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Ultracor was founded in 1995 in Benicia, California as a spinout of YLA, Inc, a leading firm in the development and marketing of high performance prepreg systems for space and aerospace.


“Core materials customized to meet your specifications”


Andrew Marshall, a pioneer in honeycomb development, and Mike Fellman developed a patented process for manufacturing superior quality carbon fiber honeycomb. This process employs a composite layup structure in order to cure the honeycomb in a single process step, producing superior quality node bonds and the most uniform structure available in any honeycomb. This structural uniformity has proven itself in improved mechanical performance, dimensional stability and electromagnetic characteristics.

Ultracor’s ability to orient extremely thin fiber plies in any direction in the web permitted the use of negative-coefficient pitch-based carbon fiber material to yield a net-zero coefficient of thermal expansion in the “L”, “W”, and “T” directions of the core material. This design enabled satellite antenna manufacturers to produce reflectors of unparalleled performance. To date the highest quality satellite antennas in the world utilize Ultracor's carbon fiber honeycomb to provide thermal dimensional stability. The company’s products are flying today in over 100 satellites.

From that beginning Ultracor has developed its heritage of engineering custom composite honeycomb from a number of prepreg materials, including quartz, Kevlar®  and fiberglass. Our customers engage us after determining that commodity type honeycombs will not perform to the requirements of an application. Working with our customers, we design and manufacture core systems that meet the highest mechanical, structural and electromagnetic criteria.


Ultracor manufactures its products at a single location in Stockton, California, United States of America.  The facility has been certified to AS9100 since 2011.  Prior to that time, it operated a quality system based upon Mil-I-45208a.  


Ultracor's staff includes degreed engineers experienced in the manufacture of composite honeycomb.  We have the experience to assist customers in producing a unique core for their applications. 

Cell Size & Densities

Ultracor possesses tooling to produce hexagonal cell sizes of 1 inch, 5/8 inch, 1/2 inch, 3/8 inch, 1/4 inch, and 3/16 inch; and Ultraflex cell sizes of 1 inch, 3/4 inch, 3/8 inch and 1/4 inch.Other cell sizes can be produced after an investment in tooling.

Ultracor can be produced from almost any non-metallic web material and in densities ranging from 0.60 lb/ft3 to over 15.0 lb/ft3.

Other Processes & Capabilities

Among our other value-added processes are splicing, heat forming and testing. Our unique splicing capability employs the neat resin of the specified prepreg to form a splice line that is barely noticeable to the naked eye.  This minimizes added weight and avoids material property mismatches.


We can heat form sheets of core in our facility to produce radiused parts for our customers.We possess a United tensile tester to verify product requirements to customer specifications.  We also maintain relationships with outside laboratories to test properties such as dielectric constant, loss tangent, CTE and high temperature properties.

Continuous Improvement

While customer specifications may limit specific changes to materials and processes, the Ultracor team continuously assesses every aspect of the operation in search of areas that can be improved.  We utilize a formal process to identify and act on improvement areas.

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