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June 2009

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Subject:
From:
Ioan Tempea <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Ioan Tempea <[log in to unmask]>
Date:
Fri, 19 Jun 2009 09:15:57 -0400
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Bonjour Sylvain,

I have recently done several boards with the exacly same components, in almost the same conditions as yours. I had ENIG/Pick'n'place/lead-free SAC305. The only difference was I did convection reflow.

They print well, they solder well. I would not dread shorts, this package is more lenient than QFNs. The only 2 special things I have observed were:
- The thermal demand is higher than for regular BGAs. I had metal top BGAs on the same board, still the LGAs were 10 deg C colder. In order to bring the LGAs at 240deg C I had to bump the BGAs up to 250 deg C.
- Hard to control voiding

Since I am not familiar with vapour phase, maybe the above will not be an issue for you.

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 : Sylvain Kaufmann [mailto:[log in to unmask]] 
Envoyé : 19 juin 2009 09:06
À : [log in to unmask]
Objet : [TN] LGA assembly question

Dear Technetters,
Our assembly workshop has to assemble 4 prototype boards where LGA
packages with 133 connections are used. I allready worked with BGAs or
QFNs but never with LGA packages and I am concerned about shorts/open
that could occur.

Provided that I cannot run tests and conditions are as followed:
- ENIG surface finish boards
- Vapor phase reflow soldering
- Pick and Place machine
- Leadfree or lead containing solder can be used

Would some of you be kind enough to share experiences/advices so that we
would have little chances to successfuly assemble these boards?

Thank you in advance for your help.

S. Kaufmann

************************************************************
Sylvain Kaufmann
CERN / European laboratory for particle physics Site de Meyrin
1211 Geneva 23
Switzerland
Dpt: EN-ICE-DEM (int mail J06600)
Phone: +41 22 767 37 02
Fax: +41 22 766 87 77
E-mail: [log in to unmask]
Web: www.cern.ch
http://cern.ch/dem
************************************************************

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