In the fall of 1997 a well-attended conference in Minneapolis called "IPC National
Conference: Surface Finishes and PWB Solderability".  The Proceedings (with
ammendment) includes the papers that were presented and the document is available
from IPC Customer Service.  "This conference . . . explored: alternative metals,
depositions processes, environmental impact, component lead to surface finish
interactions, organic solderability preservatives, testing and analysis, and end
product requirements."  I remember that there were several lively discussions related
to the use of immersion gold as a board finish.

Jack Crawford, IPC Project Manger - Assembly
2215 Sanders Road, Northbrook IL  60062-6135
[log in to unmask]        http://www.ipc.org
847-509-9700 x 393
fax 847-509-9798

>>> "Hamilton, Richard -4454" <[log in to unmask]> 02/19/98 01:27PM >>>
Mathew,

Speaking from strictly a TH background, soldering to gold is a REAL
bear!! Both from the wave aspect and from the touch up/rework aspect.

I am not familiar with some of the terminology you refer to, but
generally speaking the process needs some real TLC and monitoring. My
experience was with our commercial products that some engineer thought
gold would be a saving solution to some of the problems occurring out in
the field. We moved away from gold very quickly. If price is no qualm,
then just be ready to put in many manpower hours on the process.

Hope this helps.

Richard Hamilton
Clemar Mfg. / Rain Bird
[log in to unmask]

> -----Original Message-----
> From: Matthew Park [SMTP:[log in to unmask]]
> Sent: Thursday, February 19, 1998 10:51 AM
> To:   [log in to unmask]
> Subject:      [TN] gold over entire board
>
> One of my pcb vendors (oversea) wants to fabricate boards
> using  electrolytically deposited gold (1um of Au over 5um of Ni)
> over entire board surface.  That includes hole walls, soldering
> pads, conductive traces and ground planes.  SMOBC is out the
> window and silkscreen/LPISM are last steps in board fabration
> process.
>
> This is first time that I was informed that a board vendor
> fabricates boards by depositing gold/nickel over entire board
> surface.   My questions are:
>
> What negative effects will it have for smt and th board assembly
> manufacturing?
> Are smt/th process parameters  req to be readjusted such as
> reflow profile?
> Will it increase diffusion of gold in solderpot?
> Will it increase solder joint brittleness?
> Are there long-term reliability issues?
> Is there any other negative issue that need to be addressed?
>
> There's no qualm about price.  It is better than SMOBC boards
> with electroless Au/Ni immersion on soldering pads.
>
> regards
> Matthew Park
> NII Norsat International Inc.
>

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional
information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700
ext.311
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
################################################################