| Callout | Requirement |
| Class 0 | thickness 1 to 5 mils |
| Class 1 | thickness 1 mil minimum |
| Class 2 | thickness 50 µin minimum |
| Class 3 | thickness 10 µin minimum |
MIL-C-14550B is the latest revision. Although MIL-C-14550B has been superseded by AMS2418, the older mil spec is still on prints and should be in your scope.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
¶ 4.3.2: thickness
¶ 4.3.2: adhesion
¶ 4.3.2: embrittlement
¶ 4.3.2: solderability
Coupon/Part Testing - per lot
¶ 4.3.1: coating thickness
¶ 4.3.1: visual
AMS2418
| Callout | Requirement |
| Type I | engineering plating |
| Type II | plating for masking thickness 50-70 µin |
AMS2418G is the latest revision. Note that AMS2418 Type 1 and AMS2418 Type 2 have subtle differences in test requirements. Unique requirements include restrictions on reworking parts and underplating. Although some external specifications are referenced, there are helpful guidelines and additional requirements for hydrogen embrittlement and solderability tests. The specification includes a sampling plan for acceptance tests.
Bath Testing
¶ 4.2.2: processor to specify
frequency and analysis methods
and establish periodic test plan
Coupon Testing - periodic
¶ 3.4.4: embrittlement
¶ 3.4.5: solderability
Coupon/Part Testing - per lot
¶ 3.4.1: coating thickness
¶ 3.4.2: porosity
¶ 3.4.3: adhesion
ASTM B734
| Callout | Requirement |
| -X | thickness specified on print |
| -5 | minimum 5 µm (197 µin) |
| -12 | minimum 12 µm (473 µin) |
| -20 | minimum 20 µm (788 µin) |
| -25 | minimum 25 µm (985 µin) |
ASTM B734-97(2008) is the current revision.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
sampling plan may require
¶ 8.2: coating thickness
¶ 8.3: adhesion
¶ 8.3: porosity
¶ 8.5: solderability
Coupon/Part Testing - per lot
sampling plan may require
¶ 8.2: coating thickness
¶ 8.3: adhesion
¶ 8.3: porosity
¶ 8.5: solderability
AMS2402
| Callout | Requirement |
| -1 | 100 - 300 µin |
| -2 | 200 - 400 µin |
| -3 | 300 - 500 µin |
| -4 | 400 - 600 µin |
| -5 | 500 - 700 µin |
| -6 | 600 - 800 µin |
| -X | X - X+200 µin |
| if dash unspecified thickness must be on print | |
The current revision is AMS2402J and is available from SAE International.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
¶ 3.4.2: adhesion bend test
¶ 3.4.3: corrosion resistance
Coupon/Part Testing - per lot
¶ 3.4.1: coating thickness
ASTM B633
| Callout | Requirement |
| SC 1 | minimum 5 µm |
| SC 2 | minimum 8 µm |
| SC 3 | minimum 12 µm |
| SC 4 | minimum 25 µm |
| Type I | As-plated |
| Type II | With colored chromate |
| Type III | With colorless chromate |
| Type IV | With phosphate conversion |
| Type V | With colorless passivation |
| Type VI | With colored passivation |
ASTM B633 describes zinc plating on iron and steel. ASTM B633-07 is the current revision. This is a specification that references many other ASTM specifications and really doesn’t spell out much in the way of requirements. Tests and test methods are specified, but its up to the purchaser and supplier to determine whether these tests are to be done lot by lot, monthly, yearly or never. Note that the specification reference is critical to defining the required test procedures. For example, ASTM B633 Type I and ASTM B633 Type IV require no salt spray testing, while ASTM B633 Type II, ASTM B633 Type III, ASTM B633 Type V and ASTM B633 Type VI all require salt spray testing. The ASTM B633 Service Classes (e.g. ASTM B633 SC4) determine plating thickness as well as test requirements, so these SC designations should be used with or without specific thickness callouts added for clarity.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
¶ 10.3: corrosion resistance
¶ 10.4: hydrogen embrittlement
Coupon/Part Testing - per lot
¶ 10.1: coating thickness
¶ 10.2: adhesion
¶ 10.5: visual
& Chrome-Nickel-Copper
on Iron, Steel, Copper & Zinc
ASTM B456
| Callout | Requirement |
| SC 1 | mild service |
| SC 2 | moderate service |
| SC 3 | severe service |
| SC 4 | very severe service |
| SC 5 | extended severe service |
ASTM B456 describes chrome/nickel and chrome/nickel/copper multi-layer plating on iron, steel, copper and zinc alloyed basis materials. ASTM B456-03 is the current revision. The plating thicknesses and deposit types vary depending on the plating, basis material and service condition. The spec defines a syntax for describing the plating; for example, Fe/Ni35d Cr mc describes a duplex nickel underplate with a micro-cracked chromium outer plate. You will definitely need the specification, and a PhD in table reading, to figure out how to specify what you want or to figure out what has been specified. Moreover, your plating supplier must conform to a number of specifications for elongation, ductility and sulfur content and will need to properly select chemistries and control bath parameters; although the specification does not mention any bath control requirements. We would recommend acid copper underplate, sulfamate nickel for the bottom layer of the duplex or triplex nickel, and Watts nickel for the middle and outer nickel layers. Does your plater have both types of nickel baths? This is a tough specification, and you don’t want premature corrosion in the field to be your first indication of non-conformance. A purchaser who is asking for conformance to ASTM B456 should clearly define and document a test plan with the supplier to define acceptance criteria for each lot and the frequency at which process control tests should be performed.
Bath Testing
no bath parameters or tests
mentioned in specification
Destructive Testing - periodic
¶ 6.4: elongation
¶ 6.5: ductility
¶ 6.7: corrosion resistance
salt spray requirements listed by SC
¶ 6.8: intra-layer potential
¶ 6.9: sulfur content
¶ 6.10: chromium discontinuities
Coupon/Part Testing - per lot
¶ 6.2: coating thickness
¶ 6.3: adhesion
¶ 10.5: visual
FED QQ-C-320
| Callout | Requirement |
| Type I | Bright finish |
| Type II | Satin finish |
| Class 1 | Corrosion protective |
| Class 2 | Engineering plating |
| Class 2a | Processed to print dimensions |
| Class 2b | <RC40 not requiring shot peening |
| Class 2c | <RC40 requiring shot peening |
| Class 2d | >RC40 requiring embrittlement bake |
| Class 2e | >RC40 requiring peening and baking |
QQ-C-320 is still referenced on many prints and certificates of conformance are still offered by many plating shops. Although FED QQ-C-320B was cancelled and superseded by AMS2460, it is still worthwhile keeping it handy. QQ-C-320 Class 1 is for corrosion protection while QQ-C-320 Class 2 is engineering plating. Although it is not exactly clear why corrosion resistance is not an engineering requirement, the specification calls completely different test requirements for the two classes. QQ-C-320B Class 1/2 can be specified as fully bright (Type I) or satin finish (Type II). There are some interesting prep, underplating and plating instructions toward the end of the specification.
Bath Testing
¶ 4.3.1: processor to maintain
bath records showing analysis
results and chemical additions
Coupon Testing - monthly
¶ 3.4.2.3: hardness
¶ 3.4.2.4: porosity
¶ 3.2.6: embrittlement
Coupon/Part Testing - per lot
¶ 3.4.1.1: thickness
¶ 3.4.1.3: adhesion
AMS2460
| Callout | Requirement |
| Type I | Bright finish |
| Type II | Satin finish |
| Class 1 | Corrosion protective |
| Class 2 | Engineering plating |
AMS2460 was released in 2007 with no revision letter. (That would be a document control finding at a Nadcap audit.) AMS2460 is the successor to the QQ-C-320 specification. There are a few additions, like disallowing add plate procedures, so if you plan to certify to the spec you should read it carefully.
Bath Testing
¶ 4.2.2.1: processor to maintain
bath records showing analysis
results and chemical additions
Coupon Testing - monthly
¶ 3.4.1: thickness
¶ 3.4.2: adhesion
¶ 3.4.3: hardness
¶ 3.4.4: porosity
¶ 3.4.5: embrittlement
Coupon/Part Testing - per lot
¶ 3.4.1: thickness
¶ 3.4.2: adhesion
¶ 3.5: general quality
AMS2408
| Callout | Requirement |
| -flash | ~100 µin |
| -1 | 100 - 300 µin |
| -2 | 200 - 400 µin |
| -3 | 300 - 500 µin |
| -4 | 400 - 600 µin |
| -5 | 500 - 700 µin |
| -6 | 600 - 800 µin |
| -X | X - X+200 µin |
| if dash unspecified thickness must be on print | |
AMS2408 describes tin plating on various basis materials. The current revision is AMS2408J and is available from SAE International.
Bath Testing
¶ 4.2.2: periodic tests of cleaning
and plating solutions to ensure results
Coupon Testing - periodic
¶ 3.4.2: adhesion
Coupon/Part Testing - per lot
¶ 3.4.1: coating thickness
¶ 3.4.2: adhesion
¶ 3.4.3: solderability if req’d
AMS2409
| Callout | Requirement |
| none | 100 µin unless other thickness is specified on print |
AMS2409 describes tin plating on various basis materials using a dipped processes (not electroplated). The current revision is AMS2409G and is available from SAE International.
Bath Testing
¶ 3.2: concentration of tin
stannate, pH and temperature
Coupon Testing - periodic
¶ 3.5.1: coating thickness
¶ 3.5.2: adhesion
Coupon/Part Testing - per lot
¶ 3.5.3: general quality
ASTM B545
| Callout | Requirement |
| A | thickness 100µin |
| B | thickness 200µin |
| C | thickness 320µin thickness 400µin for steel |
| D | thickness 600µin thickness 800µin for steel |
| E | thickness 1.2 mil |
| F | thickness 60µin |
ASTM B545 describes electrolytic tin plating on various basis materials. The thickness callouts are inexplicable, until you realize that ASTM B545 Class F is a "Flash" - never mind that many people are likely to think that ASTM B545 Class F should be a thicker plate than ASTM B545 Class E or ASTM B545 Class A. ASTM B545-97 is the current revision which was reissued in 2004.
Bath Testing
no bath testing is specified
Coupon Testing - periodic
¶ 8.1: deposit purity
¶ 8.5: porosity
Coupon/Part Testing - per lot
¶ 8.2.1: thickness
¶ 8.3: adhesion
¶ 8.4: solderability
| Callout | Requirement |
| Type I | Electrodeposited |
| Type II | Hot Dipped |
MIL-T-10727 covers both electroplated and hot-dipped tin. MIL-T-10727C has been superseded, but is still called out on prints. MIL-T-10727 Type I is electroplated tin, while MIL-T-10727 Type II is hot dipped.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
¶ 4.6.4: salt spray test
Coupon/Part Testing - per lot
¶ 4.4.2.1: visual
¶ 4.6.1: coating thickness
¶ 4.6.2: adhesion
¶ 4.6.3: solderabililty
| Element | Percent by weight |
| Tin (Sn) | 50 to 70% |
| Other metals & non-metallics | 1.0% maximum |
| Lead (Pb) | Remainder |
MIL-P-81728 specifies procedures and uses for electrodeposited tin-lead plating. MIL-P-81728A is the latest specification.
Bath Testing
no bath parameters or tests
mentioned in specification
Coupon Testing - periodic
¶ 4.5.1: composition
¶ 4.5.4: porosity
¶ 4.5.6: embrittlement
Coupon/Part Testing - per lot
¶ 4.5.2: thickness
¶ 4.5.3: adhesion
¶ 4.5.5: solderabililty
AMS2416
| Callout | Requirement |
| -X | X to X+200 µin NICKEL |
| nickel thickness 200-400 µin if not specified cadmium 100-300 µin and may not be changed conversion coat or dye may be specified on print | |
AMS2416L is available from SAE International. AMS2416 is targeting high-temperature, corrosive environments. Beware of regulations banning the use of Cadmium. As always, the supplier should purchase and follow the specification. AMS2416 contains helpful instructions and specific requirements for plate thickness and heat treatments required to achieve proper diffusion.
Bath Testing
¶ 4.2.2: periodic testing of
cleaning and plating solutions to
ensure specification conformance
Coupon Testing - periodic
¶ 3.3.2: heat resistance
¶ 3.3.3: corrosion resistance
¶ 3.3.4: nickel stress test
Coupon/Part Testing - per lot
¶ 3.3.1: nickel thickness
¶ 3.4: general quality
FED QQ-P-416
| Callout | Requirement |
| Type I | As plated |
| Type II | Chromate treatment |
| Type III | Phosphate treatment |
| Class 1 | 50 µin minimum thickness |
| Class 2 | 30 µin minimum thickness |
| Class 3 | 20 µin minimum thickness |
FED QQ-P-416 seems to be active at QQ-P-416F, although AMS QQ-P-416 has been referenced as superseding. QQ-P-416 Type I gets no post plate treatment; QQ-P-416 Type II gets a post-plate chromate conversion treatment; and QQ-P-416 Type III gets a post-plate phosphate treatment. Print notes should reference the thickness Class, even if a specific thickness is also specified, since the detailed plating requirements are a function of the Class callout.
Bath Testing
¶ 4.4.1: processor to maintain
bath records showing analysis
results and chemical additions
Coupon Testing - monthly
¶ 4.5.1: plating adhesion
¶ 4.5.2: corrosion resistance
¶ 4.5.3: embrittlement
Coupon/Part Testing - per lot
¶ 4.4.2.2.1: visual inspection
¶ 4.4.2.2.2: coating thickness
AMS2400
| Callout | Requirement |
| -flash | ~100 µin no salt spray requirements when flash is specified |
| -1 | 100 - 300 µin |
| -2 | 200 - 400 µin |
| -3 | 300 - 500 µin |
| -4 | 400 - 600 µin |
| -5 | 500 - 700 µin |
| -6 | 600 - 800 µin |
| -X | X - X+200 µin |
| if dash unspecified thickness 100 - 400 µin | |
AMS2400W is available from SAE International. AMS2400 is targeting corrosive environments. Beware of regulations banning the use of Cadmium. As always, the supplier should purchase and follow the specification. AMS2400 contains restrictions on underplating and requires compliance with some unusual test specifications.
Bath Testing
¶ 4.4.2: processor to specify
frequency and analysis methods
and establish periodic test plan
Coupon Testing - periodic
¶ 3.4.3: corrosion resistance
¶ 3.4.4: embrittlement
Coupon/Part Testing - per lot
¶ 3.4.1: coating thickness
¶ 3.4.2: adhesion