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HQ 084660

September 7, 1989

CLA-2 CO:R:C:G 084660 AJS


TARIFF NO.: 8541.29.00; 8542.20.00

Mr. Joseph A. Black
Dewey, Ballantine, Bushby, Palmer & Wood
1775 Pennsylvania Avenue, N.W.
Washington, D.C. 20006

RE: Transistor modules from Japan

Dear Mr. Black:

Your letter of April 25, 1989, on behalf of Collmer Semiconductor Inc., requesting a tariff classification under the Harmonized Tariff Schedule of the United States Annotated (HTSUSA) has been referred to this office for reply.


The articles in question are described as power transistors and Darlington transistors. They are composed of a Darlington Transistor Chip, which consists of two or more transistors and resistors on the same semiconductor material. Technically, Darlington transistors are a form of monolithic integrated circuit. There are two of these chips in each device.

The Darlington transistors are also composed of diode chips. There are two types of diodes in each transistor. One is a high current diode connected from the collector to the emitter of each Darlington chip. These diodes are referred to as fast recovery diodes (FRD). The other type, a speed up diode (SUD), is connected from the base to the emitter of the first two stages of each Darlington chip. All diodes, six in total, are on separate individual chips.

The individual chips described above are mounted on a thick- film substrate. The thick-film substrate also serves to
electrically isolate the chips from the base plate of the device assembly, a technology that is common to hybrid integrated circuits.

The top service elements of the Darlington transistor and diode chips are interconnected by wire bonding to bus bars and external terminals. The internal parts and circuits are sealed with silicon rubber and epoxy resin. This assembly is enclosed within a plastic cover.


Whether Darlington transistors are properly classifiable in subheading 8541.29.00, HTSUSA, which provides for other transistors; or in subheading 8542.20.00, HTSUSA, which provides for hybrid integrated circuits.


Chapter 85, note 5 (a), HTSUSA, states transistors are semi- conductor devices, "the operation of which depends on variations in resistivity on the application of an electric field." The Explanatory Notes, for heading 8541 at (A)(II) describe transistors as follows:

"Transistors are three- or four- terminal devices capable of amplification, oscillation, frequency conversion, or switching of electrical currents. The operation of a transistor depends on the variation in resistivity between two of the terminals upon the application of an electric field to the third terminal. The applied control signal or field is weaker than the resulting action brought about by the change in resistance and thus amplification results.

Transistors include:

(1) Bipolar transistors, which are three terminal devices consisting of two diode type junctions, and whose transistor action depends on both positive and negative charge carriers (hence, bipolar).

(2) Field effect transistors (also known as metal oxide semiconductors (MOS)), which may or may not have a junction, but which depend on the induced depletion (or enhancement) of available charge carriers between two of the terminals. The transistor action in a field effect transistor employs only one type of charge carriers (hence, unipolar). MOS type transistors which have four terminals are known as tetrodes."

In ruling letter HQ 084659 this office held that similar Darlington transistors met the Chapter and Explanatory Notes description of transistors. This office found that Darlington transistors are multi-terminal devices which are capable of amplification, oscillation, frequency conversion, or switching of electrical currents. The operation of the Darlington transistor depends on the variation in resistivity between two of the terminals upon the application of an electric field to a third terminal. For the same reasons as listed above, the transistors in question are a similar type of Darlington transistor which also meets the HTSUSA's description of transistors.

In sum, Darlington transistors modules satisfy the Explanatory Notes description of how transistors operate electronically. Also, none of these provisions or any other section or chapter notes specifically exclude transistor modules operating in an identical manner as transistors from heading 8541.

Trade practice in the industry also supports the classification of the articles in question as transistors. The Joint Electronic Device Engineering Council (JEDEC), which is an organization leading a comprehensive and industry wide effort to harmonize all basic semiconductor definitions, classifies the Darlington transistor as a discrete semiconductor device. The JEDEC defines a discrete semiconductor device as a "device that is specified to perform an elementary electronic function and that is not divisible into separate components functional in themselves." They list transistors as examples of discrete semi- conductor devices, and state that "other semiconductor structures having the physical complexity of integrated circuits but performing elementary electronic functions (e.g., complex Darlington transistors) are usually considered to be discrete semiconductor devices."

In addition, independent authority recommended to this office by the Semiconductor Association of San Jose, California, confirm that the Darlington transistor module is considered by the trade to be a transistor. The Darlington transistor module is reported by the industry in their statistics as a transistor. They are also not considered to be integrated circuits by the industry. Thus trade practice as well as the HTSUSA Chapter and Explanatory Notes indicate that transistor modules are considered transistors and not integrated circuits.

Subheading 8542.20.00, HTSUSA, provides for hybrid integrated circuits. Chapter 85, Note 5(B)(b) states that hybrid integrated circuits are electronic integrated circuits in which passive elements, obtained by thin- or thick film technology, and active elements (transistors etc.), obtained by semiconductor
technology, are combined to all intents and purposes indivisibly, on a single insulating substrate (glass, ceramic, etc.). In making a distinction between transistors and integrated circuits, Explanatory Note 85.42 (II) describes transistors as discrete components which are indivisible and possess a single active electrical function. While in contrast, integrated circuits are described as components consisting of several electric circuit elements which have multiple electrical functions, and that are not considered as discrete components. Therefore, the articles in question cannot be considered as the hybrid integrated circuits described above. They are instead discrete indivisible components which can only perform a single function and not multiple circuits that perform multiple functions.

In conclusion, Darlington transistor modules are classifiable as transistors. This conclusion is based on both the Chapter and Explanatory Notes as well as relevant trade practice. These articles are not hybrid integrated circuits, even though in some cases they are produced by thick film technology, because they do not function in the same manner. They are instead transistors, which are discrete indivisible components that perform a single active electric function.


The Darlington transistors in question are properly classifiable as other transistors with a dissipation rate of more than 1W, provided for in subheading 8541.29.00, free of duty. This conclusion regarding dissipation rate is based on the fact that these articles are used in power circuits. However, if they in fact do possess a dissipation rate of less than 1W they would instead be classifiable in subheading 8541.21.00, free of duty.


John Durant, Director
Commercial Rulings Division

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