DCT
8:25-cv-01329
Denso Corp v. Skyworks Solutions Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: DENSO Corporation (Japan)
- Defendant: Skyworks Solutions, Inc. (USA) and Skyworks Filter Solutions Japan Co., Ltd. (Japan)
- Plaintiff’s Counsel: Wiggin and Dana LLP; Thinkingforward LLC
- Case Identification: 8:25-cv-01329, C.D. Cal., 06/20/2025
- Venue Allegations: Venue is alleged to be proper based on Defendants having established places of business in the district and having committed acts of infringement there.
- Core Dispute: Plaintiff alleges that Defendant’s Bulk Acoustic Wave (BAW) filters and front-end modules, used in 5G mobile devices, infringe a patent related to scandium-doped aluminum nitride piezoelectric thin films.
- Technical Context: The technology involves specialized materials for radio-frequency (RF) filters, which are critical components for enabling the high-frequency, wide-bandwidth performance required by modern 5G telecommunication standards.
- Key Procedural History: The complaint details a multi-year history of licensing negotiations, alleging that Skyworks first contacted Denso to inquire about a license in November 2019, but that substantive negotiations stalled and no license was taken. This history is presented as the basis for a claim of willful infringement.
Case Timeline
| Date | Event |
|---|---|
| 2007-05-31 | '979 Patent Priority Date |
| 2010-07-20 | '979 Patent Issue Date |
| 2019 | Skyworks launched its new Film Bulk Acoustic Resonator (FBAR) product |
| 2019-11-08 | Skyworks allegedly first contacted Denso to license its ScAlN patent portfolio |
| 2020-07-21 | Skyworks announced shipping over 150 million modules with BAW filters for 5G |
| 2024-04-10 | Denso allegedly sent Skyworks a chart demonstrating infringement by its products |
| 2025-06-20 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
- Patent Identification: U.S. Patent No. 7,758,979, “Piezoelectric Thin Film, Piezoelectric Material, and Fabrication Method...”, issued July 20, 2010.
The Invention Explained
- Problem Addressed: The patent’s background section explains that conventional piezoelectric thin films made of aluminum nitride (AlN), while having some preferable characteristics, suffer from a low piezoelectric constant. This deficiency requires higher operating voltages for devices like RF filters, leading to increased power consumption, signal loss, and difficulties in miniaturization (’979 Patent, col. 1:50-2:1). The complaint echoes this, noting that traditional AlN BAW filters struggle to meet the performance requirements of some 5G bands (Compl. ¶34).
- The Patented Solution: The invention addresses this problem by adding a specific amount of a rare earth element—scandium (Sc)—to the aluminum nitride thin film (’979 Patent, Abstract). This doping process is described as improving the film’s piezoelectric response, which allows for lower-power and more compact filter components, while preserving AlN's other favorable characteristics like its elastic wave propagation speed and Q value (’979 Patent, col. 3:45-50; Compl. ¶65).
- Technical Importance: This material innovation was significant for advancing RF filter technology, enabling components that could meet the demanding high-frequency and wide-bandwidth requirements of 4G and 5G mobile communications (Compl. ¶¶ 32, 37).
Key Claims at a Glance
- The complaint asserts infringement of at least exemplary Claim 6, which is an independent claim (Compl. ¶66).
- The essential elements of independent Claim 6 are:
- A piezoelectric thin film comprising an aluminum nitride thin containing scandium,
- a content ratio of the scandium being in a range of 10 atom % to 35 atom % or 40 atom % to 50 atom % on an assumption that a total amount of a number of atoms of the scandium and a number of atoms of aluminum in the aluminum nitride thin film is 100 atom %.
- The complaint does not explicitly reserve the right to assert other claims, but refers to "Example Patent Claims" in its infringement count (Compl. ¶77).
III. The Accused Instrumentality
Product Identification
The accused products are Skyworks' Bulk Acoustic Wave (BAW) filters, specifically its Film Bulk Acoustic Resonator (FBAR) products, and the integrated front-end modules that incorporate these filters (Compl. ¶¶ 44, 49). The complaint identifies "Sky5 modules" as an exemplary product line, listing several specific part numbers (Compl. ¶49).
Functionality and Market Context
The accused products are radio-frequency (RF) filters and modules that use scandium aluminum nitride (ScAlN) as a piezoelectric material (Compl. ¶¶ 46, 49). They are marketed as being "particularly beneficial for next-generation wireless standards, including Wi-Fi and 5G" (Compl. ¶45). The complaint alleges these products are incorporated into 5G-compliant devices from major manufacturers, including Apple (Compl. ¶50).
IV. Analysis of Infringement Allegations
The complaint references an "Exhibit 2 (claim chart)" that was not filed with the complaint; the following summary is based on the narrative allegations (Compl. ¶77). No probative visual evidence provided in complaint.
’979 Patent Infringement Allegations
| Claim Element (from Independent Claim 6) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A piezoelectric thin film comprising an aluminum nitride thin film containing scandium, | The accused Skyworks FBAR and Sky5 modules use scandium aluminum nitride (ScAlN) as a piezoelectric material. | ¶46, ¶49 | col. 24:25-26 |
| a content ratio of the scandium being in a range of 10 atom % to 35 atom % or 40 atom % to 50 atom % on an assumption that a total amount of a number of atoms of the scandium and a number of atoms of aluminum in the aluminum nitride thin film is 100 atom %. | The complaint alleges that the accused products practice the technology claimed in the patent and satisfy all elements of the exemplary claims, as set forth in a non-public claim chart. | ¶77 | col. 24:27-33 |
- Identified Points of Contention:
- Evidentiary Question: A primary factual dispute will concern the precise chemical composition of the accused filters. What is the actual atomic percentage of scandium relative to aluminum in Skyworks' ScAlN thin films? The complaint makes conclusory allegations of infringement but does not provide public-facing evidence (such as from reverse engineering) that the scandium content falls into one of the two specific ranges recited in Claim 6.
- Technical Question: The claim recites two distinct, non-contiguous ranges for the scandium content ratio ("10-35 atom %" OR "40-50 atom %"). This raises the question of whether the accused products, upon technical analysis, will be found to have a composition that falls within either of these specific ranges, or if they fall into the unclaimed "gap" between 35% and 40% or outside the ranges entirely.
V. Key Claim Terms for Construction
- The Term: "a content ratio of the scandium being in a range of..."
- Context and Importance: The determination of infringement hinges entirely on whether the measured composition of the accused products falls within the specific numerical ranges defined in this limitation. Practitioners may focus on this term because the methodology for calculating this atomic ratio in a manufactured ternary compound could be a point of dispute.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party might argue for a straightforward mathematical application of the definition provided in the specification, which defines "atom %" as "the number of scandium atoms or the number of aluminum atoms on the assumption that a total amount of the number of scandium atoms and the number of aluminum atoms equals 100 atom %" (’979 Patent, col. 7:42-47).
- Evidence for a Narrower Interpretation: A party could argue that the term must be construed in light of the patent's overall teachings, potentially limiting the method of measurement to those consistent with the experimental results and characterization techniques described in the patent, which might exclude certain impurities or non-ideal structures found in a mass-produced product.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Skyworks induces infringement by encouraging and instructing its partners and customers to use and import the accused products in an infringing manner, specifically by selling the components with the knowledge that they will be incorporated into 5G-compliant mobile products sold in the United States (Compl. ¶¶ 78, 80).
- Willful Infringement: The willfulness claim is based on alleged pre-suit knowledge of the ’979 Patent. The complaint alleges that Skyworks has had actual knowledge since at least November 8, 2019, when it purportedly initiated licensing discussions with Denso (Compl. ¶81). The complaint further alleges that Skyworks continued its infringing activities despite this knowledge and despite receiving a specific notice of infringement via a claim chart in April 2024 (Compl. ¶¶ 57, 82).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of evidentiary proof: Can Denso produce technical evidence, likely through discovery and reverse engineering, to demonstrate that the scandium-to-aluminum atomic ratio in Skyworks' mass-produced BAW filters falls squarely within one of the two specific, non-contiguous numerical ranges recited in Claim 6?
- A second central question will concern willfulness and damages: The court will be asked to interpret the alleged five-year history of pre-suit communications. The key determination will be whether Skyworks' alleged conduct during licensing negotiations rises to the level of egregious or bad-faith behavior that could justify an award of enhanced damages.