Surface Finishing Tutorial

#220 Methods of Thickness Test for Plate Coating

Category : Electroplating

November27, 2015

When you place or receive an order of plate coating work, the thickness of the plating film is probably the most important specifications. The plating type and thickness are determined by the operating environment and purposes of the particular product. This section explains how to measure the thickness of plate coatings.

(1) Methods of the thickness test

JIS provides the following methods to test the thickness of plate coatings:

No.	Measurement method	Accuracy	Description of the method
1	Microscopical exam of cross section	0.8um	Prepare a cross-section sample of the plating surface. Measure the thickness by enlarging it by a microscope.
2	Coulometric method	Within 10% from the true value in the range of 0.2 to 50um	Set the electrolysis equipment on the plating surface. Dissolve the metallic plating film by electrolysis and measure the thickness.
3	Eddy current method	Around 10% from the true value	Place a probe supplying high-frequency current on the plating surface and read the plating thickness directly.
4	Magnetic method	Within 10% from the true value excluding the thin film of 5um or less	Place a probe emitting lines of magnetic force on the plating surface and read the plating thickness directly.
5	X-ray spectrometric method	Within 10% from the true value	Irradiate X-ray on the plating surface. Measure the plating thickness by the intensity of fluorescent X-ray generated.
6	Beta backscatter method	Within 10% from the true value	Irradiate beta ray on the plating surface. Directly read the plating thickness from the back-scattered volume.
7	Micrometer test method		Use a micrometer or a dial gauge to measure the plating thickness based on the dimensional difference before and after the plating work.
8	Coating weight measurement by gravimetric method		Peel off the sample plating of a specified area. Based on the weight difference before and after this process, calculate the adhesion amount per unit area.

(2) Sampling method

	1.	In general, collect a sample from the significant surface of the plated goods. If it is not possible, substitute the significant surface of the plated goods with a test piece made of the same materials and created in the same conditions as the subject goods.
	2.	The sample surface must be clean. If any dust or oil content was found on the surface, remove them without damaging the plated surface before performing the test.

« PREV