Tin & Lead Process

TMF Tin Process

Simple immersion technique for tin plating process. Deposit pure tin onto copper, brass, other copper-based alloys, gold and lead-tin electroplate.

Features:

• Plates pure tin rapidly
• Plating exhibits fine-grain tin structure
• Affords unusual resistance to humidity and salt-spray
• Excellent solderability
• Process simple to operate and maintain

Immersion Description

Immersion Tin is a well-developed formulation based upon the reduction characteristics of chelated tin in the divalent state. Under proper conditions reduction to pure tin occurs readily. A grain-refining agent, free of phosphorus, is present as well as an activator and buffers for pH control.

The deposited tin, in addition to good chemical resistance, exhibits excellent adhesion and is very solderable even after exposure to extreme humidity testing. Tin is therefore used to provide corrosion protection to copper and lead-tin electroplate. A minimum of 25 millionths of an inch of tin deposit is required.

Immersion Tin is recommended to preserve solderability of printed circuit boards, either copper or lead-tin electroplate. It is also used for plating electronic parts such as diodes or leads and for the corrosion protection of die stampings and machined copper or brass parts.

Tin plating is normally done to impart solderability to variety of base metal substrates. Tin (tin plating) is a silvery, blue-white metal that is ductile, solderable, and covers very well. The solderability of time can be affected by the substrate, since several metals tend to react with and migrate into the tin (tin plating) forming relatively non-solderable intermetallic layers. Of particular concern is tin plating over brass or zinc die-cast (zinc diecast plating). The zinc will migrate into the tin and severely limit the shelf life of the finished parts. The migration can be mitigated by the common practice of applying an undercoat of copper or nickel or a combination of copper with a flash of nickel through which the zinc cannot migrate. Matte tin generally has better solderability, but bright tin is specified more because of its appearance. Tin (tin plating) does not tarnish easily, making it a good choice as a decorative finish.

Tin/Lead Plating Description

Alloys containing between 5-12 pct tin are used on bearings. For preserving solderability and providing corrosion protection, alloys between 10-60 pcs tin are deposited on wire and strip. On printed circuit boards, a 60-65 pct tin alloy is used commonly as a metal etch resist and to preserve solderability. Alloys containing 88-98 pct tin are preferred for contact surfaces.

Either a matte or bright luster is acceptable. Has excellent solderability. 0.0002" copper plate generally required on copper base alloys. No undercoating required on steel substrates unless otherwise specified.