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Dull joints caused by NiAu PCB surface ?

Brian Sloth Bentzen

#18051

Dull joints caused by NiAu PCB surface ? | 1 November, 2001

Will the gold from some Ni/Au surfaces make the solder joints appear dull and a slightly rugged on the surface ?

Does anyone have any experience with this ? Thanks !

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#18055

Dull joints caused by NiAu PCB surface ? | 1 November, 2001

Hi Brian,

yes that�s possible due to the presence of Au in the joint but nothing to worry if the Ni/Au is done properly (means not to much Au in your plating). "rugged" I haven�t noticed yet, that may depend on the definition and maybe the magnification you use for inspection. The only time I noticed "rugged" surface on the joints was with Au plated components leads where the plating obviously was to much for the joint and the joint itself was that much "brittle" that rework had to be performed. Sometimes,... and I heard voices that said always, the gold plating of leads should be removed before you put them on your boards. I once checked the amount ( in %) of gold I would have in a joint assuming worst case plating thickness for both the pad and the lead and ended up with less than 1%. That gave a good feeling.

You will find a lot more on this topic in the archives.

Good luck

Wolfgang

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#18074

Dull joints caused by NiAu PCB surface ? | 1 November, 2001

Listen to Wolfgang.

Your dull solder connection is a process indicator. Some 63Sn / Au solder connections look grainy, depending on how your process them and the materials involved. Gold dissolving in tin forms an intermetallic compound [AuSn4] that can affect reliability problems, depending on the amount, product end-use, bla bla. So, most recommendations have been in the 3 to 5 weight % gold range for the maximum allowable percent.

Solder connections should be smooth.

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Mr.T

#18087

Dull joints caused by NiAu PCB surface ? | 5 November, 2001

hi,

I have found dull joint when I have done trial if boards and cooling too fast.Also with Nitrogen.Some of paste don�t like Nitrogen too much.

Also I have seen this when profile is not hot enough or flux haven�t survived to liquidus point.

I would recomented to check profile and see how fast you ramp up your profile usually for us it is 1-2C/sec.

Regards, MadReindeer

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