DCT
3:24-cv-01437
Hildebrandt v. Google LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: James Hildebrandt (California)
- Defendant: Google LLC (Delaware)
- Plaintiff’s Counsel: WEEKS NELSON
- Case Identification: 3:24-cv-01437, S.D. Cal., 08/13/2024
- Venue Allegations: Venue is alleged to be proper because Google has a regular and established place of business in the Southern District of California and has committed acts of alleged infringement in the District.
- Core Dispute: Plaintiff alleges that Defendant’s Google Tensor Processing Unit (TPU) servers, which utilize liquid cooling, infringe a patent related to systems and apparatuses for cooling electronic components.
- Technical Context: The lawsuit concerns thermal management for high-performance computing hardware, a critical technology for enabling the power-intensive processors required for artificial intelligence (AI) and data center workloads.
- Key Procedural History: The complaint alleges that Google knew or should have known of the patent-in-suit for over six years based on constructive notice from its publication by the USPTO.
Case Timeline
| Date | Event |
|---|---|
| 1998-12-22 | ’901 Patent Priority Date |
| 2003-04-22 | ’901 Patent Issued |
| 2018-05-01 | Alleged Launch of Accused Google TPUv3 Liquid-Cooled Pods |
| 2024-08-13 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,552,901 - "Apparatus and System for Cooling Electronic Circuitry, Heat Sinks, and Related Components"
- Patent Identification: U.S. Patent No. 6,552,901, "Apparatus and System for Cooling Electronic Circuitry, Heat Sinks, and Related Components," issued April 22, 2003.
The Invention Explained
- Problem Addressed: The patent describes the challenge of thermal constraints limiting the power density and efficiency of electronic components. It notes that traditional cooling methods can be cumbersome or inefficient, particularly when cooling vapor must escape in opposition to the direction of incoming liquid coolant (e.g., in spray cooling systems) ('901 Patent, col. 1:15-28; col. 3:5-15).
- The Patented Solution: The invention proposes a cooling system where the electronic component or its heat sink acts as an "injection source" for the coolant ('901 Patent, col. 2:50-53). Cooling fluid is supplied to internal passageways within a heat sink and then exits through ports or nozzles on the heat sink’s surface. This provides both conductive cooling to the core of the component and evaporative cooling to its surface, aiming to remove heat more effectively from its source ('901 Patent, Abstract; col. 2:61-65). Figure 1 of the patent illustrates a heat sink (12) receiving fluid from a manifold (14) and expelling it through nozzles (22, 24).
- Technical Importance: This approach seeks to increase the power density and efficiency of electronics by integrating the cooling mechanism directly into the components, thereby eliminating additional manifolds and improving heat removal at the source ('901 Patent, col. 2:54-64).
Key Claims at a Glance
- The complaint asserts independent claim 16 ('901 Patent, col. 14:15-30; Compl. ¶15).
- The essential elements of independent claim 16 are:
- A system for cooling an electronic component comprising: at least one electronic component;
- a heat sink attached to said at least one electronic component;
- said heat sink having at least one interior passageway within said heat sink and at least one secondary passageway in fluid communication with said at least one interior passageway connecting said interior passageway to an exterior surface of said heat sink;
- means for supplying cooling fluid capable of phase change to said interior passageway;
- means for adjusting the rate at which said cooling fluid passes through said interior passageway so that substantially no cooling fluid is vaporized within said interior passageway; and
- means for collecting and recycling said cooling fluid.
- The complaint reserves the right to assert other claims from the ’901 patent (Compl. ¶16).
III. The Accused Instrumentality
Product Identification
- The "Accused Devices" are identified as Google's version 3 Tensor Processing Units ("TPU" or "TPUv3") and the servers that contain them (Compl. ¶8).
Functionality and Market Context
- The complaint alleges that the Accused Devices are used in Google's data centers and cloud servers for AI workloads (Compl. ¶8). Plaintiff alleges Google began using "eight-rack pods of liquid-cooled TPU servers" around May 2018, which enabled the processors to run at higher capacity (Compl. ¶9). The complaint includes a photograph of these server racks to illustrate their industrial scale and deployment. (Compl. p. 4).
- The core accused functionality involves a liquid cooling system where a "dielectric liquid" is brought to four TPUv3 ASIC chips on each motherboard. Each chip is topped with a heat sink, and the system allows the coolant to "circulate through the tubing and heat sinks to remove heat from the chips" (Compl. ¶10). A photograph of an accused motherboard shows four chip modules, each with a heat sink, interconnected by tubing labeled "FLUID IN" and "FLUID OUT," illustrating the alleged fluid circulation path (Compl. p. 4).
IV. Analysis of Infringement Allegations
The complaint states that a claim chart is attached as Exhibit 2, but this exhibit was not included with the filing. The following chart is constructed based on the allegations in the body of the complaint.
’901 Patent Infringement Allegations
| Claim Element (from Independent Claim 16) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| at least one electronic component | The Google TPUv3 ASIC chip. | ¶10 | col. 14:17-17 |
| a heat sink attached to said at least one electronic component | The heat sink "sitting atop each TPUv3 ASIC chip." | ¶10 | col. 14:18-19 |
| said heat sink having at least one interior passageway within said heat sink and at least one secondary passageway... connecting said interior passageway to an exterior surface of said heat sink | The tubing and internal channels of the heat sinks that allow coolant to circulate. The photograph on page 4 depicts tubing labeled "FLUID IN" and "FLUID OUT" connected to the heat sinks, suggesting an internal fluid path that connects to the exterior. | ¶10, p. 4 | col. 14:20-24 |
| means for supplying cooling fluid capable of phase change to said interior passageway | The system that brings "dielectric liquid" to the chips via tubing, as shown by the "FLUID IN" port in the complaint's photograph. | ¶10, p. 4 | col. 14:25-26 |
| means for adjusting the rate at which said cooling fluid passes through said interior passageway so that substantially no cooling fluid is vaporized within said interior passageway | The complaint does not provide sufficient detail for analysis of this element. It makes no specific allegations regarding a mechanism for adjusting the coolant flow rate to prevent vaporization. | N/A | col. 14:27-29 |
| and means for collecting and recycling said cooling fluid | The system that allows coolant to "circulate," as implied by the "FLUID OUT" port shown in the complaint's photograph and the closed-loop nature of the server rack pods. | ¶10, p. 4 | col. 14:30-30 |
- Identified Points of Contention:
- Evidentiary Question: A central issue will be whether Plaintiff can produce evidence of a "means for adjusting the rate" of coolant flow for the purpose of preventing vaporization inside the heat sink's interior passageway. The complaint provides no factual allegations to support the existence of a structure performing this specific function in the Accused Devices.
- Scope Questions: The case may turn on the construction of the claim's structural requirements. A question exists as to whether the internal plumbing of the accused heat sinks meets the distinct limitations of both an "interior passageway" and a "secondary passageway," or if these terms describe a single, undifferentiated fluid channel.
- Technical Questions: A key factual dispute may arise over how the accused system actually operates. The claim requires that "substantially no cooling fluid is vaporized within said interior passageway." The infringement analysis will depend on whether Google's system is a single-phase liquid cooling loop that meets this limitation or if it operates as a two-phase system where vaporization occurs internally, potentially placing it outside the claim's scope.
V. Key Claim Terms for Construction
The Term: "means for adjusting the rate at which said cooling fluid passes through said interior passageway so that substantially no cooling fluid is vaporized within said interior passageway"
Context and Importance: This is a means-plus-function limitation governed by 35 U.S.C. § 112(f). Its construction will be critical because the infringement analysis requires identifying a corresponding structure in the accused device that performs the claimed function. Practitioners may focus on this term because the complaint does not identify any corresponding structure in the accused system, and the patent's disclosure of such a structure may be subject to debate.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification discusses regulating coolant flow more generally through "the size and placement of perforations or inlets" ('901 Patent, col. 4:16-18) or by using conventional components like pumps ('901 Patent, col. 6:23-24). A party might argue these general disclosures constitute the structure for performing the function.
- Evidence for a Narrower Interpretation: The patent does not appear to explicitly link a specific structure to the precise function of "adjusting the rate" for the specific purpose of preventing vaporization inside an interior passageway. A party could argue that the absence of a clearly linked, specific structure renders the claim indefinite or limits its scope to the few embodiments described, such as the specific porting configurations shown.
The Term: "secondary passageway"
Context and Importance: Claim 16 requires both an "interior passageway" and a "secondary passageway" that connects the interior one to the heat sink's exterior. The definition of "secondary passageway" is critical to determining if the accused heat sinks, which contain internal fluid channels, meet this two-part structural requirement.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent refers generally to fluid exiting through "ports or nozzles on the surface" ('901 Patent, col. 2:64-65). This could support an interpretation where the "secondary passageway" is simply the terminal port or nozzle assembly (e.g., nozzle 22 in FIG. 1A) where fluid exits.
- Evidence for a Narrower Interpretation: The use of two distinct terms—"interior passageway" and "secondary passageway"—suggests they are structurally different. A party could argue that "secondary passageway" requires a distinct channel or conduit connecting the main internal passage to the exit port, not just the exit port itself. The specification’s description of "a plurality of other passageways connecting said interior passageway to the exterior surface" could support the need for a more complex network of channels ('901 Patent, col. 12:62-65).
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Google induces infringement by selling the Accused Devices to customers and encouraging their use for AI processing and cloud services (Compl. ¶¶25, 27). Knowledge is alleged on the basis that Google "knew or should have known" its actions would result in its customers' infringement (Compl. ¶25).
- Willful Infringement: The willfulness allegation is based on the claim that "Google knew or should have known of the '901 patent for over six years with at least constructive notice through USPTO publication" (Compl. ¶18). This pleading appears to rely on pre-suit constructive notice and continued infringement after the complaint was filed.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of proof regarding a means-plus-function limitation: Can the Plaintiff establish that Google’s TPU cooling system contains a structure corresponding to the claimed "means for adjusting the rate" of coolant flow to prevent internal vaporization, a technical detail absent from the complaint's allegations?
- A second key question will be one of claim scope and structural mapping: Does the internal plumbing of the accused Google heat sinks embody the distinct "interior passageway" and "secondary passageway" structure recited in Claim 16, or is there a technical mismatch between the patent's specific architecture and the accused design?
- The case will also likely involve a central factual dispute over the mode of operation: Does the accused system function as a single-phase liquid cooling loop where "substantially no" vaporization occurs internally, as required by the claim, or does it utilize a different thermal mechanism (e.g., two-phase flow) that falls outside the patent's asserted scope?