Genny,

The design isn't required to be RoHS compliant. I would prefer to stay away
from the lead-free components at this time, but some of the components
designed  in are lead-free and some aren't just yet, thus there will be a mixture on
the  board.

Bob


In a message dated 1/18/2006 1:01:44 P.M. Eastern Standard Time,
[log in to unmask] writes:

First  suggestion is that you search the archives of the IPC LeadFree
forum - you  can get to them off the IPC.org site.  There is tons of info
on that  forum.  To a lesser extent, search the archives of this forum as
well  (Technet).
You will see many heated arguments about the pros and cons of  ENIG, Imm
Ag, Imm Sn, and maybe even a little about OSP.
Why are you  using SnPb components if you are doing a design for Pb free?

Talk to  your board supplier about recommendations for Pb free FR4 - I'm
sure they  have options available.  Td and Tg are the main factors to
look  into.
If this is supposed to be RoHS compliant, you may need to verify  that
your soldermask is RoHS compliant as well.

Good  luck.

-----Original Message-----
From: TechNet  [mailto:[log in to unmask]] On Behalf Of Robert Walker
Sent: 18-Jan-06 11:39  AM
To: [log in to unmask]
Subject: [TN] RoHS board finish

Hi  All,

I'm doing my first PCB design that will use lead-free components  and I
need to change my board finish from what I've always used.....HASL.  I'm
looking for  any recommendations or comments on the best board  finish to
use.

The components used on the design will be a mixture  of tin-lead and
lead-free (SAC), so I'm not sure if there is a preferred  finish to use
in this  type of situation. I work in a prototype  environment where the
boards may be reworked (BGA removal/replaced) a  number of times, so I'm
concerned about the ability of the finish being  able to handle being
reworked/reflowed a  number of times.

I'd  also welcome any recommendations on the type of board material to
use since  it will see an elevated temperature of up to 260C. I've always
just  specified FR4 in the past.

Thanx in advance for any  feedback.

Regards,
Bob Walker
[log in to unmask]  (mailto:[log in to unmask])

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