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Subject:
From:
"Bill Fabry" <[log in to unmask]>
Date:
9 Jan 1996 11:29:45 -0800
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        Reply to:   RE>Re[2]: Ni/Au SMP mounting
Dennis:

I don't want to get caught up in a semantic misunderstanding.  The use of the
word "virtually" still leaves room for isolated exceptions without distorting
the picture as a whole.  

Truevision purchases all of the components, PCBs, etc. for their products and
provides complete kits to several assembly subcontractors.  These assembly
houses use a variety of solder pastes and fluxes (Kester, Alpha Metals, Delta,
etc.)  With the implementation of ENTECH fabs in the SAME kit as HASL  PCBs,
the assembly yield improvement with ENTECH was significant, especially for fine
pitch QFPs (.016"-0.25" lead pitch). There was NO required change in stencils,
paste or profiles.  These assemblers are full aqueous houses with both SMT
convection reflow and wave solder capability (our products require both).   
All of our assembly subcontractors prefer ENTECH-106 fabs to HASL fabs, without
exception.

No major assembly facility uses FREON for board cleaning any more.  ENTECH will
dissolve in FREON or IPA, leaving the bare copper without any protection from
natural oxidation, thus reducing the board's solderability over time.  If the
potential user still uses FREON, ENTECH is NOT the copper coating of choice.

Seagate (my former home) has converted their entire production to ENTECH-106A,
using Kester NO-CLEAN paste.  This means that >20,000 PCAs per day are being
assembled in the hot and humid environment of Singapore without the use of
aqueous cleaning  and without assembly issues related to HASL PCBs.  In all of
the PCB assembly that I have witnessed over the past few years, I have not seen
an incompatability of solder paste for SMT assembly with ENTECH-106A.

Let there be no mistake.  I have no ties with Enthone and only pass on the
information because IT WORKS!  The boards using ENTECH should be cheaper to
build than HASL fabs (less thermal stress, less board warpage, etc.), the
assembly houses will have fewer assembly-related problems, the component lands
are flatter, the deposition of solder paste is more consistent from board to
board, the fine-pitch QFP placement is more accurate with fewer solder bridges,
etc.  Each user needs to satisfy themselves that ENTECH is the best choice for
their application.  We already have!

Bill Fabry
Process/Quality Assurance Manager
Truevision, Inc.
[log in to unmask]
--------------------------------------
Date: 1/9/96 7:33 AM
To: Bill Fabry
From: dmitchel
 
Bill,

Tell me more about your experience with Entek 106A. You say it is compatible
"with virtually all solder pastes and solders (fluxes?) currently being used
in SMT assembly". Even Enthone admits there may be some compatibility 
problems with their OSP and assembly materials. 


Regards,

Dennis Mitchell
[log in to unmask]

______________________________ Reply Separator
_________________________________
Subject: Re: Ni/Au SMP mounting
Author:  [log in to unmask] at corp
Date:    1/8/96 8:31 PM


        Reply to:   RE>Ni/Au SMP mounting
Doug:
 
100-150 micro-inches of Ni followed by 3-5 micro-inches of Au will do the job 
without causing solder joint embrittlement.
 
If the object is flat pads for fine pitch components, why not specify the OSP 
coating ENTECH-106A by Enthone-OMI? It is cheaper than either NI/AU or HASL, 
requires less processing steps and thermal cycles, has >2 year of unassembled 
shelf life and most PCB vendors have it as a copper coating option.  Also, 
there is NO process changes required for assembly.  It is compatable with 
virtually all solder pastes and solders currently being used in SMT assembly.
 
Bill Fabry
[log in to unmask]
 
-------------------------------------- 
Date: 1/8/96 7:34 PM
To: Bill Fabry
From: MR DOUGLAS C JEFFERY
-- [ From: Doug Jeffery * EMC.Ver #2.10P ] --
 
Help,
 
We have been looking into using electroless ni/au smp surfaces instead 
of solder..I was wondering if anyone had a recommendation on how much 
ni is required.  
 
Is it the same as a tab application?  Is it minimual like the gold? 
How much ni do you have to have to prevent any migration? How much ni 
is too much?
 
Thanks for your input...
 
Doug Jeffery
Electrotek
 
 
 
 
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From: "dmitchel" <[log in to unmask]>
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Subject: Re[2]: Ni/Au SMP mounting






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