High Density Interconnect (HDI) PCBs

HDI PCBs are manufactured with several prominent features. These PCBs have higher circuitry density, higher connection pad density, and finer traces and gaps. Additionally, these PCBs are characterized by their smaller vias and capture pads, blind/buried vias, and through vias from surface to surface. HDI PCBs are largely chosen for enhancing the electrical performance of the device, and are finding their way into many applications including military communication devices, aerospace, computers, smartphones, and medical equipment, among several others. Being a leading HDI PCB manufacturer, we at Sierra Assembly Technology Inc. offer precision designed boards for use in high density applications. We have high tech capabilities and the right people to design advanced circuit boards to the exact customer’s specifications.

Sierra Assembly’s Expanded Capabilities

Being the prominent HDI PCB manufacturer, we can get the job done right the first time be it quick turn prototypes, medium and large production runs. Our capabilities in this area include:
  • Professional PCB fabrication team including engineers with years’ experience in the field.
  • Advanced machinery that allows utilization of technologies to produce ultra-thin cores, fine line geometries, and alternative via technologies to produce advanced PCBs.
  • High precision inspection & testing tools
  • Superior quality raw material usage for the production.
  • Advanced surface finish equipment for ENIG, immersion silver, immersion Tin, OSP, HASL.

Technical Details

You can customize your HDI PCBs utilizing the best options from the list below.
Laminate Choices  High Tg, BT resins
Low Dk, Low Df Formulations
High Strength, Low CTE selections
Multi-function FR-4
Min Cladding ¼ oz
Max Cladding 2 oz
Min Thickness .03mm (.0012)
Surface Finishes Wirebondable Structures
Differential Metalizations
Electrolytic/Electroless Plating
Full Body, Selective and Contact Gold
Immersion Silver
Solder Mask Per IPC-SM-840
Taiyo and Conventional Epoxies
Liquid Photo-Imageable and Dry Films
"Flex" Mask
Line and Space Min Line .020mm (.0008)
Min Space .020mm (.0008)

Rigorously Tested High Performing PCBs

At Sierra Assembly, each component of HDI PCBs is stringently tested to ensure maximum performance. We employ in-circuit testing systems such as GenRad 2283 & GenRad 2280S, bed of nails with fixture, and open express equipped & boundary scan capable to check shorts, opens, resistance, and capacitance, whilst ensuring that the PCB is rightly assembled. Moreover, our X-ray testing such as Vision Systems, Scienscope, Microscopes, and Clear view detect hidden PCB assembly defects.

As mentioned earlier, HDI PCBs are widely chosen for applications that call for compact, yet higher functional boards. These boards help minimize the size of the application, and enhances their electrical performance and lowers power consumption. Also, they ensure stable voltage rail, minimal stubs, and lower RFI/EMI. Since, we employ quality systems such as ISO 9001 to develop well-defined PCBs, our customers can rest assured with the quality of the final assembly. With us, you will find dedicated sales and technical support teams who dedicatedly meet ever-increasing customer demand for low cost, and high-quality PCBs.

Quick Contact


I approached Sierra after being referred to them from another PCB designer. What impressed me was that they were more than willing to take a complex PCB requirement. The PCB assembly they provided was small, lightweight, but provided the amount of power needed for our computer product. Great experience.

- Susan R – Business Computer Industry

I liked Sierra’s quick turn PCB assembly services. They provided a prototype within a few days, and it worked without a hitch. I was extremely satisfied with the quality of the PCB. Their prices are great too.

- Jason G. – Telecom Industry

Sierra Assembly Technology has a great group of people to work with. They are open to almost any request and always get the job done quickly. I’ve been in some tight spots before and needed certain products within a small time window, and Sierra has always been reliable.”

- Richard S. – LED Lighting Manufacturer

Your Partner in Southern California for Circuit Board Assembly Services GET A QUOTE

Sierra Assembly Technology Inc.

10880 Mulberry Ave

Fontana, CA 92337

Phone: 909.355.5400

Email: sales@sierraassembly.com