Shenzhen Tuozhu Technology Co Ltd v. Stratasys Inc

1. Case Identification

• Case #: IPR2025-00257
• Patent #: 9,592,660
• Filed: December 9, 2024
• Petitioner(s): Shenzhen Tuozhu Technology Co., Ltd.
• Challenged Claims: 1-15

2. Patent Overview

• Title: Heated Build Platform and System for Three Dimensional Printing Methods
• Brief Description: The ’660 patent discloses a heated build platform for 3D printing that uses a polymer coating on a removable, thermally conductive plate. This system is designed to improve adhesion of the printed object during printing and facilitate easy, non-damaging removal of the object after it has cooled, serving as an alternative to polymer tapes.

3. Grounds for Unpatentability

Ground 1: Claims 1-13 and 15 are obvious over Cable in view of Naware

• Prior Art Relied Upon: Cable (Application # 2016/0075091) and Naware (Application # 2016/0096326).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Cable taught the core elements of the ’660 patent, including a 3D printing system with a heated build platform supporting a flexible, removable substrate. This substrate featured a thermoplastic polymer coating designed to promote adhesion and allow for easy object removal by flexing the substrate, causing the object to "pop off" without damage to the coating or object. Petitioner asserted that Naware supplemented Cable by teaching a more advanced build plate with an integrated array of temperature control modules, including heating/cooling mechanisms and sensors, to precisely control the thermal gradient and prevent part warping. The combination, Petitioner contended, met the limitations of the independent and dependent claims. For example, Cable's polymer coating met the functional requirements of claim 1, including being a non-tape coating, and Naware’s temperature control modules met the limitations for the claimed temperature control unit, thermocouples (a known sensor type), and heater cartridges (a known heater type).
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references for several reasons. First, Cable broadly taught heating its build platform with "any suitable heating element," which would have prompted a POSITA to look to contemporaneous art like Naware for specific, effective heating solutions. Second, heated build platforms were a ubiquitous and well-known solution to the problem of part adhesion and warping, and Naware provided an effective, known approach. Third, a POSITA would recognize that the benefits described in Naware—such as optimized temperature control to reduce curling and delamination—were directly applicable to improving the performance of the system in Cable.
  • Expectation of Success: Petitioner argued that a POSITA would have had a high expectation of success. Both references operate in the same technical field of 3D printing, and temperature-controlled build plates were a mature and successfully demonstrated technology by 2014. Combining Naware's specific heating element design with Cable's platform and coated substrate was a predictable integration of known technologies.

Ground 2: Claims 1-3 and 5-15 are obvious over Comb in view of Tummala

• Prior Art Relied Upon: Comb (Patent 9,744,730) and Tummala (Application # 2013/0310507).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Comb disclosed a 3D printing platen assembly with a heatable platen plate (the build platform) and a removable, flexible, multi-layer build sheet (the thermally conductive plate). This build sheet included a top film made from a polymeric material, such as polyimide, which could be a coating, tape, or other lamina. Comb taught that after printing, the flexible sheet could be removed and flexed to cleanly detach the 3D part without damage. Petitioner argued that Tummala provided a complementary teaching of a polymer material applied as a coating or gel—explicitly not as a tape—that provided satisfactory bonding during printing but also acted as a releasing agent after cooling. Petitioner contended the combination taught all limitations, with Comb providing the core heated apparatus and removable plate, and Tummala teaching the specific non-tape polymer coating that facilitates adhesion and easy, non-damaging removal.
  • Motivation to Combine: A POSITA would combine Comb and Tummala because both address the same problem of creating a reusable build surface that allows for easy part removal. Comb explicitly mentioned that its polymeric top layer could be a "coating," not just a tape. This would have motivated a POSITA to look for known, effective non-tape coating solutions like that taught by Tummala, which offered advantages of easier application (as a gel) over the known frustrations of applying tape. A POSITA would have used Tummala's polymer coating as a direct substitute for the polymer layer in Comb's system to achieve the predictable result of a non-tape, reusable build surface.
  • Expectation of Success: Petitioner asserted a reasonable expectation of success because applying polymer coatings to build plates was a well-understood technique. The combination involved substituting one known type of polymer surface (as broadly disclosed in Comb) with another known type of polymer surface (as specifically taught by Tummala) to achieve the predictable benefits described in both references.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Cable with Kritchman (Application # 2006/0054039) as an alternative to Naware for teaching a temperature control unit (Ground 1B). Further grounds added Comb's teachings on material selection to the Cable combinations (Ground 1C) and added Kritchman's teachings to the Comb/Tummala combination (Ground 2B).

4. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under both §325(d) and §314(a).
• §325(d) (Advanced Bionics): Petitioner contended that the asserted prior art and arguments were not the same or substantially similar to those considered during prosecution. Key references like Cable and Tummala, and the specific combinations of Cable/Naware and Comb/Tummala, were never before the examiner. Petitioner argued the examiner erred by overlooking key disclosures in Comb and deeming the "not a polymer tape" limitation novel without proper support.
• §314(a) (Fintiv): Petitioner argued that the Fintiv factors strongly favored institution. The petition was filed early in a parallel district court case, before an answer was filed. Petitioner asserted that court and party resources invested were minimal, a stipulation was offered to streamline issues, and any FWD would issue nearly contemporaneously with the scheduled trial date, minimizing concerns of duplicative efforts.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-15 of the ’660 patent as unpatentable.