If heat caused the pad to come off the PCB should be blistered or
discolored in the area and other similar pads using the same parameter so
affected.
I have dissolved pads and knees in a tin lead Wenesco leaving the module in
for 60 seconds during a SIP replacement. It takes extreme time duration to
cause this. It was clear that the part had been in contact with solder too
long.

The pad to laminate interface or other fabrication defect per George is
suspect.

On Fri, Nov 11, 2016 at 9:34 AM, George Wenger <[log in to unmask]>
wrote:

> Going back to a previous comment Richard made I too would never use
> immersion tin as a PCB surface finish. My preference still is immersion
> silver. Now to Julianos comment about a pad disappearing during selective
> wave soldering. I can't believe a pad disappearing has any thing to do
> about immersion tin surface finish or selective wave soldering parameters
> as much as it base to do with poor PCB fabrication. I would cross section a
> pad before soldering to see what the copper thickness is
>
> Sent from my iPhone
>
> > On Nov 11, 2016, at 8:40 AM, Stadem, Richard D. <
> [log in to unmask]> wrote:
> >
> > One, or many?
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Datacom - Juliano
> Ribeiro
> > Sent: Friday, November 11, 2016 5:21 AM
> > To: [log in to unmask]
> > Subject: [TN] RES: [TN] Immersion Tin - problems
> >
> > Damaged = "Pad disappeared" the track has broken
> >
> > _____________________________
> > Juliano Bettim Ribeiro
> > DATACOM
> > +55 (51) 8446-2135
> > +55 (51) 3933-3000
> > Ramal: 3484
> >
> >
> >
> > -----Mensagem original-----
> > De: TechNet [mailto:[log in to unmask]] Em nome de George Wenger
> > Enviada em: quinta-feira, 10 de novembro de 2016 17:32
> > Para: [log in to unmask]
> > Assunto: Re: [TN] Immersion Tin - problems
> >
> > What do you mean by "damaged"?  Do you mean solder doesn't wet the pad
> or is
> > there physical damage?
> >
> > Sent from my iPhone
> >
> >> On Nov 10, 2016, at 1:16 PM, Vladimir <[log in to unmask]>
> wrote:
> >>
> >> Hi Juliano,
> >>
> >> The board finish most probably has nothing to do with the problem. It
> must
> > be your process.
> >>
> >> Regards,
> >>
> >> Vladimir
> >> SENTEC
> >>
> >> Sent from my BlackBerry 10 smartphone on the Rogers network.
> >>  Original Message
> >> From: Datacom - Juliano Ribeiro
> >> Sent: Thursday, November 10, 2016 13:13
> >> To: [log in to unmask]
> >> Reply To: TechNet E-Mail Forum
> >> Subject: [TN] Immersion Tin - problems
> >>
> >> Hello to all,
> >>
> >>
> >>
> >> We recently are changing to Lead Free process to specific products and
> >> we need to change the finishes boards from (HAL Tin Lead) to Immersion
> > Tin.
> >>
> >> But during the Selective Soldering process the component pad is damaged.
> >>
> >> Are there limitation about Immersion Tin about Max. Temperature, Max.
> >> Reflow/Wave process, Max Soldering Contact Time, etc.???
> >>
> >> In this case the HAL Lead Free is better?
> >>
> >>
> >>
> >>
> >>
> >> Thank you
> >>
> >> Juliano Ribeiro
>