Carl,



Peter is correct about acoustic instrumentation.



Moisture in the solder mask can cause:

* Voiding in the underfill

* Part movement when a no flow underfill is used.



A while ago, we talked to Bob Willis about general underfill inspection
criteria.  He may have voiding guidelines for you.



Bob Willis; Electronic Presentation Services; Work: (44) 01245 351502; Fax:
(44) 01245 496123; Other: www.bobwillis.co.uk; E-Mail: [log in to unmask];
2 Fourth Avenue; Chelmsford, Essex CM1 4HA; England



Dave Fish



----- Original Message -----
From: "Carlr Ray" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, May 23, 2003 2:01 PM
Subject: [TN] Checking and measuring voids in underfil


> Hey Techer's,
>
>  Currently I an assisting with the development of a underfilling a FPBGA.
As part of the qualification I was wondering what amount of voiding should I
expect and accept. I have been unable to find any standards for underfil
voids and methods of detection.
>
> Any information would be greatly appreciated.
>
> Carl Ray
> Sr. Manufacturing Engineer
> Huntsville, AL 35807
> Phone: 256-882-4800 ext. 8845
> Cell: 256-990-1990
>
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