PTAB

IPR2017-01470

Broadcom Corp v. Tessera Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: HIGH-FREQUENCY CHIP PACKAGES
  • Brief Description: The ’007 patent is directed to a semiconductor package and printed circuit board (PCB) assembly designed to improve heat dissipation. The invention purports to achieve enhanced thermal conductivity by incorporating a large metallic thermal conductor on the chip carrier that can be solder-bonded directly to a circuit board.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over MLF Application Notes - Claims 1, 11-13, 16, and 18 are anticipated by or obvious over MLF Application Notes in view of general knowledge of a person of ordinary skill in the art (POSA).

  • Prior Art Relied Upon: MLF Application Notes (Amkor Technology, Mar. 2001) (“MLF Notes”), Luo (2001 journal article), Clech (1996 conference proceedings), Gustafsson (1998 conference proceedings), and Syed (2000 conference proceedings).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the MLF Notes, which describe Amkor’s MicroLeadFrame package, anticipate every limitation of independent claim 1. For the dependent claims, the MLF Notes allegedly teach using a single, large stencil opening for smaller packages to apply solder, resulting in a “unitary layer of solder” (claim 12) covering the thermal pad. Further, the MLF Notes disclose a component “standoff height” of about 50 to 75 microns, which Petitioner contended is anticipatory because it overlaps with the claimed solder thickness range of “about 25 µm and 50 µm” (claims 13 and 16). The same teachings were argued to disclose the spacing limitation of claim 18.
    • Motivation to Combine (for §103 grounds): Petitioner asserted that even if the MLF Notes were not found to be anticipatory, the claims would have been obvious. A POSA would combine the MLF package with the well-understood principles of thermal management evidenced by Luo, Clech, Gustafsson, and Syed. These references establish that solder thickness was a known result-effective variable for optimizing heat transfer. A POSA would be motivated to select a thickness within the claimed range, a predictable design choice, to solve the known problem of heat dissipation.
    • Expectation of Success: Because the relationship between solder thickness, thermal resistance, and mechanical reliability was well-documented, a POSA would have a high expectation of success in applying a solder layer of the claimed thickness to the MLF package to achieve improved thermal performance without undue experimentation.

Ground 2: Anticipation of Claim 1 by Sharma - Claim 1 is anticipated by Sharma under 35 U.S.C. §102.

  • Prior Art Relied Upon: Sharma (Patent 6,420,779).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Sharma, which discloses a quad flat no-lead (QFN) package, expressly teaches every feature of claim 1. Petitioner mapped Sharma’s leadframe, including its die pad and leads, to the claimed “chip carrier.” The conductive material plated on Sharma’s exposed die pad was identified as the “metallic thermal conductor” having a “unitary solder-wettable area.” Petitioner argued that this area is shown to be larger than the area of the individual terminals, thus meeting all limitations of claim 1.

Ground 3: Obviousness over Sharma and POSA Knowledge - Claims 11-13, 16, and 18 are obvious over Sharma in view of Luo, Clech, Gustafsson, and Syed.

  • Prior Art Relied Upon: Sharma (Patent 6,420,779), Luo (2001 journal article), Clech (1996 conference proceedings), Gustafsson (1998 conference proceedings), and Syed (2000 conference proceedings).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds upon the assertion that Sharma discloses all limitations of claim 1. Petitioner argued that incorporating the additional features of the dependent claims would have been an obvious modification. Sharma teaches soldering its die pad to a PCB for improved thermal reliability. The secondary references (Luo, et al.) were again used as evidence that the claimed solder dimensions (e.g., a unitary layer with a thickness of 25-50 µm) were well-known design parameters for thermal management.
    • Motivation to Combine: A POSA starting with Sharma's QFN package would be motivated to optimize its thermal performance, a stated goal of the reference. The knowledge in the secondary art provided a finite number of known, predictable solutions for solder application and thickness. A POSA would combine Sharma's package with these known techniques to achieve the desired, predictable result of improved heat dissipation.
    • Expectation of Success: Given that the effects of solder dimensions on thermal and mechanical performance were well-understood, a POSA would have been confident that applying a solder layer with the claimed characteristics to Sharma's package would predictably improve its function.

4. Key Claim Construction Positions

  • Petitioner proposed, for the purposes of the IPR, adopting several constructions consistent with those from a related ITC investigation.
    • “Chip carrier” (claims 1, 11, 18): Construed as “a connection component that facilitates handling of the chip during manufacture of and mounting of the chip on an external substrate such as a circuit board or other circuit panel.”
    • “Unitary solder wettable area” / “unitary layer of solder” (claims 1, 11-13, 16): Construed as “a single, continuous solder-wettable area” and “a single continuous layer of solder,” respectively.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under §325(d) would be inappropriate because the grounds presented in the petition were substantially different from those considered by the examiner during prosecution. The core argument was that the primary references (MLF Notes and Sharma) are not cumulative to the art of record. Petitioner asserted that none of the references applied by the examiner taught a “metallic thermal conductor” with a “unitary solder-wettable area,” a key limitation that was added to the claims to secure their allowance.

6. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1, 11-13, 16, and 18 of the ’007 patent as unpatentable.