Question 1

Q: What is ENIG electroless nickel immersion gold?

Accepted Answer

A: ENIG is chemical plating without electricity, first depositing nickel-phosphorus layer then thin immersion gold layer on copper pads for protection and stable soldering.

Question 2

Q: Core advantages making ENIG fit BGA & fine-pitch SMT?

Accepted Answer

A: Ultra-flat pad surface, outstanding anti-oxidation property, long storage shelf life and capability to endure multiple high-temperature reflow cycles.

Question 3

Q: Main typical application fields of ENIG PCB?

Accepted Answer

A: Automotive electronics, medical equipment, 5G RF circuit, aerospace and high-density consumer products with BGA components.

Question 4

Q: What existing drawbacks of ENIG surface finish?

Accepted Answer

A: Higher cost than HASL/OSP, risk of black pad with poor production control, inconvenient rework and slight high-frequency signal attenuation from nickel layer.

Question 5

Q: Standard nickel and gold thickness range for regular ENIG?

Accepted Answer

A: Nickel layer 3~6μm(100–200μin), immersion gold thickness 0.05~0.1μm(10–15μin) per common IPC specification.

Question 6

Q: Difference among ENIG, HASL and OSP in cost & flatness?

Accepted Answer

A: ENIG high cost with excellent flatness; HASL lowest cost but uneven surface; OSP low cost with good flatness yet limited storage time.

Question 7

Q: Is ENIG fully RoHS compliant for global export?

Accepted Answer

A: Yes, ENIG is lead-free chemical finish and meets RoHS regulation for worldwide shipment to EU, USA and other regulated regions.

Question 8

Q: Why ENIG outperforms HASL on high-precision component assembly?

Accepted Answer

A: Irregular solder bumps of HASL easily trigger bridging on tiny pads, while flat ENIG ensures consistent stencil printing for fine-pitch BGA.

ENIG Process

PCB Immersion Gold (ENIG) Surface Finish: Benefits, Process & Full Guide