Block Mica

Block Mica is knife dressed mica with a minimum thickness of 7 mil (0.18 mm). It is available in sizes up to 12” to 14” (30 to 35 cm) square. Block Mica larger than this is rare. Mica in this form is available in sheets with an average thickness between 7 mils & 30 mils (0.18 mm & 0.75 mm). Block Mica is supplied in both natural (random) and calibrated thickness as required. After splitting into a specified thickness, the mica is then cut and punched to a required size and shape to meet the desired specifications.

Mica Thins

“Mica Thins” refers to mica that is knife dressed to a specified thickness range between 2 mil (0.05 m) and less than 7 mil (0.18 mm). Mica Thins are used in electrical and allied industries for applications, such as stove windows, lamp chimneys, heating elements and other similar requirements.

Mica Films

“Mica Films” refers to knife dressed mica of a specified quality that split to a thickness range between 0.08 mil (0.02 mm) to 4 mil (0.1 mm). Mica Film is used as a dielectric in capacitors for the electronic industry.

Film Mica is usually manufactured from superior quality block mica, such as stained ‘A” and better. Each film is carefully inspected and split into a close range of a specified thickness with a thickness tolerance of 0.0001 “ (1 I 10 of a mil). The accuracy in thickness , clean-cut edges without fraying or splintering, flawlessness and freedom from stains, spots, dots, impurities, cracks, buckles, pinholes, etc. are critical in the manufacture of high quality Mica Film.

Classifications of Mica Films

• 1st Quality has a visual quality that would result from splitting of Fair Stained or a higher quality mica or its equivalent.
• 2nd Quality has a visual quality that would be made from the splitting of Good Stained mica or its equivalent.
• 3rd Quality has a visual quality that would made from splitting of Stained “A” mica or its equivalent.

Lower grade Stained 1st, Stained “B” and Heavy Stained quality mica is available for various electronic and non electronic applications where you do not need the following specifications:

• A high dielectric constant.
• A very high dielectric strength.
• A very high “Q” and power loss requirement.

Typical applications for this lower grade mica would be, backing mica for capacitors, washers for transistors, interlayer insulation in transformers and similar uses.

Mica Splittings

Mica Splittings are laminae split from Block Mica and Mica Thins where the thickness of ten layers of this film measured together does not exceed a combined thickness of 0.011” (0.29 mm). Unlike other forms of sheet mica, Mica Splittings are not normally used as such in end-use products. Mica Splittings are more commonly used in the manufacture of built up mica insulating raw materials that are used for making parts for in electric motors, generators, transformers and other electrical products.

Grading and Classification of Muscovite Mica Splittings - For many years mica producers in India have been using a particular system of grading and classification of Muscovite Mica Splittings which has been generally accepted in international trade.

However, business is usually carried on based on a mutual understanding between the buyer and seller, based on the customer’s specifications and sample material supplied by the seller

Muscovite Mica Splittings are commercially marketed in the following three forms

Book-Form Mica Splittings - Book-Form Splittings are splittings arranged and supplied in the form of individual books. Each book is comprised of splittings obtained from the same piece of Block Mica or Mica Thin and is therefore termed “Book Form Mica Splittings. “Book-Form Mica Splittings are dusted with pure mica powder to offset residual cohesive forces.

Wrapper Mica Splittings - Wrapper Mica Splittings are book-form splittings that are split into a thickness between .00075” (0.019 mm) to .0015” (0.38 mm). Wrapper splittings are not dusted with mica powder.

Loose Mica Splittings - Loose Mica Splittings are heterogeneous shapes mica arranged in irregular order that are packed loosely in containers in bulk form. These may or may not be dusted with mica powder. Loose Splittings that are dusted with mica powder are known as “Dusted Loose Mica Splittings.”