PTAB

IPR2021-01195

CoolIT Systems Inc v. Asetek Danmark AS

Key Events

Petition

petition Intelligence

Title: Liquid-Cooling System for a Computer Processing Unit
Brief Description: The ’601 patent relates to a compact liquid-cooling system for a computer processing unit (CPU). The system purports to offer improved efficiency over conventional air-cooling arrangements through an integrated unit comprising a reservoir, pump, and heat exchanging interface.

Prior Art Relied Upon: Batchelder (Patent 6,019,165) and Shin (Japanese Application Publication No. 2002-151638).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued Batchelder’s "active spreader plate" teaches the claimed "reservoir," including an upper and lower chamber, a central first passage, and a peripheral second passage. Petitioner contended that substituting one of Batchelder's disclosed pump types (a "viscosity pump") for another would result in the claimed center-to-perimeter fluid flow in the lower chamber. Shin was alleged to teach the missing element of an external radiator spaced apart from and fluidly coupled to the reservoir assembly. For dependent claim 2, Petitioner asserted that Shin’s disclosure of a DC motor teaches a control system that can adjust pump speed.
- Motivation to Combine: A POSITA would combine Shin’s external radiator with Batchelder’s integrated cooling plate to improve heat management for high-power semiconductor devices, a problem both references sought to solve. An external radiator was a known method to augment cooling capacity when an integrated solution became insufficient.
- Expectation of Success: A POSITA would have a reasonable expectation of success in this combination, as adding a radiator to a liquid cooling loop is a conventional and predictable modification.

Prior Art Relied Upon: Batchelder (Patent 6,019,165), Shin (Japanese Application Publication No. 2002-151638), and Admitted Prior Art (APA) from the ’601 patent specification.
Core Argument for this Ground:
- Prior Art Mapping: This ground incorporated the arguments from Ground 1 to meet the common limitations of independent claims 6 and 12. For the additional limitations of a mounting frame with four holes and a gasket, Petitioner turned to the APA and Batchelder, respectively. Petitioner argued the APA (Figures 1-3 of the ’601 patent) explicitly discloses a four-hole frame for fastening a cooling apparatus to a motherboard. Further, Batchelder was alleged to disclose an o-ring to seal interfaces, which Petitioner argued is a type of gasket.
- Motivation to Combine: A POSITA would combine the APA’s frame with the Batchelder/Shin system because securing the cooling unit to the CPU is a functional necessity, and the APA provided a well-understood mounting solution. Likewise, a POSITA would use a gasket as taught by Batchelder to prevent fluid leakage, a basic requirement for any liquid cooling system.
- Expectation of Success: Success would be expected as mounting frames and gaskets are standard components whose integration into a cooling system is straightforward and predictable.

Prior Art Relied Upon: Batchelder (Patent 6,019,165), Shin (Japanese Application Publication No. 2002-151638), and Nakano (Patent 6,915,653).
Core Argument for this Ground:
- Prior Art Mapping: This ground built upon the base combination of Batchelder and Shin by adding Nakano to teach the specific control system features of dependent claims 3-5. Petitioner asserted that Nakano discloses a controller that measures the temperature of a semiconductor element to represent operating load (claim 3), uses this data to determine the required cooling capacity (claim 4), and adjusts the pump speed accordingly, including reducing speed when lower capacity is required (claim 5).
- Motivation to Combine: A POSITA would incorporate Nakano's control system into the Batchelder/Shin combination to achieve greater efficiency, reduce noise, and conserve power. Adjusting pump speed based on real-time thermal load was a known technique for optimizing cooling systems.
- Expectation of Success: The integration of a control system with a pump and fan was a familiar concept to a POSITA, and the combination would yield the predictable result of more efficient, demand-based cooling.
Additional Grounds: Petitioner asserted additional obviousness challenges for claims 7-11 and 13-16 based on the combination of Batchelder, Shin, the APA, and Nakano, which relied on similar arguments to incorporate control system features into the base cooling system.

Petitioner noted that the parties stipulated in a co-pending district court action that "reservoir" means a "single receptacle defining a fluid flow path." Petitioner argued this construction supports its assertion that Batchelder's "active spreader plate" meets the limitation, as it is a single unit containing the claimed internal components that define a fluid path.

A central technical argument was that a POSITA would find it obvious to modify Batchelder's device to achieve the claimed center-to-perimeter fluid flow. Petitioner contended that substituting Batchelder's disclosed "centrifugal pump" with its alternative "viscosity pump" would reverse the flow direction. This modification would improve cooling performance by impinging the coldest fluid directly onto the center of the heat source, which is typically the hottest spot on a CPU.

Petitioner argued against discretionary denial under Fintiv, asserting that: (1) the petition's merits are particularly strong, as they rely on the same primary prior art used by the Board to institute an IPR against a related patent (’354 patent); (2) the co-pending district court trial is likely to be delayed past the Final Written Decision date due to court backlogs; and (3) institution would serve judicial economy as the petition challenges all 16 claims, whereas only 4 are asserted in the district court case.

Petitioner requests institution of an inter partes review and cancellation of claims 1-16 of the ’601 patent as unpatentable under 35 U.S.C. §103.