The Electroless Nickel Immersion Gold process typically involves two main steps Electroless Nickel Deposition In this step a thin layer of nickel is deposited onto the exposed copper surfaces of the PCB through a chemical reaction without the need for an electrical current The nickel layer is a barrier between the copper and the final gold
Now let s delve into the process of implementing ENIG on a printed circuit board Materials This includes electroless nickel solution gold solution cleaning agents activators etc Cleaning The prepared cleaning agent is applied to wipe the circuit board ensuring the removal of surface grease dust and contaminants After confirming cleanliness
Page 1 of 1 Revision 073109 Product ENIG Process Flow Electroless Nickel Immersion Gold Process # PROCESS STEP TEMPERATURE DWELL TIME 1 ENIG PC300 Cleaner Alternately CK300 Cleaner 90 120 F 120 32 49 C 49 3 5 min 4 2 DI water rinses 2x counterflow Room temp 1 2 min in each
Furthermore the thin layer of gold deposited during the immersion process provides a smooth and uniform surface which is essential for consistent signal transmission across the PCB In addition to its conductivity immersion gold offers remarkable corrosion resistance the next step is the application of the immersion gold finish This
aggressive low in gold content high in acidity immersion gold bath Process control and reduced dwell time in the immersion gold bath are the primary mitigating methods used to date Figure 3 SEM Nickel no corrosion Control Sample 1 Sample 2 Cleaner 5 5 5 Micro etch 2 2 2 Catalyst 1 1 1 Electroless Ni 24 22 22 Immersion Gold IG 9
High performance Cyanide free Immersion Gold 2016 IEEE REPRINTED WITH PERMISSION FROM development of cyanide free immersion gold process is one of remarkable research topics However up to now there is only surface cleaning and surface activation steps appropriate for ENIG were carried out A typical EN with 8 10 wt
Page 1 of 1 Revision 073109 Product ENIG Process Flow Electroless Nickel Immersion Gold Process # PROCESS STEP TEMPERATURE DWELL TIME 1 ENIG PC300 Cleaner Alternately CK300 Cleaner 90 120 F 120 32 49 C 49 3 5 min 4 2 DI water rinses 2x counterflow Room temp 1 2 min in each
These innovations have led to improved wire bonding and solderability making next generation immersion gold processes crucial for high reliability electronic applications Fig 2 A green PCB finished with immersion gold process Self Limiting Gold Deposition The development of self limiting gold deposition chemistries introduces innovative
Disclosed in the present invention is a processing method for electroless nickel immersion gold at the bottom of a step slot of a PCB comprising performing selective gold immersion treatment on a first core board and performing pre controlled depth electric milling blind slot treatment on a second core board; separately performing brown oxide treatment on the first core board and
step After Ni is deposited gold is then plated via an immersion process This time the gold is plated by replacing the Ni atoms in the EN layer Figure 6 depicts an ENIG finish The EN layer is considerably thick with thickness from 3 to 6 um followed by a thin layer of ImmAu um a b
ENIG stands for Electroless Nickel Immersion Gold It s a type of surface finish used on Printed Circuit Boards The process involves two main steps First a layer of nickel is applied to the PCB Nickel is tough and acts as a barrier protecting the underlying copper from wear and tear Then a thin layer of gold is added on top
DIG process Plating of direct immersion gold Ever increasing electric components density and high frequencies of signal transmission require new concepts of final finishes in PCB manufacturing too By direct gold plating on copper DIG beside ISIG and EPIG a further process has been provided which is free from nickel and has a high HF
Nickel thickness typically between 1µm and 5µm; up to 20µm for special applications Gold layer as oxidation protection with a typical thickness between 20nm and 70nm Process Steps Step 1 Pad cleaning; Step 2 Seeding with Zink or Palladium; Step 3 Autocatalytic deposition of Nickel; Step 4 Immersion Gold exchange reaction Applications
4 The gold ions exchange with the palladium metal to deposit a thin gold layer μm thick on the surface Gold provides oxidation resistance solderability and wire bondability Rinses are performed between each process step to remove solutions from the board surface and prevent solution dragout
The process steps for the ENIG under bump metallization are shown in Table 1 The first step is a plasma etch in an oxygen/argon plasma The plasma etching removes surface organics with the immersion gold but had very good adhesion with the thicker autocatalytic gold Table 2 STUD BUMP ADHESION 60
Chemical Gold or Immersion Gold ENIG Today the term chemical gold or call immersion gold usually refers to the ENIG Electroless Nickel Immersion Gold surface treatment method One of its main advantages is that it doesn t require the complex electroplating process to bond nickel and gold to the copper surface
Immersion Gold ENIG process is one of the most used selective finish for PCB production Although it is one of the most expensive process requiring a high number of steps it allows to obtain a
The immersion gold process typically involves the following steps Surface Preparation The base metal surface is thoroughly cleaned and pretreated to ensure proper adhesion of the gold coating Activation The surface is activated often by dipping it into an acidic solution to create a catalytic layer that facilitates the deposition of gold
What is Immersion Gold PCBs At its core an Immersion Gold PCB refers to a type of PCB where the surface finish comprises a thin layer of gold applied through a chemical deposition process This gold layer typically only a few microinches thick is added over a copper substrate ensuring a robust and highly conductive surface
Electroless Nickel/Immersion Gold plating or ENIG is a versatile process and enables fabrication of high density flip chip BGA substrates needed for high performance IC chips ENIG is used extensively in advanced IC packaging of microprocessors ASIC and DSP components By its nature ENIG plating forms brittle intermetallic compounds of
