Flexible and Rigid-Flex Circuit Boards Patents: Leaders & Trends 2026
- Filing has cooled since 2017. The peak year (79 filings) sits nearly a decade back, and the 2022 midpoint (46) already shows the decline — this is a maturing claim space, not a growing one.
- H05K dominates by a wide margin. 1,230 of 1,270 records sit in printed-circuits-and-assemblies (H05K), with lamination (B32B) and condensation-polymer chemistry (C08G) a distant second tier.
- Ownership is fragmented at the top. The strongest co-assignee link is worth 14 shared filings, and most tracked assignees logged zero filings in the latest year — momentum has scattered rather than concentrated.
What this landscape covers
This dataset tracks 1,270 patent families filed against flexible printed circuit and rigid-flex board technology, spanning bending-endurance claims, coverlay formulations, polyimide substrates, dynamic-flex applications and adhesiveless laminate structures. The search string combines title/abstract terms for flexible and rigid-flex constructions with IPC coverage across H05K (printed circuits), H05K3 (manufacturing processes) and C08G73 (condensation polymers used in substrate chemistry), so it captures both the mechanical/electrical structure claims and the materials science behind them.
Publication data lags actual filing by roughly 18 months, so the most recent year in any trend line understates real activity. Read the last one to two years as a floor, not a ceiling.
Filing trends and technology composition
The filing curve and the IPC mix together show a technology whose structural claims were staked out early and whose remaining activity clusters in materials refinement rather than new architecture.
A decade of declining filing volume
Filings peaked at 79 in 2017, held at 46 by the 2022 midpoint, and have fallen further since — consistent with a field where the core rigid-flex and FPC structures were claimed in the 2010s and later filings are incremental.
H05K dominates; chemistry classes trail
H05K appears in 1,230 of 1,270 records, effectively defining the dataset. B32B (188), C08G (123), C09J (121) and C08L (99) form a materials-and-adhesives tier below it, with H01L, H01R and C08K appearing as smaller, application-specific slices.
Shares are the percentage of the 1,270 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Flexible and Rigid-Flex Circuit Boards with Eureka
This page is one run against one query. Ask Eureka your own question about flexible and rigid-flex circuit boards and every answer comes back with the patent numbers behind it.
Try EurekaThe prior art everyone in this space cites
Flexible printed circuit and antenna structure (US20230363089A1)
Filed by Wistron NeuWeb, this filing covers a flexible printed circuit with a main body and a bending part, built from a substrate sandwiched between two copper foil layers, each covered by a coverlay with at least two coverlay holes penetrating the main body section. It positions the antenna structure directly on the flex construction rather than as a separate component.Published 2023-11-09 — illustrates how antenna integration is now being layered onto standard coverlay/copper-foil FPC structures.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5428190A | Rigid-flex board with anisotropic interconnect and method of manufacture | 278 |
| 2 | US5261593A | Direct application of unpackaged integrated circuit to flexible printed circuit | 196 |
| 3 | WO2016114287A1 | Resin film for flexible printed circuit board, metal foil provided with resin, coverlay film, bonding sheet, … | 194 |
| 4 | US5719749A | Printed circuit assembly with fine pitch flexible printed circuit overlay mounted to printed circuit board | 188 |
| 5 | JP2011068713A | Coverlay film | 152 |
| 6 | US6249404B1 | Head gimbal assembly with a flexible printed circuit having a serpentine substrate | 150 |
| 7 | JP1990175247A | Release film composed of laminate | 100 |
| 8 | US5478244A | Hybrid junction box | 99 |
| 9 | US20150296622A1 | Flexible Printed Circuit With Semiconductor Strain Gauge | 93 |
| 10 | US5349500A | Direct application of unpackaged integrated circuit to flexible printed circuit | 75 |
Citation counts favour older filings simply because they have had more time to accumulate citations inside the searched corpus — treat this as a map of foundational influence, not of current commercial weight.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the numbers say about where this field stands
Three signals matter more than the headline count: the direction of the filing curve, the concentration of the IPC mix, and how thin the strongest ownership links actually are.
Volume has receded from its 2017 peak
The 2022 midpoint of 46 filings already sat below peak, and the trend has continued downward since. This is the profile of a field consolidating around established structures rather than one still being defined.
Almost the entire dataset sits in one IPC subclass
H05K's dominance means the differentiators in recent filings are less about circuit architecture and more about the secondary classes attached alongside it — lamination, adhesives and polymer chemistry.
Collaboration exists but stays shallow
Only ten co-assignee pairs appear in the dataset, and the strongest link tops out at 14 shared filings between two related entities. There is no evidence of a broad cross-company collaboration network in this space.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to flexible and rigid-flex circuit boards, with the prior art for and against each one.
Who is active, and who has gone quiet
Recent-year momentum figures tell a different story than raw historical volume: several assignees with substantial filing histories show zero activity in the latest tracked year, suggesting either portfolio maturity or a shift away from public filing in this specific claim space.
Historically active filers have gone quiet
Samsung Electro-Mechanics, Fujikura, Sumitomo Electric Industries, Shin-Etsu Chemical and Arisawa Manufacturing all show zero filings in the most recent tracked year, despite established filing histories in the space.
Even the most active recent filer is slowing
Samsung Electronics (Korea) recorded just 1 filing in the latest year, down 50% year-on-year — the single clearest sign of continued, if diminishing, activity among the tracked assignees.
Filing tends to happen within corporate families
The strongest co-assignee relationships sit between related entities under the same corporate umbrella rather than across competitors, pointing to internal R&D-to-manufacturing handoffs rather than joint development deals.
| Assignee | Recent year | YoY |
|---|---|---|
| Samsung Electronics Co., Ltd. (Korea) | 1 | -50% |
| Samsung Electro-Mechanics Co., Ltd. | 0 | — |
| Fujikura Ltd. | 0 | — |
| Sumitomo Electric Industries, Ltd. | 0 | — |
| Shin-Etsu Chemical Co., Ltd. | 0 | — |
| Arisawa Manufacturing Co., Ltd. | 0 | — |
| LG Chem, Ltd. | 0 | — |
| Nippon Mektron, Ltd. | 0 | — |
Where to take this analysis
The dataset points to a mature but still-shifting field: structural claims are largely staked out, while materials and integration details remain open to challenge or refinement.
Check freedom-to-operate before filing in coverlay chemistry
With C08G, C09J and C08L all appearing as secondary classes on a large share of H05K filings, new coverlay or adhesive formulations are the most likely place to collide with existing claims.
Run a freedom-to-operate checkModel the declining filing curve against your own roadmap
A filing count moving from 79 to single digits changes what 'active competitor' means in this space — verify whether a target assignee's quiet recent years reflect abandonment or a shift to trade secret.
Explore filing trends in EurekaCommon questions about flexible and rigid-flex circuit board patents
The filing trend in this dataset peaked at 79 filings in 2017 and has fallen steadily since, reaching just 2 in the most recent (partial) year. This pattern typically means the core structural claims — substrate, copper foil layering, coverlay construction — were staked out during the 2010s, leaving later filers to compete on narrower materials or process refinements rather than new architectures. It does not mean the underlying technology has stopped being used commercially; production and R&D can continue long after patent filing slows, especially once a design space becomes standardized.
In this corpus, coverlay claims (frequently tied to C09J adhesive classifications) describe the protective film bonded over exposed copper traces, often including specific hole or opening geometry for component or antenna access. Laminate claims, tied more often to B32B, describe the layered stack-up itself — how substrate, copper foil and protective layers are bonded together, including adhesiveless approaches that remove a separate bonding layer entirely. A single flexible circuit board patent will often combine both types of claims, but they represent distinct technical problems: surface protection versus structural bonding.
Recent-year momentum data shows most historically prolific assignees — including Samsung Electro-Mechanics, Fujikura, Sumitomo Electric Industries, Shin-Etsu Chemical and Arisawa Manufacturing — recorded zero filings in the latest tracked year. Samsung Electronics (Korea) is the most visible continuing filer, though even its filing count fell 50% year-on-year to a single filing. Given an 18-month publication lag, the truest picture of who is currently filing will only become clear in later data releases, so current 'zero' readings should be treated cautiously rather than as confirmed exits.
The IPC composition shows H05K structural claims heavily dominant (1,230 of 1,270 records) with materials classes like C08G, C09J and C08L trailing well behind, suggesting the thinner claim density sits in specific materials and integration details rather than in circuit architecture itself. Sub-areas worth checking include adhesiveless laminate interfaces, dynamic flex fatigue testing methodologies, coverlay hole geometry designed for antenna or sensor integration, and fine-pitch interconnects at the rigid-flex connector boundary. These are not guaranteed open space — they simply show lower filing density relative to the core structural claims, so a freedom-to-operate search is still necessary before filing.
US20230363089A1, filed by Wistron NeuWeb and published November 2023, claims a flexible printed circuit with a bending part and a main body, built from a substrate between two copper foil layers each covered by a coverlay containing at least two coverlay holes over the main body section. For companies building antenna structures directly onto flexible circuit substrates, this filing is a signal that the industry is actively claiming the specific combination of coverlay hole placement and bending-zone geometry for antenna integration purposes, not just for standard component mounting. Anyone designing a similar bending-zone antenna layout should check this filing's specific claim language on hole count, placement and the bending-part boundary before finalizing a design.
Research Flexible and Rigid-Flex Circuit Boards in depth with Eureka
Go past this page: query the whole flexible and rigid-flex circuit boards corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.