Stellar Industries’ plating line provides the capability to process multiple finishes in a fully programmed automatic plating facility. Thicknesses from micro-inches to microns are accurately deposited on various configurations to ensure the best quality available for your product.
Nickel plating is a barrier layer that prevents the diffusion of copper into the gold top layer. If the copper is diffused into the gold the electrical characteristics (i.e. contact resistance), corrosion resistance of the contact will be degraded. The nickel layer also prevents the copper layer from physically deforming with repeated insertions of contacts.
Gold plating has excellent electrical and thermal conductivity, it also offers exceptional solderability and is a superb reflector of infrared radiation
This gold is specified when the assembly operations require wire bonding with gold wire. The purity and hardness of bondable soft gold must be closely monitored and controlled. The hardness must be 90 Knoop (25g load) or less. The purity must be 99.7% or greater to meet Type I requirements and 99.9% or greater to meet Type III requirements.
Stellar Industires’ copper plate up processes can provide thicknesses over 100 microns.
Electroless Nickel (EN Plating) is applied after copper trace/feature definition (after Cu plate, image, and etch operations). It can be applied before or after the soldermask application providing a conformal coating on all exposed copper surfaces including sidewalls.
The electroless nickel acts as a barrier layer between the copper and the gold, preventing unwanted intermetallic formation. The electroless nickel layer also adds strength to plated through holes and vias.
Immersion Gold is applied after the electroless nickel process and provides a gold coating on all exposed nickel surfaces including sidewalls.
Gold is applied by a molecular replacement process in which previously deposited nickel molecules are replaced by gold molecules in a processing tank. The gold deposited is 99.99% pure, and its thickness is allowed to build up to 2 to 5 micro-inches.
The combined nickel/gold, ENIG, metallization provides excellent corrosion resistance, solderability, pad coplanarity, and shelf life. It is a good choice for fine-pitch SMT and BGA technologies.