This part of IEC 60664 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 Part 1. This standard describes the requirements and test procedures for two methods of protection: type 1 protection improves the microenvironment of the parts under the protection type 2 protection is considered to be similar to solid insulation. This standard 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 Part 1. NOTE 1 Examples of substrates are hybrid integrated circuits and thick-film technology. This standard 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.