If you say "Kirkendall voiding," be sure to send flowers in the morning. :)
73/jeff/ac0c
--------------------------------------------------
From: "Steve Thompson" <g8gsq@f2s.com>
Sent: Monday, March 29, 2010 1:46 AM
To: <amps@contesting.com>
Subject: Re: [Amps] Good engineering
>>> Some semiconductors I worked with years ago were rated for 25 years
>>> continuous operation at maximum temperature. It was said that the
>>> tracks inside the part migrated to the next nearest track over time
>>> and stress.
>> I doubt the tracks themselves migrate.
>
> The metal does migrate, dependent on temperature and current
> density. Aluminium is much worse than gold (these are the two
> metals mostly used in rf semiconductors). Amongst others, TRW
> published some work on this which was carried as a App note in the
> Motorola RF data books after the takeover.
>
> There's also something known as 'purple plague' - not migration,
> but reaction between gold and aluminium that showed up when gold
> metallised die were bonded with aluminium wires.
>
> Steve
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