Tin Plating Services (Electroplating) per MIL-T-10727, ASTM B545 and AMS 2408
Advanced Plating Technologies has provided engineered bright and matte (solderable) tin plating services to MIL-T-10727, ASTM B545 and AMS 2408 for over sixty years. Our expertise in providing precision barrel, rack and vibratory bright and matte tin plating services is currently employed in numerous industries including the power transmission/distribution, electronic, telecommunication, medical, marine and aerospace industries.
Advanced Plating Technologies can underplate tin electrodeposits with copper plating or nickel plating to enhance solderability and improve durability of the tin deposit in high temperature applications (reference: How do I make a solderable deposit or What type of tin plating should I use for my application in our Plating Topics section). A nickel or copper underplate prior to tin plating will minimize migration of alloying metals such as zinc from the substrate into the tin deposit in applications such as switchgear, terminal spades or fuse caps. For critical defense or aerospace applications, codeposited lead – commonly referred to as solder deposits – can be provided to enhance wetting during soldering and minimize the potential for whisker growth.
Tin is a soft, ductile, silvery-white metal that is not easily oxidized in air. It has good conductivity and corrosion resistance while enhancing solderability of substrates that are not otherwise easily soldered to. Tin is generally considered non-toxic and non-carcinogenic and as such its use is generally approved for food contact applications. Tin’s use can be traced back to 3000 BC when it was first alloyed with copper to make bronze weapons and products.
Tin plating services can be broken up into two primary categories: Bright tin and matte (solderable) tin. Both deposits are electrolytically applied. Bright tin plating has a high degree of luster and is generally preferred for electrical contact applications such as bus bars, terminals and switching components that are not soldered to. If bright tin plating is soldered, the codeposited organics in the deposit can burn, resulting in a dewetting of the solder and a visible charring of the solder joint.
For solderable applications matte (solderable) tin plating services are recommended, as the deposit is free of the codeposited brighteners found in bright tin plating. For substrates alloyed with zinc (such as brass alloys) it is generally recommended to apply a diffusion barrier of nickel plating or copper plating to prevent zinc migration into the tin deposit and resultant intermetallic formation. Artistic recommends the use of an unbrightened nickel deposit such as sulfamate nickel as a diffusion barrier as it affords an excellent solder base for soldering applications.
It is important to note that solderability of tin plated products is a perishable attribute that has a finite life. APT engineers can work with companies to help extend the soldering life of products by properly specifying the deposit, preparing the substrate and packaging the plated components. Sealed nitrogen bag packaging can be provided in which plated products are heat sealed in a pure nitrogen-filled bag to prevent oxidation of the tin deposit. With this method the solderability shelf-life can be extended to over ten times that of parts packed with traditional methods.
Tin deposits can have the potential to form filiform tin whiskers that propagate from the surface of the deposit. For applications where tin whiskers could negatively impact the function of the product, Advanced Plating Technologies offers tin/lead plating services that are immune to the potential for whisker growth. In addition, reflow of tin deposits can help minimize but not fully prevent the formation of tin whiskers.
The two most common tin plating services certified by Advanced Plating Technologies are MIL-T-10727, ASTM B545 and AMS 2408. APT can also certify tin plating services to ISO 2093 as well as most company-specific tin plating specifications. A summary of tin plating services per the MIL, ASTM and AMS specs is as follows:
Tin Plating Services to MIL-T-10727
Type I – Electrodeposited (Recommends referencing ASTM B545 for electrodeposits of tin)
Type II – Hot Dipped (Artistic Plating does not offer hot dip services)
Intended Uses per Section 6.1 of MIL-T-10727
a. MIL-T-10727 cross references to ASTM B545 which outlines thicknesses for various service conditions in section 6, paragraph 6.1
b. 0.0001-0.00025 inch for tin flashing of articles to be soldered
c. 0.0002-0.0004 inch for articles to prevent galling or seizing
d. 0.0003 inch minimum for articles generally plated to prevent corrosion of basis metals
e. 0.0002-0.0006 inch for articles to prevent formation of case hardening during nitriding
Tin Plating Services to ASTM B545
Class A – 0.0001 inch minimum, mild service conditions for applications where the significant surface is shielded from the atmosphere
Class B – 0.0002 inch minimum, mild service conditions with exposed significant surface
Class C – 0.00032 inch minimum (nonferrous), 0.0004 inch minimum (ferrous), moderate service conditions
Class D – 0.0006 inch minimum (nonferrous), 0.0008 inch minimum (ferrous), severe service conditions
Class E – 0.0012 inch minimum, very severe service conditions
Class F – 0.00006 inch minimum, service conditions similar to class A but for short term contact applications and short shelf-life requirements
4.3.1 – Section Defines Matte Tin Electrodeposits
4.3.2 – Section Defines Bright Tin Electrodeposits
4.3.3 – Section Defines Flow Brightened Electrodeposits
6.8 – Class A and F coatings that will not be exposed to solder temperatures should have a nickel underplate of at least 1.3um (50uin) before tin plating. To prevent zinc migration and impairment of solderability during service or storage, substrates of brass or other copper alloys containing more than 5% zinc must have a copper undercoating of at least 2.5um (100uin) or a nickel underplating of at least 1.3um (50uin) prior to tin plating. A thicker coating of nickel may be required in some situation for additional retardation (of zinc migration into the tin).
3.1.1 Steel parts having a hardness of 40 HRC or higher and which have been ground after heat treatment shall be cleaned to remove surface contamination and stress relieved before preparation for plating. Unless otherwise specified, the stress relief shall be 275F +/- 25F for not less than 5 hours for parts with hardness of 55 HRC or greater and 375F +/- 25F for not less than 4 hours for other parts.
3.2.1 Except as stated in 188.8.131.52 or 3.2.2 tin shall be electrodeposited directly on the basis metal from a suitable tin plating bath.
184.108.40.206 Aluminum and aluminum alloys shall be zinc treated in accordance with ASTM B253 or other method acceptable to the cognizant engineering organization prior to plating.
3.2.2 Prior to electrodeposition of tin for solderability on aluminum or copper-zinc alloy parts, a copper plate shall be deposited to a thickness of 0.0002 to 0.0003 inch (5.1 to 7.6um)
220.127.116.11. Plate thickness may be specified by this specification number and a suffix number designating the minimum thickness in ten-thousandths of an inch (2.5um); thus, AMS 2408-1 designates a plate thickness of 0.0001 to 0.0003 inch, AMS 2408-6 designates a thickness of 0.0006 to 0.0008 inch, etc. A tolerance of 0.0002 inch will be allowed.
18.104.22.168. Where “tin flash” is specified, plate thickness shall be approximately 0.0001 inch.
Advanced Plating Technologies provides expertise in tin plating services demanding applications. From prototyping and PPAP qualification to full production processing, it is APT’s dedicated effort to exceed your expectations. The following points highlight why Advanced Plating Technologies is a leader in tin plating services:
- Diversity of Substrates: Advanced Plating Technologies provides rack, barrel and vibratory tin plating services on nearly any metallic substrate including copper & copper alloys such as beryllium, chromium and tellurium copper, hardened and alloyed steel, stainless steel, Inconel, Hastalloy, Monel, ductile & cast iron and metalized plastic.
- High Production Commercial Applications: Advanced Plating Technologies utilizes one of the highest capacity commercial rack and barrel lines in the Midwest to ensure competitive pricing and short lead times on even the largest high-volume requirements.
- RoHS and REACH Compliance: Advanced Plating Technologies is at the forefront of environmental compliance and can certify our solderable and bright tin plating services as needed to the current RoHS, ELV and REACH regulations.
- Competitive Pricing: Advanced Plating Technologies has been providing quality tin plating services for over sixty years. Competitive pricing in tin plating services is paramount to gaining and maintaining our customers in today’s competitive global marketplace.
- Reliable Lead Times: In today’s manufacturing climate, dependable lead times are essential to ensure on-time deliveries. At APT customer responsiveness is a core tenant of our company culture.
- Value Added: At Advanced Plating Technologies we take pride in meeting customer needs. Whether it’s custom engineering packaging, vacuum or nitrogen sealed packaging to enhance storage, Kanban inventory management, subassembly or multiple finishing combinations – you will find an open-minded engineering group focus on your tin plating application.
- Extensive in House Analytical and Quality Lab Services: SPC is employed in all wet-lab work surrounding our tin plating services to ensure baths are analyzed and adjusted at optimum frequencies to maintain operation between critical upper and lower control points. Our quality lab employs the latest in x-ray, coulometric and spectrophotometer technologies to inspect your parts and will work to your requirements to provide testing as needed. Our quality lab can certify salt spray performance to ASTM B117, adhesion to ASTM B571 and solderability to ASTM B678. Mounted cross sections of parts are also available.