Mike,

I have used immersion silver (Alpha Level) at times in the past using the
same temperature profile as for HASL finished boards and had good wetting at
both bottom and topside. Are you subjecting this assembly to any surface
mount processes before wave soldering? Multiple processing of this type of
finish can progressively degrade the solderability at each stage but you'd
have to be pretty aggressive.

What is the state of the unpopulated PCB's? Is the finish bright or dull
with black or dark areas on the solderable surfaces? What is the finish
called?

Also,like other responses on this forum your preheat temperature seems
excessively high, even if you were using a water based VOC free flux you'd
only need a max. of around 110-115 deg. C topside. What flux are you using?

Regards

Peter Barton
ACW Technology Limited

===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at
28/11/01 18:59
>Hi there Technetters,
>
>I have now exhausted my efforts of improving the solderability (T/H) of some
>RF Organic Silver PCB's we are currently making.  Every attempt to improve
>the solderability has had no impact.  The soldered PCB's show very poor
>wetting, partial joints and in some areas there is no evidence of solder.
>The PCB is curretly being pre-heated to around 160 deg. C topside and a bath
>temperature of 256 deg. C.  Is there something I am over looking with the
>Organic Silver?  Is there any special method/ or profile for Organic SIlver
>finished PCB's???  Any feedback would be appreciated.
>
>Cheers
>
>Mike

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------