What Sierra Circuits does

Sierra Circuits, Inc., operating through the ProtoExpress brand, is a US-headquartered printed circuit board (PCB) fabrication and assembly company founded in 1986 and based in Sunnyvale, California. The company operates a 70,000 sq. ft. Silicon Valley manufacturing campus and produces rigid, flex and rigid-flex, HDI, microelectronics, controlled-impedance, RF/microwave, and aerospace/defense Mil-Spec PCBs, complemented by full SMT and through-hole PCB assembly services, component sourcing/stocking (via COIN and CCI consignment programs), flying probe testing, and PCB design support. Customers can order through three online tiers—Turnkey PRO (bundled fabrication, components and assembly with turn times as fast as 5 business days), Web PCB (standard fabrication with optional assembly), and No Touch PCB (automated quick-turn)—or via direct sales for advanced and Mil-Spec quotes. Free browser-based design tools (Stackup Designer, impedance and via calculators, Better DFM, BOM Cleaner, PDN Analyzer) and the SierraConnect community forum function as top-of-funnel acquisition channels and ecosystem infrastructure.

The company derives revenue from per-board PCB fabrication pricing, assembly labor and component markup, professional design support services, and hardware sales of components, supported by a hybrid self-serve/enterprise GTM motion. It serves aerospace and defense, automotive (including EV and ADAS), healthcare and medical devices, consumer and wearables, industrial manufacturing, and academic/research customers. Notable enterprise logos include Amazon, Apple, Google, Meta (Oculus), Logitech, Boeing, NASA, Lockheed Martin, and Thermo Fisher Scientific, with a cumulative base of more than 20,000 PCB designers and engineers served since 1986. Sierra Circuits maintains an extensive compliance stack—AS9100D, ISO 9001:2015, ISO 13485:2016, ITAR, MIL-PRF-31032, MIL-PRF-55110, IPC-6012/6013/6015/6018, UL, RoHS, REACH, NIST 800-171, JCP, and NMSDC—positioning the business as a qualified supplier for highly regulated defense, aerospace, and medical programs. Operating geographies span North America (Sunnyvale HQ, San Jose warehouse, Delta BC office) with global shipping; the company is privately held under President and CEO Ken Bahl and reports an employee base of 501–1,000.

Name

Sierra Circuits

Legal name

Sierra Circuits, Inc.

Website

https://protoexpress.com

Company type

Private

Founded year

1986

Operating status

Operating

Headcount range

501–1,000 employees

Short description

Sierra Circuits is a US-headquartered PCB fabrication and assembly manufacturer specializing in rigid, flex, HDI, Mil-Spec, and RF/microwave circuit boards with full turnkey services. It serves aerospace/defense, automotive, medical, consumer electronics, and industrial customers worldwide from its Silicon Valley campus.

Ownership category

akta.pro rank

Product category

PCB Manufacturing

NAICS

Bare Printed Circuit Board Manufacturing (334412), Printed Circuit Assembly (Electronic Assembly) Manufacturing (334418)

SIC

Printed Circuit Boards (3672), Electronic Components, Nec (3679)

akta.pro primary industry

PCB Fabrication (Rigid PCBs) (HDAHAOAG)

akta.pro secondary industries

PCB Fabrication (Flex & Rigid-Flex PCBs) (HDAHAOAH), PCB Assembly (PCBA/EMS) (HDAHAOAI), Industrial PCB & Substrate Components (Bare PCBs, rigid-flex, ceramic substrates, thick-film) (IMAGAJAM)

Keywords

• PCB fabrication
• PCB assembly
• Quick-turn prototyping
• Component sourcing
• PCB design tools

Headquarters

HQ city

Sunnyvale

HQ country

United States

HQ region

North America

Offices3 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Personnel, Operations, Supply Chain, Technology or R&D, Infrastructure, Marketing or Sales

Revenue model

1. PCB Fabrication (Bare Boards): Manufacturing of printed circuit boards including rigid, flex, rigid-flex, HDI, and microelectronics PCBs. Revenue is generated through per-board pricing based on layer count, materials, tolerances, and turn time. Options include standard PCBs, advanced PCBs with exotic materials, and quick-turn prototypes.
2. PCB Assembly Services: Assembly services for PCBs including SMT assembly, through-hole assembly, and full turnkey assembly. Revenue generated through assembly labor charges and component procurement. Includes in-house flying probe testing and quality inspection.
3. Component Sourcing and Stocking: Component procurement and inventory management services including Customer-Owned Inventory (COIN) and Customer Consigned Inventory (CCI) programs. Revenue from component markup and handling fees.
4. Design Support Services: PCB design support including stackup assistance, DFM analysis, and CAM engineering support included with advanced PCB orders.

Pricing tiers

Go-to-market motion1 record

Distribution channels3 records

Marketing channels6 records

Core offering

Sierra Circuits manufactures printed circuit boards (rigid, flex, rigid-flex, HDI, microelectronics, controlled impedance, RF/microwave, and Mil-Spec aerospace/defense PCBs) at its Sunnyvale, California facility. The company also provides PCB assembly, component procurement and stocking, flying probe testing, and PCB design support, sold primarily through its online platform protoexpress.com under the Turnkey PRO, Web PCB, and No Touch PCB service tiers.

Product overview

Sierra Circuits operates a PCB fabrication, assembly, and component procurement platform primarily delivered through its Proto Express brand. The core product portfolio consists of three online ordering tiers: Turnkey PRO (bundled fabrication, procurement, and assembly in a single workflow), Web PCB (standard fabrication with optional assembly), and No Touch PCB (automated quick-turn for simple designs). These are supplemented by advanced PCB types including rigid, flex/rigid-flex, HDI, microelectronics, aerospace/defense mil-spec, controlled impedance, and RF/microwave boards. Sierra Circuits offers a suite of free browser-based PCB design tools including stackup designer, impedance calculators, trace width/current capacity calculators, via impedance calculator, material selector, component selector, BOM cleaner, Better DFM analysis, and PDN analyzer. Additional services include PCB assembly, component sourcing/stocking, flying probe testing, and PCB design support. The company also maintains an online community (SierraConnect) and provides educational resources including design guides and webinars. All manufacturing is performed at the company's 70,000 sq ft facility in Sunnyvale, California (Silicon Valley), with full turnkey assembly capabilities and a zero-defect guarantee on qualifying orders.

Differentiator

Problem solved

Functional benefit

Products and services

• Turnkey PRO Full turnkey PCB service bundling fabrication, component procurement, and assembly into a single online workflow. Boards are fully assembled to IPC-A-610 Class 2 and shipped in as fast as 5 business days, with DFM and DFA checks included. Designed for engineers who want a single bundled order.
• Web PCB Standard rigid PCB fabrication service with optional component procurement and assembly. Supports 2-12 layer boards up to IPC-6012 Class 1, 2, 3, 3D / IPC-6013 specifications, with instant online quoting, transparent per-board pricing, and turn times from 1 to 10 business days.
• No Touch PCB Quick-turn PCB fabrication service for straightforward designs with automated file verification. Targeted at simple, non-complex boards without manual engineering review, enabling the fastest and most automated order path.
• Rigid PCBs Standard rigid printed circuit boards built to IPC-6012 specifications, supporting IPC Class 1, 2, 3 standards. Available in multiple laminate materials including FR4, high-Tg FR4, Rogers, and polyimide. Used across consumer, industrial, and medical electronics.
• Flex & Rigid-Flex PCBs Flexible and rigid-flex circuit boards designed for dynamic flex applications. Features include bend radius optimization, polyimide materials, and stiffener integration for component support areas. Targeted at wearables, medical devices, and compact electronics.
• HDI PCBs (High Density Interconnect) High density interconnect PCBs featuring microvias, blind and buried vias, and build-up lamination processes for compact electronic designs requiring maximum routing density. Suited to smartphones, AR/VR, and high-density consumer electronics.
• Microelectronics PCBs Advanced microelectronics PCBs for miniaturized applications requiring fine feature sizes, tight tolerances, and specialized substrate materials. Targeted at miniaturized sensors, medical implants, and dense electronic modules.
• Aerospace & Defense PCBs (Mil-Spec) Military and aerospace grade PCBs certified to AS9100D, MIL-PRF-31032, MIL-PRF-55110, and IPC-6012 Class 3/ES standards for defense and space applications. Targeted at prime contractors and government programs.
• Controlled Impedance PCBs PCBs manufactured with precisely controlled impedance values for high-speed digital and RF applications. Includes impedance testing and characterization of transmission lines. Suited to high-speed digital and signal integrity-driven designs.
• RF & Microwave PCBs Radio frequency and microwave circuit boards utilizing specialized materials such as Rogers laminates for high-frequency applications including antennas, amplifiers, and RF front-ends.
• PCB Mass Production Volume PCB manufacturing service for production quantities beyond prototype volumes, maintaining consistent quality across large batch runs. Targeted at OEMs scaling from prototype to mass production.
• PCB Assembly Complete PCB assembly services including SMT and through-hole assembly, component placement, soldering (lead-free and tin-lead), and inspection to IPC-A-610 standards. Offered as a standalone service or bundled with fabrication.
• Component Sourcing and Stocking Component procurement service sourcing parts from authorized distributors (Digi-Key, Mouser) with counterfeit prevention. Includes Customer Owned Inventory (COIN) and Customer Consigned Inventory (CCI) programs for component management and storage.
• Flying Probe Testing Electrical testing service using flying probe technology to verify board connectivity and functionality without custom test fixtures. Performed in-house for assembled boards.
• PCB Design Support Engineering design services including schematic capture, PCB layout, DFM/DFA analysis, stack-up design, and high-speed layout consulting. Available as a paid professional service for customers needing expert design help.

Quantifiable outcome

• 100% USA manufacturing - all PCBs fabricated and assembled in Silicon Valley, California
• +3 more outcomes

Named customers9 records

Segments6 records

Ideal customer profiles3 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Scale indicators5 records

Recent moves5 records

Expansion highlights6 records

Direct peers

• JLCPCB: JLCPCB is a high-volume, low-cost online PCB prototype and assembly provider based in China serving a global self-serve customer base. It competes with Sierra on the online quick-turn tier where price and lead time are primary, though without Sierra's US-domestic and defense certifications.
• Bay Area Circuits: Bay Area Circuits is a Northern California PCB prototype and small-batch fabricator with an online instant-quote model. It is geographically and product-overlap-comparable to Sierra, both targeting Silicon Valley designers with quick-turn US-made boards.
• PCBWay: PCBWay is a China-based online PCB fabrication, assembly, and PCB-stencil service with global hobbyist and SMB reach. It overlaps with Sierra on the prototype/SMB tier of the online PCB market and competes on price and turn time rather than certifications.
• Advanced Circuits: Advanced Circuits is a US-based PCB fabrication and assembly shop offering quick-turn prototype and small-batch production with online quoting. It directly competes with Sierra in the same SMB/designer self-serve segment and shares a US-domestic, quick-turn value proposition.
• Sunstone Circuits: Sunstone Circuits is a US PCB manufacturer specializing in prototype and low-volume production with online ordering via its PCB123/Addison platform. It competes head-to-head with Sierra in quick-turn, US-made prototype PCBs and small-batch assembly.

Broad incumbents

• TTM Technologies: TTM Technologies is a large, publicly-traded US PCB manufacturer serving aerospace/defense, automotive, computing, and medical OEMs at production volumes. It overlaps with Sierra in aerospace/defense PCBs but operates at a much larger, mass-production scale across multiple global facilities.
• Sanmina: Sanmina is a global EMS/ODM offering PCB fabrication and full box-build assembly across communications, computing, medical, defense, and industrial. It is comparable to Sierra as an end-to-end US-based PCB + assembly supplier, but at far greater scale and with a broader systems-integration scope.
• Celestica: Celestica is a global EMS/ODM providing PCB assembly and full system integration for aerospace/defense, communications, and industrial customers. It is comparable to Sierra at the assembly and end-to-end-manufacturing layer (especially in aerospace/defense) but operates at much larger scale and is not a primary bare-board fabricator.

Regional players

• Eurocircuits: Eurocircuits is a European PCB prototype and small-batch manufacturer with online quoting and EDA tooling (similar to Sierra's tools suite). It is comparable in business model and target customer (SMB designers) but competes in EMEA rather than in Sierra's North American stronghold.

Emerging players

• MacroFab: MacroFab is a software-driven PCB assembly marketplace that aggregates US-based EMS partners for low-to-mid volume production. It overlaps with Sierra's turnkey assembly offering and self-serve/PLG motion, but takes a platform/marketplace approach rather than running its own fab lines.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

• Xx.com/SierraCircuits
• LinkedInlinkedin.com/company/sierra-circuits-inc

Compliance16 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Sierra Circuits