DETAILED ACTION
Response to Amendment
Applicant's amendment filed 12/22/2025 has been entered. Currently, claims 1-13 are pending, claims 7-10 are withdrawn and claims 11-13 are new.
Claim Rejections - 35 USC § 112
Claims 1-6 and 11-13 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 written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
In claim 1, the Examiner does not find support for the limitations of a heat sink paste “wherein the solid metal particles and the liquid metal particles are aligned in a heat transfer direction by applying an electric field to form a particle chain” in the specification as originally filed. The aligning of the particles in an electric field is performed in the process of making a heat sink film, see pages 3-4 of the application as filed, and therefore the paste does not have the particles being aligned in a particle chain as this will be in the cured heat sink film.
Claims 1-6 and 11-13 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.
In claim 1, the limitations of a heat sink paste “wherein the solid metal particles and the liquid metal particles are aligned in a heat transfer direction by applying an electric field to form a particle chain” renders the claim indefinite because a paste is a flowable composition, and therefore it would not be possible for the particles to be permanently aligned in the paste. It is clear from the specification that the aligned particles and the particle chain are in the cured heat sink film, and therefore claiming aligned particles in the paste composition does not make sense. This rejection can be overcome by changing the limitations to “wherein the solid metal particles and the liquid metal particles can be aligned in a heat transfer direction by applying an electric field to form a particle chain”, which is how the claim will be interpreted.
In claims 1 and 4, the term “liquid metal particles” at room temperature renders the claim indefinite for multiple reasons. First, it is unclear how a liquid can be a particle as particles are solid. Also, the limitations in claim 1 do not make sense as claim 4 states that the liquid metal can be selected from gallium, lead, bismuth, thallium, zinc, cadmium, gallium/lead, gallium/cadmium, gallium/bismuth, gallium/thallium, tin/silver, tin/gold, tin/copper, tin/nickel, lead/antimony, lead/gold and lead/cadmium, but none of these materials would be liquid at room temperature. It is unclear what liquid metal particle means when almost all of the materials of claim 4 would be solid at room temperature. For purposes of examination, the Examiner will be treating any of the materials of claim 4 as reading on liquid metal particles.
Claim Rejections - 35 USC § 103
Claims 1-5 and 11-13 are rejected under 35 U.S.C. 103 as being unpatentable over Nguyen (US 6,673,434).
With regard to claims 1-4 and 11-13, Nguyen teaches a thermal interface material that may be in the form of a paste (col. 2, lines 50-52). The paste may comprise a rubber compound, which reads on applicants’ elastic polymer resin, and at least one thermally conductive filler (col. 3, lines 2-5). The rubber can be EPDM rubber and thermally conductive filler may comprise metals that are selected from indium, silver, copper, aluminum, tin, bismuth and gallium (col. 3, lines 34-40, col. 4, lines 60-63 and col. 5, lines 8-25). The metal can be a metal/metal composite or combinations/mixtures of metals (col. 5, lines 19-22 and claim 12); however, Nguyen does not teach a specific example with a mixture of these materials.
It would have been obvious to one having ordinary skill in the art to have made the paste of Nguyen be a mixture of EPDM rubber with two different thermally conductive fillers, such as combining silver or aluminum particles with bismuth or gallium. These are known materials for thermal interface materials as they are taught in Nguyen for these purposes and it is prima facie obvious to combine equivalents, i.e. the thermally conductive fillers, known for the same purpose to form a third composition useful for the same purpose (see MPEP 2144.06). The silver or aluminum would read on applicants’ solid metal particles and the bismuth or gallium reads on applicants’ liquid metal particles.
With regard to limitations that the solid and liquid metal particles “can be aligned in a heat transfer direction by applying an electric field to form a particle chain” and the specific conditions of the electric field of claims 11-13, the Examiner notes that these are intended use/functional limitations of the heat sink paste. Given the fact that the composition is identical as claimed and preferentially disclosed, the solid and liquid metal particles can intrinsically be aligned by applying an electric field in a particle chain using any of the electric field conditions claimed.
With regard to claim 5, the Examples A through E show that the thermally conductive filler is present at from 80 to 90 weight percent of the paste (col. 8, lines 20-46); however, they do not specifically teach the ratio of the solid and liquid metal particles.
It would have been obvious to one having ordinary skill in the art to have combined the silver or aluminum particles with any of the indium, tin, bismuth or gallium particles in any amount, including from 1:5 to 5:1 as claimed, while keeping the total amount of thermally conductive filler from 80-90 wt % so as to adjust the thermal conductivity of the thermal interface material to the amount desired based upon the intended use of the paste.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Nguyen (US 6,673,434) in view of Deng et al. (JP 2018-538690), machine translation included.
Nguyen renders obvious all of the limitations of claim 1 above; however, they do not specifically teach the particle size of the thermally conductive filler.
Deng et al. teach a thermal interface material having metal powder as heat conducting particles, wherein the median particle size may be from 5-7 microns [0034].
Since Nguyen and Deng et al. are both drawn to thermal interface materials, it would have been obvious to one having ordinary skill in the art to have made the median particle size of all the thermally conductive filler particles in Nguyen have a median diameter of 5-7 microns as taught in Deng et al. The particle diameters of these particles would then fall within the ranges claimed. The rationale is that this is a known particle size within thermal interface materials and it will help to achieve a desired heat conduction [0023].
Claims 1-4, 6 and 11-13 are rejected under 35 U.S.C. 103 as being unpatentable over Ti et al. (WO 2019/218268).
With regard to claims 1-4 and 11-13, Ti et al. teach an adhesive paste that comprises a thermosetting or thermoplastic resin, a plurality of particles of a first metal, which reads on applicants’ liquid metal particles, and a plurality of particles of a second metal, which reads on applicants’ solid metal particles (pgs. 3, 5, 17 and 18). The thermosetting or thermoplastic resin may comprise neoprene or EPDM, which are rubbers that are intrinsically elastic, the plurality of particles of a first metal may be gallium or bismuth, and the plurality of particles of a second metal may be gold, silver, nickel, aluminum or copper (pg. 5, 17 and 18); however, Ti et al. do not teach an example with these materials.
It would have been obvious to one having ordinary skill in the art to have formed a composition from neoprene or EPDM rubber with the first metal particles of gallium or bismuth, and the second metal particles of gold, silver, nickel, aluminum or copper as these materials are all taught to be useful for the adhesive paste.
With regard to limitations that the solid and liquid metal particles “can be aligned in a heat transfer direction by applying an electric field to form a particle chain” and the specific conditions of the electric field of claims 11-13, the Examiner notes that these are intended use/functional limitations of the heat sink paste. Given the fact that the composition is identical as claimed and preferentially disclosed, the solid and liquid metal particles can intrinsically be aligned by applying an electric field in a particle chain using any of the electric field conditions claimed.
With regard to claim 6, the first metal particles may have a median particle size of 12.5 to 35 microns and the second metal particles may have a median particle size of 2 to 6 microns (pgs. 17-18); however, they do not specifically teach that the particles have a diameter of 50 nm to 50 microns.
It would have been obvious to one having ordinary skill to have made the particles have a particle diameter that is the same as the median particle sizes of Ti et al. so that the fillers are well dispersed in the adhesive composition (pg. 18).
Response to Arguments
Applicant’s arguments, see Remarks, filed 12/22/2025, with respect to some of the previous 112(b) rejections have been fully considered and are persuasive. The relevant rejections have been withdrawn.
Applicant's arguments filed 12/22/2025 have been fully considered but they are not persuasive.
Applicants argue on page 7 of their Remarks that the previously applied references do not teach or suggest the new limitations of “solid metal particles and the liquid metal particles are aligned in a heat transfer direction by applying an electric field to form a particle chain”.
The Examiner respectfully disagrees and notes that these limitations are both new matter and render the claim indefinite for all of the reasons noted above. The particle chain disclosed in the specification is for the cured heat sink film and not for the composition of the heat sink paste. For purposes of examination, the Examiner treated these limitations and the limitations of new claims 11-13 as intended use/functional limitations, i.e. “wherein the solid metal particles and the liquid metal particles can be aligned in a heat transfer direction by applying an electric field to form a particle chain”.
Given the fact that the compositions of Nguyen and Ti et al. are identical as claimed and preferentially disclosed, the solid and liquid metal particles can intrinsically be aligned by applying an electric field in a particle chain using any of the electric field conditions claimed.
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 GERARD T HIGGINS whose telephone number is (571)270-3467. The examiner can normally be reached M-F 9:30-6pm.
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, Mark Ruthkosky can be reached at (571) 272-1291. 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.
/Gerard Higgins/Primary Examiner, Art Unit 1785