US 10408546

I'll search for this patent across the specified sources.

Let me run more targeted searches.

US 10,408,546 B2 — Summary

Important caveat up front: My search results did not surface any CAFC 2026 docket, PTAB proceeding, or district-court litigation indexing this specific patent. That is a "found nothing" result, not proof of absence. The bibliographic and technical content below is taken from the authoritative full text of the patent you supplied (Google Patents, fetched 2026-09-24), which I have prioritized over the noisy search hits.

Bibliographic data (from authoritative source)

A secondary source (patentleaderboard.com listing for Nobuyuki Kurashima) independently corroborates the title ("Loop heat pipe"), co-inventor (Yoshihiro Machida), and 2019-09-10 date.

Abstract

A loop heat pipe includes an evaporator that vaporizes working fluid; a condenser that condenses the working fluid; a liquid line that connects the evaporator and the condenser; and a vapor line that connects the evaporator and the condenser. The evaporator, vapor line, liquid line and condenser form a loop flow path through which the working fluid or its vapor flows. In the condenser and the vapor line, a wall portion of the flow path is constituted by a metal layer. A drain line formed to be separated and apart from the flow path is provided in the wall portion, and a drawing line connecting the drain line and the flow path is provided in the wall portion.

Plain-language overview of the independent claim

Note on completeness: the authoritative text I retrieved includes the Summary/Abstract wording of the sole independent claim but not the verbatim numbered claim set, so I cannot state the total claim count or recite the dependent claims from authoritative text. The independent claim (claim 1) is, in essence:

A loop heat pipe comprising four elements arranged as a closed loop: (1) an evaporator that turns working fluid into vapor, (2) a condenser that turns the vapor back to liquid, (3) a liquid line joining evaporator and condenser, and (4) a vapor line joining evaporator and condenser. The four together define the looped flow path for the fluid/vapor. The distinctive structural limitations are:

• In the condenser and the vapor line (i.e., on the vapor-condensation side, not the liquid side), the flow-path wall is made of a metal layer;
• That wall contains a drain line that is separated and apart from the flow path — not open to it, so a portion of the wall intervenes; and
• That wall also contains a drawing line (drawing conduit) that connects the drain line to the flow path.

Technical purpose (from the specification): Vapor traveling away from the heat source dew-condenses into water drops that otherwise pool in the vapor line, narrowing it, blocking vapor flow, and promoting further condensation. The drawing lines wick those drops by capillary attraction into the adjacent drain lines, which run along the flow direction (X) and carry the liquid back toward the liquid line/condenser, keeping the vapor channel clear and improving heat-transfer efficiency. Keeping the drain line not directly open to the flow path is stated to improve its capillary attraction.

Disclosed dependent/embodiment features (not necessarily claimed):

• Metal-layer stack of six layers (31–36), with outer solid layers 31/36 and an intermediate metal layer 45 of layers 32–35; drain lines half-etched in one layer, drawing lines half-etched in an adjacent layer (stacked-body pairing).
• Drawing lines inclined ~45° to the drain line in the direction of vapor flow; drain line width/depth ~0.2–0.4 mm.
• Second embodiment (vapor line 30A): a partition portion (32c–35c) splitting the conduit into parallel flow paths 50a/50b, with drain lines (33z, 34z) in the partition and drawing lines (32z-1/2, 35z-1/2) alternately feeding both paths; the partition also acts as a support column.
• Third embodiment (vapor line 30B): drain lines formed by alternating half-etched bottomed holes (33d/33e, etc.) that overlap to form communicating pores (33h, 33i).
• Fabrication: openings formed by pressing/etching; lines by resist-masked half-etching (e.g., ferric chloride for copper); layers joined by solid-phase welding; then evacuation and fluid charging.

What the searches did and did not show

• CAFC / 2026 dockets: No hit tying case number or docket to US 10,408,546. The scheduled-cases page and CourtListener/PTAB records returned unrelated matters (e.g., Apple v. Corephotonics, CPC Patent Techs. v. Apple).
• A trap to flag: several search results discuss a "'466 Patent" that is not this patent — e.g., a PTAB petition concerning an "apparatus for housing an electronic device" from Application No. 13/355,447. That is a different patent whose shorthand also ends in "466." Do not conflate it with US 10,408,546 (loop heat pipe, App. No. 15/785,576, Shinko).
• The patent does appear in the citation/SEA lists of later Shinko loop-heat-pipe patents (e.g., US 10,883,770 B2; also cited against Shinko filings), confirming it is a real, granted, in-force family member.

Uncertainty statement

• Claim count and verbatim dependent-claim language: not available in the retrieved text; treat the claim overview as limited to the independent claim as reflected in the Summary/Abstract.
• Litigation status: I found no evidence of CAFC or PTAB involvement for this patent number, but absence of search hits is not conclusive — a PACER/Docket Navigator or USPTO Patent Center run would be needed for a definitive check.

I'll search for litigation involving US patent 10408546 across patent litigation databases.

Let me search more targeted litigation databases.

None of these relate to the '546 patent. Let me try more targeted searches on litigation-specific platforms.

Litigation Search Results: US Patent No. 10,408,546

Bottom line: I found no evidence of any litigation involving U.S. Patent No. 10,408,546 ("Loop heat pipe").

What I searched

I ran multiple targeted queries against patent litigation resources (including Unified Patents litigation caselist, CourtListener/RECAP, and general litigation dockets via web search), using the specific number in several formats:

• US patent 10408546 litigation
• "10408546" patent lawsuit infringement
• 10408546 patent case docket
• "10,408,546" OR "10408546" Shinko Electric loop heat pipe litigation
• patents.google.com/patent/US10408546 litigation

Why I'm reporting "none found"

Every result returned was for a different patent number or unrelated matter — e.g., Contour IP Holding v. GoPro (U.S. Pat. Nos. 8,890,954 / 8,896,694), Polaris PowerLED v. Western Digital (U.S. Pat. Nos. 9,183,085 / 8,601,346 / 8,554,968), NuCurrent v. Samsung (U.S. Pat. No. 9,300,046), and Aqua Connect v. TeamViewer (RE46,386). None cite the '546 patent, its assignee, or its inventors as a party. I did not find a single docket, complaint, or case entry naming US 10,408,546.

Patent context (for cross-checking, from the authoritative Google Patents record you provided)

• Patent: US 10,408,546 B2 — "Loop heat pipe"
• Inventors: Nobuyuki Kurashima; Yoshihiro Machida
• Assignee: Shinko Electric Industries Co., Ltd.
• Application: US 15/785,576; filed 2017-10-17
• Priority date: 2016-11-18 (JP 2016-225476)
• Grant date: 2019-09-10
• Status: Active; anticipated expiration 2037-10-17
• Related publication: US 2018/0142960 A1

Important limitations and caveats

I could not exhaustively confirm the absence of litigation, and the following limitations apply:

1. Source access. My searches relied on indexable web results. I was not able to run a live, authoritative query directly in PACER, the Unified Patents litigation portal, or Darts-IP, which are the definitive sources. A docket search in those systems (and a Docket Navigator / Lex Machina check) is the appropriate way to verify a negative with authority.
2. Possible non-U.S. or non-court-level activity. Shinko is a Japanese company; there could be foreign proceedings, ITC actions, or arbitration that would not surface in my searches.
3. No PTAB record found either — I saw no IPR/PGR/CBM involving the '546 patent in the results, but again, this was not a direct PTAB filing-system query.
4. As of the last status I can verify, the patent remains Active with no recorded assignment litigation flag.

If you need a definitive clearance statement, I recommend a direct PACER docket search and a Docket Navigator query for the patent number, which I could not perform with the tools available here.

Proceedings overview

Total AIA trial proceedings on US 10,408,546: zero (0). The USPTO Open Data Portal / PTAB structured record supplied in this prompt — the canonical source — returns no IPR, PGR, or CBM proceedings for this patent, and my independent web checks (PTAB E2E/petition documents, CourtListener-style trackers, and general search) surfaced no petition, institution decision, FWD, or appeal tied to US 10,408,546 or to application No. 15/785,576. The defensive posture this yields a defendant is therefore neither "hardened by surviving IPRs" nor "narrowed by cancellation" — it is simply untested. There are no canceled claims to lean on and no § 315(e)(2) estoppel to exploit. Whatever your invalidity position is, it is a first-mover IPR/PGR opportunity (subject to § 315(b) timing), not a follow-on to someone else's win.

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Proceedings

None on file. There is no proceeding to enumerate, so the per-proceeding template (filed date, panel, grounds, institution, FWD, settlement, appeal, defensive value) has no entries. I will not invent proceeding numbers, panels, or dispositions to fill the template.

⚠️ Identifier traps — do not conflate these with US 10,408,546

Searching by the shorthand "'546" or "10408546" is unusually noisy. Three distinct things share that string and none of them is this patent:

1. Neurelis, Inc. v. Padagis LLC — IPR2025-00464 / -00465 / -00466. A paragraph-four/ANDA dispute involving a different "'546 patent" (along with '414 and '786 patents). All three were instituted, with a trial date of 2026-06-16. These proceeding numbers attach to Neurelis's patents, not to Shinko's US 10,408,546 (App. No. 15/785,576). If a demand letter or a search result cites "IPR2025-00464 on the '546," verify the patent number before relying on it.
2. The "'466 patent" flagged in the prior summary — a PTAB petition over an "apparatus for housing an electronic device" (App. No. 13/355,447). Same last-three-digits collision, unrelated patent.
3. Non-patent noise — the string "10408546" also appears as an Estonian business registry code, an SEC filing key, a stock-photo ID, and a metagenome scaffold ID. All irrelevant.

Verification attempted

• Structured PTAB data (canonical): no AIA trials. ✅
• Web check for petitions/FWDs referencing US 10,408,546 / 10,408,546 B2 / App. 15/785,576: no authentic PTAB hits; all "hits" were the collisions above or unrelated loop-heat-pipe family documents. ✅
• Assignee-level check (Shinko Electric Industries): the patent appears in the citation/SEA/family lists of later Shinko loop-heat-pipe patents (e.g., US 10,883,770 B2; US 11,060,798 B2; EP 3,524,912 B1), confirming it is a live, in-force family member — but no PTAB challenge surfaced. ✅

Confidence: High that the ODP record is empty. Moderate-to-high that no challenge exists anywhere, given the redundant searches. This is a "found nothing" result, not proof of absence — the ODP ingest can lag for very recently filed petitions (a petition filed in the last few weeks may not yet be indexed), and post-grant challenges can be filed at any time during the 9-month PGR window or thereafter as IPRs. A definitive check requires a live run on PTAB E2E / Patent Center for App. No. 15/785,576.

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Strategic summary

Claim status — CANCELED vs. SUSTAINED vs. UNTESTED. Because no AIA trial has ever reached a Final Written Decision on US 10,408,546, every claim is UNTESTED. There are no canceled claims, no substitute claims, and no certificate of correction flowing from a PTAB proceeding. Operationally, the patent stands exactly as it issued on 2019-09-10: the independent claim (the "evaporator / condenser / liquid line / vapor line loop, with a drain line separated and apart from the flow path and a drawing line connecting them" combination) plus its dependents are all presumptively valid — and all unadjudicated. A defendant cannot point to a single FWD and say "claim X is dead."

Estoppel landscape. With no IPR/PGR that "results in a final written decision under section 318(a)," § 315(e)(2) estoppel has not attached to anyone. No petitioner, real party in interest, or privy is foreclosed from raising any § 102/§ 103 ground in district court or the ITC. This cuts both ways:

• For you (the defendant): the entire prior-art field is open. You are not limited to art a predecessor failed to raise, and there is no General Plastic follow-on risk because there is no "first petition."
• Against you: there is also no precedent narrowing claim scope, no Board claim construction to leverage, and no FWD findings you can cite to a district court. You would be building the invalidity record from scratch.

Pattern signals. None to report. No repeat petitioner, no serial filings, no patent-owner appeal activity (the patent owner has not had to defend an FWD, so there is no CAFC track record to gauge its litigation appetite). There is no defensive aggregator (e.g., Unified Patents) in the chain visible in any source I reviewed — the patent appears only in Shinko's own prosecution/citation contexts, which is consistent with a manufacturer's portfolio patent that has not yet drawn third-party attack. That ordinarily signals a patent that either is not being asserted, or has not yet been asserted widely enough to attract challengers (well-asserted patents eventually attract IPRs).

Bottom line for a defendant: you are looking at a clean, active, never-challenged patent. There is no "the claims are already dead" argument available. If you face assertion, your invalidity strategy must be independently developed, and — importantly — you may have a first-mover timing advantage if you move quickly, since no one else has consumed the art or locked in a construction.

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Recommended next steps

1. Confirm the empty record on the live system. Because the "no proceedings" conclusion rests on the ODP ingest plus search, run a direct check on USPTO PTAB E2E (search by patent number 10,408,546 and by application 15/785,576) and Patent Center before relying on it. This guards against ingest lag for a recently filed petition.

2. Do not cite any proceeding until you verify the patent number. Given the collisions above, if anyone — opposing counsel, a search vendor, or an AI summary — hands you "IPR2025-0046x" or "the '466 patent" as activity on this patent, check the underlying patent number in the caption. It is almost certainly Neurelis/Padagis or the housing-apparatus patent, not Shinko's loop heat pipe.

3. If you are the defendant and want to challenge: with no prior FWD, there is no § 315(e)(2) estoppel and no General Plastic bar, so a single, well-focused IPR petition is the efficient path. Watch the § 315(b) one-year clock from service of any complaint, and note that for an unexpired patent you may also consider PGR only within 9 months of grant — that window (closed 2019-2020) has long passed, so IPR is the only AIA vehicle now available.

4. If you are the patent owner / plaintiff: the absence of proceedings is a positive signal for enforcement — no adverse claim constructions, no cancellation certificates, all claims live. But recognize that a first IPR, once filed and instituted, carries the usual risk of narrowing or cancellation. Under 35 U.S.C. § 316(a)(11), any instituted trial must reach a Final Written Decision within one year of institution (extendable up to six months for good cause), so the timeline from institution to resolution is compressed.

5. Monitor. Set alerts on patent number 10,408,546 and App. No. 15/785,576 for new PTAB filings, since the status could change and the absence of activity is itself the current, time-sensitive signal.

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Sourcing note. This section is grounded in (a) the canonical "PTAB proceedings on file" block (USPTO ODP: empty), and (b) web verification attempts that returned only the identifier collisions described above. No PTAB opinion, FWD, or E2E link is cited because none exists to cite; I have deliberately not linked to the Neurelis/Padagis or housing-apparatus matters as if they were this patent's proceedings.

I'll research the assignment record for US 10,408,546, starting with the authoritative Google Patents legal events and then attempting to locate the USPTO Assignment Center records.

Let me dig into the USPTO Assignment Center records and Shinko's corporate/ownership history.

I was unable to complete additional live lookups (tool budget exhausted), so the following is grounded in the authoritative full text you supplied plus the corroborating hits I did retrieve. Where I could not retrieve a data element, I say so rather than filling it in.

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Inventors

Employer determination: The issued patent names the applicant/assignee as Shinko Electric Industries Co., Ltd., and the single recorded assignment (below) is an Assignment of Assignors' Interest executed by both named inventors in favor of Shinko — the standard employer-takes-title pattern for employee inventors. There is no evidence in the retrieved record of either inventor departing Shinko within 12 months of the 2017-10-17 filing (Kurashima is still filing Shinko loop-heat-pipe applications as late as 2019, corroborating continued employment). Unusual-pattern flag: not present.

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Original assignee

Shinko Electric Industries Co., Ltd. (Nagano, Japan; TYO ticker 6967).

• Primary line of business: semiconductor packaging — plastic laminate packages (PLP), IC assemblies, and metal packages including lead frames, heat sinks, ceramic electrostatic chucks and precision contact parts. A secondary/thermal-management line (heat sinks) is the relevant product context for a loop heat pipe.
• Did they ship a product embodying the claims? Likely yes, at the component level. Shinko is an operating manufacturer whose stated portfolio includes heat sinks and thermal-management components; the patent is directed to a manufacturable multi-layer-metal loop heat pipe consistent with Shinko's metal-layer/lead-frame fabrication competency. I found no retail end-product branding, so this is a component-supply inference, not a verified retail SKU.
• Current status: Operating. Shinko was still reporting normal segment results for its thermal/heat-sink business (approx. 8% of consolidated revenue, ~35% share of the high-performance semiconductor heat-sink market) in a Dec-2025 analysis. Uncertainty flag: I could not confirm, within this session, the widely-reported 2024 take-private of Shinko by a consortium (Mitsui/JIC-linked). If that transaction closed, ownership of the corporate parent may have changed even though the patent's assignee of record would remain "Shinko Electric Industries Co., Ltd." I recommend verifying the current parent/status via Shinko's TSE disclosures and its 10-K-equivalent (Yuho). I am not asserting a change-of-control transfer of the patent, because no assignment record reflects one.

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Assignment timeline

Correspondence caveat — read first: The authoritative record I retrieved (Google Patents legal events) confirms one recorded assignment, but does not expose the reel/frame number, recording date beyond the event date, or the recorded correspondent. I did not fabricate a reel/frame. Below I give the timeline using the data that is corroborated, and mark the unavailable fields.

• 2016-11-18 (executed, JP priority) / not a USPTO record — JP App. No. 2016-225476

  • Conveyance: n/a (foreign priority filing)
  • Assignor: Kurashima, Nobuyuki; Machida, Yoshihiro (as applicants)
  • Assignee: Shinko Electric Industries Co., Ltd. (JP applicant of record)
  • Correspondent: not applicable (JP filing)
  • Context: priority filing by the operating company's employee inventors — establishes the origin of the chain.

• 2017-10-17 (executed) / recorded 2017-10-17 — Reel not retrieved / Frame not retrieved

  • Conveyance: Assignment (Assignment of Assignors' Interest)
  • Assignor: KURASHIMA, NOBUYUKI and MACHIDA, YOSHIHIRO
  • Assignee: SHINKO ELECTRIC INDUSTRIES CO., LTD.
  • Correspondent: not shown in the retrieved record. The patent's own "(74) Attorney/Agent/Firm" line was not present in the authoritative text I fetched. The sibling Shinko patent US 10,962,301 (same inventor Kurashima) names IPSUSA, PLLC as attorney/firm; I flag IPSUSA as the probable prosecution/recording firm for this family, but I cannot confirm it is the correspondent of record on this specific recording. Recurrence within this chain: cannot be assessed — there is only one recording, so a repeat-correspondent signal cannot be established from this patent alone.
  • Context: routine inventor-to-employer assignment — the standard transfer of employee-inventor rights to the operating company, effected contemporaneously with the US national-stage filing (which claims the 2016-11-18 JP priority).

• 2019-09-10 — Not an assignment. Grant/issue event of US 10,408,546 B2. No title change.

No post-issuance assignments are recorded. The Google Patents legal-events set for this patent contains only the filing/assignment events and the 2019 grant; there is no assignment out of Shinko, no security agreement, no merger, no change-of-name, and no release. There is no Assignment Center record beyond the original employer assignment. (The reel/frame and recorded correspondent for that one recording remain unretrieved — verify at the link below.)

Note: the previously generated summary/litigation sections flagged that the verbatim claim set and claim count were not in the retrieved text; that gap does not affect the ownership analysis above, and I did not rely on claim language for any assignment conclusion.

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Timeline diagram

timeline
    title Ownership of US 10408546
    2016 : Priority JP application 2016-225476
         : Kurashima and Machida named inventors
    2017 : US application 15/785,576 filed
         : Inventors assign rights to Shinko Electric
    2019 : US 10408546 B2 granted

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NPE / troll-pattern signals

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Verdict

Insufficient data — the record consists only of the original inventor-to-employer assignment (recorded 2017-10-17, contemporaneous with the US filing of App. 15/785,576), with no post-issuance transfers.

Justification: The lone recorded assignment conveys both inventors' rights to Shinko Electric Industries Co., Ltd., an operating semiconductor-packaging/thermal-components manufacturer — a routine employee-assignment, not an arm's-length transfer to an assertion vehicle. None of the eight NPE signals is present: no shell entity, no known asserter, no cascading transfers, no pre-litigation timing, no bankruptcy, no privateering, and no defensive-aggregator endpoint. This patent is simply still held in the ordinary course by its original operating-company owner; there is no adverse NPE pattern to report. (Note the previously flagged trap: the unrelated "'466 Patent" in a PTAB petition is a different patent and was not conflated here.)

Verify at: USPTO Assignment Search / Assignment Center — https://assignmentcenter.uspto.gov/ (and the mirrored legacy interface https://assignment.uspto.gov/patent/index.html). Search by patent number 10,408,546 or application 15/785,576 to pull the reel/frame and the recorded correspondent that I could not retrieve in this session.

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Contradiction / gap flags for your attention:

1. Reel/frame and recorded correspondent for the single assignment were not retrievable with the tools available; I did not invent them. This is the one field the task specifically wanted and that I could not fill.
2. Possible parent-level change of control (Shinko take-private, reported ~2024) is unverified here and would not appear as a patent assignment; it does not change the assignee of record. Flagging so it is not mistaken for an NPE event.
3. No contradiction found with the previously generated summary/litigation sections; those independently reported "no CAFC/PTAB/litigation hits," which is consistent with the clean, un-assigned ownership chain above.

I'll search for the patent's citation records and prior art references.

Let me try to retrieve the patent's front-page "References Cited" section directly.

Let me try to pull the front-page reference list from alternative full-text sources.

Important limitation first

I was unable to retrieve the front‑page "(56) References Cited" list for US 10,408,546 using the tools available. Every query I ran for the citation list returned the citation lists of other patents (e.g., the References Cited blocks of US 10,962,301, US 10,352,626, US 10,269,682, US 10,881,021, US 10,108,612) or UN-related search reports — not the (56) block of the '546 patent itself. The Google Patents full text supplied to me (and reproduced in the earlier sections of this analysis) contains the description only, not the front-page references. I will not invent a (56) list. Below I separate what is grounded from what is candidate/inferred and clearly labeled as such.

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1. What IS grounded: the one reference cited in the specification

The '546 specification cites exactly one prior-art document, in the Background section:

§ 102 analysis — WO 2015/087451:

• It discloses the generic architecture the '546 preamble recites (evaporator, condenser, liquid line, vapor line forming a loop flow path) and the stacked-metal-layer / half-etching fabrication technique — but it locates the porous structure in the liquid line and is directed to capillary pumping / back-flow prevention, not to a drain line separated from the flow path with a drawing line connecting them.
• Therefore WO 2015/087451 does not anticipate claim 1 of the '546 patent under § 102: it lacks the two limitations that give the claim its novelty — (a) a drain line "separated and apart from" the flow path in the wall portion of the condenser and the vapor line, and (b) a drawing line connecting the drain line and the flow path.
• Its true role is as § 103 base art: it is the closest reference for the stacked-metal-layer loop-heat-pipe body, and an examiner would combine it with secondary art teaching condensate drainage/collection grooves.

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2. Candidate / related references found in adjacent records (NOT confirmed as citations against the '546 patent)

These surfaced in other patents' search reports and in the '546 patent's own family. I am flagging them as candidates only — I could not confirm any of them appears in the '546 (56) list. Treat this as a lead list, not a verified citation list.

Also note: US 10,881,021 B2 (Fujitsu) lists WO 2015/087451 A1 (6/2015) among its foreign patent documents — independent corroboration that the same WO reference is a widely-cited item in this art, and consistent with its being the key background reference for the '546 patent.

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3. § 102 bottom line for the '546 patent

• Claim 1 (and the dependent claims 2–12 as reflected in the Google Patents "Claims (12)" table) requires, in the condenser and vapor line: a wall formed by a metal layer, a drain line separated and apart from the flow path, and a drawing line connecting drain line to flow path. None of the references I could verify discloses that combination with dates preceding 2016‑11‑18.
• No verified reference anticipates claim 1. The only confirmed specification citation (WO 2015/087451) fails the two structural limitations. Candidate reference US 2016/0259383 A1 is pre-priority but, as abstracted, targets evaporator flow-path structure rather than the claimed condenser/vapor-line drainage structure.
• For an inventive-step (§ 103) attack, the natural combination would be WO 2015/087451 (stacked metal-layer loop heat pipe with half-etched features) + a condensate-collection/drainage-groove teaching, plus possibly US 2016/0259383 A1 for stacked-layer flow-path formation.

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4. Correction / refinement to the earlier sections

The earlier "Patent summary" flagged that the verbatim claim set was unavailable and that claim count was unknown. The Google Patents page does expose a "Claims (12)" list (claim 1 independent, with dependent claims 2, 3, 4 … and a separate "numbered clause" for a method of manufacturing a loop heat pipe). So the '546 patent appears to carry 12 claims, and claim 1's text as shown includes the phrase "wherein a drawing conduit connecting the drain line and the flow path is provided inside the wall portion of the flow path." This refines — and does not contradict — the earlier summary, but the count and phrasing come from a machine-translated claim table, so verify against the official USPTO claim set before relying on them.

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5. Recommended verification steps (I could not perform these)

1. Run the patent number 10408546 in USPTO Patent Public Search / Patent Center, open the "References Cited" (56) section, and capture both the U.S. Patent Documents and Foreign Patent Documents lists, including examiner-cited "NPL."
2. Pull the EP 3 299 758 / EP 3 524 912 examination files (EPO Register) for the search-report citations actually applied.
3. Cross-check the US 2016/0259383 A1 full text for any drain-groove disclosure before treating it as § 102 art.

If you can supply the (56) front page of US 10,408,546 (or the PDF), I will produce the complete per-reference § 102 table you asked for — which is not possible to do accurately from the sources I could reach today.

I'll gather the prior-art references relevant to this patent before analyzing.

Let me pin down the full claim set and a few additional prior-art candidates.

Let me retrieve the full claim set to ground the analysis precisely.

Obviousness Analysis — U.S. Patent No. 10,408,546 B2 ("Loop heat pipe") under 35 U.S.C. § 103

Note correcting the earlier sections: The "Patent summary" section stated that the verbatim claim set was unavailable and that the claim count could not be stated. That limitation is now resolved in part: the Google Patents record shows "Claims (12)" with the numbering and substantive text for claims 1, 2, 4, 5 and 7, plus fragmentary headers for claims 3, 6 and 8, and nothing recoverable for claims 9–12. I flag this as a correction and carry forward the residue of uncertainty rather than filling the gap.

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1. Legal framework applied

The '546 patent has an effective filing date of 2016‑11‑18 (JP App. 2016‑225476), so the AIA §§ 102/103 regime governs. Prior art must predate 2016‑11‑18 either by publication (§ 102(a)(1)) or by an effectively earlier filing date of a U.S. patent/application publication (§ 102(a)(2)).

The analysis uses the Graham v. John Deere, 383 U.S. 1 (1966) factors and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). Under KSR and MPEP § 2143, a combination is obvious where: (A) known elements are combined by known methods to yield predictable results; (B) a known element is substituted for another for a predictable result; (C) a known technique is used to improve a similar device in the same way; (D) a known technique is applied to a known device ready for improvement; (E) a finite number of identified, predictable solutions yields an "obvious to try" case; or (F) design incentives/market forces prompt a variation. A teaching, suggestion or motivation is not a prerequisite (§ 103, post‑KSR), though one may be articulated.

Person of ordinary skill in the art (POSITA): a mechanical/thermal engineer (or a packaging engineer at a heat-pipe maker) with 2–4 years' experience in two-phase thermal management for portable electronics, familiar with loop heat pipe (LHP) architecture, capillary wick/groove design, and multi-layer metal lamination/etching fabrication (as used in vapor chambers and in the patentee's own stacked-layer LHP platform).

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2. What the prior art section actually supplies

The patent's own prior-art section identifies exactly one reference, and it is the anchor for any § 103 attack:

Two points matter for attack construction:

• Ref 1 is not commonly owned with the '546. Fujitsu vs. Shinko Electric Industries. There is therefore no § 103(c) common-ownership disqualification to worry about, and Ref 1 can be combined freely.
• Ref 1 supplies the entire structural platform of the '546 except the drain/drawing feature: a loop heat pipe (evaporator, condenser, liquid pipe, vapor pipe), built as stacked, directly bonded metal layers, with the internal flow channel formed by through‑holes and with partially overlapping openings/holes across stacked layers to form fine capillary passages. Its published U.S. counterpart (US 11,009,927) recites word-for-word the "stacked metal layers with partially overlapping holes" architecture and a body separated from the pipe inner walls — i.e., the fabrication idiom the '546 uses.

Because the prior-art section supplies only Ref 1, the remaining citations below are drawn from the same field and same problem space and are offered as analogous art. I distinguish verified citations from field-knowledge classes.

Verified additional references retrieved:

References identified but NOT usable (dates too late — flag): the Shinko "bottomed-hole → fine pore" family (US 2019/0242652 A1, priority JP 2018‑018468; US 10,704,838 B2; US 11,331,443; US 2020/0200485 A1, priority JP 2018‑237703; US 11,131,509). These are post‑2016‑11‑18 and cannot be prior art to the '546. Their only use is evidentiary context about the assignee's own later development.

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3. Claim-by-claim mapping and § 103 attack

3.1 Independent claim 1

Claim 1 (as reproduced in the record) is, in substance:

A loop heat pipe comprising an evaporator, a condenser, a liquid line, and a vapor line forming a looped flow path; wherein in the condenser and the vapor line, a wall portion of the flow path is constituted by a metal layer; wherein a drain line formed to be separated and apart from the flow path is provided in the wall portion; and wherein a drawing conduit connecting the drain line and the flow path is provided inside the wall portion of the flow path.

Element mapping against Ref 1 (WO 2015/087451):

Conclusion: Ref 1 alone does not anticipate claim 1 — the two "drain line"/"drawing conduit" limitations are literally absent. Claim 1 therefore survives § 102 but is vulnerable under § 103.

Combination 1 — Ref 1 + Ref 3/Ref 4 (covered-groove / arterial wick art).

• What the secondary art teaches: In conventional heat-pipe design it is standard to form axial grooves in the pipe wall that serve as capillary liquid-return channels, and it is standard to isolate such a return channel from the vapor space — either by bridging/covering the groove with a finer-pore wick (the "inverted meniscus," Ref 4; covered-groove, Ref 3) or by providing a dedicated arterial/tunnel passage separated from the vapor core but capillary-coupled to it through smaller openings. The two functions the '546 assigns to its two features — (i) a channel that is separated from the flow path, and (ii) a smaller conduit that connects it to the flow path — are precisely the conventional separation-and-capillary-coupling relationship of a covered groove.
• Motivation (rationales A, C, D, F): Both references are in the same field of endeavor (two-phase capillary-driven heat transfer for electronics cooling) and address the same recognized failure mode — liquid accumulation in the vapor transport path degrading vapor flow and heat-transfer efficiency. The '546 specification itself states the problem as a known one (vapor dew-condensing in the vapor line and "narrow[ing]" it). Where the problem and the field are the same, substituting the known covered-groove geometry into the known stacked-layer LHP of Ref 1 is rationale (C)/(D) — applying a known technique to a known device that was ready for improvement.
• Reasonable expectation of success: Both features are purely geometric/structural and fluidic; the result (liquid is wicked away from the vapor channel into a separated channel) is a predictable consequence of capillary geometry, with no new mechanism required. Rationale (A).
• Structural caveat favorable to the patentee: Ref 1's layers are stacked, so a POSITA would implement the covered groove as a channel in one layer bridged by the adjacent layer — which is exactly claim 2's structure (see below). This weakens any argument that the claim 1 combination is mechanically incompatible.

Combination 2 — Ref 1 + Ref 6 (separated, function-specific conduits inside a heat-pipe envelope).
Ref 6 discloses a heat pipe with (a) a discrete, impermeable liquid return passage running inside the envelope and separate from the vapor volume, and (b) a vent line that is separately routed for vapor. That is the same architectural idea as claim 1 on a macroscopic scale: a dedicated, walled-off liquid line and a dedicated coupling line, inside the device envelope, with the fluid routing allocated per line. Applying that known architecture at the layer scale of Ref 1's metal stack is rationale (A)/(B)/(C) and, given a finite number of channel layouts available in a laminated stack, at worst rationale (E) ("obvious to try" among predictable solutions).

Combination 3 — Ref 1 + Ref 5 (auxiliary conduit in an LHP).
Ref 5 shows that adding a parallel, secondary passage to an LHP transport section to handle a second phase/flow was known. This supplies the design-incentive rationale (F): once the problem of condensate in the vapor line is recognized, adding an auxiliary conduit to that line is the natural design response, and the only remaining question is where to place the capillary inlet — a routine engineering optimization.

Assessment for claim 1: Strong § 103 case, but not a lock. The best patentee rebuttals are (i) that Ref 1 is directed to the liquid side while claim 1 is expressly limited to "the condenser and the vapor line," and (ii) that the secondary art is macroscopic/tubular, not laminated. Both are weakened by the analogous-art doctrine and by the fact that Ref 1's laminated fabrication is the very technique being asked to accept a known groove geometry.

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3.2 Claim 2 — drain line in one layer, drawing conduit in another

Claim 2 requires:

• a stacked body of a first metal layer in which only the drain line is formed and a second metal layer in which only the drawing conduit is formed; and
• one end of the drawing conduit communicates with the drain line and the other end with the flow path.

This is the weakest claim in the set from an obviousness standpoint, for two independent reasons.

1. Ref 1 + Ref 2 already supply the technique and the layering convention. Ref 1/Ref 2 teach forming capillary passages by through-holes and partial overlapping openings in adjacent stacked metal layers, i.e., allocating different portions of a single capillary passage to different layers so that the passage is completed only when the layers are stacked. Claim 2 is the same idea applied to two distinct channels: put one channel in layer 1, the other in layer 2, and let them overlap where they must communicate. The '546's own manufacturing description confirms the communication is achieved by "one end of each of the drawing lines overlaps the respective drain line at least at a part" — which is literally the partial-overlap stacking technique of Ref 1/Ref 2.

2. The specification concedes claim 2 is a pure strength/space optimization. The '546 states: "If the drain line and the drawing lines are provided in a same single metal layer, intensity of the metal layer is lowered. However, by using two metal layers… sufficient intensity can be retained." A stated trade-off solved by a known expedient (move one feature to an adjacent layer) is textbook rationale (B)/(C) — substitution of a known element for a predictable mechanical result. It also squarely fits KSR's "known technique to improve a similar device in the same way."

Assessment for claim 2: Very strong. The combination of Ref 1/Ref 2 (layered, partially-overlapping capillary channels) with the recognizable need for structural integrity makes claim 2 a predictable design choice. It would be difficult to show unexpected results, because the patent reports no comparative data on strength or capillary performance.

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3.3 Claim 4 — first and second wall portions, each with its own drain line and drawing conduit

Claim 4 requires the metal layer to have first and second wall portions opposite one another across the flow-path opening, each carrying a drain line and a drawing conduit (i.e., duplication of the claim 1 structure on both lateral walls).

Analysis: This is duplication of a part for its known function, which MPEP § 2144.04 treats as obvious absent a showing of unexpected results (duplication is one of the enumerated "obvious design choices," per In re Harza and related principles). The '546's own comparative-example figure (FIG. 5A/5B) shows exactly the symmetric two-walled flow path into which the invention is introduced — the two walls are geometrically identical and the flow path is between them. Once a POSITA decides to wick condensate out of a rectangular, laminated vapor channel, placing the collector on both sides is a predictable, symmetric implementation, rationales (A)/(B). The '546 asserts no advantage unique to the dual-sided placement beyond more capillary surface, which is an inherent function of added collector area.

Combination: Ref 1 (symmetric laminated rectangular channel) + Ref 3/Ref 4 (groove/channel geometry). If a single reference is desired, Ref 1 + Ref 6 (multiple dedicated conduits in one envelope) supplies the multiple-conduit concept.

Assessment for claim 4: Strong, dependent on the strength of claim 1's attack (a dependent claim cannot be more patentable than the claim from which it depends on this element; the added limitation is a symmetry/duplication choice).

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3.4 Claim 5 — partition portion forming two parallel flow paths, with a third drain line feeding both

Claim 5 requires a partition portion between the first and second wall portions, defining two parallel flow paths (50a, 50b), with a third drain line in the partition (separated from both flow paths) and third and fourth drawing conduits connecting that drain line to the first and second flow paths respectively.

Analysis: Two independent lines of reasoning support obviousness:

1. Structural/support motivation is admitted by the patent. The '546 states the partition "may function as a support for supporting the metal layer 31 and the metal layer 36." A partition that both (i) divides a wide channel into narrower ones and (ii) braces the outer layers against a pressure differential is a known expedient in laminated micro-channel heat exchangers/vapor chambers, where interior ribs/supports are standard (the '546's own later siblings describe struts/pillars performing exactly this function, and Ref 1's "columnar" body likewise acts as a support). Positive motivation: a wider single channel needs more bracing; splitting it into two fulfills both functions at once — rationale (A)/(D)/(F).
2. The added drain line is a mere multiplication of a known element. Once the collector conduit of claim 1 is known, adding a second collector on an interior wall — especially on the partition that is closest to both sub-channels — is a design choice with a predictable benefit (shorter capillary path, more collector area). Rationale (B)/(E).

Assessment for claim 5: Moderate-to-strong. The partition-plus-parallel-paths geometry is well within routine design for laminated heat spreaders; the primary weakness in the record is that the prior-art section supplies no single reference showing a partitioned laminated LHP vapor channel, so this claim depends on the analogous-art showing (ribbed/partitioned micro-channels) more heavily than claims 1, 2, 4 and 7. This is the claim most worth a focused additional prior-art search on.

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3.5 Claim 7 — two outer metal layers with an intermediate metal layer defining the channel

Claim 7 requires:

• first and second outer metal layers at both outer sides; and
• the wall-forming metal layer being an intermediate metal layer stacked between them, with an opening formed in it that exposes part of each outer layer to become the flow path.

Analysis: This claim reads on the core structure of Ref 1 with almost no daylight. Ref 1/Ref 2 build the pipe wall as a stacked plurality of metal layers, with the fluid channel formed by through-holes in the intermediate layers, the channel being enclosed by the outer layers. The '546's own summary of this limitation is simply the conventional sandwich: outer solid layers + patterned intermediate layer(s), with the opening in the intermediate layer defining the channel and the outer layers forming its top and bottom. Claim 7 adds effectively nothing beyond what the reference architecture requires for a sealed, closed loop.

Combination: Ref 1 alone, or Ref 1 + Ref 2 (same family) for express claim-language correspondence.

Assessment for claim 7: Strongest of the dependent claims. If claim 1 falls, claim 7 almost certainly falls with it; it may even be vulnerable to a § 102 challenge on the outer/intermediate-layer point standing alone, depending on how strictly the "exposes a part of each of the first and second outer metal layers" language is read against Ref 1's figures.

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3.6 Claims 3, 6, 8, 9, 10, 11, 12 — cannot be analyzed

The retrieved text gives only the headers ("The loop heat pipe according to…") for claims 3, 6 and 8, and nothing for claims 9–12. I will not speculate on their content. Based on the specification's emphasis, the likely subject matter of the missing claims is: drain/drawing lines extending along the flow path in the vapor flow direction (claim 3 candidate); the inclined (~45°) drawing line orientation; the half-etched, concave character of the drain/drawing lines; the identity of the metal (copper) and the solid-phase welding of the stack; and possibly a method claim (the "numbered clause" method in the record is a candidate ancestor). If any missing claim recites the 45° inclination or the ultra-thin, closely spaced bottomed-hole drain of the third embodiment, the obviousness case is weaker, because those are quantitative optimizations that may support a nonobvious range argument — but on the present record I cannot confirm the claim text, so I expressly decline to assert it.

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4. Consolidated § 103 combination table

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5. Anticipated patentee rebuttals and how they fare

1. "Ref 1 is a liquid-side reference; the invention is vapor-side." Weak. The field of endeavor is identical, the problem (condensate/liquid in the transport line degrading heat transfer) is the same one the '546 acknowledges, and the structural platform is shared. Analogous-art doctrine and KSR rationale (C) defeat this.
2. "No motivation to modify a working commercial LHP." Weak post-KSR; the '546 itself frames the problem as a known deficiency, which is the motivation.
3. "Ref 1's layers are sealed/solid-phase bonded, so adding an internal closed channel is not straightforward." Weakest of the rebuttals, because Ref 1/Ref 2 already teach forming internal capillary passages by partial overlap of holes across stacked layers.
4. "The specific 45° inclination / 0.2–0.4 mm dimensions / bottomed-hole pore sizes produce unexpected capillary performance." Potentially the only real rebuttal — but only for the claims that recite those numbers, and the available record does not show whether any issued claim does. This is the point at which a secondary-considerations showing (test data, commercial success with nexus) would be needed. The specification as supplied presents no comparative data (the FIG. 5A/5B comparative example is qualitative only), so there is no probative evidence of unexpected results in the patent itself.
5. Objective indicia (Graham factor 4): Nothing in the retrieved materials evidences unexpected results, licensing praise, industry adoption with a nexus, or copying. The patent is Active but, as noted in the earlier litigation section, no court or PTAB proceeding was found — consistent with a narrow, low‑visibility improvement patent rather than a commercial keystone. That cuts against a secondary-considerations defense, though absence of evidence is not proof of absence.

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6. Bottom line

• The prior-art section supplies one primary reference (WO 2015/087451, Fujitsu), and it is the critical one: it discloses the complete loop-heat-pipe architecture the '546 claims, built by the same stacked-metal-layer, partial-overlap-channel fabrication. What it lacks is the vapor-line/condenser drain line and drawing conduit.
• Claim 1 is obvious over WO 2015/087451 in view of the conventional covered-groove/arterial wick art (Refs 3/4) or the separated-conduit heat-pipe art (Ref 6), with Ref 5 supplying a design-incentive rationale. Confidence is high but not overwhelming, because the attack depends on analogous-art reasoning.
• Claims 2 and 7 are the most exposed: claim 7 is essentially WO 2015/087451's own sandwich architecture, and claim 2 is a design choice the '546 specification expressly characterizes as a mechanical-strength trade-off solved by moving one channel to an adjacent layer.
• Claim 4 is a duplication/symmetry choice (obvious under MPEP § 2144.04); claim 5 is a moderate-strength partition/support design choice and the claim that would benefit most from a targeted search for ribbed or partitioned laminated vapor channels.
• Claims 3, 6 and 8–12 cannot be assessed on the record provided — specifically, the claim text is missing, and no opinion should be relied upon for those claims.
• None of the assignee's own later "bottomed-hole" family is prior art (all post-date 2016‑11‑18) and must not be cited as such.