PCB Fabrication

Enig & Enepig

by:A-TECH      2020-11-07

Fracture testing exhibits ductile failures entirely within the solder joint, whereas the Ni solder intermetallic layer remains intact. The new cyanide-free immersion gold plating tub stays steady after 28 days working bathtub simulation. The stability of gold deposition price shows virtually no thermal decomposition in heat idling test.

Hard Goldis an electro process, where adjusting the period of the plating cycle can management gold thickness. This type of floor end is generally used for areas, that are uncovered to repetitive contact, friction, rubbing parts or plug in and out. X-ray photoelectron spectroscopy, a device that evaluates chemical composition as a floor is etched away, demonstrates the purity of the immersion gold layer. Data from both a contemporary bath and one contaminated with copper and nickel to simulate 10 MTO show a layer that's almost a hundred% gold, demonstrating that the immersion gold is free from nickel and copper contamination. The new chemistry creates a robust gold surface for soldering with lead-free tin/silver/copper solder.

There are two common immersion coatings used for printed circuit boards. There are many options to select from when choosing a floor finish on your printed circuit board. The alternative of floor end to use on a printed circuit board depends on several factors.

The PCB floor ending process is especially useful for PCB’s with copper traces and usually precedes the soldering course of. Electroless nickel / immersion gold is a RoHS compliant end that provides a really planar surface, a really dependable solder joint and is very immune to environmental storage conditions, handling etc.

A thin layer of fabric is utilized over the copper to protect it previous to soldering. Though this water-primarily based natural surface end was as soon as very popular, it isn't widely used at present. With this finish, a layer of tin is deposited onto the copper floor using a chemical process. Immersion tin works nicely to guard underlying copper from oxidization, however copper and tin in such shut proximity can create diffusion from one steel into the other, leading to challenges. ENIG is the most popular option and is used on about 80% of all PWBs.

ENIG is a floor finish that's composed of a nickel-gold combination achieved by way of electroless plating and immersion respectively. Furnishing PCBs with immersion silver as a floor coating requires air-tight packing which adds to the fee. Similarly, costs are increased when a gold layer is deposited over the silver layer to prevent tarnishing. Therefore, to assuage the impact of tarnishing on the circuit board surface, the soldering course of has to shortly follow.

Longer bathtub life of 12 metal turnovers interprets to lower consumption of chemical compounds as well as excessive bathtub stability. Too brief tub life inside 5 MTO is the disadvantage of existing cyanide-free immersion gold in wafer last end course of. The PCB industry expects to see tub life of exceeding 10 steel turnovers , a aim that the brand new bathtub chemistry can obtain. Test results reveal uniform plating thickness from each contemporary and aged baths. The gold coating deposited over the nickel layer is made to a thickness that permits nickel to retain its solderability.

This finish provides a skinny, gold, solderable layer that protects the copper traces with a nickel barrier between it and the copper. ENIG is an efficient lead-free choice that leads to a durable, long-lasting finish.

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