Request for Internal Advice No. 55/91; Epoxy Prepreg; Subheading 7019.20.20; HQ 087721; GRI 2(b); GRI 3(b); Headings 3921, 7019, 8546, 8547, and 8548
Active· CBP ruling HQ 951321· Issued 1992-07-28
Ruling text
HQ 951321
July 28, 1992
CLA-2 CO:R:C:M 951321 EJD
CATEGORY: Classification
TARIFF NO: 3921.90.40
District Director of Customs
U.S. Customs Service
511 N.W. Broadway Federal Building
Portland, Oregon 97209
RE: Request for Internal Advice No. 55/91; Epoxy Prepreg;
Subheading 7019.20.20; HQ 087721; GRI 2(b); GRI 3(b);
Headings 3921, 7019, 8546, 8547, and 8548
Dear Sir:
This is in reference to your memorandum of March 6, 1992,
forwarding a request for Internal Advice No. 55/91 filed by the
law firm of Gibney, Anthony & Flaherty, on behalf of Tektronix
Asia Ltd., concerning the classification of material referred to
as epoxy prepreg.
FACTS:
Epoxy prepreg is a composite material that is manufactured
by Matsushita Electric Works in Japan. It is made of woven glass
cloth material that is thoroughly and completely impregnated with
an epoxy resin through a dipping and drying process, and then
placed on rolls or sliced into sheets for shipment. After
importation, the prepreg is cut to shape and subsequently
assembled with other components into printed circuit or wire
boards (PCBs). In the PCBs, the prepreg will act as an
insulating base, will perform the essential role of the bonding
agent or adhesive which joins or, literally, "glues" the several
layers of the PCB together, and will act as structural support.
The importer's submission states:
* * * PCB fabricators first slice prepregs from the
rolls and trim the sheets to the size of the PCB being
manufactured. If the prepregs are imported in sheet form,
only the trimming step is necessary.
* * *
During assembly of the PCB, the fabricator places the
prepregs in an automated hole puncher which punches up to 4
small holes for later positioning only. The prepreg then
moves to the PCB press, where it is properly positioned in
relation to the other PCB components by spindles which match
the location of the holes. The press then applies heat and
pressure to the prepreg and other components, which causes
the resin to flow. The resin acts as an adhesive which
bonds or, literally "glues" together two or more layers of
copper foil laminates (formed by joining copper foil and
prepreg together under heat and pressure). Upon cooling,
the resin again hardens or cures, forming a rigid multi-
layer board, consisting of alternating layers of copper-
clad laminates and prepreg.
* * *
The National Import Specialist responsible for this type of
commodity has classified the merchandise under the provision for
glass fiber woven fabric, in subheading 7019.20.20, Harmonized
Tariff Schedule of the United States (HTSUS).
The importer believes that the prepreg is classifiable under
the provision for electrical insulators of any material, in
heading 8546, HTSUS, or, in the alternative, under one of the
following headings: 8547, HTSUS, which provides for insulating
fittings for electrical machines, appliances, or equipment; 8548,
HTSUS, which provides for electrical parts of machinery or
apparatus; 3921, HTSUS, which provides for other plates, sheets,
film, foil and strip, of plastic; or 7019, HTSUS, which provides
for other woven glass fibers and articles thereof.
The importer's submission states:
Epoxy prepregs are complex, "hi-tech" electronic
components which are specifically designed and constructed
for one purpose: as electrical insulators. More
specifically, prepregs are electrically insulating
substrates of PCBs. * * *
* * *
ISSUE:
What is the proper classification of epoxy prepreg under the
HTSUS?
LAW AND ANALYSIS:
Merchandise is classifiable under the HTSUS in accordance
with the General Rules of Interpretation (GRIs). GRI 1 states in
part that for legal purposes, classification shall be determined
according to the terms of the headings and any relative section
or chapter notes, and provided the headings or notes do not
require otherwise, according to GRIs 2 through 6.
GRI 2(b) provides that a reference to a material in a
heading shall be taken to include mixtures or combinations of
that material with other materials and that any reference to
goods of a given material shall be taken to include goods partly
of that material; if goods consist of more than one material,
then classification will be according to GRI 3.
GRI 3(a) requires that where two or more headings describe
the merchandise, the more specific will prevail; or if two or
more headings each refer to part only of the materials in the
goods, then classification will be by GRI 3(b). GRI 3(b) states
that the material or component which imparts the essential
character to the goods will determine their classification.
After reviewing the file on this matter, by memorandum dated
April 10, 1992, the Customs Office of Laboratories and Scientific
Services has furnished us with the following information.
* * * The prepreg is in a semicured state
allowing the prepreg sheet to be handled easily during
laminating operations as it is reasonably stiff and not
tacky or oily (as in the case of uncured epoxy resins).
It is during the laminating operations, completed
domestically, that the prepreg is totally cured.
The prepreg product under consideration is used to
manufacture a product which is known as an electrical
laminate, a product in which epoxy resins are commonly
found. Epoxy resins have gained wide acceptance in
electrical applications due to their exceptional
combination of properties such as toughness, adhesion,
chemical resistance and superior electrical properties.
Epoxy resins which are used to produce electrical
laminate sheets, such as the prepreg, are present due
to its excellent electrical properties as well as its
adhesive properties.
Information in the file shows that the prepreg
layers are used to separate layers of copper foil
and/or printed circuits in the construction of multi-
layer printed circuit boards. Therefore, it appears
that the prepreg is being used not only for its
excellent insulative (electrical) properties but also for
its adhesive properties and its ability to cure to a rigid
infusible machineable (engineering plastic) state. These
characteristics are given to the prepreg by the epoxy resin
and not the fiberglass component. Therefore, although the
prepreg would probably not be excluded from Heading 7019 and
directed to Chapter 39 by Exclusionary Note (a) to that
Heading, the prepreg sheet in its cured state most
definitely would.
We note that fiberglass is an excellent insulative
material in its own right. However, in the case at
hand, it appears that the fiberglass material is used
as a carrier for the epoxy resin in its precured state
and acts as a reinforcement material in the finished
product. An analogous situation is the molded
fiberglass components of auto bodies. The components
are fiberglass fabrics which have been impregnated with
a thermoset plastics material and then is molded and
cured. In the cured state, the presence of the
fiberglass is not noticeable until the body part is
dented or smashed. It appears that in the case of the
prepreg, fiberglass fabric is used as the carrier and
reinforcement agent because it is a highly non-
conductive material and it is more resistive to heat
than ordinary fabrics of organic composition. Based on
our experience with plastics sheeting materials, we are
of the opinion that the primary purpose of the
fiberglass is to act as a carrier for the prepreg and a
reinforcement material for the finished product. The
fiberglass material's insulative and thermal properties
simply make it more suitable for usage in the product
than any other reinforcement fabric.
In its condition as entered, the prepreg has the identity of
a glass cloth and epoxy resin composite material, and does not
meet the criteria in GRI 1 analysis of a merchandise of any of
the following headings: 8546, HTSUS, electrical insulators;
8547, HTSUS, insulating fitting; or 8548, HTSUS, electrical
parts. Even after the imported product has been cut to shape and
processed into its finished state, electrical insulation is just
one of several important functions it performs.
In addition to the information furnished by the Office of
Laboratories and Scientific Services, the various functions of
the product are described in Manas Chanda and Salil K. Roy,
Plastics Technology Handbook (1987), which at pages 462-463,
states:
* * * The main attributes of properly cured epoxy
systems are outstanding adhesion to a wide variety of
substrates, including metals and concrete; ability to cure
over a wide temperature range; very low shrinkage on cure;
excellent resistance to chemicals and corrosion; excellent
electrical insulation properties; and high tensile,
compressive, and flexural strengths. In general, the
toughness, adhesion, chemical resistance, and corrosion
resistance of epoxies suit them for protective coating
applications. * * *
* * *
For electrical and electronic applications epoxy
formulations are available with low or high viscosity,
unfilled or filled, slow or fast curing at low or high
temperatures. Potting, encapsulation, and casting of
transistors, integrated circuits, switches, coils, and
insulators are a few electrical applications of epoxies.
With their adhesion to glass, electrical properties, and
flexural strength, epoxies provide high-quality printed
circuit boards.
In a relative new development, epoxy photopolymers have
been used as solder masks and photoresists in printed
circuit board fabrications.
Adhesion properties of epoxies, complete reactivity
with no volatiles during cure, and minimal shrinkage make
the materials outstanding for adhesives, particularly in
structural applications. * * * A novel, latent curing
system, which gives more than one year pot life at room
temperature, has increased the use of epoxies for specialty
adhesives and sealants, and for vinyl plastisols. * * *
Epoxies are used in fiber-reinforced composites,
providing high strength-to-weight ratios and good thermal
and electrical properties. * * *
Pursuant to GRI 2(b), the merchandise is described by and
prima facie classifiable under heading 3921, HTSUS, as other
sheets and film of plastics, and heading 7019, HTSUS, as articles
of glass fibers. Therefore, it must be determined whether the
glass cloth or epoxy resin gives the merchandise its essential
character.
In Headquarters Ruling letter (HQ) 087721, dated March 5,
1992, Customs classified polyimide prepreg. Customs determined
that polyimide plastics is a very specialized type of
plastics with unique insulating and heat resistent
properties. As such, while it appears that the glass fiber
fabric in the instant merchandise has similar properties,
those properties merely make the glass fiber fabric more
suitable as a carrier for the polyimide plastics material.
On the basis of all the information that we have available,
it appears that it is the polyimide plastics which provides
the primary insulative attributes to the prepreg.
Accordingly, it is the polyimide plastics which imparts the
essential character to the imported merchandise[.]
In view of the above, and other product information, we are
of the opinion that the essential character of the subject
composite good is derived from the epoxy resin material.
GRI 3(b) requires that the epoxy prepreg is classified under
subheading 3921.90.40, HTSUS, which provides for "[o]ther plates,
sheets, film, foil and strip, of plastics...[o]ther...
[o]ther...flexible," with a rate of duty of 4.2 percent ad
valorem.
HOLDING:
The subject composite merchandise is classifiable under the
provision for other flexible plates, sheets, film, foil, and
strip of plastics, in subheading 3921.90.40, HTSUS.
Sincerely,
John Durant, Director
Commercial Rulings Division
Source: rulings.cbp.gov — ruling 951321, retrieved 2026-10-12T05:26:21Z, republished verbatim. This digest is informational; only CBP issues binding rulings.