This part of IEC60664 applies to assemblies protected against pollution by the use of coating, potting or moulding, thus allowing a reduction of clearance and creepage distances as described in IEC60664‑1 . This document describes the requirements and test procedures for two methods of protection: type1 protection improves the microenvironment of the parts under the protection; type2 protection is considered to be similar to solid insulation. This document also applies to all kinds of protected printed boards, including the surface of inner layers of multi-layer boards, substrates and similarly protected assemblies. In the case of multi-layer printed boards, the distances through an inner layer are covered by the requirements for solid insulation in IEC60664‑1 . NOTE Examples of substrates are hybrid integrated circuits and thick-film technology. This document refers only to permanent protection. It does not cover assemblies that are subjected to mechanical adjustment or repair. The principles of this standard are applicable to functional, basic, supplementary and reinforced insulation.