Ioan,
I have to respond since your comment hit a nerve. Producibility is a prime reason why operation costs go out of control...
In a prior life (too long ago - circa 1985), I brought up a producibility issue concerning tolerances - a board, backplane, and drawer had a 0.010 mil interference when the three were mated together. The design engineering manager wrote an memo (before E-Mail - I wished I kept the memo) indicating that the design was perfect and it was due to a lack of process control. I went ballistic.
Fortunately, cooler heads prevailed, specifically a Operations Manager who had the offending manager reassigned to a different program before we went into full production.
Lee Whiteman, PMP
Senior Member Engineering Staff
L-3 Communications East
Telephone: (856) 338-3508
FAX: (856) 338-2906
E-Mail: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Thursday, April 16, 2009 11:25 AM
To: [log in to unmask]
Subject: Re: [TN] LGAs in a military environment?
What am I going to do with this one then? I have to assemble 3 of them on a fairly large 14 layers RoHS board...
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1010,C1778,C1764,P60551,D26185
Please also note the "wise" layout suggested on page 19. Does anybody think about us assemblers?
Regards,
Ioan Tempea, ing.
t : 450-967-7100 ext : 244
[log in to unmask]
www.digico.cc
P N'imprimer que si nécessaire - Print only if you must
-----Message d'origine-----
De : Stadem, Richard D. [mailto:[log in to unmask]]
Envoyé : 16 avril 2009 11:11
À : [log in to unmask]
Objet : Re: [TN] LGAs in a military environment?
Bev's assessment is right on.
The particular component that Graham's designer wishes to use is a real
"problem child" from a long term reliability standpoint, not only
because of the fact that it is an LGA with very large delta CTE between
component and substrate, but also from the standpoint of having a lot of
connections underneath, which reduces cleanability even more.
And no-clean fluxes typically don't completely activate underneath a
package of this type, even if it were able to be used.
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