Stephen,
      To help answer the second half of your question "..... is it worth 
it", I offer this summary of responses to a note I posted here several weeks 
ago concerning Au/Ni vs. HASL thickness on boards with fine pitch (<= 20 
mil) pad patterns.
       We have been seeing a consistantly inconsistant variation in the 
thickness of the solder coatings on these pad patterns.  The main concern 
was random excess solder.
        Of the responses I rec'd, NONE were negative about replacing HASL 
with Au/Ni plated finishes and no one tried to recommend the use of HASL on 
fine pitch boards.  In fact several responses were clear that the HASL 
process should not be recommended for fine pitch patterns.
        One additional observation from the responding people that have been 
directly involved with conversion to Au/Ni, they were able to drop it 
directly into their present processes without changing fluxes, cleaners, 
etc.
        Changing from HASL to any other copper coating represents a major 
change (potential disruption) in the board assembly process.  I was 
impressed with the over all positive attitudes and the simplicity of the 
change.
        If your board has fine pitch pad patterns on it, you may want to 
consider using gold.

            Norm Dill

 ----------
From: TechNet-request
To: TechNet
Subject: Re: Gold Flash on PWB's
Date: Wednesday, April 24, 1996 8:01AM

     STEPHEN,
                IPC-D-275 SECT 3.8.4.3 (SOUNDS LIKE A STAR DATE DOESN'T?),
     CONTAINS INFORMATION ON GOLD PLATING.  ALSO REFERENCE SECTION 3.8.4.4 
 ON NICKEL UNDERPLATING.  TABLES 3-8 AND 3-9 WILL GIVE YOU AN IDEA OF WHAT 
YOU NEED FOR YOU'RE END PRODUCT.  AS TO WETHER IT'S WORTH IT, YOU MUST 
CONSIDER YOUR END USAGE AND THEN TALK WITH YOU'RE FAB HOUSE.
        REGARDS,

     ROB BUTTERWORTH
     SR PWB DESIGNER
     ADC VIDEO SYSTEMS
     999 RESEARCH PARKWAY
     MERIDEN, CT 06450
     [log in to unmask]


______________________________ Reply Separator
_________________________________
Subject: Gold Flash on PWB's
Author:  [log in to unmask] at internet-mail
Date:    4/24/96 2:52 AM


Can anyone supply a specification to call up when requesting a Gold
Flash finish on a PWB and is it worth it today, with the advances
with the HASL finishes.

Regards

Stephen Cooper
Manufacturing Projects Manager
SCITEC LIMITED
Apollo Place
Lane Cove NSW 2066
Australia
PH  : +612 428 9500
Fax : +612 428 9589
Email : [log in to unmask]