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 .
Claim Rejections - 35 USC § 112
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 7 and 10-13 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.
Regarding claims 7, 10, and 12, these claims have been converted from an apparatus claim (a power conductor module comprising) to a method claim in the most recent amendment, but they include language such as “formed” and “brazed”, but the claim is directed to a method step. This type of language is unclear as to the scope specifically as to what is the meaning of: having happened in the past (i.e. formed or brazed) vs active method steps (i.e. removing, disposing… ). Method claims can include structure, but they should describe only the structure that helps further define the method step, for example claim 7 can state “wherein the ceramic substrate comprises: a metal electrode pattern on top of a ceramic base plate”. Also, if the ‘formed or brazed’ is intended to be an active method step then these claims should describe the active steps. For example, in claim 7 - “The method of claim 1, further comprising: forming the ceramic substrate, before the step of laminating and brazing the ceramic substrate, by forming an electrode pattern composed of a metal on a ceramic base material.”
Claims 11 and 13 further limit claims 10 and 12 above, therefore, fall under the same rejection.
While this is not part of the rejection - it is also noted in claims 8, 9, 11, and 13 some of them say “made of” and others say “composed of”, for claim consistency, it is recommended to keep the same wording or possibly simply claiming “wherein the brazen filler layer includes at least one of Ag, Cu, AgCu, and AgCuTi.”
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
Claims 1-4, 7-13 are rejected under 35 U.S.C. 103 as being unpatentable over Yokota et al (US Publication 20090045506) in view of Kirkham (US Publication 20210237183).
Regarding claim 1, Yokota teaches a power semiconductor module, the method comprising:
disposing the[[a]] brazing filler layer on an upper surface of the annealed base plate (Fig. 6, 51 between Cu-Mo substrate 30 and ceramic substrate 50a, para 171); and
laminating and brazing a ceramic substrate onto the base plate on which the brazing filler layer is disposed[[.]] (para 171)
Yokota does not specifically teach:
removing [[a]] thermal stress by annealing a base plate before disposing a brazing filler layer;
wherein the removing thermal stress by the annealing the base plate relieves thermal stress in the base plate generated by expansion and thermal contraction during the brazing process.
Kirkham teaches:
removing [[a]] thermal stress by annealing a base plate before disposing a brazing filler layer (para 38, “pre-braze condition provided in a fully-annealed “O” temper”);
wherein the removing thermal stress by the annealing the base plate relieves thermal stress in the base plate generated by expansion and thermal contraction during the brazing process (an O temper is a full anneal in metal and removes thermal and mechanical stresses by heating the material above its recrystallization temperature and cooling it slowly).
It is noted that it is well known within the art that a benefit of metal/alloy annealing prior to brazing (thermal bonding processes in general) is removal of internal thermal stress thus relaxing the crystal structure, reducing dislocations, decreasing hardness, and increasing ductility of the metal/alloy. It is also noted that it is well known within the art that annealing of thermal baseplates prior to brazing or soldering is common practice to reduce residual stresses and manage warpage. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Yokota to include annealing a baseplate to remove thermal stress prior to brazing as taught by Kirkham in order to improve the mechanical and thermal properties of the device.
Regarding claim 2, Yokota as modified teaches the limitations of claim 1 upon which claim 2 depends.
Yokota teaches wherein in the removing of the thermal stress by the annealing, an annealing temperature is 600°C to 750°C (para 150, 700°C).
Regarding claim 3, Yokota as modified teaches the limitations of claim 1 upon which claim 3 depends.
Yokota teaches wherein in the disposing of the brazing filler layer, the brazing filler layer (para 171, Ag-Cu type brazing material) is disposed on the upper surface of the base plate by any one method of paste application, foil attachment, and P-filler (para 171).
Yokota does not specifically teach the brazing filler layer having a thickness that is equal to or larger than 5 µm and equal to or smaller than 100 µm.
The typical thickness for Cu-Ag brazing material in the industry is known to be between 10-100µm.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Yokota to include the semiconductor industry standard brazing filler layer thickness in order to improve the thermal conductivity of the device. A thinner brazing filler layer can reduce thermal resistance, which is critical for the efficient heat dissipation required by high-power semiconductor devices.
Regarding claim 4, Yokota as modified teaches the limitations of claim 1 upon which claim 4 depends.
Yokota teaches wherein the brazing is performed at 800°C to 950°C (para 150, 800°C), and upper weighting or pressurizing is performed during brazing (para 150, pressed together).
Regarding claim 7, Yokota as modified teaches the limitations of claim 1 upon which claim 7 depends.
Yokota teaches wherein in the ceramic substrate, an electrode pattern composed of a metal is formed on a ceramic base material (Fig. 8, 108 b, para 4).
Regarding claim 8, Yokota as modified teaches the limitations of claim 1 upon which claim 8 depends.
Yokota teaches wherein the brazing filler layer is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi (para 171, AgCu).
Regarding claim 9, Yokota as modified teaches the limitations of claim 1 upon which claim 9 depends.
Yokota teaches wherein the base plate is composed of at least one of Cu, Al, W, AlSiC, CuMo, CuW, Cu/CuMo/Cu, Cu/Mo/Cu, and Cu/W/Cu, or a composite material thereof (para 163, Cu and Mo).
Regarding claim 10, Yokota as modified teaches the limitations of claim 1 upon which claim 10 depends.
Yokota teaches wherein the base plate comprises:
a first metal sheet (Fig. 4, 13b);
a second metal sheet formed on an upper surface of the first metal sheet (Fig. 4, 12 on upper surface of 13b); and
a third metal sheet formed on an upper surface of the second metal sheet (Fig. 4, 13a on upper surface of 12), wherein the first metal sheet and the third metal sheet are formed of the same metal material (para 150, Cu alloys), and wherein the second metal sheet is formed of a metal material different from the metal material of the first metal sheet and the third metal sheet (para 150, Mo).
Regarding claim 11, Yokota as modified teaches the limitations of claim 10 upon which claim 11 depends.
Yokota teaches wherein the second metal sheet is composed of one metal sheet of Mo, W, CuMo, and CuW, or a mixed metal sheet thereof (para 150, Mo), and
wherein the first metal sheet and the third metal sheet are composed a Cu metal sheet (para 150, Cu alloys).
Regarding claim 12, Yokota as modified teaches the limitations of claim 10 upon which claim 12 depends.
Yokota teaches comprising a brazing filler disposed between the first metal sheet and the second metal sheet and between the second metal sheet and the third metal sheet, wherein the first metal sheet, the second metal sheet, and the third metal sheet are brazed onto each other through the brazing filler (Fig. 4, para 144-150, Sn-Cu layers 13a and 13b brazed to Mo base 12).
Regarding claim 13, Yokota as modified teaches the limitations of claim 12 upon which claim 13 depends.
Yokota teaches wherein the brazing filler is made of a material including at least one of Ag, Cu, AgCu, and AgCuTi (para 171, Ag-Cu type brazing material).
Response to Arguments
Applicant’s arguments with respect to claim 1 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument (Applicant’s arguments are directed to the annealing aspects and why it is believes that Yokata does not disclose the specific annealing process – which a new reference is now used to teach that aspect of the claim language).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to NICHOLAS HUTSON whose telephone number is (571)270-1750. The examiner can normally be reached Mon-Fri 8am-5pm.
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/NICHOLAS LELAND HUTSON/ Examiner, Art Unit 2818
/JEFF W NATALINI/ Supervisory Patent Examiner, Art Unit 2818