" ...  more difficult to solder and handle OSPs."  is an opinion based
on a given assembly operation.  With an assembly process properly
optimized for OSP boards, it can be just as easy as HASL.  In fact, I
know assemblers that prefer OSP boards due to the ability to "see"
plugged stencil related problems from a distance (copper/paste contrast
shows up nicely).  There are obvious other advantages to OSP already
discussed on this forum, such as flatness of pads, etc.  One significant
advantage not often discussed is the ability to eliminate lead from the
PCB fabricator  --  not a bad thing to do for the environment...

Dave Boggs
Merix Corporation



> ----------
> From:         Eddie Brunker[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Eddie Brunker
> Sent:         Friday, February 20, 1998 9:10 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] gold over entire board
>
> Hi,
> The solder on the Gold boards looks dull and grainy because it is an
> alloy
> with a solution of Gold. It should not look like HASL or OSP boards.
> There
> are guys on this forum who can give you more detail on this.
> You had issues with HASL finish PCBs. I'm amazed you changed
> technologies
> for the reasons stated. I personnally would go the other way. The HASL
> (solder) finish should take to solder without any difficulty. The only
> way I
> can think of there being issues is if the coating of solder is less
> than 0.5
> micron thick and intermetalic growth takes place during an earlier
> thermal
> cycle to the extent that it reaches the surface and is thus
> unsolderable.
> This has taken place once in my career but the incident was a one off.
> The
> thickness of solder was low due to the supplier trying to be too high
> tech.
> The levelling system was Horizontal and in an attempt to give a flat
> finish
> the thickness was low. I don't have an issue with HASL dome (20 thou
> pitch
> is standard here, including connectors on large dense assemblies), so
> I
> rather a decent thickness of solder to maintain solderability.
> Try changing supplier of HASL PCBs for improved reliability. Are you
> sure
> your problems are down to PCB finish? It is more difficult to solder
> and
> handle OSPs.
>
> Regards
>
> Eddie Brunker
> Tadpole Tech,
> Ditton Walk,
> Cambridge,
> CB5 8FN
>
> +44 1223 278200
>
>
> At 07:53 20/02/98 -0800, you wrote:
> >Technetters,
> >
> >My $.02.
> >
> >We use fine pitch parts and have a very dense board (12" x 15") and
> had
> >some solderability issues with HASL.  We went to "immersion gold" and
> it
> >got a little better, but the solder looked grainy and dull.  We have
> since
> >gone to OSP and are expecting more improvement.  I have not received
> any
> >
> >>################################################################
> >>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
> >################################################################
> >
> >
> >
>
> ################################################################
> 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
################################################################