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Flash Gold over Nickel - PCB finishing

Roni H.

#7640

Flash Gold over Nickel - PCB finishing | 1 February, 2000

Hi,

Does anyone have experience with gold over nickel (electroless) PCB finish: - Repeatble quality from PCB mfg. (very "painfull" with ENTEK). - Environment condition sensitivity. - Thermal processes sensitivity. - Solderability (Reflow & wave). - Any other important issue.

I need to check this PCB finishing vs. ENTEK 106 (because of pads flatness in 20mil comp.).

Thanks Roni

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Ron Costa

#7641

Re: Flash Gold over Nickel - PCB finishing | 1 February, 2000

I've been using the Electroless Nickel/Immersion Gold plating process for some time now. Here is what i know: It's very flat and solderable if you hold the board house to the following criteria: 120u inches of Nickel 4-9u inches of Gold

What type of solder paste are you using? Hope this helps you. Ron Costa Qualitronics,Inc. SMT Process Engineer 978-453-4667 ext. 349

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#7642

Re: Flash Gold over Nickel - PCB finishing | 1 February, 2000

Roni: Ron gives good advice on the thickness of your Electroless Nickel - Immersion Gold (ENIG) solderability preservative. Several additional comments are ENIG:

� More expensive than OSPs and HASL. � Much flatter surface than HASL, similar to OSPs. � Very supplier process control dependent, like OSPs. Make sure they meet Ron�s conditions. � Good (6 months +) shelf life (Environment condition sensitivity???), assuming Ron�s conditions are met. � Excellent solderability (reflow & wave), if Ron�s conditions are met. Can be much more difficult to solder than OSPs and HASL, if Ron�s conditions are not met. � Sensitive thermal processes, relative to HASL and OSP, to ensure gold is in solution.

As an aside, "flash gold" means different things to different people. Sometimes flash gold is "electroless gold" and sometimes it is "immersion gold." Your supplier should be able to tell you which you are buying. Be nervous if she says "electroless gold."

My2�

Dave F

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