Will do that tomorrow.
Thanks.
Inge
----- Original Message -----
From: "Igoshev, Vladimir" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October 09, 2008 10:00 AM
Subject: Re: [TN] Need soldering advice ASAP!
> Inge,
>
> Tilt the sample as much as possible as go to 8-10 kV. You should be able
> to figure the sequence of the layers playing with the accelerating voltage
>
> Good luck,
>
> Vladimir
>
> ----- Original Message -----
> From: TechNet <[log in to unmask]>
> To: [log in to unmask] <[log in to unmask]>
> Sent: Thu Oct 09 12:48:08 2008
> Subject: Re: [TN] Need soldering advice ASAP!
>
> We got an EDX spectra with Cd, Ag, Ni at 30 kV. The order may be Cd, Ni,
> Ag,
> I'm not sure. One can hardly mistake Cd for Cr. Why Cd? Don't get that.
>
> Outgassing from the thickfilm gold...possible. But rare.
>
> Inge
>
>
> ----- Original Message -----
> From: "Creswick, Steven" <[log in to unmask]>
> To: "TechNet E-Mail Forum" <[log in to unmask]>; "Inge"
> <[log in to unmask]>
> Sent: Thursday, October 09, 2008 9:36 AM
> Subject: RE: [TN] Need soldering advice ASAP!
>
>
> Ingemar,
>
> Ours used to be CrNiAg backside metallization.
>
> My experience with the resultant AuSnAg alloy that forms is that once it
> has reflowed, it virtually is impossible to rework [if you ever wanted
> to].
>
> Outgassing of the substrate metallization? Thin film or thick?
> Obviously, thick film worse.
>
> Are the voids so huge as to provide good mechanical clamping of the die
> for bonding? It would seem to have to be absolutely terrible voiding to
> cause that. Is there something else going on, like a flux, or change in
> clamping, etc.
>
> Seems like I have bonded some really badly voided parts with out issue
>
> Steve
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
> Sent: Thursday, October 09, 2008 12:00 PM
> To: [log in to unmask]
> Subject: [TN] Need soldering advice ASAP!
>
> Hi all, especially the Indi-man,
> We have soldered IRC's power MOSFET (100-250 W) dice for a decade
> without
> problems. They use to be vacuum soldered to a solderable gold thickfilm
> Al2O3 substrate with AuSn 50 micrometer preforms. Now there is a
> production
> stop because of Al heavy wire wedge bonding problems. My analysis of
> this
> case points at the presence of large voids in the solder joints or
> maybe
> partly dewetting (FineFocus is good but the resolution is not sufficient
> to
> make me sure), something the US mechanical waves don't like. The die
> backside is plated with something that I don't recognize: Cadmium over
> Silver over Nickel. What the heck is that? Anyone who can figure out if
> AuSn
> is the best preforms for that plating?
> Thanks
> /Inge
>
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