I have always seen fairly good wetting of immersion silver PCBs and whilst
they may not be as good as HASL this is usually only evident on the lack of
wetting to the outer edges of lands on the topside of PTH boards and less
fill on larger hole sizes.  I have certainly never seen anything like you
are describing.

My first question would be what flux are you using?  160degC topside
temperature after preheat sounds very hot (regardless of finish) and it may
be that a problem with your profile is more evident on the immersion silver
boards.

Regards,

Neil Atkinson


 -----Original Message-----
From:   Michael Bell [mailto:[log in to unmask]]
Sent:   28 November 2001 19:00
Subject:        Organic Silver PCB's

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

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