Most engineers inherit plating specifications from legacy designs or rely on what is commonly used in their industry for similar applications. But here's the challenge: Do those standards actually validate what your part needs to do in the field?
The electroplating industry relies heavily on 8-10 common specifications, many developed in the 1940s and 1950s for military and aerospace applications. While these standards have proven their value over decades, understanding what they actually test—and what they don't—can mean the difference between specifying requirements that validate real-world performance and simply checking compliance boxes.
In this article, we'll explore the most common electroplating testing standards, explain what each one measures, and help you determine when standard specifications align with your application requirements and when they need adjustment.
Approximately 85% of high-reliability electroplating work follows just two primary standards: AMS QQ-N-290 for nickel plating and ASTM B488 for gold plating. These specifications have become industry workhorses because they cover the fundamental quality requirements for corrosion protection, electrical conductivity, and mechanical durability across aerospace, medical, telecommunications, and automotive applications.
However, the prevalence of these standards doesn't automatically make them the right choice for every application. The key question isn't "what test should I run?" but rather "does this testing protocol validate how my part will actually perform?"
This specification covers electrodeposited nickel coatings and defines requirements for adhesion, thickness, appearance, and corrosion resistance. It's the go-to standard for parts requiring corrosion protection, solderability, or wear resistance.
AMS QQ-N-290 is well-suited for parts that will experience mechanical stress, environmental exposure, or require a foundation layer for subsequent plating processes (such as gold or silver over nickel).
This standard specifies requirements for gold electroplating on metal substrates. Its flexibility allows engineers to specify different gold purities and hardness levels within the same standard, making it adaptable to various applications.
ASTM B488 is a good fit for applications requiring electrical conductivity, corrosion resistance, biocompatibility, or where oxidation would compromise performance. The standard's built-in flexibility allows engineers to specify soft gold for solderability or hard gold for wear resistance in connector applications.
This military specification sets higher requirements for adhesion and environmental resistance than standard commercial gold plating specifications. It's designed for components that must survive extreme conditions, including thermal cycling, high humidity, and corrosive atmospheres.
Silver offers the highest electrical conductivity of any metal, making these specifications critical for RF/microwave applications where minimizing signal loss is paramount. However, silver's tendency to tarnish requires careful consideration of the operating environment and may necessitate additional protective measures.
Rather than specifying plating processes, this standard defines environmental test methods, including thermal shock, vibration, humidity resistance, and solderability. These tests validate how components will perform under real-world stress conditions, making them valuable additions to process-focused specifications.
Thickness measurement is the most frequently performed "test" in electroplating, though technically, it's measuring rather than testing. Methods include X-ray fluorescence (XRF), cross-sectioning, and microscopy, each with specific advantages depending on part geometry and deposit layers.
Consider this scenario: A specification calls for 10 micro-inches of gold plating. The parts measure correctly at the designated test points and pass inspection. However, if those parts have deep internal diameters that require plating coverage, achieving adequate adhesion and thickness in those recessed areas may require 50+ micro-inches on the exterior surfaces. The parts meet the thickness specification but may not meet the functional requirement.
Adhesion testing validates whether the plating will remain bonded to the substrate under mechanical stress, thermal cycling, or environmental exposure. Ultimately, what our customers want is a plating deposit that's going to stand up and not fail.
While most plating specifications define their own adhesion test methods, ASTM B571 serves as the foundational standard for adhesion testing of metallic coatings. This specification is referenced in virtually every finishing specification and provides multiple test methods that can be applied across different plating types and applications. ASTM B571 includes procedures for bend testing, heat-quench testing, and file testing, giving engineers flexibility to select the adhesion validation method most appropriate for their specific application and substrate-coating combination.
Why It Matters: Parts can meet every thickness specification and still fail catastrophically if the plating doesn't adhere properly. Adhesion problems often trace back to contamination before plating, improper surface preparation, or incompatible substrate-coating combinations. This is why adhesion testing is one of the most important requirements in high-reliability plating, and why ASTM B571 appears as a reference in almost every plating specification across industries.
This accelerated corrosion test exposes parts to a salt fog environment for a specified duration. While useful for comparing relative corrosion resistance, salt spray results don't always correlate directly with real-world service life. Parts that pass salt spray may still corrode in actual use, and vice versa, depending on the specific environmental conditions they encounter.
This test identifies porosity in noble metal deposits (gold, silver, palladium) over base metals. Nitric acid vapor penetrates through pores to attack the base metal, creating visible spots. It's particularly valuable for high-reliability applications where even microscopic porosity could lead to corrosion or electrical failure.
For parts that will be soldered in assembly, solderability testing validates that the plated surface will wet properly with solder. This becomes critical when excessive gold thickness can cause embrittlement during soldering, or when oxidation of underlying layers compromises solder joint formation.
The gap between standard specifications and actual application requirements creates some of the most persistent challenges in electroplating. Here are real-world examples where following standard testing protocols doesn't necessarily validate part performance.
Industry specifications often include test methods developed for broad applications. A customer might specify crush testing because it's listed in the standard they selected, but if the part never experiences compression forces in service, that test validates nothing about actual performance.
This is one of the most common disconnects between specifications and manufacturing reality. Engineers often specify minimum plating thickness without considering part geometry.
Achieving adequate adhesion and thickness in recessed areas requires significantly more metal deposition on exterior surfaces—potentially 50+ micro-inches. The customer may be budgeting for 10, but the plating process requires 50 to meet their actual functional needs. Either the specification fails to meet the application requirement, or the customer faces an unwelcome surprise that reaching the requirements requires more cost.
Sometimes standard specifications lead engineers to specify materials that actually compromise performance for their specific application.
While industry standards cover fundamental quality requirements, some applications demand more sophisticated analysis. This is particularly true when troubleshooting failures, validating new designs, or working with complex geometries.
SEM provides visual analysis at magnifications up to 20,000x or higher, revealing surface morphology, coverage uniformity, and defects invisible to conventional inspection methods. This becomes invaluable when investigating plating failures or validating processes for parts with challenging geometry.
EDX analyzes the elemental composition of plating deposits, identifying contamination, verifying alloy ratios, or detecting unexpected elements that might compromise performance. Combined with SEM imaging, EDX provides comprehensive material characterization.
Cutting through plated parts reveals the layer structure, interfaces between deposits, and actual thickness distribution across the part profile. Microhardness testing on cross-sections validates mechanical properties and can identify processing issues that affect performance.
Advanced testing capabilities often reveal that problems attributed to plating actually originated elsewhere in the manufacturing process. Consider this example:
A customer reported plating adhesion failures and coverage problems in deep internal diameters. Initial testing focused on the plating process variables—bath chemistry, current density, cleaning procedures. However, SEM analysis at high magnification revealed the root cause: poor machining practices.
Tool chatter had left microscopic grooves on the internal surfaces. Worn dies created micro-burrs and surface irregularities. Machining coolant contamination had left residues that prevented proper plating adhesion. The plating process was performing correctly, but it couldn't overcome the upstream manufacturing problems.
This type of analysis requires metallurgical lab capabilities that many plating facilities don't have. When troubleshooting complex failures or validating critical new designs, advanced testing capabilities can save significant time and cost by identifying the actual root causes rather than repeatedly adjusting variables that aren't causing the problem.
Rather than defaulting to familiar specifications, a systematic approach helps ensure testing validates actual performance requirements.
Before selecting any testing specification, clearly define what the part must do in service:
Understanding these requirements focuses testing on validating actual performance rather than checking specification boxes.
Once you understand what the part must survive, select test methods that simulate those conditions:
Don't specify testing for conditions that the part will never experience. Resources spent on irrelevant testing could be better used to validate actual failure modes.
Industry standards provide valuable starting points based on decades of experience. Use them as frameworks rather than rigid requirements:
Part geometry significantly affects what's achievable and what testing is meaningful:
For Deep Internal Features:
For Miniature Components:
For Complex Shapes:
Experienced plating providers offer more than manufacturing services. They bring decades of process knowledge that can help optimize specifications and avoid common pitfalls.
"A lot of times customers will say, well, I need gold plating, so I'm just going to pick a spec... but that test that they're asking for doesn't necessarily equate to how the part is going to function." This common scenario wastes resources testing irrelevant properties while actual performance requirements go unvalidated.
Engineers sometimes specify requirements that violate the physics of electroplating—like expecting uniform thickness in extremely deep recesses without compensating for current density distribution, or demanding mirror finishes on parts with rough substrate surfaces.
When plating problems persist despite process adjustments, experienced platers can identify upstream issues: heat scale from improper heat treatment, surface contamination from machining operations, or dimensional problems that make consistent plating impossible.
Electro-Spec's engineering team brings decades of experience in high-reliability plating for aerospace, medical, telecommunications, and automotive applications. Our metallurgical lab capabilities—including SEM, EDX, and cross-sectioning—go beyond standard testing to identify root causes and optimize specifications for actual application requirements.
Whether you're developing new products, troubleshooting quality issues, or optimizing existing specifications, we can help ensure your testing protocols validate real-world performance.
Connect with an Electro-Spec expert today to discuss how proper specification and testing validation can improve your component reliability.