– IPC-TM-650 is a detailed, widely used reference guide of testing methods of foil-printed PCB.
– IPC-4101 - the document contains a list of technological requirements for basic PCB materials of commercial/military use.
– IPC-4103 - the documentation contains requirements for basic materials based on Teflon (polytetrafluoroethylene) and another microwave PCB.
– IPC-4104 - the document contains data on the specification of HDI board materials.

ASTM

American standards for methods of testing and classification of PCB materials.

NEMA

European standards for classification, verification, and production technology, most often considered in the production of single- and multi-layer PCB.

IEC

List of methods for testing product quality, as well as raw materials.

The fitting substrate with foil copper (subtractive technologies) are used as composites or polymers - laminated plastic which has passed the preliminary pressing, reinforced by:

– woven/non-woven fabric;
– organic or glass fiber;
– polytetrafluoroethylene threads- PTFE;
– various resins (phenolic, polyester, epoxy, polymeric, etc.) and their mixtures - multifunctional, mixed, etc.;
– hardeners - dicyandiamide, phenol-formaldehyde resin, isocyanurate and cresol novolac, p-aminophenol, etc.;
– powdered organic/ceramic fillers.

The basic materials can be both flexible and rigid. There are also liquid (pasty) bases of printed circuit boards. Let us consider types of dielectric bases according to the NEMA classification more detailed:

Types of basic materials

XXXPC

Paper

Фенольная

Laminated pressed electrical insulating paper impregnated with a binding agent based on phenolic compounds - getinax. Flammability class: UL94-HB. The material is cheap and suitable for single-sided printed circuit boards. Color: light brown. Feature: there is no possibility of metallization of via holes and finishing coat HASL.

FR-2 и FR-1

Paper

Фенольная

Made in the form of getinax. Feature: fireproof properties. The main difference between FR-1 and FR-2 is the temperature regime of vitrification: for the first one - 130˚, for the second one - 105˚. Flammability class of materials: UL94-V0.

FR-3

Paper

Epoxy

Getinax impregnated with an epoxy binding agent. It is fireproof, it has high insulation resistance.

CEM-1

Paper + glass

Epoxy

The material is based on epoxy paper with the addition of glass fiber (FR-4) as one surface layer. Fireproof. It is widespread in the production of single-layer printed circuit boards, as a low-cost alternative to FR-4. Color: milky white. Feature: there is no possibility of metallization of via holes. Flammability class: UL94-V0.

CEM-2

Paper + glass

Epoxy

The material is like CEM-1 by its nature, but it is not fireproof.

CEM-3

Glass combined filling

Epoxy

The basis is non-woven glass fiber with epoxy resin, the surface layer is smooth woven glass fiber. According to its technological characteristics it is like FR-4, it is used to produce two- and multi-layer PCB. The material is fireproof. Color: milky white. It can be easily processed (stamped and drilled).

CEM-4

Glass combined filling

Epoxy

The material is like CEM-3, but it is not fireproof.

FR-6

Non-woven fabric:

Polyester

Fireproof non-woven glass fabric with the addition of polyester binders.

G-10

Fiberglass fabric

Epoxy

Fiberglass cloth with the addition of epoxy substances. Flammability class: UL94-HB. The ease of stamping makes optimal conditions to produce PCB for wristwatches.

FR-4

Fiberglass fabric

Epoxy

The most widespread fireproof epoxy fiberglass cloth. Thickness: 1.6 mm (8 layers). Maximum operating temperature: 130˚.

G-11

Fiberglass fabric

Epoxy

Fiberglass with the addition of heat-resistant epoxy compounds.

FR-5

Fiberglass fabric

Epoxy

Fireproof fiberglass with the addition of heat-resistant epoxy compounds. It is like FR-4, but the operating temperature is 140˚-180˚.