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enig

#31880

enig | 3 January, 2005

We are looking at potentially doing a pcb that is enig finished as called out on its fab. drawing. We plan on a standard 63/37 water soluble paste. Is there any pro's and cons to this process with a pcb plated as such. What is the main advantage that a enig board has that would warrant a designer to choose this plating on his bare pcb?

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#31884

enig | 3 January, 2005

The main advantage if ENIG over HASL is that ENIG is flat and HASL generally is not.

The main disadvanages to ENIG over HASL are: * Cost of ENIG is 1.5 - 2X higher than HASL * Selflife is less than HASL * You solder to nickel, rather than copper * ENIG has potential fabrication processing issues [eg, porousity of gold plating, black pad, thick gold plating, etc] that can affect assembly processing

For more on solderability protection, look here: http://www.smta.org/files/smtai03_opening_ceremony_substrates.pdf

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Cmiller

#31893

enig | 4 January, 2005

We have been using this finish almost exclusively for fine pitch boards for about 5 years. Make SURE you use a board house that does the gold plating in-house. There are some potential issues as DaveF stated. The only problem we have encountered is when boards were sent out for gold plating and sat idle for some time before the nickel was covered. I have heard arguments that it wont oxidize but I can tell you it caused major solderability issues. I have also noticed that most of the boards we buy off-shore do not solder quite as well as domestically supplied and does not seem related to specific suppliers. Some houses do not charge more if the line spacing ir really tight because HASL can bridge on tight spacing so the cost is a wash. Normally though you will pay more. You may also see an issue with customers thinking you have insufficient joints on large pad, through hole pads, because the solder will not wick all the way to the outer edge of the annular ring. HASL is the same but you cant really notice because the plating and the solder look the same, it is very obvious when you have a gold ring around the outside of the pad. I have heard some horror stories about Black Pad but have never seen it myself. Use a high quality board house. You will love the flat pads.

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le dao

#37123

enig | 14 October, 2005

What enig stands for. is it entek?

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GS

#37153

enig | 14 October, 2005

It stands for Elettroless Nikel Immersion Gold, a kind of PCB finishing

Entek (there are several kinds) is a brand name of an OSP (Organic Solderability Preservative)kind of PCB finishing.

Regards............GS

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Mika

#37155

enig | 14 October, 2005

I thought OSP stand for: Organic Surface Protection. I learn a new thing every day. Sincerly,

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GS

#37165

enig | 15 October, 2005

Organic Solderability Preservative, is a definition that you can find, for istance, on IPC-2221A (geneiric standard on printed board design) Tabel 4-3 (Final Finisch, etc)

Regards............GS

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