Jim,
VIPs (Via in Pads) are at too many locations i.e. requires to mask whole board of the size 12"x12".
re,
ken patel
"Marsico, James" wrote:
> Couldn't you temporarily mask the bottom of the vias with tape, then remove
> the tape after reflow? Wouldn't the void be open on the bottom side of the
> board?
>
> Jim Marsico
> Senior Engineer
> Production Engineering
> EDO Electronics Systems Group
> [log in to unmask] <mailto:[log in to unmask]>
> 631-595-5879
>
> -----Original Message-----
> From: Marki Sasportas [SMTP:[log in to unmask]]
> Sent: Tuesday, March 05, 2002 7:00 AM
> To: [log in to unmask]
> Subject: Re: [TN] Via in Pad? Need Help!!!
>
> Hello Siggi,
> We had the same problem,
> 1) Using HASL finish to the board will not help you because as Brain
> Ellis
> said the amount of solder that drains down the via is much more then
> you
> supply (coat + print )- we tried it without success.
> 2) DO not Mask the Vias from the bottom side it will cause very big
> voids.
> 3) You can try to seal the vias with paste but note that if it will
> have
> height it can cause problem during printing.
> 4) I recommend you to use blind microvias or just take the holes out
> of the
> pads.
>
> Regards,
> Marki Sasportas.
>
> -----Original Message-----
> From: Zweigart, Siegmund [mailto:[log in to unmask]]
> Sent: Tuesday, March 05, 2002 9:53 AM
> To: [log in to unmask]
> Subject: Re: [TN] Via in Pad? Need Help!!!
>
> Hello Ken
>
> We had the same problem (or still have).
> We tried HASL and OCC Boards but there was no difference.
> We also tried plugging with a special stencil and 63/37 but this
> don't
> works.
> We did not try a high temperature solder.
> Masking is quite critical because of voids.
> Beside redesign you have only one chance: Look for new process
> parameters.
>
> Siggi
>
> ----------
> From: Ken Patel [SMTP:[log in to unmask]]
> Sent: Montag, 4. März 2002 23:37
> To: [log in to unmask]
> Subject: [TN] Via in Pad? Need Help!!!
> Importance: High
>
> Guys,
> On our nickel gold board, solder joints are below IPC spec
> (insufficient
> solder) where there are vias in pad. Solder is drained down
> the via
> holes and deprived the joint of necessary solder. I would
> like to
> know
> the following.
> (1) How about using the surface finish 63/37 coating HASL
> instead of
> Ni-Gold? I think gold dissolves in solder so quickly that I
> rather
> use
> HASL processed boards, any thoughts?
> (2) Do you guys mask the via on bottom side to avoid solder
> draining
> out
> on the other side?
> (3) Does anybody try Hi Temp solder paste to fill the vias
> as our
> assembly house ordered via stencils to fill the via using
> eutectic
> (63/37) solder paste which didn't work?
>
> Looking for
> re,
> Ken Patel
>
>
>
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