Cspeed IO is a stealth start up backed by Sutter Hill Ventures and Atreides Capital - headquartered in Palo Alto, CA. Our executive team has a demonstrated track record of building and scaling category-defining semiconductor and infrastructure businesses at companies like Broadcom, Lumentum, Tesla, Apple, Samsung, Intel, and VMware.
Cspeed IO is developing next-generation optical semiconductor solutions for the AI infrastructure market, focused on enabling true “scale-up” architectures. Our mission is to replace traditional copper interconnects with advanced fiber-optic technologies that overcome the limitations of existing optics solutions and architectures.
The Role
You will own the physical design of our optical engine packages — redistribution layers, substrate, and the bump and ball maps that tie the die stack to the host board. This is a hands-on layout role with real architectural influence.
You will work between our PIC and EIC design teams, our SI/PI and thermal engineers, and our supply chain (wafer fab, substrate vendor, OSAT). You will not be handed a finished floorplan to route — you will help define it.
What You'll Do
Layout execution
- Deliver RDL/UBM and package substrate layouts for our optical engine products and test vehicles, from floorplan through tape-out.
- Define and release bump maps, ball maps, and escape routing strategies for multi-die assemblies (PIC, EIC, and light source die).
- Design to 200G/lane-class electrical requirements: differential pair routing, reference-plane integrity, crosstalk isolation, and power delivery for high-current, low-noise rails.
Co-design and floor planning
- Participate from concept phase: produce preliminary floorplans and stack-up proposals that reconcile electrical, optical, thermal, and mechanical constraints before they are frozen.
- Iterate with SI/PI engineers on test routes to converge routing topologies and design rules.
Design rules, DFM, and supplier engagement
- Work directly with wafer fabs, substrate suppliers, and OSATs to capture and negotiate design rules, stack-ups, and assembly constraints.
- Generate fab and assembly release packages; drive DFM/DFA closure and design reviews through to sign-off.
- Flag rule conflicts early and propose alternatives rather than routing around them silently.
Verification and automation
- Run and own physical verification: DRC, connectivity/LVS-style netlist checks, and cross-domain consistency between die, package, substrate, and board.
- Manage netlists for heterogeneous assemblies across revisions and product variants.
- Build scripted automation (SKILL, Python, or equivalent) for repetitive layout, checking, and release tasks.
Build support
- Support test vehicle definition, first builds, bring-up, failure analysis, and yield learning — including layout changes driven by assembly reality.
Required Qualifications
- BS or MS in Electrical Engineering, or equivalent practical background.
- 6+ years of IC package physical design, including at least one product taken from concept through tape-out and volume-relevant build.
- Expert-level proficiency in a package layout tool: Cadence Allegro Package Designer / APD+ / SiP, Siemens Xpedition Package Designer, Synopsys IC Package, or equivalent.
- Demonstrated experience with multi die packaging: 2D or 2.5/3D integration.
- Working fluency with multi-layer organic substrate construction and how material and stack-up choices constrain routing.
- Practical experience closing DFM/DFA with external substrate suppliers and OSATs.
- Comfortable working in English across a distributed team and multiple time zones.
Preferred Qualifications
- Demonstrated experience with advanced packaging: 2.5D/3D integration, RDL, TSV interposers, fan-out, microbump or Cu-pillar flip-chip.
- Layout for 112G/224G SerDes or comparable high-speed interfaces; familiarity with signal and power integrity workflows (e.g. Cadence Sigrity/PowerSI, Ansys).
- Familiarity with mask and RDL vendor flows, GDS-based layout environments (Virtuoso, KLayout), and AutoCAD file exchange.
- Experience with package/IC co-design environments (e.g. Cadence Integrity 3D-IC).
- Scripting for design automation and rule checking.
- Experience at a startup or on a first-of-its-kind product, where the design rules did not exist yet.
Why This Role Is Different
Most package layout roles are a step in someone else's flow. Here, the package is the product. You will be one of a handful of people who determine whether a next-generation optical engine is manufacturable, and you will see your layout decisions land in silicon and in an OSAT line within months, not years.
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