[PCB_FORUM] Re: Finish: Matte tin vs ENIG ?

Hey Tom,

Working with the Fab house we typically use (DDI), and with a BGA pitch of 1
mm (thinking towards 0.8 to 0.5 mm), they suggested a finish of ENIG
(Electroless Nickel Immersion Gold).  Here's how I word the Fab drawing
note:

"Surface finish shall be Electroless Nickel Immersion Gold: nickel 100 micro
inches minimum and gold 3-8 micro inches."


As far as the FR4 and Pb free, it has to be a special kind in order to
handle the higher temperatures involved.  Here is the Fab note I use for
this:

"Material: FR4, Polyclad 370HR or equivalent.  Material should meet IPC-4101
Standards, including IPC-4101/98."

NOTE:  Your Fab house may have to special order this material, which could
affect your lead-time.

You really should contact your Fab house to see what they suggest.

Good luck!

Gary E. MacIndoe
PCB Design Engineer
Advanced Micro Devices, Inc.
Longmont, Colorado







> -----Original Message-----
> From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
> [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx]On Behalf Of Tom Robinson
> Sent: Monday, June 27, 2005 1:13 PM
> To: icu-pcb-forum@xxxxxxxxxxxxx
> Subject: [PCB_FORUM] Finish: Matte tin vs ENIG ?
>
>
>
> With LeadFree coming, I'm trying to find out what is the best all around
> finish requirement to put on my fab drawing.
>
> My boards have a 50mil pitch BGA. The soic's down to .4mm pitch.
>
> Matte tin, ENIG ?? I imagine Matte tin would be the cheapest.
>
> Also, with the extra heat needed in reflow, will FR4 be ok?
>
> Any help will be appreciated.
>
> tr :)
>
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