SU1670591A1 - Method of determining product coating plasticity - Google Patents

Abstract

This invention relates to the acoustic emission control of the ductility of product coatings. The purpose of the invention is to improve the measurement accuracy by eliminating the influence of roughness on the measurement result. For a reference sample, the dependence of the number of points on the surface with the same acoustic emission activity on the average amplitude of the signals is revealed. Comparing such dependencies for products with the obtained standard dependencies, judging plasticity. 2 Il.

Description

The invention relates to a measurement technique and can be used to determine the plasticity of the coating of products.

The purpose of the invention is to improve the measurement accuracy by eliminating the influence of roughness on the measurement result.

FIG. 1 and FIG. Figure 2 shows the dependences (histograms) of the number of points on a product with the same acoustic emission (AE) activity on the average amplitude of signals from two different samples.

The method is carried out as follows.

A batch of samples (50 pcs.) Is made of stainless steel grade 12X18H10T, on which a copper coating is deposited. Copper is deposited in electroplating baths of different composition and varying degrees of contamination of the electrolyte with organic matter. After measuring the coating thickness (h), the specimens are subjected to plasticity testing using the acoustic emission method.

At 100 points selected on the surface of the sample in an arbitrary way, under mechanical loading (pressure of 1 kgf / mm) with a steel indenter with a diameter of 0.8 mm, the acoustic emission signals were recorded. After processing the statistical data, a histogram and a smoothing distribution of acoustic signals are constructed. The abscissa axis lay the average amplitude, the coordinate axis - the number of points with the same number of acts (AE activity).

For comparison and quantification of the plasticity value, the copper coating is separated from the sample and subjected to tensile plastic destructive tests to tensile strength using a tensile testing machine.

To do this, strips are cut out of the sheet of the removed copper, which are subjected to tensile tests, after which the relative elongation (f) and relative XJ are calculated

Yo

about

3

ate yu

my elongation per unit thickness with

ti (t) according to the formula

As reference samples of the product, samples are taken from the entire batch with coatings that differ sharply from one another in quality and characterize the operation of the baths both in composition and in the degree of contamination with organic matter.

Sample No. 1 was obtained by deposition of copper in a laboratory electroplating bath with copper sulfate electrolyte with LTI lens forming agent (ml / l) at a current density of A / dm and a coating time t of 1.5 h.

Coating thickness µm, roughness, 6 µm, relative elongation (, 8%, relative elongation per unit thickness of the coating, 19% / µm.

On the histogram, the smoothing distribution curve (Fig. 1) has a relatively small span (about 60 units), which indicates a high plasticity and uniformity of the coating.

Sample tsfe 2 was obtained by deposition of copper in a workshop galvanic bath with copper sulfate electrolyte with a dispersant NP at a current density of dic 1 A / dm and a coating time t of 2 hours.

Coating thickness µm, relative elongation q 4.18%, relative elongation per unit coating thickness, 12% / µm.

In the histogram, the smoothing distribution curve (Fig. 2) is polymodal (two vertices). The range is very large - about 500 units, which means that the coating is non-uniform and has low plasticity.

A comparative analysis of the histograms of the reference samples of the product allows the samples to be arranged in order of degraded plasticity.

The calculated parameter t varies in the same sequence, which allows to conclude that the value of m is an information indicator of the plasticity of the coating and allows us to give a quantitative assessment of the plasticity: the more t, the greater the plasticity and uniformity of the coating, the less the span of the smoothing curve of the distribution of acoustic signals.

Determination of plasticity of the coating

the test article (printed circuit board) is mechanically loaded on the process area of the board. Acoustic emission signals are recorded at selected points, a histogram and

smoothing distribution curve of acoustic signals. Comparing the histogram of the printed circuit board with histograms of reference samples of the product, according to the nature of the smoothing curve

the distribution of acoustic signals is judged on the plasticity of its coating. So, if the span of the smoothing curve of the distribution of acoustic signals on the histogram of the printed circuit board is less or

equal to the sweep of the smoothing curve of the hologram of the reference sample Nb 1 (Fig. 1), the coating has high plasticity and uniformity; if the nature of the curve is close to the histogram 2 (figure 2), then the coating has

low b plasticity.

Thus, the use of the proposed method in comparison with the prototype makes it possible to determine the plasticity of the coating directly in

the process of making a printed circuit board by a non-destructive method, control the operation of coating baths according to the degree of contamination with organic matter, since the change in the operation of the bath changes the character

coatings (ductility).

Claims (1)

The invention of the method for determining the plasticity of a product coating, is that the coated product loads and records acoustic emission signals, according to the parameters of which plasticity is judged, which differs from the fact that, in order to improve the accuracy, are addicted the number of points on the surface of the product with the same acoustic emission activity from the average amplitude of the acoustic emission signals, and the ductility of the coating of the controlled product is judged by the result of the comparison of these dependencies for the reference sample and the controlled product. w 300400 FIG. Z 500600 # Wed