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July 2003

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From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 29 Jul 2003 12:31:40 -0400
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Frank,

 

In order to be in a better position to decide if the fabricator didn't do a good job cleaning the board prior to plating, or let the nickel oxidize prior to immersion gold, or plated too thin a layer of immersion gold, you should inspect the board and judge what the reflowed surface mount solder joints look like after wave soldering.  If the surface mount joint looked good after reflow and still look good after wave soldering than you might rule out poor cleaning or oxidation of the nickel prior to immersion gold plating.  If the surface mount joints look good and the wave soldering joints look bad one would suspect that the reflow process and wave soldering preheat may have caused diffusion of nickel to the surface of the immersion gold or oxidation of teh nickel beneath the imemrsion gold.  If there are any non-soldered ENIG areas on the assembled boards I'd recommend doing an XRF measurement to determine the immersion gold thickness and the underlying elelectroless nickel thickness.



	-----Original Message----- 

	From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]] 

	Sent: Tue 7/29/2003 11:47 AM 

	To: [log in to unmask] 

	Cc: 

	Subject: Re: [TN] PICTURES: Wave solder process gone bad

	

	



	Frank,

	

	Before I can answer, does normal touchup fix these joints quickly using an

	RMA flux? Or is there considerable effort to get these pads to flow?

	

	

	Bill Kasprzak

	Moog Inc, Electronics Process Engineering

	

	

	-----Original Message-----

	From: Frank L Norman [mailto:[log in to unmask]]

	Sent: Tuesday, July 29, 2003 10:37 AM

	To: [log in to unmask]

	Subject: [TN] PICTURES: Wave solder process gone bad

	

	

	Technet,

	

	PWA's experienced solder wetting difficulties to plated through holes

	including via's during the wave solder process. PWA's are two sided

	multilayer finished with Electroless Nickel Immersion Gold (ENIG). Top

	side SMT components were reflowed and bottom side SMT and through hole

	components were wave soldered.

	

	SEE PICTURES of bottom side of PWA at this website.

	

	http://www.ripus.com/images/pwa/index.htm

	

	Does anyone know what may have caused this issue?

	

	Regards,

	Frank Norman

	Manufacturing Support Engineer

	Raytheon, Space and Airborne Systems (SAS)

	(805)879-2745

	[log in to unmask]

	

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