if one of ordinary skill in the art did know the specific composition, at least the thermal conductivity of the composition may be unpredictable due to the unpredictable interaction between the resin base and inorganic filler.
RE: Factor F above, the inventor identified that the thermal interface materials include a resin and filler, see instant specification at [0051]. The inventor identified the fillers as including aluminum oxide or aluminum nitride, as well as the amounts of the fillers, [0051]. The inventor also identified that the third thermal interface material may include carbon fiber, [0063].
The above is essentially the extent of the direction provided by the inventor.
The inventor did not disclose the type of resin(s) used, and the inventor did not disclose the presence of any additional ingredients such as for example a curing agent, a curing accelerator, or an additive.
RE: Factor G above, there are no working examples in the instant specification.
RE: Factor H above, the quantity of experimentation is expected to result in undue experimentation based on the content of the disclosure since the thermal conductivity of a resin composition is unpredictable, and since the instant specification does not disclose the type of resin(s) used, and the inventor did not disclose the presence of any additional ingredients such as for example a curing agent, a curing accelerator, or an additive, and the inventor did not disclose any working examples of resin compositions. Each ingredient would change the thermal conductivity and stiffness of the resulting resin composition simultaneously and one of ordinary skill in the art would need to experiment by selecting one or more resin categories, selecting one or more resin types within the category(ies), selecting different ingredients, adjusting the amounts of these ingredients, and form the resin composition to determine the thermal conductivity and stiffness of the resulting resin composition. Further, one skilled in the art would also have to determine if the different resin compositions would result in a structurally stable overall structure with first and second chip stacks.
For the above reasons, claims 1-11 fail to comply with the enablement requirement as these claims contain subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim Rejections - 35 USC § 112 (b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-11 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 includes “wherein a stiffness of the first thermal interface material is greater than a stiffness of the second thermal interface material,” and the term “stiffness” is indefinite as it is unclear if this means that the Young’s modulus of the first thermal interface material is greater than a Young’s modulus of the second thermal interface material, if the storage modulus of the first thermal interface material is greater than a storage modulus of the second thermal interface material, or if some other parameter/measurement is used to quantify or measure stiffness. For example, US 20240286391A1 (“Arihara”) discloses stiffness may be evaluated, for example, by a storage elastic modulus, [0039]. US20150116946 A1 (“Katase”) discloses stiffness is known as Young’s modulus, [0035]. US 20210272935 A1 (“Wang”) also discloses Generally, materials with higher Young's modulus (lower strain for a stress σ) is stiffer than a material with lower Young's modules (higher strain for the same σ). Other measures may also be used to represent stiffness of a material, such as storage modulus, which also accounts for dynamic performance of the material, [0016].
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over US20160035648A1 (“Zhou”) in view of US20130119527A1 (“Luo”), further in view of Wong (cited in the rejection under 35 USC 112(a)).
RE: Claim 19, Zhou discloses A semiconductor package (100 in FIG. 1), comprising:
a substrate (102b) including a plurality of vias (120 or 102b) including a plurality of vias (120 includes vias, [0012]; FIG. 1 shows 102b includes vias 110);
a first chip stack mounted on the substrate, the first chip stack including a plurality of first semiconductor chips (bottommost 102a and second 102a from the bottom as shown in Annotated FIG. 1 below) sequentially stacked on the substrate;
a second chip stack mounted on a top surface of the first chip stack, the second chip stack including a plurality of second semiconductor chips (third 102a and fourth 102a from the bottom as shown in Annotated FIG. 1 below) sequentially stacked on the first chip stack;
a plurality of first thermal conductive layers (115 under first 102a from the bottom, 115 over first 102a from the bottom as shown in Annotated FIG. 1 below), a first one of the plurality of first thermal conductive layers (115 under first 102a from the bottom, hereinafter “first underfill layer”) between the substrate and the first chip stack, and at least a second one of the plurality of first thermal conductive layers (115 over first 102a from the bottom, hereinafter “second underfill layer”) between first semiconductor chips that are adjacent to each other, the first thermal conductive layers including a first thermal interface material (115 includes underfill material based on its thermal conductivity, [0014], accordingly the first and second underfill layers would have thermal conductive interface material interfacing with 102b and/or with each other);
a plurality of second thermal conductive layers (115 under third 102a from the bottom, 115 over third 102a from the bottom as shown in Annotated FIG. 1 below), a first one of the plurality of second thermal conductive layers (115 under third 102a from the bottom, hereinafter “third underfill layer”) between the first chip stack and the second chip stack, and at least a second one of the plurality of second thermal conductive layers (115 over third 102a from the bottom, hereinafter “fourth underfill layer”) between second semiconductor chips that are adjacent to each other, the second thermal conductive layers including a second thermal interface material (115 includes underfill material based on its thermal conductivity, [0014] accordingly the third and fourth underfill layers would have thermal conductive interface material interfacing with each other); and
a molding layer (132) on the substrate, the molding layer covering the first chip stack and the second chip stack (FIG. 1 shows 132 covering all 102a; Zhou teaches 132 (e.g., an epoxy mold compound) surrounds the first semiconductor dies 102 a, [0016]).
Zhou does not explicitly disclose wherein the first thermal interface material and the second thermal interface material include aluminum oxide,
wherein an amount of the aluminum oxide in the second thermal interface material is greater than an amount of the aluminum oxide in the first thermal interface material.
However, Zhou teaches the assembly 100 can be configured as a hybrid memory cube (HMC) in which the first semiconductor dies 102 a provide data storage (e.g., DRAM dies) and the second semiconductor die 102 b provides memory control (e.g., DRAM control) within the HMC, [0015]. Zhou further teaches although the assembly 100 includes six dies stacked on the interposer 120, in other embodiments the assembly 100 can include fewer than six dies (e.g., two dies, three dies, four dies, or five dies) or more than six dies (e.g., eight dies, twelve dies, sixteen dies, thirty-two dies, etc.). For example, in one embodiment, the assembly 100 can include seven memory dies stacked on two logic dies, [0015].
In the same field of endeavor, Luo discloses the same or different underfill materials 160 may be employed between logic die 102 and memory die 108a, and between each of memory dice 108a through 108d, [0041]. Accordingly, before the effective filing date of the claimed invention, there was a need to determine if the material of the third and fourth underfill layers should be different or the same relative to the material of the first and second underfill layers.
Luo further discloses For example, aluminum oxide fillers have been proposed to enhance thermal conductivity of underfill materials, [0041].
Further Luo discloses it may be desirable to employ an underfill exhibiting a relatively low thermal conductivity (e.g., low k) between logic die 102 and DRAM die 108 a to inhibit heat transfer, while employing another, different underfill material exhibiting a relatively high thermal conductivity (e.g., high k) between DRAM dice 108 a through 108 d to enhance heat transfer, [0041].
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the first underfill layer to have a different thermal interface material from that of the second, third, and fourth underfill layers such that the thermal conductivity of the first underfill layer is relatively lower than the thermal conductivity in the second, third, and fourth underfill layers, and each underfill layer has aluminum oxide as a filler as taught by Lou in order to inhibit heat transfer between the DRAM control die 102b and the DRAM dies 102a, which would prevent the DRAM dies 102 from overheating. The thermal interface material of the first underfill layer corresponds to the claimed first thermal interface material. The thermal interface material of the third and fourth underfill layers corresponds to the claimed second thermal interface material.
In the same field of endeavor, Wong teaches The thermal conductivity as a function of filler loading is shown in Figure 4. It shows a superlinear increase with increase in the filler loading, see bottom paragraph in left column in section titled “Thermal Conductivity” on pg. 3401.
It would have been further obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the first underfill layer to include an aluminum oxide filler amount that is lower relative to the aluminum oxide filler amount in the second, third, and fourth underfill layers as taught by Wong in order to ensure the first underfill layer has a lower thermal conductivity relative to the second, third, and fourth underfill layers in order to inhibit heat transfer between the DRAM control die 102b and the DRAM dies 102a, which would prevent the DRAM dies 102a from overheating.
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Annotated FIG. 1 of Zhou
Claim(s) 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou in view of Luo, further in view of Wong as applied to claim 19, further in view of JP2019052316A (“Nakamura” – previously cited).
RE: Claim 20, the combination of Zhou, Luo, Wong does not explicitly disclose The semiconductor package of claim 19, wherein
the amount of the aluminum oxide in the first thermal interface material is in a range of 20 vol% to 50 vol%, and
the amount of the aluminum oxide in the second thermal interface material is in a range of 80 vol% to 97 vol%.
In the same field of endeavor, Nakamura discloses The resin composition for mold underfill of the present invention preferably contains (E) an inorganic filler. The inorganic filler is not particularly limited as long as it is generally used for a sealing molding material. For example, spherical silica (fused silica etc.), crystalline silica, glass, alumina, pg. 30, lines 7-10.
Alumina is aluminum oxide.
Nakamura further discloses There is no particular limitation on the content in the case where the resin composition for mold underfill contains an inorganic filler, and it is 30% by volume to 90% by volume in the total amount of the resin composition for mold underfill from the viewpoint of fluidity and strength, and is more preferably 40% to 70% by volume, pg. 30, lines 21-30.Nakamura further discloses If the content of the inorganic filler in the resin composition for mold underfill is 30% by volume or more, properties such as the thermal expansion coefficient, thermal conductivity, and elastic modulus of the cured product tend to be further improved, pg. 30, lines 25-27.
Nakamura further discloses when the content is 90% by volume or less, the filling property tends to be better, pg. 30, lines 27-30.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the second, third, and fourth, underfill layers to include an underfill composition containing 90% or less aluminum oxide by volume as taught by Nakamura in order to improve the filling property while increasing thermal conductivity.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the first underfill layer to include 30% by volume as taught by Nakamura in order to ensure the thermal conductivity of the first underfill layer is relatively lower compared to the thermal conductivity of the second, third, and fourth, underfill layers, thereby preventing heat transfer between the between the DRAM control die 102b and the DRAM dies 102a, which would prevent the DRAM dies 102a from overheating.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MICHAEL ANGUIANO whose telephone number is (703)756-1226. The examiner can normally be reached Monday through Friday.
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/MICHAEL ANGUIANO/Examiner, Art Unit 2899
/Brent A. Fairbanks/Supervisory Patent Examiner, Art Unit 2899
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