About Sierra Circuits, Inc. (Sierra Proto Express)

We are America's Complete PCB Resource.

Serving over 20,000 Designers, Engineers, and Innovators since 1986.

Sierra Circuits is an ISO 9001:2015, ISO 13485:2016 and MilSpec MIL-PRF-55110, MIL-PRF-31032/1, MIL-PRF-31032/2 certified, Silicon Valley-based, high-technology Printed Circuit Boards manufacturer and Assembler. We specialize in quick turn PCBs and medium production. Unlike some PCB companies that are simply brokers/middlemen, we are the actual manufacturer and assembler of our PCBs. By owning our manufacturing and Assembly facilities, we control every aspect of the production schedule and quality. And this is why we can provide our customers unprecedented quality, reliability and a single point of support.

We continuously update our capabilities and equipment, like sophisticated direct imaging machines and laser drills, enabling us to do reliable and repeatable 3 mil trace /space with an aspect ratio of 10. We can make rigid PCBs up to 30 layers with board thickness of up to 250 mils (0.250"). Our high technology boards have features like HDI, Blind vias, Buried vias, Filled vias (via-in-pads), Controlled Impedance (with +/-5% tolerance), high aspect ratios and micro-BGAs. We regularly make specialty products with special materials. Other more complex boards we make include Burn-in Boards, Metal Core PCBs, boards with Carbon Print features, Backer boards, and rigid boards with Coverlay. We can do boards with multi-stage milling, step milling, laser milling and plated cavities. Our latest offerings include Flex PCBs, Rigid-flex PCBs, and Microelectronics PCBs down to 1 mil trace/space (some restrictions apply).

Fact Sheet

  • High quality prototype PCBs in fast turn times. See capability list here.
  • ~45,000 square feet PCB Manufacturing facility, ISO & MilSpec certified, in Sunnyvale, California.
  • ~10,000 square feet PCB Assembly facility, in Sunnyvale, California.
  • Over $10 million high technology equipment investments in recent years.
  • All capabilities for Lead-free PCBs available. RoHS/WEE compliant.
  • The quickest of the quick turn shops.
  • Full Service PCB Manufacturer and Assembler, able to guarantee its products and offer one-stop support.
  • Our Tech Center specializes in HDI protos, Microelectronics, and 0.5mm pitch BGAs.
  • Ability to manufacture down to 0.001 "(1 mil) trace / space.
  • Ability to do Consigned, Partial Turnkey, or Full Turnkey Assembly.
  • As quick as 12-24 hours for 2 -10 layers, depending on location.
  • As quick as 2-3 days for 12-20 layers.
  • 4-7 days for 22+ layers.
  • A California corporation since 1986. Headquartered in Silicon Valley.
  • Privately held, woman and minority owned business.

Silicon Valley Office (HQ)

Sierra Circuits

1108 West Evelyn Avenue

Sunnyvale, CA 94086

Phone: 408-735-7137

Fax: 408-735-1408

Web: www.protoexpress.com

Customer Testimonials

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Please convey to all the Sierra Circuits team our thanks for a job well done. We received the boards as promised and they are now in use in our production test areas.

Earl B. (Siemens Medical Solutions)


The boards are here and in the hands of the people who need them. Good job by Sierra! That's the kind of service customers appreciate.

Kathy W.


Wanted to let you know that quality and delivery over the past several months has been very good. Quality has been 100%. Delivery at 100 or 99%. Good job and thank you!

James B.