Detection methods for hazardous substances in the RoHS directive in the PCB industry

Lead, mercury, hexavalent chromium, cadmium, polybrominated biphenyls (PBB), and polybrominated diphenyl ethers (PBDE) are prohibited in electronic and electrical equipment; the limit for cadmium is 100 ppm (0.01%), and the limit for the other five is 1000 ppm (0.1%). Products exported to the EU by enterprises must meet the above limit requirements and display the corresponding certification documents. Products that do not meet the requirements will be refused entry into the EU market. The following introduces the detection methods of the six hazardous substances in the RoHS Directive.

1. X-ray fluorescence spectrometry

① Scope of application:
Screening test of lead, mercury, cadmium, total chromium, and bromine in plastic parts, metal parts, and electronic components
② Technical features:
One-time rapid qualitative analysis of lead, mercury, cadmium, chromium, and bromine elements in samples. No sample preparation is required for homogeneous samples, and non-destructive testing can be performed.

X-ray fluorescence spectrometer

2. Fourier transform infrared spectroscopy

① Scope of application: Screening test of high content of PBB and PBDEDD in polymer materials.
② Features: Based on the characteristic infrared spectra of PBB and PBDE as qualitative basis, some samples can be non-destructively tested.

Fourier infrared spectrometer

3. Spot method for hexavalent chromium

① Scope of application: Qualitative screening test of hexavalent chromium in colorless and colored chromate coatings.
② Features: Directly and qualitatively test the hexavalent chromium in the surface coating of the sample by using color development reaction, which is simple and fast. If a positive reaction occurs, it is necessary to use spectrophotometry and other methods for confirmation analysis.

4. Gas chromatography/mass spectrometry analysis method (GC-MS method)

① Scope of application: Quantitative analysis of PBB and PBDE flame retardants in plastic parts and electronic components.
② Instrument: Desktop gas chromatography-mass spectrometer
③ GC-MS method is a common method for qualitative and quantitative testing of volatile and semi-volatile organic compounds, and is widely used in residual analysis projects of various organic poisons.

Gas chromatography-mass spectrometer

5. Liquid chromatography (HPLC method)

① Scope of application: Quantitative analysis of PBB and PBDE flame retardants in plastic parts and electronic components.
② Main instrument: liquid chromatograph;
③ Technical features: suitable for the test of low-volatile flame retardants such as decabromobiphenyl and decabromodiphenyl ether, making up for the weakness of GC-MS method.

Liquid chromatograph

6. Spectrophotometric analysis method

① Scope of application: test of hexavalent chromium content
② Main instrument: UV spectrophotometer;
③ Technical features: This method is a classic method for testing hexavalent chromium, and can refer to many domestic and international standards, such as EPA3060A.

UV-visible spectrophotometer

7. Inductively coupled plasma atomic emission spectrometry (ICP-AES method)

① Scope of application: test of lead, mercury, cadmium and total chromium content in plastic parts, metal parts and electronic components.
② Main instrument: inductively coupled plasma atomic emission spectrometer;
③ Technical points: choose to use microwave digestion, wet digestion, dry digestion and other means to dissolve the sample, and simultaneously determine the content of lead, mercury, cadmium and total chromium at one time.

Inductively coupled plasma atomic emission spectrometer

8. Atomic absorption analysis (AAS method)

① Scope of application: Testing the content of lead and cadmium in plastic parts, metal parts and electronic components.
② Instrument: Atomic absorption spectrometer;
③ Technical features: AAS method is one of the most mature instrumental testing methods for metal elements, with strong selectivity of characteristic atomic absorption spectral lines and high sensitivity for testing elements such as lead and cadmium.

Atomic absorption spectrometer

9. Cold atomic absorption spectrometry (CVAAS method)

① Scope of application: Testing the content of mercury in plastic parts, metal parts and electronic components
② Main instrument: Mercury analyzer;
③ Technical points: Cold atomic absorption spectrometry is a classic method for testing mercury content, with strong selectivity, low detection limit and high sensitivity.