Base material:

Standard FR4 materials:

The standard FR4 base material for single sided and double sided printed circuit boards is based on FR4 epoxy glass weave laminate with a TG value of at least 130° C and a CTI value of 175.

The standard FR4 base material for multilayer boards is based on FR4 epoxy glass weavelaminate with a TG value of at least 150° C and a CTI value of 175.

All base materials are specified by their manufacturers for flammability class UL 94 V0.

Special FR4 materials:
Special FR4 materials like halogen-free, filled, high thermal stability or other materials can also be produced with UL approval.

Non-FR4 materials:
IMS boards on aluminium base
Polyimide (flex) for flexible boards
High frequency boards made of Rogers 4000
High frequency multilayer boards made of Rogers 4000 combined with FR4

FR4 base material thicknesses and tolerances

Some base material, board thickness and copper thickness combinations are not available directly ex stock.
*There is no distinction between the nominal thicknesses 1.5, 1.55 and 1.6 mm.The specified base material thickness only defines the thickness of the dielectric including the base copper lamination. Any additional layers as e.g. plated copper layers and solderresist masks increase the final thickness. For practical purposes a plus tolerance has to be taken into consideration.  

Single-sided PCBs and inner layers of ML boards

In the normal manufacturing process, single sided PCBs and inner layers of ML boards are produced exclusively by etching and are not reinforced by plating. Thus, in terms of the final copper thickness of the board only the laminated copper thickness is considered. Some base material, board thickness and copper thickness combinations are not available directly ex stock.

Double-sided plated-through PCBs and outer layers of ML boards

In the manufacturing process the outer layers are generated in semi-additive technology. The final copper thickness includes the base copper plus the plated copperreinforcement.

Copper laminations up to 400 µ can be made upon individual agreement.
*)12µ base copper thickness is-used for special purposes only. Some base material, board thickness and copper thickness combinations are not availabledirectly ex stock.

Additionally, the plated layer thickness and thus the final thickness depend on the copper pattern and its distribution and homogeneity as this determines the deposition rate of the copper plating process.

Copper thickness in plated-through holes

The plated-through barrel is generated during the copper plating process and must achieve a minimum wall thickness to withstand all subsequent mechanical, electrical and thermal stresses.