The electroplating master will meet: Analysis of the causes of errors in the Hall tank test

Hall cell test is a test method often used by electroplating engineers and field managers, and it is also a method often used in technical reports or technical papers.

Because the state of the Hall groove test piece involves the evaluation of process performance, and sometimes the evaluation of product quality, there is an issue of fairness and fairness in the evaluation. Only when the results of the test piece are compared with the standard, or when everyone is experimenting according to the same standard, can the comparison and evaluation be credible, and it is fair and just.

At present, when providing the results of the Hall tank test, it is based on the premise that everyone has used the same Hall tank test method, and by default, these tests have been tested under standard conditions using standard Hall tanks. However, this recognition is worth discussing.

Because many testers did not carefully correct or record the relevant parameters when doing the Hall cell test, and did not operate in accordance with the Hall cell test specifications, the obtained parameters will inevitably be biased and give wrong results. information.

The most common errors are the following:

1 Anode thickness over 5mm

Many of the anodes in the Hall cell test did not use standard anodes, but saw a piece from the anode of the plating bath to substitute. These anodes are usually thicker, sometimes up to 10mm thick. This kind of non-standard anode is equivalent to Huo The size of the bath has undergone a little change, so that the situation in the high-current area becomes worse and the situation in the low-current area is better, which is not good for understanding the real situation of the plating bath. When there is no standard test piece, I would rather use an insoluble anode (such as stainless steel or titanium) to make a standard anode. It will be accurate to do only one test per sample. For plating species with more main salts, only 2 at most Times test.

2 More than 3 test pieces made with the same plating solution

The standard Hall cell test takes one plating solution and only 1~2 slices should be made, because the concentration of the plating solution will change due to not being replenished in time, and the result will not be comparable or reproducible. Unless you need to test the supplementary rules or adjustment methods during your own development process, you can make a record while adding relevant ingredients to the test solution before you can make a few more slices, but when providing such test results, you must record the parameters at the same time. Provided to readers. Many people who do the Hall cell test will sample three or four test pieces at a time; sometimes even more, the plating solution concentration of the later pieces has changed, and the results are difficult to compare.

3 Incomplete records of test conditions

In order to make the Hall cell test comparable, the process conditions during the test should be reported together with the results. However, many of the test results of the Hall cell did not provide perfect process conditions, either without temperature indicators, or without Provides the plating solution formula used, or does not indicate whether there is a method of stirring the plating solution or stirring, so that the result of the test piece made cannot be compared with other same processes.

4 Non-standard Hall slots or power supplies are used

Some experimenters use non-standard Hall grooves. There are two situations. One is that they are made of plexiglass or other plastics, and they are handmade, with inaccurate dimensions and geometric shapes that do not conform to the Hall grooves. The structural requirements. The other is that the Hall groove produced by the manufacturer of the purchased Hall groove is not standard enough. For example, the assembly error exceeds the standard when the assembly method is used, and the mold size of the molding method does not meet the requirements, so a complete Hall groove test report It should include a description of the Hall slot used, such as “Use a self-made Hall slot”.

The test power supply is also very important for the Hall cell test. It is necessary to use a stable DC power supply. For self-developed comparative tests, it is not a big problem to use the same power supply all the time, but when you want to provide other people’s comparative tests, you must specify the type of power used. The parameters of the power supply are single-phase full-wave or half-wave, as well as filtering conditions, etc., because this has a great influence on the test results. Many service technicians do tests in their own laboratories, but they fail to get it to users. They rarely think that the power supply is actually causing trouble.