ASTM B507-14

Standard Practice for Design of Articles to Be Electroplated on Racks

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 electroplating 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 electrode (usually cathode) in a given solution, under specified conditions.
SCOPE
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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2014
• ICS: 25.220.20 - Surface treatment
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.01 - Ancillary Activities

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B507 −14
Standard Practice for
1
Design of Articles to Be Electroplated on Racks
This standard is issued under the fixed designation B507; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope plates have a nonuniform distribution of current when freely
suspended in a bath as shown in Fig. 1. In this example, the
1.1 This practice covers design information for parts to be
current lines tend to concentrate as corners, and edges (high-
electroplated on racks. The recommendations contained herein
current density) of the part. Consequently more metal is
are not mandatory, but are intended to give guidance toward
deposited at the high-current density areas than at the low-
good practice.
current density areas.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Relative Throwing Powers of Different Electrolytes
standard.
4.1 Throwing power is not the same for all metals and all
1.3 This standard does not purport to address all of the
electroplating baths. Table 1 lists the commonly used electro-
safety concerns, if any, associated with its use. It is the
plating processes. They are arranged according to decreasing
responsibility of the user of this standard to establish appro-
throwing power.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4.2 A Rochelle-type copper electroplating solution has ex-
cellent throwing power compared to the poor throwing power
2. Significance and Use
of a chromic acid solution used to deposit chromium. The
2.1 When an article is to be electroplated, it is necessary to
widely used Watts-type nickel bath has fair throwing power.
consider not only the characteristics of the electroplating
process, but also the design of the part to minimize electro-
5. Geometric Factors Determining Deposit Distribution
plating and finishing costs and solution dragout as well as to
5.1 Since a metal deposits preferentially at protuberances,
improve appearance and functionality. It is often possible
such as sharp corners, edges, fins, and ribs, these should be
during the design and engineering stages to make small
rounded to a radius of at least 0.4 and preferably 0.8 mm to
adjustments in shape that will result in considerable benefit
avoid excessive buildup. Contouring a base corner in a
toward a better quality part at a lower cost.
depression is also recommended to avoid thickness deficiency
2.2 The specific property of an electroplating process that
at the location.
would require some attention to the details of optional designs,
is the throwing power of the electroplating solution. This term
5.2 The width-to-depth ratio of a depression or recess
describes the properties of the solution as it relates to the
should be held to more than three as shown in Fig. 2.
solution electrical resistance and solution capacitance at the
Otherwise, a special auxiliary anode must be employed inside
cathode and overall efficiency of the electrolyte system.
the recess to promote more uniform current distribution. An
Throwing power is defined as the improvement of the coating
auxiliary anode is usually made of the depositing metal and is
distribution over the primary current distribution on an elec-
placed close to the low-current density areas to enhance metal
trode (usually cathode) in a given solution, under specified
deposition at those regions.
conditions.
5.3 All sharp edges and base angles of a recess should be
3. Current Distribution and Throwing Power
rounded to a radius of 0.25 times or more the depth of the
recess as shown in Fig. 3. When sharp recess angles are
3.1 The apparent current during practical electroplating is
required for a functional purpose, the electroplater cannot be
never uniform over the surface of the product. Even parallel
expected to meet a minimum thickness at those locations
unlessitisspecificallyrequiredandoptionalplatingtechniques
1
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
are employed.
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.01 on
Ancillary Activities.
NOTE 1—Electroplating techniques can be used to address uniform
Current edition approved May 1, 2014. Published June 2014. Originally
ε1
approved in 1970. Last previous edition approved in 2008 as B507 – 86 (2008) . deposition in the recess angle. These techniques include bi-polar plating
DOI: 10.1520/B0507-14. and directed flow electroplating in addition to conforming anodes.
Copyright © ASTM International, 100 Barr Harbor Drive,
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: B507 − 86 (Reapproved 2008) B507 − 14
Standard Practice for
1
Design of Articles to Be Electroplated on Racks
This standard is issued under the fixed designation B507; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—The units statement in subsection 1.2 was corrected editorially in April 2008.
1. Scope
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 appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
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 electroplating 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 electrode (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 electroplating
processes. They are arranged according to decreasing throwing power.
4.2 A Rochelle-type copper electroplating solution has excellent 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.
1
This practice is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.01 on Ancillary
Activities.
Current edition approved April 1, 2008May 1, 2014. Published April 2008June 2014. Originally approved in 1970. Last previous edition approved in 20032008 as
ε1
B507 – 86 (2003).(2008) . DOI: 10.1520/B0507-86R08E01.10.1520/B0507-14.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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B507 − 14
FIG. 1 Current Density Distribution and Typical Electrodeposit (filled area)
TABLE 1 Relative Throwing Powers of Common Electroplating
Baths
Bath/Metal Ranking
Rochell copper (cyanide based) Excellent
Cyanide cadmium Excellent
Cyanide gold Good
Cyanide silver Good
Alkaline tin Good
Cyanide zinc Good
Alkaline non cyanide zinc Good
Fluoborate lead Good
All chloride nickel Fair
T
...