DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Information Disclosure Statement
The information disclosure statement (IDS) filed on August 22nd, 2024, is being considered by the examiner.
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. However, should applicant desire to obtain the benefit of foreign priority under 35 U.S.C. 119(a)-(d) prior to declaration of an interference, a certified English translation of the foreign application must be submitted in reply to this action. 37 CFR 41.154(b) and 41.202(e). Failure to provide a certified translation may result in no benefit being accorded for the non-English application.
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed. The following title is suggested: ”CERAMIC SUBSTRATE UNIT FOR DISPERSING STRESS CONCENTRATED ON AN EDGE AREA AND METHOD FOR MANUFACTURING SAME”.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
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Annotated Fig. 1 - Oi
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Claim(s) 1-4, 9, 12, 13, and 14 is/are rejected under 35 U.S.C 103 as being unpatentable over Oi et al. (US20170053852A1) hereinafter Oi, and in further view of Masuo et al. (JP2011091184A) hereinafter Masuo.
As to Claim 1, Oi teaches: A ceramic substrate unit (Annotated Fig.1, power-module substrate unit 50) comprising: a ceramic substrate (power-module substrate 10) having a metal layer provided on upper (first layer 15, [0040] “made of an aluminum plate”) and lower surfaces (metal layer 13) of a ceramic base (ceramic substrate 11);
an upper electrode (second layer 16) bonded to an upper metal layer (first layer 15) of the ceramic substrate (power-module substrate 10) so that a semiconductor chip (semiconductor element 30) is mounted thereon (Annotated Fig.1, [0056] ”the semiconductor element 30 is bonded by soldering at an upper surface of the circuit layer 12 (the second layer 16)
and a heat sink (heat sink 20) bonded to a lower metal layer (metal layer 13) of the ceramic substrate (Fig. 1, power-module substrate 10).
Oi does not explicitly teach: having a first stair-shaped protrusion formed on an outer circumferential surface thereof. and having a second stair-shaped protrusion formed on an outer circumferential surface thereof. Oi does teach design changes to the heat sink where thickness of the heat sink is adjusted to reduce thermal stress ([0057]), but does not explicitly teach an upper electrode having a first stair-shaped protrusion formed on an outer circumferential surface and a heat sink having a second stair-shaped protrusion formed on an outer circumferential surface
However, in an analogous art, Masuo teaches: an upper electrode (metal circuit 2) bonded to an upper metal layer of the ceramic substrate (ceramic substrate 1, [0014] “metal circuit 2 formed in one or more appropriate numbers on the surface of the ceramic substrate”) so that a semiconductor chip is mounted thereon, and having a first stair-shaped protrusion (Annotated Fig.2, metal circuit protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0008] “ends of the metal circuit and the metal heat sink both have a stepped structure, the stepped structure having a step portion 5 with a length… and a slope portion 6 that is continuous with the step portion”). and having a second stair-shaped protrusion (Annotated Fig.2, metal heat sink protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0020] “ends of the metal circuit and metal heat sink of the circuit board of the present invention have a stepped structure”). Further, Masuo teaches that modifying edges of metal circuits and heat sinks on a surface of a ceramic substrate improves thermal cycle resistance characteristics ([0003]-[0005]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode to have stair-shaped protrusions. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
As to Claim 2, Oi teaches: The ceramic substrate unit (Annotated Fig.1, power-module substrate unit 50) of claim 1,
Oi does not explicitly teach: wherein each step forming the stairs in the first protrusion and the second protrusion has a different protruding length. Oi does teach an upper electrode and a heat sink but fails to disclose protrusions in a stepped formation.
However, in an analogous art, Masuo teaches: wherein each step (Annotated Fig.2, first step MC, second step MC, first step HS, second step HS) forming the stairs in the first protrusion (metal circuit protrusion) and the second protrusion (Annotated Fig.2, metal heat sink protrusion) has a different protruding length (Annotated Fig.2, [0008] “total length from the end of the brazing material layer to the side wall of the step portion is L1 for the metal circuit and L2 for the metal heat sink “ [0024] “L1 for a metal circuit and L2 for a metal heat sink…it is preferable that L1 ≤ L2”). L1 and L2 correspond to one lower step of first and second stepped protrusions respectively. L1 and L2 correspond to the first step MC and first step HS respectively. Additionally, annotated FIG 2 displays an additional upper step [Annotated Fig.2, second step HS, second step MC] in both the stepped protrusions with no assigned variable, however there is a distinguishable difference in length of between the upper step [Annotated Fig.2, second step HS, second step MC] and lower step [Annotated Fig.2, first step HS, first step MC] in both first (metal circuit protrusion) and second stepped protrusions (metal heat sink protrusion) .
Therefore, it would have been obvious to one of the ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode to have differing protruding lengths for the steps of the stair-shaped protrusions. One would be motivated to do so as differing lengths of the steps significantly influence the amount of warping caused by heating (Masuo, [0026]).
As to Claim 3, Oi teaches: The ceramic substrate unit (Annotated Fig.1, power-module substrate unit 50) of claim 1,
Oi does not explicitly teach: wherein each step forming the stairs in the first protrusion and the second protrusion has an increasing protruding length toward the ceramic substrate. Oi does teach an upper electrode and a heat sink but fails to disclose protrusions in a stepped formation wherein each step forming the stairs has an increasing protruding length towards the ceramic substrate [power-module substrate 10].
However, in an analogous art, Masuo teaches: wherein each step (Annotated Fig.2, first step MC, second step MC, first step HS, second step HS) forming the stairs in the first protrusion (Annotated Fig.2, metal circuit protrusion) and the second protrusion (Annotated Fig.2, metal heat sink protrusion) has an increasing protruding length (Annotated Fig.2, second step MC, second step HS) toward the ceramic substrate (ceramic substrate 1).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode with protrusions with having an increasing protruding length towards the ceramic substrate. One would be motivated to do so as an increase of protruding length allows for a decrease in the amount of warping on the metal circuit side and decreases the stress from the thermal cycle on the heat sink (Masuo, [0026]).
As to Claim 4, Oi teaches: The ceramic substrate unit of claim 1 (Annotated Fig.1, power-module substrate unit 50),
Oi does not explicitly teach: wherein each step forming the stairs in the first protrusion and the second protrusion has a side surface with a shape perpendicular to a horizontal line.
However, in an analogous art, Masuo teaches: wherein each step (Annotated Fig.2, first step MC, second step MC, first step HS, second step HS) forming the stairs in the first protrusion (Annotated Fig.2, metal circuit protrusion) and the second protrusion (Annotated Fig.2, metal heat sink protrusion) has a side surface with a shape perpendicular to a horizontal line step (Annotated Fig.2, [0008] “slope portion 6 with respect to the ceramic substrate (slope angle α1 of the metal circuit, slope angle α2 of the metal heat sink” [0009] “preferable to have at least one embodiment selected from the following: (a) L1 < L2 and L1 + E1 > L2 + E2; (b) α1 ≥ α2, particularly α1 > α2)”). Masuo teaches α1 of the first step MC and α2 of the first step can be adjusted.
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have each step forming the stairs to be right-angled. One would be motivated to do so as having too large of a slope makes horizontal cracks more likely to occur while too small of a scope means a smaller area for the semiconductor element to be mounted (Masuo, [0026]).
As to Claim 9, Oi/Masuo teaches: The ceramic substrate unit of claim 1 (Oi, Annotated Fig.1, power-module substrate unit 50), wherein the upper electrode (Oi, second layer 16) and the heat sink (Oi, heat sink 20) are each made of any one of Cu, Al, and a Cu alloy (Oi, [0040] “second layer 16 is made of an aluminum plate having purity lower than 99.90 mass %...or an aluminum alloy plate such as A3003, A6063, A5052 or the like of the JIS standard.” [0042] “material of the heat sink 20… or an aluminum alloy plate such as A3003, A6063, A5052 or the like can be used”). Note: The claims recite at least one of the materials listed, Oi teaches aluminum alloy which satisfies this limitation .
As to Claim 12, Oi teaches: A method of manufacturing a ceramic substrate unit (Annotated Fig.1, power-module substrate unit 50), comprising: preparing a ceramic substrate (power-module substrate 10, Annotated Fig.1) including a metal layer provided on upper (first layer 15, [0040] “made of an aluminum plate”) and lower surfaces (metal layer 13) of a ceramic base (ceramic substrate 11);
preparing an upper electrode (second layer 16) formed so that a semiconductor chip (second layer 16) is mounted thereon (Annotated Fig.1, [0056] ”the semiconductor element 30 is bonded by soldering at an upper surface of the circuit layer 12 (the second layer 16”)
preparing a heat sink (heat sink 20)
bonding the upper electrode (second layer 16) to an upper metal layer (first layer 15) of the ceramic substrate (Annotated Fig.1, power-module substrate 10) and bonding the heat sink (heat sink 20) to a lower metal layer (metal layer 13) of the ceramic substrate (Annotated Fig.1, power-module substrate 10).
Oi does not teach: and having a first stair-shaped protrusion formed on an outer circumferential surface thereof having a second stair-shaped protrusion formed on an outer circumferential surface thereof. Oi does teach design changes to the heat sink where thickness of the heat sink is adjusted to reduce thermal stress ([0057]) but does not explicitly teach preparing an upper electrode having a first stair-shaped protrusion formed on an outer circumferential surface and preparing a heat sink having a second stair-shaped protrusion formed on an outer circumferential surface.
However, in an analogous art, Masuo teaches: and having a first stair-shaped protrusion (Annotated Fig.2, metal circuit protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0008] “ends of the metal circuit and the metal heat sink both have a stepped structure, the stepped structure having a step portion 5 with a length… and a slope portion 6 that is continuous with the step portion”); having a second stair-shaped protrusion (Annotated Fig.2, metal heat sink protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0020] “ends of the metal circuit and metal heat sink of the circuit board of the present invention have a stepped structure”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode to have stair-shaped protrusions. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
As to Claim 13, Oi teaches: The method of claim 12 (Annotated Fig.1, power-module substrate unit 50), wherein in the preparing of the upper electrode (second layer 16),
Oi does not teach: the first protrusion is formed by at least one of chemical etching and cutting machining. Oi does teach an upper electrode but fails to disclose the formation of a first protrusion by at least one of chemical etching and cutting machining.
However, in an analogous art, Masuo teaches: the first protrusion (Annotated Fig.2, metal circuit protrusion) is formed by at least one of chemical etching and cutting machining ([0029] “was used as an etchant to form the circuit pattern and heat dissipation pattern.” [0030] ”then cutting a predetermined shape of step portion using, for example, a vertical machining center.”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure of the upper electrode as taught by Oi to have a first protrusion made from at least one of etching and machining. One would be motivated to do so as etching allows for the slope portion of the step structure to be formed at a desired angle, and cutting by way of machine allows for a desired thickness to be achieved (Masuo, [0029]-[0030]).
As to Claim 14, Oi teaches: The method of claim 12 (power-module substrate unit 50, Annotated Fig.1), wherein in the preparing of the heat sink (heat sink 20),
Oi does not teach: the second protrusion is formed by at least one of chemical etching and cutting machining. Oi does teach design changes to the heat sink where thickness of the heat sink is adjusted to reduce thermal stress ([0057]) but fails to disclose the formation of a second protrusion by at least one of chemical etching and cutting machining.
However, in an analogous art, Masuo teaches: the second protrusion (Annotated Fig.2, metal heat sink protrusion) is formed by at least one of chemical etching and cutting machining ([0029] “was used as an etchant to form the circuit pattern and heat dissipation pattern.” [0030] ”then cutting a predetermined shape of step portion using, for example, a vertical machining center.”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure of the heat sink as taught by Oi to have a second protrusion made from at least one of etching and machining. One would be motivated to do so as etching allows for the slope portion of the step structure to be formed at a desired angle, and cutting by way of machine allows for a desired thickness to be achieved (Masuo, [0029]-[0030]).
Claim(s) 5 and 6 is/are rejected under 35 U.S.C 103 as being unpatentable over Oi/Masuo as applied to claims 1-4, 9, 12, 13, and 14 above, and in further view of Seong et al. (KR20190119000 A); hereinafter Seong.
As to Claim 5, Oi teaches: The ceramic substrate unit of claim 1 (Annotated Fig.1, power-module substrate unit 50),
Oi does not explicitly teach: wherein each step forming the stairs in the first protrusion and the second protrusion includes a concave portion, and the concave portion has a shape that is concave toward the ceramic substrate. Oi does teach the upper electrode [second layer 16] and the heat sink [heat sink 20] but fails to disclose a first and second protrusion. Additionally, Oi does teach design changes to alleviate thermal stress [0057].
However, in an analogous art, Masuo teaches: wherein each step (Annotated Fig.2, first step MC, second step MC, first step HS, second step HS) forming the stairs in the first protrusion (Annotated Fig.2, metal circuit protrusion) and the second protrusion (Annotated Fig.2, metal heat sink protrusion).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode to have stair-shaped protrusions. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
However, Oi as modified by Masuo, does not explicitly teach: includes a concave portion, and the concave portion has a shape that is concave toward the ceramic substrate.
In an analogous art, Seong teaches: includes a concave portion, and the concave portion has a shape that is concave toward the ceramic substrate (Fig.6, [0046] “tapered protrusion (142) has a curved slope and can be formed in a concave shape toward the ceramic substrate (120)”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Seong to modify the structure as taught by Oi/Masuo to have a protrusion end portion formed on a portion on which any one concave portion is in contact with the other concave portion. One would be motivated to do so as the tapering can maintain its bonding strength since “the area protruding in the outer direction is narrow” (Seong, [0048]).
As to Claim 6, Oi teaches: The ceramic substrate unit of claim 5 (Annotated Fig.1, power-module substrate unit 50),
Oi does not explicitly teach: wherein the first protrusion and the second protrusion each have a protrusion end portion formed on a portion on which any one concave portion is in contact with the other concave portion. Oi does teach the upper electrode where the first protrusion is formed and the heat sink where the second protrusion is formed but fails to disclose a first and second protrusion. Additionally, Oi does teach design changes to alleviate thermal stress [0057].
However, in an analogous art, Masuo teaches: wherein the first protrusion (Annotated Fig.2, metal circuit protrusion) and the second protrusion (Annotated Fig.2, metal heat sink protrusion)
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a heat sink and upper electrode to have stair-shaped protrusions. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
However, Oi as modified by Masuo, does not explicitly teach: each have a protrusion end portion formed on a portion on which any one concave portion is in contact with the other concave portion.
In an analogous art, Seong teaches: each have a protrusion end portion formed on a portion on which any one concave portion is in contact with the other concave portion (Fig.6, [0020] “multiple concave portions formed therein, and a protrusion may be formed at the portion where the concave portion contacts another concave portion” [0050] “a pointed protrusion may be formed in the multi-stage protrusion (144) at the part where the concave part (146) and another concave part (146) meet”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Seong to modify the structure as taught by Oi/Masuo to have a protrusion end portion formed on a portion on which any one concave portion is in contact with the other concave portion. One would be motivated to do so as the multi-stage protrusion can maintain a strong bonding strength (Seong, [0051]).
Claim(s) 7, 8, 10, 11, 15, and 16 is/are rejected under 35 U.S.C 103 as being unpatentable over Oi/Masuo as applied to claims 1-4, 9, 12, 13, and 14 above, and in further view of Hiroshi et al. (EP2492958 A1); hereinafter Hiroshi.
As to Claim 7, Oi teaches: The ceramic substrate unit of claim 1 (Annotated Fig.1, power-module substrate unit 50), wherein the heat sink includes (heat sink 20):
a body portion having an upper surface (Annotated Fig.1, heat sink 20) bonded to the lower metal layer (Annotated Fig.1, metal layer 13);
Oi does not explicitly teach: a body portion having an upper surface bonded to the lower metal layer; and a flow path portion disposed on a lower surface of the body portion and forming a passage through which refrigerant flows, and the body portion has the second protrusion formed on an outer circumferential surface thereof. Oi does teach a body portion having an upper surface [heat sink 20] bonded to the lower metal layer [metal layer 13].
However, in an analogous art, Masuo teaches: and the body portion (Annotated Fig.2, metal heat sink 3) has the second protrusion (Annotated Fig.2, metal heat sink protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0008]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a second protrusion formed on an outer circumferential surface thereof. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
However, Oi as modified by Masuo, does not explicitly teach: a body portion having an upper surface bonded to the lower metal layer; and a flow path portion disposed on a lower surface of the body portion and forming a passage through which refrigerant flows
In an analogous art, Hiroshi teaches: a body portion having an upper surface (top plate part 141) bonded to the lower metal layer (metal layer 113); and a flow path portion (flow passages 142) disposed on a lower surface of the body portion (Fig.7) and forming a passage through which refrigerant flows (Fig. 7, [0067] “supplying a cooling medium (for example cooling water) therethrough”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the structure of the heat sink as taught by Oi/Masuo to include an upper body portion and a flow path portion disposed on a lower surface of the body portion. One would be motivated to do so as the flow portions supply a cooling medium that allows the heat sink to cool the substrate unit (Hiroshi, [0067]).
As to Claim 8, Oi/Masuo teaches: The ceramic substrate unit of claim 7 (Oi, Annotated Fig.1, power-module substrate unit 50),
Oi/Masuo does not explicitly teach: wherein the plurality of flow path portions are provided in a bar shape and disposed horizontally at an interval. Oi does teach a heat sink [heat sink 20] assembled as part of a cooler in which coolant circulates but fails to disclose the shape of the plurality of flow path portions.
However, in an analogous art, Hiroshi teaches: wherein the plurality of flow path portions (flow passages 142) are provided in a bar shape and disposed horizontally at an interval (Fig.7)
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the structure of the heat sink as taught by Oi/Masuo to have a plurality of flow path portions in a bar shape disposed horizontally at an interval. One would be motivated to do so as the flow portions supply a cooling medium that allows the heat sink to cool the substrate unit (Hiroshi, [0067]).
As to Claim 10, Oi/Masuo teaches: The ceramic substrate unit of claim 1 (Oi, Annotated Fig.1, power-module substrate unit 50, Annotated Fig.1), further comprising a first bonding layer (Oi, Annotated Fig. 1, brazing material 40 first bonding layer (FBL)) disposed between the upper metal layer (Oi, first layer 15) of the ceramic substrate (Oi, power-module substrate 10) and the upper electrode (Oi, second layer 16) and bonding the ceramic substrate (Oi, power-module substrate 10) and the upper electrode (Oi, second layer 16),
Oi/Masuo does not explicitly teach: wherein the first bonding layer is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body. Oi does teach brazing material 40 composed of an alloy as a bonding layer used to bond the upper electrode and upper metal layer but fails to disclose one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body [0048].
However, in an analogous art, Hiroshi teaches: wherein the first bonding layer (Ag sintered layer 124) is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body ([0079] “the ceramic substrate 111 and the circuit layer 112 (metal plate 122) are bonded with each other by having Ag in the Ag sintered layer 124 formed on the one surface of the ceramic substrate 111”. Note: The claims recite at least one of the materials listed, Hiroshi teaches a material including an Ag sintered body which satisfies this limitation.
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the composition of the first bonding layer as taught by Oi/Masuo. One would be motivated to do so as the presence of an Ag sintered body in the bonding layer [fixation layer] creates a strong bond even under bonding conditions of a low temperature and short period of time (Hiroshi, [0079]).
As to Claim 11, Oi/Masuo teaches: The ceramic substrate unit of claim 1 (Oi, Annotated Fig.1, power-module substrate unit 50, Annotated Fig.1), further comprising a second bonding layer (Oi, Annotated Fig. 1, brazing material 40, second bonding layer (SBL)) disposed between the lower metal layer (Oi, metal layer 13) of the ceramic substrate (Oi, power-module substrate 10) and the heat sink (Oi, heat sink 20) and bonding the ceramic substrate (Oi, power-module substrate 10) and the heat sink (Oi, heat sink 20),
Oi/Masuo does not explicitly teach: wherein the second bonding layer is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body. Oi does teach brazing material 40 composed of an alloy as a bonding layer used to bond the heat sink and lower metal layer but fails to disclose one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body [0048].
However, in an analogous art, Hiroshi teaches: wherein the second bonding layer (Ag sintered layer 125) is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body ([0079] “Ag in the Ag sintered layer 125 formed on the other surface of the ceramic substrate 111…and thereby the ceramic substrate 111 and the metal layer 113 (metal plate 123) are bonded with each other”). Note: The claims recite at least one of the materials listed, Hiroshi teaches a material including an Ag sintered body which satisfies this limitation.
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the composition of the second bonding layer as taught by Oi/Masuo. One would be motivated to do so as the presence of an Ag sintered body in the bonding layer [fixation layer] creates a strong bond even under bonding conditions of a low temperature and short period of time (Hiroshi, [0079]).
As to Claim 15, Oi teaches: The method of claim 12 (Annotated Fig.1, power-module substrate unit 50), wherein in the preparing the heat sink (heat sink 20), the heat sink (heat sink 20) includes:
a body portion having an upper surface (Annotated Fig.1, heat sink 20) bonded to the lower metal layer (Annotated Fig.1, metal layer 13);
Oi does not explicitly teach: a body portion having an upper surface bonded to the lower metal layer; and plurality of flow path portions disposed on a lower surface of the body portion and forming a passage through which refrigerant flows, and the body portion has the second protrusion formed on an outer circumferential surface thereof. Oi does teach a body portion having an upper surface [heat sink 20] bonded to the lower metal layer [metal layer 13].
However, in an analogous art, Masuo teaches: and the body portion (annotated Fig.2, metal heat sink 3 has the second protrusion (Annotated Fig.2, metal heat sink protrusion) formed on an outer circumferential surface thereof (Annotated Fig.2, [0008]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Masuo to modify the structure as taught by Oi to have a second protrusion formed on an outer circumferential surface thereof. One would be motivated to do so as the stepped structure is “responsible for distributing the vertical tensile stress generated at the ends of the metal circuit and metal heat sink due to the thermal cycle into a horizontal direction” (Masuo, [0021]).
However, Oi as modified by Masuo, does not explicitly teach: a body portion having an upper surface bonded to the lower metal layer; and a flow path portion disposed on a lower surface of the body portion and forming a passage through which refrigerant flows.
In an analogous art, Hiroshi teaches: a body portion having an upper surface (top plate part 141) bonded to the lower metal layer (metal layer 113); and a flow path portion (flow passages 142) disposed on a lower surface of the body portion and forming a passage through which refrigerant flows (Fig. 7, [0067] “supplying a cooling medium (for example cooling water) therethrough”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the structure of the heat sink as taught by Oi/Masuo to include an upper body portion and a flow path portion disposed on a lower surface of the body portion. One would be motivated to do so as the flow portions supply a cooling medium that allows the heat sink to cool the substrate unit (Hiroshi, [0067]).
As to Claim 16, Oi/Masuo teaches: The method of claim 12 (Oi, Annotated Fig. 1, power-module substrate unit 50, Annotated Fig.1), wherein the bonding of the upper electrode (Oi, second layer 16) to the upper metal layer (Oi, first layer 15) of the ceramic substrate (Oi, power-module substrate 10) and bonding of the heat sink (Oi, heat sink 20) to the lower metal layer (Oi, metal layer 13) of the ceramic substrate (Oi, power-module substrate 10) includes:
arranging a first bonding layer (Oi, Annotated Fig. 1, FBL) between the upper metal layer (Oi, first layer 15) and the upper electrode (Oi, second layer 16) and arranging a second bonding layer (Oi, Annotated Fig. 1, SBL) between the lower metal layer (Oi, metal layer 13) and the heat sink (Oi, heat sink 20); and
bonding the upper electrode (Oi, second layer 16) and the heat sink (Oi, heat sink 20) to the ceramic substrate (Oi, power-module substrate 10) via the first bonding layer (Oi, Annotated Fig. 1, FBL) and the second bonding layer (Oi, Annotated Fig. 1, SBL), and
Oi/Masuo does not explicitly teach: the first bonding layer and the second bonding are made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body. Oi does teach brazing material 40 as two separate layers that are analogous to a first bonding layer and second bonding layer but fails to disclose one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body [0048].
However, in an analogous art, Hiroshi teaches: the first bonding layer and the second bonding layer (metal layer 113) are made of a material including at least one of Ag, Cu, AgCu, and AgCuTi or a material including an Ag sintered body ([0079] “the ceramic substrate 111 and the circuit layer 112 (metal plate 122) are bonded with each other by having Ag in the Ag sintered layer 124 formed on the one surface of the ceramic substrate 111…Ag in the Ag sintered layer 125 formed on the other surface of the ceramic substrate 111…and thereby the ceramic substrate 111 and the metal layer 113 (metal plate 123) are bonded with each other”). Note: The claims recite at least one of the materials listed, Hiroshi teaches a material including an Ag sintered body which satisfies this limitation.
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Hiroshi to modify the composition of the first and second bonding layer as taught by Oi/Masuo. One would be motivated to do so as the presence of an Ag sintered body in the bonding layer [fixation layer] creates a strong bond even under bonding conditions of a low temperature and short period of time (Hiroshi, [0079]).
Conclusion
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/MASHAL AHMED/Examiner, Art Unit 2812
/William B Partridge/Supervisory Patent Examiner, Art Unit 2812
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