Prosecution Insights
Last updated: April 19, 2026
Application No. 18/375,324

ISOLATION ENHANCED THERMALLY PROTECTED METAL OXIDE VARISTOR

Non-Final OA §103
Filed
Sep 29, 2023
Examiner
LEE, KYUNG S
Art Unit
2831
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Dongguan Littelfuse Electronics Company Limited
OA Round
1 (Non-Final)
87%
Grant Probability
Favorable
1-2
OA Rounds
2y 2m
To Grant
92%
With Interview

Examiner Intelligence

Grants 87% — above average
87%
Career Allow Rate
984 granted / 1129 resolved
+19.2% vs TC avg
Minimal +5% lift
Without
With
+4.8%
Interview Lift
resolved cases with interview
Typical timeline
2y 2m
Avg Prosecution
33 currently pending
Career history
1162
Total Applications
across all art units

Statute-Specific Performance

§101
0.2%
-39.8% vs TC avg
§103
39.2%
-0.8% vs TC avg
§102
41.4%
+1.4% vs TC avg
§112
10.7%
-29.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1129 resolved cases

Office Action

§103
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 . Drawings Figures 1C and 1D should be designated by a legend such as --Prior Art-- because only that which is old is illustrated. See MPEP § 608.02(g). The drawings are objected to because some of are “drawings other than black and white line drawings.” Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Specification The disclosure is objected to because of the following informalities: In paragraph 0026, line 7, replace “the electrode 104b with --the electrode 204b--. In paragraph 0031, line 3, replace “Line” with --line--. Appropriate correction is required. Claim Objections Claim 11 is objected to because of the following informalities: claim 11 contains a typographical error. Claim 11 should depend on claim 10 and not claim 5. Appropriate correction is required. 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 and 9-11 is rejected under 35 U.S.C. 103 as being unpatentable over Crevenat (US Pub. 2018/0102640) in view of Kasuga et al. (EP2194541; in English) and in further view of Knab et al., (CN101641757; machine translation attached). Regarding claims 1 and 9-11, Crevenat teaches a metal oxide varistor (MOV, ZnO varistor; see at least fig. 3) comprising: an MOV body (zinc oxide body 9; paragraph 0077) comprising a crystalline microstructure featuring zinc oxide; a first electrode (conductive metal electrode 11; see paragraph 0077) disposed adjacent a first side of the MOV body, wherein the first electrode is coupled to a first radial lead (electrical lead 15); a second electrode (electrode 10) disposed adjacent a second side of the MOV body, wherein the second electrode is coupled to a second radial lead (electrical lead 16); and a thermal cut-off (comprising of heat fusible bar 13 and solder joint 8) disposed adjacent the second electrode (10), the thermal cut-off comprising solder paste. Crevenat teaches the claimed invention except for the MOV comprising zinc oxide mixed with one or more metal oxide. Kasuga teaches that the metal-oxide ceramic material may be varied depending on its use to suppress line voltage surges, that the material differs with electrical resistivity that varies with the applied voltage (at least Mn, Co and Ni are added; see “Summary of the Invention”). It would have been obvious to one skilled in the art before the effective filing date of the claimed invention to combine the teachings of Kasuga with Crevenat, since mixing one or more metal oxide to the main zinc oxide as taught by Kasuga allows for controlling the non-linear resistance characteristics, and energy absorption capability and thermal stability for the MOV device of Crevenat. Regarding the claimed thermal cut-off, Crevenat and Kasuga teach the claimed invention except for the thermal cut-off comprising a solder having at least one core, the at least one core comprising a solid at a first temperature and a liquid at a second temperature. Knab teaches a thermal cut-off (conductive bar 14) comprising of solder (SnAgCu), the thermal cut-off having a core made of rosin (figs. 6A and 6B shows a pattern of the solder with a core containing rosin; 5th paragraph of the 6th page and the last paragraph of the 8th page of the translation) for the purpose of controlling the melting temperature of the thermal cut-off (melting point of the thermal cut-off is “selected”). It would have been obvious to one skilled in the art to combine the teachings of Knab with Crevenat and Kasuga, since the thermal cut-off taught by Knab allows Crevenat and Kasuga the ability to control the melting point for MOV device. Regarding claims 9-11, rosin melts at above 120 °C (flux material, the core comprising of rosin melts at above 120 °C; see paragraphs 0028-0029 of the current Specification). Claims 2-4 are rejected under 35 U.S.C. 103 as being unpatentable over Crevenat, Kasuga and Knab as applied to claim 1 above, and further in view of Hsu (US Pub. 2016/0125983). Regarding claim 2, Crevenat, Kasuga and Knab teach the claimed invention except for the MOV, further comprising: a first ceramic resistor adjacent the first electrode; and a second ceramic resistor adjacent the second electrode. Hsu teaches a MOV device (zinc oxide varistor; paragraph 0027) with a thermal cut-off (130) having multiple ceramic resistors (see fig. 10 and paragraph 0055), wherein the combination of connections (parallel and/or series connection) are used to protect against excessive transient voltages among the multiple ceramic resistors (the varistor devices). It would have been obvious to one skilled in the art before the effective filing date of the claimed invention to combine the teachings of Hsu with Crevenat, Kasuga and Knab, since connecting multiple ceramic resistors taught by Hsu allows for multiple voltage protections for multiple lines or for a high voltage protection for the MOV device of Crevenat, Kasuga and Knab. Regarding claims 3 and 4, Crevenat teaches the protective coating (resin coating 20; paragraph 0095 and fig. 5) comprising of epoxy resin (see claim 7). Claims 7 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Crevenat, Kasuga and Knab as applied to claim 1 above, and further in view of Yang et al. (CN104409616, machine translation attached). Regarding claims 7 and 8, Crevenat, Kasuga and Knab teach the claimed invention except for using the solder comprising of 96.5 % Sn, 3.0 % Ag, and 0.5 % Cu (SAC 305) or solder comprising 99.3 % Sn and 0.7 % Cu (SN100C). Yang teaches the use of lead-free solder including SAC305 and SN100C (see paragraph 0008) for the purpose of controlling the melt temperature of the solder (paragraph 0062). It would have been obvious to one skilled in the art before the effective date of the claimed invention to combine the teachings of Yang with Crevenat, Kasuga and Knab, since the solder materials taught by Yang allows for controlling the melting temperature of the solder for the MOV device of Crevenat, Kasuga and Knab. Claims 12-14 are rejected under 35 U.S.C. 103 as being unpatentable over Hsu in view of Xu (US Pat. 8,870,521). Regarding claims 12-14, Hsu teaches a metal oxide varistor (MOV; zinc oxide varistor, see paragraph 0027) comprising: an MOV body (center MOV body in fig 10 and reference number 511 in fig. 13) comprising a crystalline microstructure that blocks conduction at low voltages (metal-oxide materials are selected with electrical resistivity that varies with applied voltage; see paragraph 0027 for the MOV materials); a first ceramic resistor (first resistor 513 is on the right side of the MOV; fig. 13); a second ceramic resistor (second resistor 512 is on the left side of the MOV; fig. 13), wherein the MOV body (511) is disposed between the first ceramic resistor (512) and the second ceramic resistor (513); a first electrode (each varistor body has at least one electrode 121 which is shown in fig. 10, the first electrode being electrically connected to the first radial lead 530) disposed between the MOV body (511) and the first ceramic resistor (512), wherein the first electrode is coupled to a first radial lead (530); a second electrode (electrode 121 electrically connected to the second radial lead 540 between the second resistor 513 and the MOV 511) disposed between the MOV body (511) and the second ceramic resistor (513), wherein the second electrode is coupled to a second radial lead (540); and a barrier layer (590) being disposed between the first electrode (electrode 121 between the MOV 511 and the first resistor 512) and the first ceramic resistor, wherein the barrier layer keeps the encapsulant from catching fire in response to overheating of the MOV body (the barrier layer 590 is used for blocking heat conduction for the MOV device; see paragraph 0059). Hsu teaches the claimed invention except for using encapsulant to cover the MOV device. Xu teaches a MOV device being encapsulated by epoxy for the purpose of enclosing and protecting the MOV device from its environment (see col. 4, lines 35-46). It would have been obvious to one skilled in the art before the effective filing date of the claimed invention to combine the teachings of Xu with Hsu, since the epoxy coating taught by Xu provides structural integrity and protects the MOV device of Hsu from its environment. Claims 16-20 are rejected under 35 U.S.C. 103 as being unpatentable over Hsu in view Xu as applied to claim 12 above, and further in view of Knab. Regarding claims 16-17 and 20, Hsu and Xu teach the claimed invention except for the thermal cut-off disposed adjacent the barrier layer, the thermal cut-off comprising solder paste having at least one core, wherein the at least one core comprises a solid at a first temperature and a liquid at a second temperature. Knab teaches a thermal cut-off (conductive bar 14) comprising of solder (SnAgCu), the thermal cut-off having a core made of rosin (figs. 6A and 6B shows a pattern of the solder with a core containing rosin; 5th paragraph of the 6th page and the last paragraph of the 8th page of the translation) for the purpose of controlling the melting temperature of the thermal cut-off (melting point of the thermal cut-off is “selected”). It would have been obvious to one skilled in the art before the effective filing date of the claimed invention to combine the teachings of Knab with Hsu and Xu, since the thermal cut-off taught by Knab allows Hsu and Xu the ability to control the melting point for MOV device. Regarding claims 18 and 19, rosin melts at above 120 °C (flux material, the core comprising of rosin melts at above 120 °C; see paragraphs 0028-0029 of the current Specification). Allowable Subject Matter Claims 5-6 and 15 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. Regarding claim 5, the prior art does not teach or suggest the MOV having a barrier layer disposed between the second electrode and the second ceramic resistor. Claim 6 depends on claim 5. Regarding claim 15, the prior art does not teach or suggest the MOV having the barrier layer being composed of a foil layer with tin plating on each side. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to KYUNG S LEE whose telephone number is (571)272-1994. The examiner can normally be reached 7AM-3PM M-F. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Renee Luebke can be reached at 571-272-2009. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /KYUNG S LEE/Primary Examiner, Art Unit 2833
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Prosecution Timeline

Sep 29, 2023
Application Filed
Feb 12, 2026
Non-Final Rejection — §103 (current)

Precedent Cases

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
87%
Grant Probability
92%
With Interview (+4.8%)
2y 2m
Median Time to Grant
Low
PTA Risk
Based on 1129 resolved cases by this examiner. Grant probability derived from career allow rate.

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