Hi Jim - 
     
     Have you ever noticed that specifications and technology just don't 
     track together very well! The solderability of BGA components is a 
     good instance of this fact. The ANSIJ-STD-002 doesn't specifically 
     exclude the solderability testing of BGAs but the methods don't fit 
     very well. One consideration is what solder sphere metallurgy do you 
     have - 63/37 or 90/10 solder alloy? The 90/10 would allow you to do 
     some solder dipping. My suggestion is to do a simulated surface mount 
     test - this test will be in the next revision of the 002 spec but 
     isn't in the current rev. The test amounts to stenciling a solder 
     paste deposit that matches the component footprint on a nonsolderable 
     substrate (PTFE, ceramic,etc), placing the component, running it 
     through a reflow process, cleaning and inspecting for 95% wetting. 
     This testing would satisfy both the solderability concerns and the 
     001B question. As for your oxide question - it shouldn't be any 
     different than other components if the  solder alloy is the same. Good 
     Luck.
     
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: ASSY: BGA SOLDERABILITY
Author:  [log in to unmask] at ccmgw1
Date:    11/14/96 2:51 PM


     
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Date: Thu, 14 Nov 1996 11:44:00 EST
From: "Jim Marsico"@mr.ail.com
Subject: ASSY: BGA SOLDERABILITY
MIME-version: 1.0
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Posting-date: Wed, 13 Nov 1996 23:00:00 EST 
A1-type: DOCUMENT
     
Here's a thought...
     
Can solderability be specified for BGA components?
     
How much oxidation would render a BGA unsolderable?
     
How would one test for solderability on BGAs?
     
How does one "... ensure that all components... are solderable at the start of 
hand and/or machine soldering operations." (J-STD-001B, para 5.4) for BGAs?
     
Any comments?
     
Jim Marsico
(516) 595-5879
[log in to unmask]
     
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