ASTM B507-14(R2021) pdf free download
ASTM B507-14(R2021) pdf free download.Standard Practice for Design of Articles to Be Electroplated on Racks
1.1 This practice covers design information for parts to be electroplated on racks. The recommendations contained herein are not mandatory, but are intended to give guidance toward good practice.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use.
1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Significance and Use
2.1 When an article is to be electroplated, it is necessary to consider not only the characteristics of the electroplating process, but also the design of the part to minimize electro- plating and finishing costs and solution dragout as well as to improve appearance and functionality. It is often possible during the design and engineering stages to make small adjustments in shape that will result in considerable benefit toward a better quality part at a lower cost.
2.2 The specific property of an electroplating process that would require some attention to the details of optional designs, is the throwing power of the electroplating solution. This term describes the properties of the solution as it relates to the solution electrical resistance and solution capacitance at the cathode and overall efficiency of the electrolyte system. Throwing power is defined as the improvement of the coating distribution over the primary current distribution on an elec- trode (usually cathode) in a given solution, under specified conditions.
3. Current Distribution and Throwing Power
3.1 The apparent current during practical electroplating is never uniform over the surface of the product. Even parallel plates have a nonuniform distribution of current when freely suspended in a bath as shown in Fig. 1. In this example, the current lines tend to concentrate as corners, and edges (high- current density) of the part. Consequently more metal is deposited at the high-current density areas than at the low- current density areas. 4. Relative Throwing Powers of Different Electrolytes
4.1 Throwing power is not the same for all metals and all electroplating baths. Table 1 lists the commonly used electro- plating processes. They are arranged according to decreasing throwing power.
4.2 A Rochelle-type copper electroplating solution has ex- cellent throwing power compared to the poor throwing power of a chromic acid solution used to deposit chromium. The widely used Watts-type nickel bath has fair throwing power. 5. Geometric Factors Determining Deposit Distribution
5.1 Since a metal deposits preferentially at protuberances, such as sharp corners, edges, fins, and ribs, these should be rounded to a radius of at least 0.4 and preferably 0.8 mm to avoid excessive buildup. Contouring a base corner in a depression is also recommended to avoid thickness deficiency at the location.
5.2 The width-to-depth ratio of a depression or recess should be held to more than three as shown in Fig. 2. Otherwise, a special auxiliary anode must be employed inside the recess to promote more uniform current distribution. An auxiliary anode is usually made of the depositing metal and is placed close to the low-current density areas to enhance metal deposition at those regions.
5.3 All sharp edges and base angles of a recess should be rounded to a radius of 0.25 times or more the depth of the recess as shown in Fig. 3.
