Boron trichloride is a highly reactive, corrosive gas that distributors who provide gases to the electronics, pharmaceutical and fibers industries may find increasing demand for as its uses multiply. With demand increasing, distributors should be aware of the uses of this gas, which also is known as trichloroborane, and of the precautions that are needed when dealing with it.

Exact figures are not available for the size of the U.S. boron trichloride market. However, this gas is a part of the nearly $200 million market for high-purity gases that were used in the semiconductor industry in 2002, the last full year for which figures are available. Semiconductor manufacturers used an estimated $1.8 billion worth of ultrapure chemicals, water and gases in 2002, and the value of that market segment was forecast to reach $2.8 billion by 2007. Within that market segment, the market for high-purity gases is expected to double to $400 million by the year 2007.

Semiconductor and semiconductor wafer manufacturers use boron trichloride as a dopant or an agent in etching. Dopants are substances that are added to pure semiconductor materials in small amounts to alter the semiconductor's conductive properties so that they can be used as transistors and diodes. Etching is an operation that involves the removal of different materials from the surface of the semiconductor wafer in defined patterns so that the wafers can be made into computer chips. The gas used for etching silicon chips is 99.999 percent-pure boron trichloride gas. Pharmaceutical manufacturers also use highly pure boron trichloride gas, either as a catalyst or as an intermediate in the production of pharmaceuticals.

For example, Merck Research Laboratories uses boron trichloride in the synthesis of drug candidates, and members of Pennsylvania State University's Department of Chemistry, Anacor Pharmaceutical Inc. and Stanford University School of Medicine use boron trichloride in the development of compounds based on boron that demonstrate broad spectrum antibacterial activity, an important find as bacterias continue to develop resistance toward currently used antibiotics. Other pharmaceutical researchers are using boron trichloride in the development of Alzheimer treatments.

In the fiber industry, boron trichloride is a raw material needed to produce pyrolytic boron nitride and boron fiber, components of high-tech composite structures.

When these boron-based fibers and cotton fibers are woven together, they create a strong and lightweight reinforcing fabric, an advanced composite material that is used to reinforce aircraft wings and tailfins. In fact, the main structural member of the B-1 bomber is a single beam constructed with boron fiber as its base material. Boron fibers also are used in composites to make high performance sports cars and in the manufacture optical fibers where they reduce the index of refraction.

Boron trichloride gases also are used:

• As a soldering flux for alloys of aluminum, iron, zinc, tungsten and monel.
• In the plasma etching of aluminum alloys, tungsten and tungsten silicide.
• To remove nitrides, carbides and oxides in the refining of aluminum, magnesium, zinc and copper alloys.
• To treat the melt in the casting of aluminum.
• As a source of boron in high energy fuels and rocket propellants.
• To douse fires in heat-treating ovens that contain magnesium products.

DOT DIV 2.3 C and Safety
The Department of Transportation's classification for boron trichloride is PIH Zone C. Zone C defines compounds that have a toxicity level defined by a lethal concentration of 50 (LC-50). In government tests, the gas caused the deaths (within 14 days) of one half of the animals that had inhaled it continuously for one hour.

If the gas is released into the surrounding atmosphere, the government recommendation call for getting anyone subject to inhaling it immediately to fresh air, and the following procedures should be taken:

• If the person is not breathing, artificial respiration should be administered.
• If breathing is a problem, oxygen may be administered.
• If contact with the skin occurs, the skin should be doused with water while clothing, including shoes, is removed.
• If it is swallowed, vomiting should not be induced, but the person should be given two (eightounce) glasses of water to drink immediately.
• If the gas comes in contact with the person's eyes, they should be flushed thoroughly with water for at least 15 minutes by holding the eyelids open and away from the eyeballs to ensure that all surfaces are flushed.
• A physician or, in the case of contact with the eyes, an ophthalmologist, should be contacted immediately.
• And, anyone who approaches the area, such as medical and fire personnel, should be warned and should wear self-contained breathing apparatus and protective clothing.

Vapors from the gas can be reduced with fog or fine water spray, but the vapors may spread, so personnel in the area must be cautious.

Description
The gas is colorless but it has a pungent, acrid, choking odor that has been described as being similar to the smell of rotting fish. It is packaged in steel containers as a liquid under its own pressure of 19.1 psia at 70 F.

Handle with care
Boron trichloride hydrolyzes to hydrochloric acid and boric acid on contact with water or moist air. If water comes in contact with the compound while it is still in a closed container or cylinder, pressure will build and an explosion will occur.

Three-point safety plan
The three things any organization needs to know about handling such gases are:

• Follow the gas manufacturer's MSDS (material safety data sheet.)
• Know the building and regulatory codes of any city and state in which you operate because the codes may differ.
• Obtain and read pertinent publications from the Compressed Gas Association.

All chemicals that meet the Occupational Occupational Safety and Health Administration's definition of hazardous must be accompanied by an MSDS, according to OSHA's Hazard Communication Standard (HCS).

The HCS is a performance standard, not a specification standard, and does not require a specific format for MSDS, but does require it to be in English and contain, as a minimum, certain information about the hazardous chemical.

In 1993, the American National Standards Institute (ANSI) published the American National Standard for Hazardous Industrial Chemicals — Material Safety Data Sheets — Preparation, ANSI Z400.1-1993. The ANSI standard recommends titles and specific order for the sections of a MSDS, and recommends sixteen sections, the first ten of which are the OSHA required elements. This format has been widely accepted and is in use throughout the world.

The information used in the MSDS comes from the Compressed Gas Association. OSHA regulations often refer to the association's guidelines.

For safety's sake, read the MSDS, implement the safety codes and follow the rules.