5. Polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE): These two substances are common flame retardants, but they release toxic substances when burned, which are harmful to the human body and the environment. The RoHS directive also has strict limits on the content of these two substances.

LED display EU ROHS testing and certification process:

1. Self-assessment: Before applying for RoHS certification, companies should first conduct self-assessment to understand the product's material composition and supply chain situation to ensure that the product does not contain hazardous substances restricted by the RoHS directive. This can be done by reviewing the material declarations, test reports and other documents provided by the supplier.

2. Choose a certification agency: Enterprises should choose an authoritative and professional certification agency for RoHS certification. When selecting a certification agency, factors such as the agency's qualifications, experience, service quality, and price should be considered, and a formal certification contract should be signed.

3. Preparation of application materials: Enterprises should prepare relevant application materials in accordance with the requirements of the certification body, including product specifications, circuit diagrams, material lists, supplier information, etc. In addition, companies also need to provide product samples for testing by certification agencies.

4. Submit application: The enterprise submits an application to the certification agency and pays the relevant certification fees. When submitting an application, enterprises should ensure the completeness and accuracy of application materials to avoid affecting the progress and results of certification.

5. Sample testing: After receiving the application, the certification body will test the provided samples. The testing content mainly includes testing the content of harmful substances in electronic products to ensure that the products comply with RoHS certification standards. During the testing process, the certification agency will follow strict testing methods and procedures to ensure the accuracy and reliability of the test results.

6. Review and evaluation: After completing the sample testing, the certification body will review and evaluate the company's technical documents, production processes, etc. This step is designed to ensure that companies can continue to comply with RoHS certification standards during their production processes. During the audit and evaluation process, the certification body may require the enterprise to provide additional supporting materials or conduct an on-site audit.

7. Issuing a certificate: If the product meets the RoHS certification standards, the certification agency will issue a RoHS certification to the enterprise. Companies can mark the RoHS certification mark on their products to prove that their products comply with the EU's environmental requirements.