Bev,

 

I believe there was an evaluation of wetting versus surface roughness
done by Sandia participants in the NCMS PWB Surface Finishes Program.
The name from Sandia I remember is Mike Hoskins.  If I remember
correctly there was a roughness that actually increased wetting due to
capillary flow in surface grooves.  Unfortunately my memory isn't good
enough to remember the details.

 

Regards,

George

George M. Wenger Andrew Corporation

40 Technology Drive, Warren, NJ 07059

(908) 546-4531 [log in to unmask]

 

-----Original Message-----
From: David Douthit [mailto:[log in to unmask]] 
Sent: Friday, October 24, 2003 7:52 PM
To: [log in to unmask]
Subject: Re: [TN] Gross surface roughness and solderability

 

Bev, 

A "rough" surface has a much larger surface area than a smooth clean
one. 
So the basic answer to your question is yes. There is a lot more work 
needed to be done by the flux. 

By the way the increased surface area will collect reactive gases and
particles much more efficiently. 

David A. Douthit 
Manager 
LoCan LLC 

Bev Christian wrote: 

TechNetters,Can gross (and I mean gross) surface roughness of a
component termination be enough to almost completely retard
solderability compared to one with a smooth finish?  No, this is NOT a
case of the roughness being a result of a thin coating being completely
oxidized or having the intermetallic "come through".  That is not to say
that the coating isn't oxidized on the surface, though.regards,Bev
ChristianResearch in Motion 

 

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