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 § 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.
Claims 1-4 and 6 are rejected under 35 U.S.C. 103 as being unpatentable over Terasaki et al. (US 9648737, hereafter “Terasaki”) in view of Schwobel et al. (US 2022/0411339, hereafter “Schwobel”).
Regarding claim 1, Terasaki discloses a method for producing an active metal ceramic substrate for manufacturing a power module substrate (see Technical field- col. 1), comprising:
coating/printing a Ti paste 24 (first paste) prepared by mixing titanium (first metal composition) and a first organic medium (resin) onto a side surface of a ceramic substrate 11 (see fig. 5; col. 4, lines 63-66) to form a first sub-layer (fig. 5; col. 5, lines 32-44; col. 6, lines 24-30); wherein the first metal composition consists of titanium as active metal and thickness of the first sub layer is 10 micron in one embodiment (col. 6, lines 50-52), which meets endpoint of recited range between 1-10 microns;
coating/printing a second layer 25 (brazing filler material) prepared by using second metal composition onto a side surface of the first sub layer that is away from the ceramic substrate 11 (fig. 5; col. 4, lines 63-66) to form a second sub-layer (fig. 5; col. 6, lines 37-44); wherein the second metal composition includes copper (Cu) and tin (Sn) in the brazing filler (Cu-P-Sn-Ni filler) and thickness of the second sub layer is set in a range of 5-150 microns- exemplary thickness of 20 micron (see Table 1 examples), which meets recited range 6-24 microns. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990), MPEP 2144.05;
disposing a conductive metal layer 22 (Cu foil) onto a side surface of the second sub layer 25 that is away from the first sub layer 24, so as to form the active metal ceramic substrate (see fig. 5).
Terasaki differs from the claim with respect to the second metal composition including a second active metal and mixing with a second organic medium to form a second paste. However, such constituents are known in the metallized bonding art. Similar to Terasaki, Schwobel (also drawn to method of producing a metal-ceramic substrate- abstract) discloses applying a filler metal material to a side surface of a ceramic substrate [0018]. Schwobel teaches that the solder filler material can be selected from several types of metals and metallic alloys, including tin-copper, tin-bismuth, tin-antimony, and indium-tin alloys [0025] and includes an active metal selected from titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V) and hafnium (Hf) [0026], which are identical to the active metals employed in Applicant’s invention. Specifically, the active metal assists to produces a connection between the solder and ceramic by chemical reaction [0026]; the proportion of active metal is about 1-20 wt% [0027]. Schwobel teaches that the solder material can be in the form of a paste and also contains organic medium [0031-0032]; exemplary solder material is a standard paste containing copper, tin and titanium as active metal, wherein active metal is about 7 wt% [0081-0082]. After heating, an integral bond is formed between the ceramic body and the metal foil via the solder material using active metal [0048]. Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to utilize filler paste including active metal(s) similar to Schwobel as second paste in the method of Terasaki because doing so would enable to form an integral bond via chemical reaction, thereby resulting in improved connection with the ceramic substrate. Moreover, the claim would have been obvious because the substitution of one known element for another (copper, copper-tin, tin-based solder alloys) would only have yielded predictable results to one of ordinary skill in the art. KSR International Co. v. Teleflex Inc., 82 USPQ2d 1385 (2007) (see MPEP 2143- exemplary rationales). Thus, Terasaki as modified by Schwobel discloses second paste composition including at least one active metal (Ti, Zr, Ta, etc.), copper, tin and an organic medium. In the combination of Terasaki & Schwobel, the active metal content (Ti paste, >50% Ti) in the first metal composition is greater than an active metal content (Ti < 20 wt%) in the second paste composition.
As to claims 2-3, Terasaki discloses performing a vacuum brazing/sintering process to braze the conductive metal layer onto the ceramic substrate through the first sub layer and the second sub layer (col. 6, lines 60-67), wherein heating temperature is about 650 °C (see Table 1 examples- heating conditions) - this falls within the claimed temperature range between 600 °C and 900°C. Examiner maintains prior official notice with respect to utilizing vacuum during brazing or sintering process since it is conventional and doing so would prevent oxidation of the surfaces being joined.
As to claim 4, Terasaki discloses the thickness of the second sub layer (20 micron) being greater than the thickness of the first sub layer (10 micron), which overlaps with the recited range, thereby rendering the claim obvious.
As to claim 6, Terasaki as modified by Schwobel in claim 1 above discloses the active metal being titanium in both the first metal composition and the second metal composition.
Claims 4-5 are rejected under 35 U.S.C. 103 as being unpatentable over Terasaki in view of Schwobel as applied to claim 1 above, and further in view of Keusseyan (US 5033666, hereafter “Keusseyan”).
As to claims 4-5, Terasaki discloses the thickness of the second sub layer (20 micron) being greater than the thickness of the first sub layer (10 micron), but is silent with respect to first sub layer being 1-6 micron. However, such feature is known in the art. Keusseyan discloses a method for producing an active metal ceramic substrate (col. 2, lines 50-60; see examples), wherein a first solder paste (first conductor composition) is applied onto a side surface of a ceramic substrate (col. 3, lines 35-40), a second solder paste (second conductor composition- col. 5, lines 34-45) is applied onto a side surface of the first sub-layer that is away from the ceramic substrate, and drying the second solder paste to form a second solder layer (second metallization layer) (col. 3, lines 3-13; col. 7- example 1; col. 10- example 4; claim 1- steps e) to f)). Keusseyan teaches the second solder layer (second metallization layer) in the range of about 10-30 microns (col. 5, lines 29-30), greater than the thickness of the first solder layer (first metallization layer), which is about 5-20 microns (col. 3, line 58)- the thickness ranges overlap with recited ranges, wherein a thickness ratio between the second solder layer (20 microns) and the first solder layer (5 micron) is about 4. Keusseyan further teaches that the thickness of the solder/metallization layer depends on the type and the melting temperature of the braze alloy as well as peak brazing temperature (col. 5, lines 22-30). Given teachings of Keusseyan, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to form desired thickness of the first sub layer and the second sub layer from disclosed ranges in the combination of Terasaki & Schwobel in accordance with heating temperature and the type of substrate/component(s) beings brazed.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Terasaki in view of Schwobel as applied to claim 1 above, and further in view of Sakuraba et al. (US 6221511, “Sakuraba”).
As to claim 7, Terasaki or Schwobel does not mention the paste viscosity in a range of 50-300 mPa*s. However, examiner points out that viscosity is a temperature-dependent property and thus varies based on ambient conditions. Sakuraba (also directed to producing a metal-ceramic substrate by using brazing/soldering material) teaches that the braze paste includes 55-75 parts solvent & 25-45 parts binder by volume to make 10-14 parts by weight of the organic solvent to prepare the paste (col. 2, lines 40-46; col. 3, lines 30-38). If the organic vehicle is less than 10 parts by weight, the resulting viscosity tends to produce blurred printing. On the other hand, if the organic vehicle is more than 14 parts by weight, then resulting paste has very low viscosity with washout occurring (col. 3, lines 39-43). Reading this, artisan of ordinary skill would appreciate and understand the paste viscosity is a variable for achieving art-recognized result of sufficient coating on the ceramic substrate so that it prevents blurring or washout and forms the desired bonding layer. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to choose the instantly claimed paste viscosity through process optimization in the method of Terasaki & Schwobel, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. MPEP 2144.05 (II).
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Terasaki in view of Schwobel as applied to claim 1 above, and further in view of Keusseyan (US 5033666) & Eguchi et al. (CA 1287557 C, “Eguchi”, of record).
As to claim 8, Terasaki discloses the Ti paste organic medium including resin, solvent and dispersant (col. 5, lines 36-37; col. 13, lines 38-45). Keusseyan teaches that organic medium is conventional in the art and typically includes solvent, solutions of resin (paste forming agent) and thixotropic agent; the most widely used solvents includes alcohols, alcohols esters, terpenes, carbitol; most frequently used resin is ethyl cellulose; various combinations of these and solvents are formulated to obtain the viscosity and volatility requirements desired (col. 4, lines 20-37). Similarly, Eguchi (also drawn to conductive copper paste composition- abstract) discloses a conductive paste comprising copper metal powder and organic medium including solvent, resin, and assortment of additives (pg. 3, lines 19-23). Eguchi teaches commonly known solvents such as butyl carbitol, butyl carbitol acetate, toluene, xylene, etc. for controlling the viscosity of the paste (pg. 9, lines 28); thixotropic agent (soldering accelerator- e.g. acid or metal salt) in the range of 0.1-2.5 wt%, (pg. 8, lines 10-25); and paste forming agent (resin component) in the range of 2-30 wt% (pg. 9, lines 19-22; see examples in Tables 1-3) with respect to the total organic medium. The weight ranges overlap with recited ranges. Given teachings of Keusseyan & Eguchi, it would have been obvious to one of ordinary skill in the art to select recited ratio of the agents and solvent in the first organic medium of Terasaki with the motivation of formulating desired viscosity, as suggested by both Keusseyan & Eguchi.
Allowable Subject Matter
Claims 9-10 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including ALL of the limitations of the base claim and any intervening claims.
Response to Amendment and Arguments
Applicant's amendment and arguments filed 7/27/26 have been fully considered but are moot in light of new ground(s) of rejection set forth above. Examiner notes that current 103 rejection relies on newly cited reference of Terasaki and addresses the matter challenged in the arguments. Claims 9-10 appear allowable over prior art.
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.
Inquiry
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DEVANG R PATEL whose telephone number is (571) 270-3636. The examiner can normally be reached on Monday-Friday 8am-5pm, EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Keith Walker can be reached on 571-272-3458. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/DEVANG R PATEL/
Primary Examiner, AU 1735
Prosecution Insights