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February 2006

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Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, John Burke <[log in to unmask]>
Date:
Tue, 7 Feb 2006 12:29:34 -0800
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Dennis I will not be attending Apex, but would like to take part in the
committee.

You asked for inputs here they are:


I would comment that spread does not give an indicator of joint strength
as such, which is indeed a function of solderability and more
importantly maps directly to reliability. 

When you get right down to it the function of a solder joint used to be
two-fold, now of course there are 3 which are:

1       Form an interconnect of acceptably low resistance which will not
degrade under the expected working conditions/life of the product.

2       Form a reliable mechanical anchor for the component being
connected through all stages of manufacture and all expected field
conditions for the life of the product.

3       Comply with all recycling and toxicity regulations operating in
the target market.

Obviously 3 should be a given, but I believe there is a major element of
2 that cannot be satisfactorily measured by a standard spread test.

Perhaps a standard spread test will give a general indicator of
"solderability" but is going to be much impacted by the flux systems in
the paste chosen.

I believe a very useful addition to any such standard would be to
generate as part of the test coupon a ball attach area and then measure
the shear force at a committee determined shear speed.

This I believe would nail once and for all the horror stories (which are
real and have cost millions of dollars even in one example) of boards
delivered, manufactured and shipped with various metallurgy issues such
as those experienced with the ENIG process, which (apparently) pass the
"solderability tests" currently in place. The metallurgy of the ball
could map usefully to the expected joint composition and be selected
from a list.

Just my thoughts,

Kind regards,

John Burke


 

John Burke
Senior Manager - Operations , Optichron
[log in to unmask]
W: 510 249 5233
M: 408 515 4992
http://www.optichron.com
Profile: https://www.linkedin.com/e/fps/2665502/

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
Sent: Tuesday, February 07, 2006 7:19 AM
To: [log in to unmask]
Subject: [TN] Solder paste spread as a measure of solderablity

Hello - 
 
We will be starting a new focus topic at the Thursday  meeting of 5-23d 
Committee - Alternate Final Board Finishes Task Group.   That meets at
3:15 on 
Thursday in Room 208A at Expo/Apex.  
 
We are looking to develop standard testing to measure  solderablity of
all 
board finishes, particularly after stress - storage, heat,  humidity,
etc.   Our 
task group inputs to the J-003 Board  Solderablity Standards Committee.

 
Issues may come up including:
 
    A standard dot method for all finishes  would be desireable, if
possible. 

Is there a "standard solder paste"? that can be  used

Slump versus spread + hot slump method

Possibly create an "index" for paste  spread

Evaluation of paste/finish  combination

Collect information on spread - possible round  table in future. 
 
If you cannot attend, all comments on the possible test methodology
would  be 
appreciated.
 
Dennis Fritz, MacDermid
Committee Chairman - 5-23d Alt Finishes



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