What is ASIG:
“ASIG” or Autocatalytic Silver Immersion Gold, is a final finish for pcb’s that is supplied by DOW. It was released to the market in 2010, and TRAX started experimenting with it in 2012.
The finish consists of SILVERON™ MF 100 Electroless Silver which is an innovative autocatalytic silver material. The autocatalytic nature of the product provides a dense silver coating which is non-porous and prevents the formation of copper oxide on the surface of the silver. The thickness of this deposit is a nominal 0.18 microns.
The dense silver layer is then covered with AUROLECTROLESS™ SMT Immersion Gold which increases the corrosion resistance of the final finish and provides a protective layer for the silver. The thickness of the gold layer is a nominal 0.04 microns.
What are the benefits of “ASIG” ?
Silveron™ autocatalytic silver can be used for reflow or wave solder assembly, and with Aurolectroless™ SMT gold for wire bonding. It offers many advantages over current solderable finish alternatives.
The key reason that TRAX decided to offer ASIG as an alternative surface finish, was due to the excellent conductivity of the silver which makes this finish the logical choice for high frequency applications, and many of our customers were looking for alternatives to ENIG with it’s lossy Nickel layer.
ASIG also has an outstanding shelf life and solderability due to prevention of copper migration to the surface through pores. This is due to the autocatalytic nature of the silver bath, a thicker deposit of silver can be achieved than with an immersion process, this deposit is dense,crystalline and pore free.
DOW also claim improved reliability: The fast intermetallic formation during soldering brings improved reliability due to lower soldering temperatures and time compared to nickel based final finishes, as well as avoiding potentially brittle intermetallic compounds formed with nickel based finishes when used with lead free solders.
What are TRAX’s limitations with regards ASIG?
The ASIG line at TRAX is currently a low volume line, and we are limited to a few square metres per day, however this has proved more than enough for the current market requirements. TRAX would be able to scale up the line should demand for ASIG increase.
TRAX is also not able to offer ASIG currently on our 3 of 5 day FASTRAX delivery, typical lead times would be between 7 and 10 days on our speed service. Standard lead times are not affected.
Currently we are only offering ASIG to those customers who require the finish for it’s excellent RF performance, typically such boards would be made on expensive substrates like, Rogers, Taconic, and PTFE based substrates.
What does ASIG cost?
Currently we are pricing ASIG at the same price as ENIG.