Gold Plating Thickness of Connectors and Contacts
Proper specification of gold plating thickness for connector and contact applications is a key design consideration. Gold plating is an exceptional finish for connectors of that demand both high reliability and durability; however, the thickness of the gold plating will impact the durability and ultimate cycle life of the connector. Gold plated connectors have low contact resistance which is suitable for applications with low signal voltages and current in the millivolt and milliamp range. Because gold is a noble metal, it does not readily react with chemicals in most environments, meaning that gold plated connectors will retain their conductivity over time provide the thickness of the gold provides a sufficient barrier to the substrate from the environment.
Due to the high cost of the precious metal, gold plating of connectors is typically deposited in very thin layers of 5uin to 100uin (0.1um-25um) with respect to other plated metals. However, gold can be plated to thicknesses as high as 500uin to 1000uin (12.5um to 25um) in extreme cases. As the thickness of the gold is increased both the corrosion resistance and wear resistance of the gold plated connector increases. When connectors are plated with a very thin “flash” gold deposit (less than 10uin, 0.25um) the gold is a very porous. The gold plating thickness may look continuous but there are thousands of microscopic pores in the deposit making it more like a thin screen of gold rather than a continuous pore-free layer. Although the gold plating may not readily react to corrosive environments, the pores in the gold provide a path to the base material which will allow the substrate to oxidize and corrode through the gold.
One method to increase both the corrosion protection and wear resistance of gold connector is to increase the thickness. As the gold plating thickness increases the pores in the deposit become reduced in size and quantity. Eventually as the thickness continues to increase the pores in the gold plating will become completely closed creating a pore-free gold layer. When gold plating is truly pore-free it provides exceptional barrier corrosion protection preventing corrosive attack of the material. However, due to the cost of gold, it is important to balance the functional requirements of the plating against the specified gold thickness to provide the most cost effective gold plated connector or contact.
Thin Plated Gold Connectors or Contacts (4-20uin or 0.1-0.5um)
For gold connectors used in a controlled environment with minimal wear considerations, common gold plating thickness is between 4-20uin (0.1-0.5um). Thin gold layers in this range can provide low contact resistance as well as excellent solderability/wire bonding while consuming a minimal amount of gold. This is a common thickness for static gold contacts that do not repeatedly cycle or slide during use. Examples include grounding nuts or studs, fixed contacts or solder pads.
Moderate Thickness Gold Plated Connectors or Contacts (30-50uin or 0.75-1.25um)
Gold Plated Interconnect Pins
For a connectors and contacts with moderate environmental and wear cycles, common functional gold plating thickness ranges between 30-50uin (0.75-1.25um). The increase in gold thickness to this level provides greatly improved corrosion resistance over that of thin gold or gold flash plating. In addition, thicknesses in this range offer moderate to good wear resistance for dynamic connector or contacts that cycle during use. Although the gold plating is not typically pore-free at these moderate levels, the thickness of the gold is sufficient to provide some barrier to corrosion in moderate environments that do not have repeated condensation cycles or the potential for corrosive chemical attack. Examples of components plated in this range of thickness include male/female pins/sockets, phosphor bronze or beryllium copper flex contacts or gold plated contact springs.
High Thickness Gold Plated Connectors or Contacts (Greater than 50uin or 1.25um)
For applications where the highest corrosion protection and wear resistance are required, heavier gold deposits of 50uin (1.25um) or more are typically required. Depending on base material and surface finish of the connector, 100uin(2.5um) or more of gold plating is required to develop a fully pore-free layer that will provide the best barrier protection against corrosion of the base material. Gold plating of contacts or connectors greater that 50uin is common of mil-spec and Oil & Gas interconnect applications that are exposed to more aggressive environments as well as thermal and switching cycles. Heavier gold deposits in this range provide sufficient material to allow for very high cycle applications of 10,000 cycles or more when properly engineered with the proper underplate.
Underplate Considerations for Gold Plated Connectors
A nickel underplate is typically recommended for most gold plated connectors or contacts especially if the substrate is a copper or copper alloy. Nickel serves several key functions as follows:
- Diffusion Barrier: Copper and alloying elements such as zinc and lead can diffuse into the gold plating through solid state diffusion creating a weak intermetallic or eutectic at the gold/substrate interface. This consumes some of the effective gold and reduces the integrity and function of the deposit. A nickel underplate forms an effective barrier against the mobility of diffusion at the gold/substrate interface.
- Levelling Layer: A nickel underplate can act as a levelling agent which can produce a surface finish with lower roughness which can reduce friction, thereby increasing the wear protection of gold plated connectors or contacts.
- Load Bearing Layer: A nickel deposit is a hard plated layer that provides a foundation for the subsequent gold plating to be deposited upon. This can prevent cracking of hard gold deposits and improve the overall wear resistance of gold plated connectors or contacts that are used in dynamic cycling.
- Corrosion Inhibitor: Nickel underplates can serve as an effective corrosion inhibitor by working in tandem with the final gold plated layer to seal the base material from the environment. This can help reduce the overall gold thickness required to prevent corrosion of the substrate through a gold deposit. Nickel underplates such as high phosphorous electroless nickel provide outstanding corrosion resistance whereas high purity nickels such as a sulfamate nickel provide the best soldering base. As such, the type of nickel and thickness of the nickel should be carefully considered as a key element in the overall design of a gold plated connector and contact.
The thickness of the nickel underplate can vary based upon the design requirements of the connector or contact. However, a minimum thickness of 50uin (1.25um) is typically recommended to provide some of the benefits listed above.
Solderability Considerations for High Gold Thicknesses
It is important to note, as gold plating thickness increases past 50µin, the solder joint can experience embrittlement due to the diffusion of gold into the solder joint. Gold is a very mobile metal when in contact with the tin alloys commonly used in soldering. In low levels the gold does not have a deleterious impact on the strength of the joint. However, at higher thicknesses of gold, sufficient gold is present to cause embrittlement of the solder joint. 3% is commonly cited as the maximum gold allowable within a solder joint prior to significant embrittlement occurring1. As such, the thickness of the gold as well as the amount and type of soldering should all be considered when specifying the thickness of the gold plated contact or connector. This is of high concern for applications where vibration of the solder joint is a design consideration.
Summary of Common Thicknesses for Gold Plated Connector or Contacts
Table 1 below provides a summary of the various gold thicknesses for gold plated connectors and contacts along with a cross reference to common specifications and an application reference. Note that the thicknesses in this table are intended as a reference only. Due to the diversity of applications and uses of gold plating, thorough evaluation and testing is necessary to ensure the deposit meets all design requirements.
Table 1: Common Gold Plating Thickness for Functional Gold Use
Technologies to Enhance Performance of Gold Connectors and Contacts
Advanced Plating Technologies offers several gold plating technologies to enhance the corrosion resistance and durability of gold plated contacts including duplex gold and APT-PST™. In duplex gold plating both hard and soft gold layers are plated in series to provide a net-reduced porosity gold deposit that could be provided with a single layer system. APT-PST™ is a post-plate process embeds a unique molecule into the microscopic gold pores providing greatly enhanced corrosion resistance and lubricity over untreated gold plating of a like thickness. This process can be used to reduce gold thickness/cost as well as increase the performance of a gold or duplex gold deposit to meet demanding design requirements. A member of APT’s engineering staff can provide more information on these processes.
Gold offers a wealth of desirable properties when plated on connectors and contacts including low contact resistance, consistent conductivity over time, corrosion protection and solderability. The thickness of the gold plating is a key design consideration since thickness impacts the properties and durability of the gold deposit. This article is a brief over view of some of the most common aspects to consider when selecting the finish for a gold plated connector. For any additional information please feel free to contact a member of Advanced Plating Technologies engineering group at [emailprotected] or 414.271.8138.
Blog Authored By: Brad B., Process & Estimating Engineer
References:
- Glazer, J. Kramer, P.A., and Morris, J.W., Jr.; Effect of Au on the Reliability of Fine Pitch Surface Mount Solder Joints, United States Department of Energy, 1991
FAQs
For gold connectors used in a controlled environment with minimal wear considerations, common gold plating thickness is between 4-20uin (0.1-0.5um). Thin gold layers in this range can provide low contact resistance as well as excellent solderability/wire bonding while consuming a minimal amount of gold.
What is the minimum thickness for gold plating? ›
For an item to be considered “gold plated” it must have a minimum thickness of 7 microinches, which is typically done for decorative purposes. Hard gold (Type I & II) can be plated to around 100 microinches (2.5 microns) max. It is the most common choice for decorative finishes or items that require a durable finish.
How thick is gold flash connectors? ›
When gold-plated contacts are required, the connector industry tends to provide two different thicknesses: 15 microinches and 30 microinches. Both thicknesses exceed the typical industry definition of gold flash, which is less than 10 microinches.
How do you measure gold plating thickness? ›
A very common method for accurate measurement for thickness of electroplated metals is by microscopic measurement of metallographic prepared cross sections. This is a destructive test, but can be performed on almost any shape for almost any type of coating.
How much thickness does plating add? ›
There are differences of plating layer thickness by the kind as chrome plating is possible to yield 0.1～0.2mm, and as nickel plating and copper plating are possible to yield above 1mm.
What is the standard thickness of plating? ›
Coatings are typically applied to a thickness of 0.003 to 0.010 inches (0.076 to 0.25mm), but can be up to 0.020inches (0.51mm) without detrimental impact to the coating properties.
How long does 2.5 micron gold plating last? ›
Our 24K Bright Gold is capable of plating up to 100 micro-inches (2.5 microns) in one contiguous layer. These types of thickness will last a lifetime if not abrasively removed.
What is ASTM standard for gold plating? ›
The ASTM B488 gold plating standard applies to engineering applications.
Is 20 microns of gold plating good? ›
It's a little hard to visualize, but basically any gold plating that's 1 micron or up is good quality gold plating. As a comparison, flash plating is less than one micron- it's actually under 0.175 micron.
What is standard size of connector? ›
These connectors actually come in three common sizes: 1/4" (6.35mm), 1/8" (3.5mm), and 2.5mm. ¼" size connectors find a lot of use in the professional audio and music community- most electric guitars and amplifiers have 1/4" tip-sleeve (TS) jacks on them.
In general, using gold connectors means you get greater durability than with tin, more cycles and higher conductivity. That said, the use of gold as a contact or connector can create unique challenges.
How thick is PCB flash gold? ›
Unlike thicker hard gold coatings, flash gold remains solderable for SMT assembly because its coating thickness is approximately 10% as thick as hard tab gold. Like ENIG, its thickness range is limited – typically . 0000015”-. 000003” thick.
What is the difference between gold plating and gold flash plating? ›
Flash gold just means rapid gold plating. In fact, it is the pre-process of hard gold plating. It uses a large current and the solution with a higher gold content to forms a dense but thinner gold plating layer upon the nickel layer to facilitate subsequent electroplating of gold nickel or gold-cobalt alloy.
Will a magnet stick to gold plating? ›
On the other hand, a piece may be gold plated, but it will not attach to a magnet because its core metal is non-magnetic.
How many microns is a good plating? ›
Choice of thickness when replating
It might not sound like a lot, but plating from 1 micron and up is deemed good quality – under 1 micron is mostly referred to as flash plating and is not part of our offering, as the quality is too low.
How thick is 0.5 oz plating? ›
0.5 oz copper (~17.5µm thick or 0.7 mils) — Available on internal layers if requested as part of a "non-standard" construction. This is also the standard starting copper weight for external layers for PCBs with the 1 oz finished copper weight selection.
How is plate thickness measured? ›
A procedure is described to determine the thickness of a plate material by infrared scanning. It consists of heating the material with a moving heat source and measuring the temperature of the plate by infrared scanning when the material has reached a quasisteady state.
What is the formula for thickness in electroplating? ›
As per this plate thickness formula, dividing the product of current efficiency ratio, current flows through plating tank, current flow time and 12.294 by surface area to be electroplated will give you the nickel plate thickness.
Which instrument measure plating thickness? ›
One instrument commonly used for this function is the X-ray fluorescence spectrometer (XRF). This non-destructive instrument uses X-rays to probe the thickness of different metallic coatings.
What is a plating thickness tester called? ›
A coating thickness gauge (also referred to as a paint meter) is used to measure dry film thickness. Dry film thickness is probably the most critical measurement in the coatings industry because of its impact on the coating process, quality and cost.
The optimal gold plating thickness is between. 5 and 1.0 microns. While this may be a tiny layer, it is sufficient even for jewelry exposed to heavy usage. Heavy gold plating is a plating that is thicker than 2.5 microns.
How many microns is heavy gold plating? ›
Gold plating refers to the process of depositing a layer of gold onto a surface. The thickness of gold can vary greatly among makers. The Federal Trade commission classes “gold plate” at . 5 microns and “heavy gold plate” at 2.5 microns.
What is the thickest gold plating? ›
Gold plating can range in thickness between 0.17 to 2.5 microns. A micron is a unit of length that equals 0.001 millimetres and is used by jewellery manufacturers to differentiate between lower-end plating and higher-end plating.
What is ASTM coating thickness? ›
A thickness range of 8 ''m to 7.60 mm (0.3 to 300 mils) has been demonstrated. 1.4''The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
What is ASTM plating specifications? ›
ASTM specifications are one of the most common set of standards used for Zinc and Zinc-Nickel electroplating. ASTM B633 is a widely used standard for Zinc plating, and ASTM B841 for Zinc-Nickel.
What is mil g 45204 gold plating? ›
MIL-G-45204 is a gold plating specification for the electrodeposition of gold and the properties of the deposit. These specifications are typically used within the aerospace, automotive, home electronics, oil & gas, as well as the pharmaceutical industry.
Is 10 micron gold plating good? ›
What is the typical thickness of gold on a high quality plated watch? The thickness range should be between 7- 10 microns.
How thick is 24K gold plating? ›
The density of 24K gold plating is ~ 12.45mg for each square inch of area plated to a thickness of one micron,(~0.00004 inch).. Therefore, if evenly distributed, 1 gram of 24K gold will plate approximately 160 square inches of area to a thickness of 1/2 micron, (0.00002" or 20 micro-inches).
What is the highest quality gold plating? ›
That means you're paying for something that will last. The 18K gold plating contains 75% of pure gold mixed with other metals for better hardness and strength, whereas the 24K gold plating is 100% pure gold. However, 24K gold is usually not used in jewelry making as it is very soft and vulnerable to damage.
What are the 3 types of connectors? ›
Electrical connectors are classified into three types based on their termination ends: board-to-board connectors, cable/wire-to-cable/wire connectors, and cable/wire-to-board connectors.
Wire size is important when choosing connectors, especially in applications where the current rating required is near the maximum for the chosen connector family, or where mechanical strength in the wire is required. In both cases, a heavier wire gauge should be chosen.
What are the requirements of connectors? ›
Some principal requirements of good connector design are as follows:
- Coupling loss. The connector assembly must maintain stringent alignment tolerances to ensure low mating losses. ...
- Interchangeability. ...
- Ease of assembly. ...
- Low environmental sensitivity. ...
- Low cost and reliable construction. ...
- Ease of connection.
While many metals have different benefits in the electroplating process, hard chrome shines as the best coating for hardness. Hard chrome provides extreme hardness, as well as corrosion and wear resistance.
Are gold-plated connectors worth it? ›
Superior Corrosion Resistance
As a result, gold-plated connectors are an excellent choice for more corrosive applications where the connector or contact may be exposed.
Why are gold connectors better? ›
Gold is incredibly resistant to oxidation, especially when compared to other metals. If a connector's contacts will be exposed to corrosive environments or agents, gold plating can provide a strong defense and protect against oxidation and corrosion.
How thick is hard gold plating PCB? ›
According to IPC-4556, the normal PCB gold finger thickness is 32u" (microinch), and the gold thickness range of PCB gold fingers is 3u" to 50u". This gold plated deposit is an alloy, which has a higher hardness than typical immersion gold plating.
How thick is 20 layer PCB? ›
20 Layer PCB design consists of one or more prepregs and cores. The cores are made up of a copper-plated glass protected by epoxy laminate sheets. While the core thickness ranges from 0.1mm to 0.3mm.
How thick is standard PCB mm? ›
What is Standard PCB Thickness? Many contract manufacturers may say that the standard PCB thickness is 1.57 mm, or approximately 0.062 in.
Is there fake gold plating? ›
No, gold-plated does not mean fake. Gold-plated jewelry uses the same gold for its golden layer as solid gold jewelry. The only difference is that solid gold is made entirely of gold and alloys, while gold-plated jewelry has a metal base that is covered in gold.
How can you tell real gold plating? ›
Acid test.
An acid test can reveal the karat of solid gold jewelry, but it can also show whether jewelry is solid gold or gold-plated. With an acid test, a small sample of the jewelry is removed and exposed to acid to induce a color change. The resulting colors indicate which type of metal the jewelry is made of.
There are five recognized classes of gold plating chemistry: Alkaline gold cyanide, for gold and gold alloy plating. Neutral gold cyanide, for high-purity plating. Acid gold plating for bright hard gold and gold alloy plating.
Can I use apple cider vinegar to test gold? ›
The apple cider vinegar gold test is a great choice if you want to test your jewelry at home, as it is readily available and easy to do. After all, real gold will not react when exposed to the acids in vinegar, toothpaste and more.
What is the best magnet to test gold with? ›
Neodymium magnets are very strong and can help to test the authenticity of gold and silver bars, coins, bullion, or jewelry.
What is thicker 200 micron or 100 micron? ›
They measure the holes in the mesh in microns, so the higher the number, the larger the holes. 100 micron mesh holes are 0.003925” compared to 600 micron mesh which is 0.023550”. 400 micron mesh has 0.015700” holes, and 200 micron mesh has 0.007850” holes.
What is thicker 50 micron or 100 micron? ›
Complete answer:100 Microns is the thickness of plastic cover permissible for use. The minimum thickness of plastic bags has been increased from 40 microns to 50 microns as the bags have more strength so that they are more durable and so can be reused.
What is better 2 micron or 10 micron? ›
If you flip the math around, what you find is that the 10 micron filter allows 25x more to pass through than the 2 micron filter. Putting another way, there's a 5x raw difference between 10 and 2, but a 25x difference in the space they have to allow contaminants through.
How much gold is in gold plated connectors? ›
The part that is gold plated is generally 5 to 10 microinches of gold over 20-50 microinches of nickel plate.
What is standard gold plating thickness PCB? ›
The plating thickness of a PCB gold finger is typically a mere 300 micro-inch. At this thickness the hard gold is expected to survive 1,000 cycles before wear through.
Is 20 micron gold plating good? ›
It's a little hard to visualize, but basically any gold plating that's 1 micron or up is good quality gold plating.
How much gold is in connector pins? ›
Not much at all. About 1 to three grams depending on the type and era of the computer pins.
40 micro-inches (1 micron) is a relatively thick layer of gold plating and will last many years if not a lifetime if taken care of correctly. Our 24K Bright Gold is capable of plating up to 100 micro-inches (2.5 microns) in one contiguous layer. These types of thickness will last a lifetime if not abrasively removed.
Are gold plated connectors worth it? ›
Superior Corrosion Resistance
As a result, gold-plated connectors are an excellent choice for more corrosive applications where the connector or contact may be exposed.
What is the recommended PCB thickness? ›
What is Standard PCB Thickness? Many contract manufacturers may say that the standard PCB thickness is 1.57 mm, or approximately 0.062 in.
Is .2 microns of gold plating good? ›
2 microns (our general recommendation)
Recommended for earrings, bracelets, rings, and necklaces. With regular and considerate wear, it will last you approximately 2-3 years for earrings, 1-3 years for necklaces, and 1-2 years for rings and bracelets.
Which is better 1 micron or 20-micron? ›
Consequently, the 20-micron filter element will let larger particles pass through the filter than the 5-micron media would. Bacteria range in size from 0.2 to 2 microns in width or diameter and from 1 to 10 microns in length for the nonspherical specie, so a 1-micron filter will remove most bacteria and cysts.
