The thickness of the electroplating layer is an important indicator to measure the quality of the coating, which directly affects the corrosion resistance and conductivity of the workpiece, which in turn has a significant impact on the reliability and service life of the product. Therefore, the method of accurately determining the thickness of the coating is crucial. This article will introduce various methods for testing the thickness of the coating.
1. Sabotage law
Destruction methods are a group of methods that are characterized by destroying or damaging the coating under test during testing. These methods include:
Dissolution method: This method measures the average thickness of the entire coating, dissolves the coating or base metal by soaking the sample in an appropriate solution, and then compares the weight of the sample before and after dissolution or uses chemical analysis to determine the coating quality.
Coulomb method (electricity method): The Coulomb method uses a constant DC current to pass through the electrolytic solution to dissolve the coated metal anode, and calculates the coating thickness according to the electricity consumed. This applies to the local thickness of single-layer or multi-layer single-metal coatings.
Timed flow method: Calculate the thickness of the coating by dissolving the local coating of the sample under the action of liquid flow, and then recording the time required for dissolution.
2. Non-destructive method
Nondestructive methods are a group of methods that are characterized by not destroying the coating under test during testing. These methods include:
Magnetic method: suitable for measuring the thickness of non-magnetic coatings on magnetic metal substrates. This method usually has small measurement errors, but may be slightly less accurate for thinner coatings.
Eddy current method: Using high-frequency coils to generate high-frequency magnetic fields, eddy currents are generated in the sample to be tested, and the thickness of the coating is measured according to the amplitude and phase of the eddy currents. This method is suitable for thickness measurement of non-conductive coatings on non-magnetic metal substrates.
Beta-ray reflection method: Using radioisotopes to release X-rays, the thickness of the coating is determined according to the intensity of the beta rays reflected by the tested coating. Suitable for thin precious metal coatings.
X-ray fluorescence method: By measuring the secondary X-rays generated on the metal surface, the thickness of the metal coating on the metal or non-metal substrate can be measured, and the composition of the alloy coating can also be determined.
3. Other methods
In addition to the above-mentioned destructive and non-destructive methods, there are some other methods used to measure the thickness of the coating, such as metallographic microscopy, profilometer method, interference microscopy method, double beam of light microscopy method, etc. These methods have their own advantages and applicability in specific situations, and the appropriate method can be selected for testing according to needs.
Summary and recommendations
Accurate measurement of electroplating layer thickness is essential to ensure product quality. Choosing an appropriate test method depends on the type of coating being tested, thickness range and test accuracy requirements. In addition, international and industry standards also provide detailed test procedures and requirements to ensure the accuracy and repeatability of the test. Therefore, when conducting electroplating layer thickness tests, it is recommended to refer to relevant standards and select appropriate test methods to ensure product quality and performance.