Invalidity dossier
US 4862197
Process for manufacturing thermal ink jet printhead and integrated circuit (IC) structures produced thereby
Current assignee: HP Inc
Added 9/23/2026, 9:28:34 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 4,862,197 A
Title: Process for manufacturing thermal ink jet printhead and integrated circuit (IC) structures produced thereby
Inventor: John L. Stoffel. Original assignee: Hewlett-Packard Co. (current assignee listed as HP Inc).
Dates: Priority/filing date 1986-08-28 (application US06/902,287); granted and published 1989-08-29. Legal status listed as expired — lifetime, with anticipated expiration 2006-08-29. Related filings were made in EP, DE, CA, JP, and later SG/HK. This is bibliographic data from the source, not a legal conclusion.
Purpose: The invention relates generally to thermal ink jet printhead construction, and more particularly to "an improved integrated interconnect circuit extending between the printhead heater resistors and external pulse drive circuitry for supplying drive current to these heater resistors." The stated general purpose is to provide a new and improved integrated circuit interconnect structure for supplying drive current to thermal ink jet printhead heater resistors, plus a high-yield process for fabricating it. The interconnect is described as adapted for spring-biased pressure contacts, such as fingers or leads on a lead frame type flexible ("flex") circuit.
Plain-language scope: In the described prior art, a relatively large via was etched in an inert barrier layer (e.g., a silicon nitride/silicon carbide composite) over an aluminum conductive trace, and a large contact pad formed in that opening for wire-bond or pressure-contact connection. The source lists disadvantages attributed to that approach: exposed barrier sidewalls prone to pinholes/cracks and shorts; a "diving board" stepped geometry from differing silicon nitride/silicon carbide etch rates; oxide formation on large exposed aluminum areas; undercutting during via etching; and a non-flat, dish-shaped pad that is scratch-prone and hard to connect to by pressure. The described fabrication begins with forming a resistive layer on an insulating substrate (the excerpt then truncates). Resistive heater material may be tantalum-aluminum (TaAl); conductive traces are most typically aluminum, though gold or other compatible conductors are possible.
What the excerpt does not establish: It does not include the full claims, the complete process steps after the truncation point, the exact materials/layer stack, or the figures. It gives no litigation, validity, or prior-art analysis beyond the summarized background discussion. Confirm details against the full source.
Generated 10/1/2026, 9:34:18 PM
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Litigation summary
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Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.