An XRF is an X-Ray Fluorescence analytical instrument that impinges x-rays on the surface and a detector (proportional on cheaper machines or solid state on more expensive machines) collects what fluoresces and the instrument gives a spectrum showing what it sees.
Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]
-----Original Message-----
From: Carl VanWormer [mailto:[log in to unmask]]
Sent: Monday, September 19, 2011 5:10 PM
To: TechNet E-Mail Forum; Wenger, George M.
Subject: RE: [TN] large parts falling off finished surface mount board assemblies
Ignorance alert!
What is an XRF measurement, and how do I get one?
Thanks,
Carl
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
Sent: Monday, September 19, 2011 1:54 PM
To: [log in to unmask]
Subject: Re: [TN] large parts falling off finished surface mount board
assemblies
Carl,
Do not scrap the pad or do any heating or mechanical testing of the
surface where the component fell off. Simply do an XRF measurement of
the pad surface and see what is left. You can also do an XRF
measurement on the component surface. That should give you a first
order approximation of what the problem is. My guess is the gold is
probably completely dissolved in the solder and the solder is on the
component and the failure is at the nickel-tin ICM interface.
Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer Andrew Corporation -
Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Monday, September 19, 2011 3:48 PM
To: [log in to unmask]
Subject: [TN] large parts falling off finished surface mount board
assemblies
A surface mount PC board assembly (made by a local assembly house and
passed by our outgoing test) was returned from the end user, along with
an electrolytic capacitor that they had "knocked off" the board. After
looking at the assembly and component under a microscope, I noticed that
the "gold plated" PC board (Lead free) had a fine granular solder
appearance (much smaller grain than solder paste balls) on the pads
newly exposed, with the whole "melted solder" blobs (in the shape of the
pads) attached to the capacitor leads (with a similar granular
appearance). After minor scraping of various parts, I had come to no
brilliant conclusions, so I pressed my finger nail against an inductor
that was of similar size to the capacitor. It popped off the board with
the same symptoms as the capacitor. After recovering from my surprise,
I realized that I have no clue about the causes or cures for my
component adhesion problem. Can any of the more experienced members of
this fine group direct me to some key words that might lead me to a
quick education (and solution)?
Thanks,
Carl
Carl Van Wormer, P.E., AE7GD
Senior Hardware Engineer
Cipher Systems
1800 NW 169th Place, Suite B-100
Beaverton, OR 97006
Cipher Systems (503) 617-7447 x 5163
Direct Line (503) 425-5163
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