Printed Circuit Board

The names of printed circuit board materials often look like little more than a jumble of letters and numbers to the layperson. Manufacturers use a combination of mat, fabric, nonwoven material or roving with resin to create reinforced bases, which are called prepregs (pre-impregnated material cured by heat to complete).

Deciphering Printed Circuit Board Materials

Common flame resistant or retardant materials--the FR in the names--used in printed circuit boards are FR2 (phenolic cotton paper), FR3 (cotton paper and epoxy), FR4 and FR5 (woven glass and epoxy) and FR6 (matte glass and polyester). Flame Retardant 4 (F4) works well under both budget and time constraints, while offering a quality alternative to paper-bonded choices, which can be flammable. It meets all UL standards for safety and absorbs minimal mounts of moisture, creating a product that withstands the pressure of consistent use.

In order for the printed circuit board to be effective, it must withstand high heat without cracking or becoming brittle. FR4 commonly comes in two different heat sensitivities: 130 or 170 Tg. The Tg (glass transition temperature) measures the exact temperature that the material begins to expand and cause loss of the electromagnetic field traveling through the pathways.

Since it offers a good combination of value and caliber, FR4 makes up many common circuit boards in high-end consumer electronics and military equipment. It is also a popular choice for custom printed circuit boards.

Almatron manufactures custom printed circuit boards using FR4 materials, which allows for short runs at an affordable price. The company offers services specific to small businesses that need smaller orders and may be ignored by some of the larger circuit board manufacturers.