Printed circuit board plating bath control solution

Sept. 30, 2010 - PRLog -- RayMing PCB - www.raypcb.com

Printed circuit board plating bath control solution
System circuit board plating bath solution, the main purpose is to keep control of all the chemical composition within the limits prescribed in the process. It is only within the parameters specified in the process, to ensure the chemical and physical properties of coatings. Process control methods used in many types, including chemical sub-packs, the acid value of the physical test and measurement solution, the solution of the weight or other colorimetric assay. These methods are process parameters to ensure the accuracy of Bath, consistency and stability. The choice of control method is laminated type. Such as high throwing power, high brightness with low acid copper plating bath to determine the parameters is offered by chemical methods to adjust the sub off or adjust the data; electroless copper solution in addition to chemical analysis, but also the acid number or ratio of PH color measurement and so on. If the analysis in the process of its chemical composition range; we should pay close attention to changes in other parameters and the state of the substrate surface is coated, such as bath temperature, current density, racking substrate surface treatment methods and the impact of the state of the bath. Particularly bright acid copper plating bath to control the inorganic impurities - zinc, more than the process provided by the allowed values, it will directly affect the surface state of the copper layer; tin-lead alloy plating bath must be strict control of copper impurities, such as more than a certain number, it will affect the tin-lead alloy coating wettability and solderability performance and protective. Although the method is reliable for the control of the bath, but can not guarantee access to good plating layer. Therefore, the test must also be by means of electroplating. In particular, many plating bath to ensure good electrical performance and mechanical properties of the organic additives are added to improve the coating structure and performance. By chemical analysis of these additives is very difficult to work, test the process using electroplating method of analysis and comparison of chemical composition of the bath as a control of the important supplementary means. Determination of additive content, including additional control and adjustment, filtration and purification, the need to test the board by the Hough bath to be carefully "observe", and then coating by the model distribution, research and analysis and inference, to improve or to improve the process Step purposes.

First, the plating test

Plating bath control principles should include the main chemical components of the bath. To achieve the correct diagnosis requires the use of advanced, reliable testing equipment and analysis methods, and some need to use aids such as bath: To determine the specific gravity, acid value (PH) and so on. In order to directly observe the coating surface state, most manufacturers are now testing the technique using Fourier transform method of groove. Specific test step is to test board tilted 37 ° with the long side of the same length, the anode placed vertically along the long side. Anode to cathode distance changes will be along the cathode away from the regular rules, the results of changing currents along the test plate. Current distribution from the test board the state of science will be able to determine the plating bath is used in the current density within the limits prescribed in the process. Additive content can be observed also on the direct impact of the current density and the quality of the surface coating. Figure 1: Hull test cell surface perspective

Second, the bending test negative plate:

Adopt this method because it can cover a wide range, it is exposed to an angle, the vertical shape because it can adapt to the surface of the upper and lower dielectric effect. Which can test out the current range, the merits of throwing power. Figure 2: Diagram of bending test cathode

Third, judgments and inferences:

Through the above test method used to test plates by the actual record, first of all to the test can determine plating low current district board phenomenon, we can determine need to add additional agents; in high current areas, coating surface appears rough, irregular appearance of the black and the other defects, indicating that the metal bath containing inorganic impurities directly affect the state of the coating surface. Such as the coating surface showing pits, that means to reduce surface tension. Damaged plating bath often show an excess amount of memory additives and decomposition. Full description of these phenomena are analyzed and adjusted to in a timely manner, consistent with the chemical composition of the bath under the process parameters. The excessive additives and decomposition of organic matter must be treated with activated carbon and other filtration and purification.

In short, despite the use of computer automatic control, but must also be tested by means of aid, be achieved double insurance. So, it used the control method used or needed further research and development of new test methods and technology equipment, so that the electroplating and printed circuit board coating process more perfect.


RayMing PCB - HTTP://www.raypcb.com

# # #

RayMing PCB - www.raypcb.com . RayMing Technology (HK) Co., Ltd is a professional High-tech PCB Manufacturer of single-sided, double-sided and multilayer printed circuit boards(up to 20L), and some high end boards,